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[gawk-diffs] [SCM] gawk branch, gawk-4.1-stable, updated. gawk-4.1.0-695
|
From: |
Arnold Robbins |
|
Subject: |
[gawk-diffs] [SCM] gawk branch, gawk-4.1-stable, updated. gawk-4.1.0-695-g5947a3b |
|
Date: |
Thu, 14 May 2015 12:16:18 +0000 |
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "gawk".
The branch, gawk-4.1-stable has been updated
via 5947a3b6d75062b11d5e68b8bbfb5250e703ae26 (commit)
via e0a3a3191f80dca16a7ab569fdd9412497ea7f24 (commit)
from 434e51fd58545078c0bda06e3951999d6ccae01e (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=5947a3b6d75062b11d5e68b8bbfb5250e703ae26
commit 5947a3b6d75062b11d5e68b8bbfb5250e703ae26
Author: Arnold D. Robbins <address@hidden>
Date: Thu May 14 15:15:54 2015 +0300
Regenerate doc, now using makeinfo 5.2.
diff --git a/doc/gawk.info b/doc/gawk.info
index eb9aec1..74a579e 100644
--- a/doc/gawk.info
+++ b/doc/gawk.info
@@ -1,19 +1,10 @@
-This is gawk.info, produced by makeinfo version 4.13 from gawk.texi.
+This is gawk.info, produced by makeinfo version 5.2 from gawk.texi.
-INFO-DIR-SECTION Text creation and manipulation
-START-INFO-DIR-ENTRY
-* Gawk: (gawk). A text scanning and processing language.
-END-INFO-DIR-ENTRY
-INFO-DIR-SECTION Individual utilities
-START-INFO-DIR-ENTRY
-* awk: (gawk)Invoking gawk. Text scanning and processing.
-END-INFO-DIR-ENTRY
-
- Copyright (C) 1989, 1991, 1992, 1993, 1996-2005, 2007, 2009-2015
+Copyright (C) 1989, 1991, 1992, 1993, 1996-2005, 2007, 2009-2015
Free Software Foundation, Inc.
- This is Edition 4.1 of `GAWK: Effective AWK Programming: A User's
+ This is Edition 4.1 of 'GAWK: Effective AWK Programming: A User's
Guide for GNU Awk', for the 4.1.2 (or later) version of the GNU
implementation of AWK.
@@ -21,12 +12,21 @@ implementation of AWK.
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "GNU General Public License", with the
-Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts
-as in (a) below. A copy of the license is included in the section
-entitled "GNU Free Documentation License".
+Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts as
+in (a) below. A copy of the license is included in the section entitled
+"GNU Free Documentation License".
a. The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual."
+INFO-DIR-SECTION Text creation and manipulation
+START-INFO-DIR-ENTRY
+* Gawk: (gawk). A text scanning and processing language.
+END-INFO-DIR-ENTRY
+
+INFO-DIR-SECTION Individual utilities
+START-INFO-DIR-ENTRY
+* awk: (gawk)Invoking gawk. Text scanning and processing.
+END-INFO-DIR-ENTRY
File: gawk.info, Node: Top, Next: Foreword3, Up: (dir)
@@ -34,14 +34,14 @@ File: gawk.info, Node: Top, Next: Foreword3, Up: (dir)
General Introduction
********************
-This file documents `awk', a program that you can use to select
+This file documents 'awk', a program that you can use to select
particular records in a file and perform operations upon them.
Copyright (C) 1989, 1991, 1992, 1993, 1996-2005, 2007, 2009-2015
Free Software Foundation, Inc.
- This is Edition 4.1 of `GAWK: Effective AWK Programming: A User's
+ This is Edition 4.1 of 'GAWK: Effective AWK Programming: A User's
Guide for GNU Awk', for the 4.1.2 (or later) version of the GNU
implementation of AWK.
@@ -49,9 +49,9 @@ implementation of AWK.
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "GNU General Public License", with the
-Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts
-as in (a) below. A copy of the license is included in the section
-entitled "GNU Free Documentation License".
+Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts as
+in (a) below. A copy of the license is included in the section entitled
+"GNU Free Documentation License".
a. The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual."
@@ -64,14 +64,14 @@ entitled "GNU Free Documentation License".
* Preface:: What this Info file is about; brief
history and acknowledgments.
* Getting Started:: A basic introduction to using
- `awk'. How to run an `awk'
+ 'awk'. How to run an 'awk'
program. Command-line syntax.
-* Invoking Gawk:: How to run `gawk'.
+* Invoking Gawk:: How to run 'gawk'.
* Regexp:: All about matching things using regular
expressions.
* Reading Files:: How to read files and manipulate fields.
-* Printing:: How to print using `awk'. Describes
- the `print' and `printf'
+* Printing:: How to print using 'awk'. Describes
+ the 'print' and 'printf'
statements. Also describes redirection of
output.
* Expressions:: Expressions are the basic building blocks
@@ -80,36 +80,36 @@ entitled "GNU Free Documentation License".
* Arrays:: The description and use of arrays. Also
includes array-oriented control statements.
* Functions:: Built-in and user-defined functions.
-* Library Functions:: A Library of `awk' Functions.
-* Sample Programs:: Many `awk' programs with complete
+* Library Functions:: A Library of 'awk' Functions.
+* Sample Programs:: Many 'awk' programs with complete
explanations.
* Advanced Features:: Stuff for advanced users, specific to
- `gawk'.
-* Internationalization:: Getting `gawk' to speak your
+ 'gawk'.
+* Internationalization:: Getting 'gawk' to speak your
language.
-* Debugger:: The `gawk' debugger.
+* Debugger:: The 'gawk' debugger.
* Arbitrary Precision Arithmetic:: Arbitrary precision arithmetic with
- `gawk'.
+ 'gawk'.
* Dynamic Extensions:: Adding new built-in functions to
- `gawk'.
-* Language History:: The evolution of the `awk'
+ 'gawk'.
+* Language History:: The evolution of the 'awk'
language.
-* Installation:: Installing `gawk' under various
+* Installation:: Installing 'gawk' under various
operating systems.
-* Notes:: Notes about adding things to `gawk'
+* Notes:: Notes about adding things to 'gawk'
and possible future work.
* Basic Concepts:: A very quick introduction to programming
concepts.
* Glossary:: An explanation of some unfamiliar terms.
* Copying:: Your right to copy and distribute
- `gawk'.
+ 'gawk'.
* GNU Free Documentation License:: The license for this Info file.
* Index:: Concept and Variable Index.
-* History:: The history of `gawk' and
- `awk'.
+* History:: The history of 'gawk' and
+ 'awk'.
* Names:: What name to use to find
- `awk'.
+ 'awk'.
* This Manual:: Using this Info file. Includes
sample input files that you can use.
* Conventions:: Typographical Conventions.
@@ -117,23 +117,23 @@ entitled "GNU Free Documentation License".
this Info file.
* How To Contribute:: Helping to save the world.
* Acknowledgments:: Acknowledgments.
-* Running gawk:: How to run `gawk' programs;
+* Running gawk:: How to run 'gawk' programs;
includes command-line syntax.
* One-shot:: Running a short throwaway
- `awk' program.
+ 'awk' program.
* Read Terminal:: Using no input files (input from the
keyboard instead).
-* Long:: Putting permanent `awk'
+* Long:: Putting permanent 'awk'
programs in files.
-* Executable Scripts:: Making self-contained `awk'
+* Executable Scripts:: Making self-contained 'awk'
programs.
-* Comments:: Adding documentation to `gawk'
+* Comments:: Adding documentation to 'gawk'
programs.
* Quoting:: More discussion of shell quoting
issues.
* DOS Quoting:: Quoting in Windows Batch Files.
* Sample Data Files:: Sample data files for use in the
- `awk' programs illustrated in
+ 'awk' programs illustrated in
this Info file.
* Very Simple:: A very simple example.
* Two Rules:: A less simple one-line example using
@@ -141,11 +141,11 @@ entitled "GNU Free Documentation License".
* More Complex:: A more complex example.
* Statements/Lines:: Subdividing or combining statements
into lines.
-* Other Features:: Other Features of `awk'.
-* When:: When to use `gawk' and when to
+* Other Features:: Other Features of 'awk'.
+* When:: When to use 'gawk' and when to
use other things.
* Intro Summary:: Summary of the introduction.
-* Command Line:: How to run `awk'.
+* Command Line:: How to run 'awk'.
* Options:: Command-line options and their
meanings.
* Other Arguments:: Input file names and variable
@@ -153,13 +153,13 @@ entitled "GNU Free Documentation License".
* Naming Standard Input:: How to specify standard input with
other files.
* Environment Variables:: The environment variables
- `gawk' uses.
+ 'gawk' uses.
* AWKPATH Variable:: Searching directories for
- `awk' programs.
+ 'awk' programs.
* AWKLIBPATH Variable:: Searching directories for
- `awk' shared libraries.
+ 'awk' shared libraries.
* Other Environment Variables:: The environment variables.
-* Exit Status:: `gawk''s exit status.
+* Exit Status:: 'gawk''s exit status.
* Include Files:: Including other files into your
program.
* Loading Shared Libraries:: Loading shared libraries into your
@@ -170,7 +170,7 @@ entitled "GNU Free Documentation License".
* Regexp Usage:: How to Use Regular Expressions.
* Escape Sequences:: How to write nonprinting characters.
* Regexp Operators:: Regular Expression Operators.
-* Bracket Expressions:: What can go between `[...]'.
+* Bracket Expressions:: What can go between '[...]'.
* Leftmost Longest:: How much text matches.
* Computed Regexps:: Using Dynamic Regexps.
* GNU Regexp Operators:: Operators specific to GNU software.
@@ -178,9 +178,9 @@ entitled "GNU Free Documentation License".
* Regexp Summary:: Regular expressions summary.
* Records:: Controlling how data is split into
records.
-* awk split records:: How standard `awk' splits
+* awk split records:: How standard 'awk' splits
records.
-* gawk split records:: How `gawk' splits records.
+* gawk split records:: How 'gawk' splits records.
* Fields:: An introduction to fields.
* Nonconstant Fields:: Nonconstant Field Numbers.
* Changing Fields:: Changing the Contents of a Field.
@@ -190,7 +190,7 @@ entitled "GNU Free Documentation License".
* Regexp Field Splitting:: Using regexps as the field separator.
* Single Character Fields:: Making each character a separate
field.
-* Command Line Field Separator:: Setting `FS' from the command
+* Command Line Field Separator:: Setting 'FS' from the command
line.
* Full Line Fields:: Making the full line be a single
field.
@@ -199,37 +199,37 @@ entitled "GNU Free Documentation License".
* Splitting By Content:: Defining Fields By Content
* Multiple Line:: Reading multiline records.
* Getline:: Reading files under explicit program
- control using the `getline'
+ control using the 'getline'
function.
-* Plain Getline:: Using `getline' with no
+* Plain Getline:: Using 'getline' with no
arguments.
-* Getline/Variable:: Using `getline' into a variable.
-* Getline/File:: Using `getline' from a file.
-* Getline/Variable/File:: Using `getline' into a variable
+* Getline/Variable:: Using 'getline' into a variable.
+* Getline/File:: Using 'getline' from a file.
+* Getline/Variable/File:: Using 'getline' into a variable
from a file.
-* Getline/Pipe:: Using `getline' from a pipe.
-* Getline/Variable/Pipe:: Using `getline' into a variable
+* Getline/Pipe:: Using 'getline' from a pipe.
+* Getline/Variable/Pipe:: Using 'getline' into a variable
from a pipe.
-* Getline/Coprocess:: Using `getline' from a coprocess.
-* Getline/Variable/Coprocess:: Using `getline' into a variable
+* Getline/Coprocess:: Using 'getline' from a coprocess.
+* Getline/Variable/Coprocess:: Using 'getline' into a variable
from a coprocess.
* Getline Notes:: Important things to know about
- `getline'.
-* Getline Summary:: Summary of `getline' Variants.
+ 'getline'.
+* Getline Summary:: Summary of 'getline' Variants.
* Read Timeout:: Reading input with a timeout.
* Command-line directories:: What happens if you put a directory on
the command line.
* Input Summary:: Input summary.
* Input Exercises:: Exercises.
-* Print:: The `print' statement.
-* Print Examples:: Simple examples of `print'
+* Print:: The 'print' statement.
+* Print Examples:: Simple examples of 'print'
statements.
* Output Separators:: The output separators and how to
change them.
* OFMT:: Controlling Numeric Output With
- `print'.
-* Printf:: The `printf' statement.
-* Basic Printf:: Syntax of the `printf' statement.
+ 'print'.
+* Printf:: The 'printf' statement.
+* Basic Printf:: Syntax of the 'printf' statement.
* Control Letters:: Format-control letters.
* Format Modifiers:: Format-specification modifiers.
* Printf Examples:: Several examples.
@@ -237,10 +237,10 @@ entitled "GNU Free Documentation License".
files and pipes.
* Special FD:: Special files for I/O.
* Special Files:: File name interpretation in
- `gawk'. `gawk' allows
+ 'gawk'. 'gawk' allows
access to inherited file descriptors.
* Other Inherited Files:: Accessing other open files with
- `gawk'.
+ 'gawk'.
* Special Network:: Special files for network
communications.
* Special Caveats:: Things to watch out for.
@@ -263,30 +263,30 @@ entitled "GNU Free Documentation License".
This is an advanced method of input.
* Conversion:: The conversion of strings to numbers
and vice versa.
-* Strings And Numbers:: How `awk' Converts Between
+* Strings And Numbers:: How 'awk' Converts Between
Strings And Numbers.
* Locale influences conversions:: How the locale may affect conversions.
-* All Operators:: `gawk''s operators.
-* Arithmetic Ops:: Arithmetic operations (`+',
- `-', etc.)
+* All Operators:: 'gawk''s operators.
+* Arithmetic Ops:: Arithmetic operations ('+',
+ '-', etc.)
* Concatenation:: Concatenating strings.
* Assignment Ops:: Changing the value of a variable or a
field.
* Increment Ops:: Incrementing the numeric value of a
variable.
* Truth Values and Conditions:: Testing for true and false.
-* Truth Values:: What is ``true'' and what is
- ``false''.
+* Truth Values:: What is "true" and what is
+ "false".
* Typing and Comparison:: How variables acquire types and how
this affects comparison of numbers and
- strings with `<', etc.
+ strings with '<', etc.
* Variable Typing:: String type versus numeric type.
* Comparison Operators:: The comparison operators.
* POSIX String Comparison:: String comparison with POSIX rules.
* Boolean Ops:: Combining comparison expressions using
- boolean operators `||' (``or''),
- `&&' (``and'') and `!'
- (``not'').
+ boolean operators '||' ("or"),
+ '&&' ("and") and '!'
+ ("not").
* Conditional Exp:: Conditional expressions select between
two subexpressions under control of a
third subexpression.
@@ -309,12 +309,12 @@ entitled "GNU Free Documentation License".
* Empty:: The empty pattern, which matches every
record.
* Using Shell Variables:: How to use shell variables with
- `awk'.
+ 'awk'.
* Action Overview:: What goes into an action.
* Statements:: Describes the various control
statements in detail.
* If Statement:: Conditionally execute some
- `awk' statements.
+ 'awk' statements.
* While Statement:: Loop until some condition is
satisfied.
* Do Statement:: Do specified action while looping
@@ -332,14 +332,14 @@ entitled "GNU Free Documentation License".
* Next Statement:: Stop processing the current input
record.
* Nextfile Statement:: Stop processing the current file.
-* Exit Statement:: Stop execution of `awk'.
+* Exit Statement:: Stop execution of 'awk'.
* Built-in Variables:: Summarizes the predefined variables.
* User-modified:: Built-in variables that you change to
- control `awk'.
-* Auto-set:: Built-in variables where `awk'
+ control 'awk'.
+* Auto-set:: Built-in variables where 'awk'
gives you information.
-* ARGC and ARGV:: Ways to use `ARGC' and
- `ARGV'.
+* ARGC and ARGV:: Ways to use 'ARGC' and
+ 'ARGV'.
* Pattern Action Summary:: Patterns and Actions summary.
* Array Basics:: The basics of arrays.
* Array Intro:: Introduction to Arrays
@@ -347,35 +347,35 @@ entitled "GNU Free Documentation License".
array.
* Assigning Elements:: How to change an element of an array.
* Array Example:: Basic Example of an Array
-* Scanning an Array:: A variation of the `for'
+* Scanning an Array:: A variation of the 'for'
statement. It loops through the
indices of an array's existing
elements.
* Controlling Scanning:: Controlling the order in which arrays
are scanned.
* Numeric Array Subscripts:: How to use numbers as subscripts in
- `awk'.
+ 'awk'.
* Uninitialized Subscripts:: Using Uninitialized variables as
subscripts.
-* Delete:: The `delete' statement removes an
+* Delete:: The 'delete' statement removes an
element from an array.
* Multidimensional:: Emulating multidimensional arrays in
- `awk'.
+ 'awk'.
* Multiscanning:: Scanning multidimensional arrays.
* Arrays of Arrays:: True multidimensional arrays.
* Arrays Summary:: Summary of arrays.
* Built-in:: Summarizes the built-in functions.
* Calling Built-in:: How to call built-in functions.
* Numeric Functions:: Functions that work with numbers,
- including `int()', `sin()'
- and `rand()'.
+ including 'int()', 'sin()'
+ and 'rand()'.
* String Functions:: Functions for string manipulation,
- such as `split()', `match()'
- and `sprintf()'.
+ such as 'split()', 'match()'
+ and 'sprintf()'.
* Gory Details:: More than you want to know about
- `\' and `&' with
- `sub()', `gsub()', and
- `gensub()'.
+ '\' and '&' with
+ 'sub()', 'gsub()', and
+ 'gensub()'.
* I/O Functions:: Functions for files and shell
commands.
* Time Functions:: Functions for dealing with timestamps.
@@ -403,11 +403,11 @@ entitled "GNU Free Documentation License".
variables in library functions.
* General Functions:: Functions that are of general use.
* Strtonum Function:: A replacement for the built-in
- `strtonum()' function.
+ 'strtonum()' function.
* Assert Function:: A function for assertions in
- `awk' programs.
+ 'awk' programs.
* Round Function:: A function for rounding if
- `sprintf()' does not do it
+ 'sprintf()' does not do it
correctly.
* Cliff Random Function:: The Cliff Random Number Generator.
* Ordinal Functions:: Functions for using characters as
@@ -439,19 +439,19 @@ entitled "GNU Free Documentation License".
* Library Exercises:: Exercises.
* Running Examples:: How to run these examples.
* Clones:: Clones of common utilities.
-* Cut Program:: The `cut' utility.
-* Egrep Program:: The `egrep' utility.
-* Id Program:: The `id' utility.
-* Split Program:: The `split' utility.
-* Tee Program:: The `tee' utility.
-* Uniq Program:: The `uniq' utility.
-* Wc Program:: The `wc' utility.
-* Miscellaneous Programs:: Some interesting `awk'
+* Cut Program:: The 'cut' utility.
+* Egrep Program:: The 'egrep' utility.
+* Id Program:: The 'id' utility.
+* Split Program:: The 'split' utility.
+* Tee Program:: The 'tee' utility.
+* Uniq Program:: The 'uniq' utility.
+* Wc Program:: The 'wc' utility.
+* Miscellaneous Programs:: Some interesting 'awk'
programs.
* Dupword Program:: Finding duplicated words in a
document.
* Alarm Program:: An alarm clock.
-* Translate Program:: A program similar to the `tr'
+* Translate Program:: A program similar to the 'tr'
utility.
* Labels Program:: Printing mailing labels.
* Word Sorting:: A program to produce a word usage
@@ -461,7 +461,7 @@ entitled "GNU Free Documentation License".
* Extract Program:: Pulling out programs from Texinfo
source files.
* Simple Sed:: A Simple Stream Editor.
-* Igawk Program:: A wrapper for `awk' that
+* Igawk Program:: A wrapper for 'awk' that
includes files.
* Anagram Program:: Finding anagrams from a dictionary.
* Signature Program:: People do amazing things with too much
@@ -472,27 +472,27 @@ entitled "GNU Free Documentation License".
* Array Sorting:: Facilities for controlling array
traversal and sorting arrays.
* Controlling Array Traversal:: How to use PROCINFO["sorted_in"].
-* Array Sorting Functions:: How to use `asort()' and
- `asorti()'.
+* Array Sorting Functions:: How to use 'asort()' and
+ 'asorti()'.
* Two-way I/O:: Two-way communications with another
process.
-* TCP/IP Networking:: Using `gawk' for network
+* TCP/IP Networking:: Using 'gawk' for network
programming.
-* Profiling:: Profiling your `awk' programs.
+* Profiling:: Profiling your 'awk' programs.
* Advanced Features Summary:: Summary of advanced features.
* I18N and L10N:: Internationalization and Localization.
-* Explaining gettext:: How GNU `gettext' works.
+* Explaining gettext:: How GNU 'gettext' works.
* Programmer i18n:: Features for the programmer.
* Translator i18n:: Features for the translator.
* String Extraction:: Extracting marked strings.
-* Printf Ordering:: Rearranging `printf' arguments.
-* I18N Portability:: `awk'-level portability
+* Printf Ordering:: Rearranging 'printf' arguments.
+* I18N Portability:: 'awk'-level portability
issues.
* I18N Example:: A simple i18n example.
-* Gawk I18N:: `gawk' is also
+* Gawk I18N:: 'gawk' is also
internationalized.
* I18N Summary:: Summary of I18N stuff.
-* Debugging:: Introduction to `gawk'
+* Debugging:: Introduction to 'gawk'
debugger.
* Debugging Concepts:: Debugging in General.
* Debugging Terms:: Additional Debugging Concepts.
@@ -513,7 +513,7 @@ entitled "GNU Free Documentation License".
* Debugging Summary:: Debugging summary.
* Computer Arithmetic:: A quick intro to computer math.
* Math Definitions:: Defining terms used.
-* MPFR features:: The MPFR features in `gawk'.
+* MPFR features:: The MPFR features in 'gawk'.
* FP Math Caution:: Things to know.
* Inexactness of computations:: Floating point math is not exact.
* Inexact representation:: Numbers are not exactly represented.
@@ -524,7 +524,7 @@ entitled "GNU Free Documentation License".
* Setting precision:: How to set the precision.
* Setting the rounding mode:: How to set the rounding mode.
* Arbitrary Precision Integers:: Arbitrary Precision Integer Arithmetic
- with `gawk'.
+ with 'gawk'.
* POSIX Floating Point Problems:: Standards Versus Existing Practice.
* Floating point summary:: Summary of floating point discussion.
* Extension Intro:: What is an extension.
@@ -536,7 +536,7 @@ entitled "GNU Free Documentation License".
* Memory Allocation Functions:: Functions for allocating memory.
* Constructor Functions:: Functions for creating values.
* Registration Functions:: Functions to register things with
- `gawk'.
+ 'gawk'.
* Extension Functions:: Registering extension functions.
* Exit Callback Functions:: Registering an exit callback.
* Extension Version String:: Registering a version string.
@@ -544,13 +544,13 @@ entitled "GNU Free Documentation License".
* Output Wrappers:: Registering an output wrapper.
* Two-way processors:: Registering a two-way processor.
* Printing Messages:: Functions for printing messages.
-* Updating `ERRNO':: Functions for updating `ERRNO'.
+* Updating 'ERRNO':: Functions for updating 'ERRNO'.
* Requesting Values:: How to get a value.
* Accessing Parameters:: Functions for accessing parameters.
* Symbol Table Access:: Functions for accessing global
variables.
* Symbol table by name:: Accessing variables by name.
-* Symbol table by cookie:: Accessing variables by ``cookie''.
+* Symbol table by cookie:: Accessing variables by "cookie".
* Cached values:: Creating and using cached values.
* Array Manipulation:: Functions for working with arrays.
* Array Data Types:: Data types for working with arrays.
@@ -560,34 +560,34 @@ entitled "GNU Free Documentation License".
* Extension API Variables:: Variables provided by the API.
* Extension Versioning:: API Version information.
* Extension API Informational Variables:: Variables providing information about
- `gawk''s invocation.
+ 'gawk''s invocation.
* Extension API Boilerplate:: Boilerplate code for using the API.
-* Finding Extensions:: How `gawk' finds compiled
+* Finding Extensions:: How 'gawk' finds compiled
extensions.
* Extension Example:: Example C code for an extension.
* Internal File Description:: What the new functions will do.
* Internal File Ops:: The code for internal file operations.
* Using Internal File Ops:: How to use an external extension.
* Extension Samples:: The sample extensions that ship with
- `gawk'.
+ 'gawk'.
* Extension Sample File Functions:: The file functions sample.
-* Extension Sample Fnmatch:: An interface to `fnmatch()'.
-* Extension Sample Fork:: An interface to `fork()' and
+* Extension Sample Fnmatch:: An interface to 'fnmatch()'.
+* Extension Sample Fork:: An interface to 'fork()' and
other process functions.
* Extension Sample Inplace:: Enabling in-place file editing.
* Extension Sample Ord:: Character to value to character
conversions.
-* Extension Sample Readdir:: An interface to `readdir()'.
+* Extension Sample Readdir:: An interface to 'readdir()'.
* Extension Sample Revout:: Reversing output sample output
wrapper.
* Extension Sample Rev2way:: Reversing data sample two-way
processor.
* Extension Sample Read write array:: Serializing an array to a file.
* Extension Sample Readfile:: Reading an entire file into a string.
-* Extension Sample Time:: An interface to `gettimeofday()'
- and `sleep()'.
+* Extension Sample Time:: An interface to 'gettimeofday()'
+ and 'sleep()'.
* Extension Sample API Tests:: Tests for the API.
-* gawkextlib:: The `gawkextlib' project.
+* gawkextlib:: The 'gawkextlib' project.
* Extension summary:: Extension summary.
* Extension Exercises:: Exercises.
* V7/SVR3.1:: The major changes between V7 and
@@ -596,63 +596,63 @@ entitled "GNU Free Documentation License".
Releases 3.1 and 4.
* POSIX:: New features from the POSIX standard.
* BTL:: New features from Brian Kernighan's
- version of `awk'.
-* POSIX/GNU:: The extensions in `gawk' not
- in POSIX `awk'.
+ version of 'awk'.
+* POSIX/GNU:: The extensions in 'gawk' not
+ in POSIX 'awk'.
* Feature History:: The history of the features in
- `gawk'.
+ 'gawk'.
* Common Extensions:: Common Extensions Summary.
* Ranges and Locales:: How locales used to affect regexp
ranges.
* Contributors:: The major contributors to
- `gawk'.
+ 'gawk'.
* History summary:: History summary.
-* Gawk Distribution:: What is in the `gawk'
+* Gawk Distribution:: What is in the 'gawk'
distribution.
* Getting:: How to get the distribution.
* Extracting:: How to extract the distribution.
* Distribution contents:: What is in the distribution.
-* Unix Installation:: Installing `gawk' under
+* Unix Installation:: Installing 'gawk' under
various versions of Unix.
-* Quick Installation:: Compiling `gawk' under Unix.
+* Quick Installation:: Compiling 'gawk' under Unix.
* Additional Configuration Options:: Other compile-time options.
* Configuration Philosophy:: How it's all supposed to work.
* Non-Unix Installation:: Installation on Other Operating
Systems.
* PC Installation:: Installing and Compiling
- `gawk' on MS-DOS and OS/2.
+ 'gawk' on MS-DOS and OS/2.
* PC Binary Installation:: Installing a prepared distribution.
-* PC Compiling:: Compiling `gawk' for MS-DOS,
+* PC Compiling:: Compiling 'gawk' for MS-DOS,
Windows32, and OS/2.
-* PC Testing:: Testing `gawk' on PC systems.
-* PC Using:: Running `gawk' on MS-DOS,
+* PC Testing:: Testing 'gawk' on PC systems.
+* PC Using:: Running 'gawk' on MS-DOS,
Windows32 and OS/2.
-* Cygwin:: Building and running `gawk'
+* Cygwin:: Building and running 'gawk'
for Cygwin.
-* MSYS:: Using `gawk' In The MSYS
+* MSYS:: Using 'gawk' In The MSYS
Environment.
-* VMS Installation:: Installing `gawk' on VMS.
-* VMS Compilation:: How to compile `gawk' under
+* VMS Installation:: Installing 'gawk' on VMS.
+* VMS Compilation:: How to compile 'gawk' under
VMS.
-* VMS Dynamic Extensions:: Compiling `gawk' dynamic
+* VMS Dynamic Extensions:: Compiling 'gawk' dynamic
extensions on VMS.
-* VMS Installation Details:: How to install `gawk' under
+* VMS Installation Details:: How to install 'gawk' under
VMS.
-* VMS Running:: How to run `gawk' under VMS.
+* VMS Running:: How to run 'gawk' under VMS.
* VMS GNV:: The VMS GNV Project.
* VMS Old Gawk:: An old version comes with some VMS
systems.
* Bugs:: Reporting Problems and Bugs.
-* Other Versions:: Other freely available `awk'
+* Other Versions:: Other freely available 'awk'
implementations.
* Installation summary:: Summary of installation.
-* Compatibility Mode:: How to disable certain `gawk'
+* Compatibility Mode:: How to disable certain 'gawk'
extensions.
-* Additions:: Making Additions To `gawk'.
+* Additions:: Making Additions To 'gawk'.
* Accessing The Source:: Accessing the Git repository.
* Adding Code:: Adding code to the main body of
- `gawk'.
-* New Ports:: Porting `gawk' to a new
+ 'gawk'.
+* New Ports:: Porting 'gawk' to a new
operating system.
* Derived Files:: Why derived files are kept in the Git
repository.
@@ -670,8 +670,8 @@ entitled "GNU Free Documentation License".
* Basic High Level:: The high level view.
* Basic Data Typing:: A very quick intro to data types.
- To my parents, for their love, and for the wonderful example they
-set for me.
+ To my parents, for their love, and for the wonderful example they set
+for me.
To my wife Miriam, for making me complete. Thank you for building
your life together with me.
@@ -685,86 +685,86 @@ File: gawk.info, Node: Foreword3, Next: Foreword4,
Prev: Top, Up: Top
Foreword to the Third Edition
*****************************
-Arnold Robbins and I are good friends. We were introduced in 1990 by
-circumstances--and our favorite programming language, AWK. The
-circumstances started a couple of years earlier. I was working at a new
+Arnold Robbins and I are good friends. We were introduced in 1990 by
+circumstances--and our favorite programming language, AWK. The
+circumstances started a couple of years earlier. I was working at a new
job and noticed an unplugged Unix computer sitting in the corner. No
-one knew how to use it, and neither did I. However, a couple of days
-later, it was running, and I was `root' and the one-and-only user.
-That day, I began the transition from statistician to Unix programmer.
+one knew how to use it, and neither did I. However, a couple of days
+later, it was running, and I was 'root' and the one-and-only user. That
+day, I began the transition from statistician to Unix programmer.
On one of many trips to the library or bookstore in search of books
-on Unix, I found the gray AWK book, a.k.a. Alfred V. Aho, Brian W.
-Kernighan, and Peter J. Weinberger's `The AWK Programming Language'
-(Addison-Wesley, 1988). `awk''s simple programming paradigm--find a
+on Unix, I found the gray AWK book, a.k.a. Alfred V. Aho, Brian W.
+Kernighan, and Peter J. Weinberger's 'The AWK Programming Language'
+(Addison-Wesley, 1988). 'awk''s simple programming paradigm--find a
pattern in the input and then perform an action--often reduced complex
or tedious data manipulations to a few lines of code. I was excited to
try my hand at programming in AWK.
- Alas, the `awk' on my computer was a limited version of the
-language described in the gray book. I discovered that my computer had
-"old `awk'" and the book described "new `awk'." I learned that this
-was typical; the old version refused to step aside or relinquish its
-name. If a system had a new `awk', it was invariably called `nawk',
-and few systems had it. The best way to get a new `awk' was to `ftp'
-the source code for `gawk' from `prep.ai.mit.edu'. `gawk' was a
-version of new `awk' written by David Trueman and Arnold, and available
-under the GNU General Public License.
-
- (Incidentally, it's no longer difficult to find a new `awk'. `gawk'
+ Alas, the 'awk' on my computer was a limited version of the language
+described in the gray book. I discovered that my computer had "old
+'awk'" and the book described "new 'awk'." I learned that this was
+typical; the old version refused to step aside or relinquish its name.
+If a system had a new 'awk', it was invariably called 'nawk', and few
+systems had it. The best way to get a new 'awk' was to 'ftp' the source
+code for 'gawk' from 'prep.ai.mit.edu'. 'gawk' was a version of new
+'awk' written by David Trueman and Arnold, and available under the GNU
+General Public License.
+
+ (Incidentally, it's no longer difficult to find a new 'awk'. 'gawk'
ships with GNU/Linux, and you can download binaries or source code for
-almost any system; my wife uses `gawk' on her VMS box.)
+almost any system; my wife uses 'gawk' on her VMS box.)
My Unix system started out unplugged from the wall; it certainly was
-not plugged into a network. So, oblivious to the existence of `gawk'
-and the Unix community in general, and desiring a new `awk', I wrote my
-own, called `mawk'. Before I was finished, I knew about `gawk', but it
-was too late to stop, so I eventually posted to a `comp.sources'
+not plugged into a network. So, oblivious to the existence of 'gawk'
+and the Unix community in general, and desiring a new 'awk', I wrote my
+own, called 'mawk'. Before I was finished, I knew about 'gawk', but it
+was too late to stop, so I eventually posted to a 'comp.sources'
newsgroup.
A few days after my posting, I got a friendly email from Arnold
-introducing himself. He suggested we share design and algorithms and
-attached a draft of the POSIX standard so that I could update `mawk' to
-support language extensions added after publication of `The AWK
+introducing himself. He suggested we share design and algorithms and
+attached a draft of the POSIX standard so that I could update 'mawk' to
+support language extensions added after publication of 'The AWK
Programming Language'.
Frankly, if our roles had been reversed, I would not have been so
-open and we probably would have never met. I'm glad we did meet. He
-is an AWK expert's AWK expert and a genuinely nice person. Arnold
+open and we probably would have never met. I'm glad we did meet. He is
+an AWK expert's AWK expert and a genuinely nice person. Arnold
contributes significant amounts of his expertise and time to the Free
Software Foundation.
- This book is the `gawk' reference manual, but at its core it is a
-book about AWK programming that will appeal to a wide audience. It is
-a definitive reference to the AWK language as defined by the 1987 Bell
+ This book is the 'gawk' reference manual, but at its core it is a
+book about AWK programming that will appeal to a wide audience. It is a
+definitive reference to the AWK language as defined by the 1987 Bell
Laboratories release and codified in the 1992 POSIX Utilities standard.
On the other hand, the novice AWK programmer can study a wealth of
practical programs that emphasize the power of AWK's basic idioms:
-data-driven control flow, pattern matching with regular expressions,
-and associative arrays. Those looking for something new can try out
-`gawk''s interface to network protocols via special `/inet' files.
-
- The programs in this book make clear that an AWK program is
-typically much smaller and faster to develop than a counterpart written
-in C. Consequently, there is often a payoff to prototyping an
-algorithm or design in AWK to get it running quickly and expose
-problems early. Often, the interpreted performance is adequate and the
-AWK prototype becomes the product.
-
- The new `pgawk' (profiling `gawk'), produces program execution
+data-driven control flow, pattern matching with regular expressions, and
+associative arrays. Those looking for something new can try out
+'gawk''s interface to network protocols via special '/inet' files.
+
+ The programs in this book make clear that an AWK program is typically
+much smaller and faster to develop than a counterpart written in C.
+Consequently, there is often a payoff to prototyping an algorithm or
+design in AWK to get it running quickly and expose problems early.
+Often, the interpreted performance is adequate and the AWK prototype
+becomes the product.
+
+ The new 'pgawk' (profiling 'gawk'), produces program execution
counts. I recently experimented with an algorithm that for n lines of
input, exhibited ~ C n^2 performance, while theory predicted ~ C n log n
-behavior. A few minutes poring over the `awkprof.out' profile
-pinpointed the problem to a single line of code. `pgawk' is a welcome
+behavior. A few minutes poring over the 'awkprof.out' profile
+pinpointed the problem to a single line of code. 'pgawk' is a welcome
addition to my programmer's toolbox.
Arnold has distilled over a decade of experience writing and using
-AWK programs, and developing `gawk', into this book. If you use AWK or
+AWK programs, and developing 'gawk', into this book. If you use AWK or
want to learn how, then read this book.
Michael Brennan
- Author of `mawk'
+ Author of 'mawk'
March 2001
@@ -782,17 +782,17 @@ the syntax. One needs to acquire an understanding of how
to use the
features of the language to solve practical programming problems. A
focus of this book is many examples that show how to use AWK.
- Some things do change. Our computers are much faster and have more
+ Some things do change. Our computers are much faster and have more
memory. Consequently, speed and storage inefficiencies of a high-level
language matter less. Prototyping in AWK and then rewriting in C for
performance reasons happens less, because more often the prototype is
fast enough.
Of course, there are computing operations that are best done in C or
-C++. With `gawk' 4.1 and later, you do not have to choose between
+C++. With 'gawk' 4.1 and later, you do not have to choose between
writing your program in AWK or in C/C++. You can write most of your
program in AWK and the aspects that require C/C++ capabilities can be
-written in C/C++, and then the pieces glued together when the `gawk'
+written in C/C++, and then the pieces glued together when the 'gawk'
module loads the C/C++ module as a dynamic plug-in. *note Dynamic
Extensions::, has all the details, and, as expected, many examples to
help you learn the ins and outs.
@@ -801,7 +801,7 @@ help you learn the ins and outs.
think you will too.
Michael Brennan
- Author of `mawk'
+ Author of 'mawk'
October 2014
@@ -813,19 +813,19 @@ Preface
Several kinds of tasks occur repeatedly when working with text files.
You might want to extract certain lines and discard the rest. Or you
may need to make changes wherever certain patterns appear, but leave the
-rest of the file alone. Such jobs are often easy with `awk'. The
-`awk' utility interprets a special-purpose programming language that
-makes it easy to handle simple data-reformatting jobs.
+rest of the file alone. Such jobs are often easy with 'awk'. The 'awk'
+utility interprets a special-purpose programming language that makes it
+easy to handle simple data-reformatting jobs.
- The GNU implementation of `awk' is called `gawk'; if you invoke it
-with the proper options or environment variables, it is fully
-compatible with the POSIX(1) specification of the `awk' language and
-with the Unix version of `awk' maintained by Brian Kernighan. This
-means that all properly written `awk' programs should work with `gawk'.
-So most of the time, we don't distinguish between `gawk' and other
-`awk' implementations.
+ The GNU implementation of 'awk' is called 'gawk'; if you invoke it
+with the proper options or environment variables, it is fully compatible
+with the POSIX(1) specification of the 'awk' language and with the Unix
+version of 'awk' maintained by Brian Kernighan. This means that all
+properly written 'awk' programs should work with 'gawk'. So most of the
+time, we don't distinguish between 'gawk' and other 'awk'
+implementations.
- Using `awk' you can:
+ Using 'awk' you can:
* Manage small, personal databases
@@ -838,7 +838,7 @@ So most of the time, we don't distinguish between `gawk'
and other
* Experiment with algorithms that you can adapt later to other
computer languages
- In addition, `gawk' provides facilities that make it easy to:
+ In addition, 'gawk' provides facilities that make it easy to:
* Extract bits and pieces of data for processing
@@ -846,29 +846,29 @@ So most of the time, we don't distinguish between `gawk'
and other
* Perform simple network communications
- * Profile and debug `awk' programs
+ * Profile and debug 'awk' programs
* Extend the language with functions written in C or C++
- This Info file teaches you about the `awk' language and how you can
+ This Info file teaches you about the 'awk' language and how you can
use it effectively. You should already be familiar with basic system
-commands, such as `cat' and `ls',(2) as well as basic shell facilities,
+commands, such as 'cat' and 'ls',(2) as well as basic shell facilities,
such as input/output (I/O) redirection and pipes.
- Implementations of the `awk' language are available for many
+ Implementations of the 'awk' language are available for many
different computing environments. This Info file, while describing the
-`awk' language in general, also describes the particular implementation
-of `awk' called `gawk' (which stands for "GNU `awk'"). `gawk' runs on
-a broad range of Unix systems, ranging from Intel-architecture PC-based
-computers up through large-scale systems. `gawk' has also been ported
+'awk' language in general, also describes the particular implementation
+of 'awk' called 'gawk' (which stands for "GNU 'awk'"). 'gawk' runs on a
+broad range of Unix systems, ranging from Intel-architecture PC-based
+computers up through large-scale systems. 'gawk' has also been ported
to Mac OS X, Microsoft Windows (all versions) and OS/2 PCs, and
OpenVMS.(3)
* Menu:
-* History:: The history of `gawk' and
- `awk'.
-* Names:: What name to use to find `awk'.
+* History:: The history of 'gawk' and
+ 'awk'.
+* Names:: What name to use to find 'awk'.
* This Manual:: Using this Info file. Includes sample
input files that you can use.
* Conventions:: Typographical Conventions.
@@ -879,68 +879,67 @@ OpenVMS.(3)
---------- Footnotes ----------
- (1) The 2008 POSIX standard is accessible online at
-`http://www.opengroup.org/onlinepubs/9699919799/'.
+ (1) The 2008 POSIX standard is accessible online at
<http://www.opengroup.org/onlinepubs/9699919799/>.
- (2) These utilities are available on POSIX-compliant systems, as
-well as on traditional Unix-based systems. If you are using some other
+ (2) These utilities are available on POSIX-compliant systems, as well
+as on traditional Unix-based systems. If you are using some other
operating system, you still need to be familiar with the ideas of I/O
redirection and pipes.
- (3) Some other, obsolete systems to which `gawk' was once ported are
+ (3) Some other, obsolete systems to which 'gawk' was once ported are
no longer supported and the code for those systems has been removed.
File: gawk.info, Node: History, Next: Names, Up: Preface
-History of `awk' and `gawk'
+History of 'awk' and 'gawk'
===========================
Recipe for a Programming Language
- 1 part `egrep' 1 part `snobol'
- 2 parts `ed' 3 parts C
+ 1 part 'egrep' 1 part 'snobol'
+ 2 parts 'ed' 3 parts C
- Blend all parts well using `lex' and `yacc'. Document minimally and
+ Blend all parts well using 'lex' and 'yacc'. Document minimally and
release.
- After eight years, add another part `egrep' and two more parts C.
+ After eight years, add another part 'egrep' and two more parts C.
Document very well and release.
-The name `awk' comes from the initials of its designers: Alfred V.
+ The name 'awk' comes from the initials of its designers: Alfred V.
Aho, Peter J. Weinberger, and Brian W. Kernighan. The original version
-of `awk' was written in 1977 at AT&T Bell Laboratories. In 1985, a new
+of 'awk' was written in 1977 at AT&T Bell Laboratories. In 1985, a new
version made the programming language more powerful, introducing
user-defined functions, multiple input streams, and computed regular
expressions. This new version became widely available with Unix System
V Release 3.1 (1987). The version in System V Release 4 (1989) added
some new features and cleaned up the behavior in some of the "dark
-corners" of the language. The specification for `awk' in the POSIX
+corners" of the language. The specification for 'awk' in the POSIX
Command Language and Utilities standard further clarified the language.
-Both the `gawk' designers and the original `awk' designers at Bell
+Both the 'gawk' designers and the original 'awk' designers at Bell
Laboratories provided feedback for the POSIX specification.
- Paul Rubin wrote `gawk' in 1986. Jay Fenlason completed it, with
+ Paul Rubin wrote 'gawk' in 1986. Jay Fenlason completed it, with
advice from Richard Stallman. John Woods contributed parts of the code
-as well. In 1988 and 1989, David Trueman, with help from me,
-thoroughly reworked `gawk' for compatibility with the newer `awk'.
-Circa 1994, I became the primary maintainer. Current development
-focuses on bug fixes, performance improvements, standards compliance,
-and, occasionally, new features.
+as well. In 1988 and 1989, David Trueman, with help from me, thoroughly
+reworked 'gawk' for compatibility with the newer 'awk'. Circa 1994, I
+became the primary maintainer. Current development focuses on bug
+fixes, performance improvements, standards compliance, and,
+occasionally, new features.
In May 1997, Ju"rgen Kahrs felt the need for network access from
-`awk', and with a little help from me, set about adding features to do
-this for `gawk'. At that time, he also wrote the bulk of `TCP/IP
-Internetworking with `gawk'' (a separate document, available as part of
-the `gawk' distribution). His code finally became part of the main
-`gawk' distribution with `gawk' version 3.1.
-
- John Haque rewrote the `gawk' internals, in the process providing an
-`awk'-level debugger. This version became available as `gawk' version
+'awk', and with a little help from me, set about adding features to do
+this for 'gawk'. At that time, he also wrote the bulk of 'TCP/IP
+Internetworking with 'gawk'' (a separate document, available as part of
+the 'gawk' distribution). His code finally became part of the main
+'gawk' distribution with 'gawk' version 3.1.
+
+ John Haque rewrote the 'gawk' internals, in the process providing an
+'awk'-level debugger. This version became available as 'gawk' version
4.0 in 2011.
*Note Contributors::, for a full list of those who have made
-important contributions to `gawk'.
+important contributions to 'gawk'.
File: gawk.info, Node: Names, Next: This Manual, Prev: History, Up: Preface
@@ -948,32 +947,31 @@ File: gawk.info, Node: Names, Next: This Manual, Prev:
History, Up: Preface
A Rose by Any Other Name
========================
-The `awk' language has evolved over the years. Full details are
+The 'awk' language has evolved over the years. Full details are
provided in *note Language History::. The language described in this
-Info file is often referred to as "new `awk'." By analogy, the
-original version of `awk' is referred to as "old `awk'."
+Info file is often referred to as "new 'awk'." By analogy, the original
+version of 'awk' is referred to as "old 'awk'."
- On most current systems, when you run the `awk' utility you get some
-version of new `awk'.(1) If your system's standard `awk' is the old
+ On most current systems, when you run the 'awk' utility you get some
+version of new 'awk'.(1) If your system's standard 'awk' is the old
one, you will see something like this if you try the test program:
$ awk 1 /dev/null
- error--> awk: syntax error near line 1
- error--> awk: bailing out near line 1
+ error-> awk: syntax error near line 1
+ error-> awk: bailing out near line 1
-In this case, you should find a version of new `awk', or just install
-`gawk'!
+In this case, you should find a version of new 'awk', or just install
+'gawk'!
Throughout this Info file, whenever we refer to a language feature
-that should be available in any complete implementation of POSIX `awk',
-we simply use the term `awk'. When referring to a feature that is
-specific to the GNU implementation, we use the term `gawk'.
+that should be available in any complete implementation of POSIX 'awk',
+we simply use the term 'awk'. When referring to a feature that is
+specific to the GNU implementation, we use the term 'gawk'.
---------- Footnotes ----------
- (1) Only Solaris systems still use an old `awk' for the default
-`awk' utility. A more modern `awk' lives in `/usr/xpg6/bin' on these
-systems.
+ (1) Only Solaris systems still use an old 'awk' for the default 'awk'
+utility. A more modern 'awk' lives in '/usr/xpg6/bin' on these systems.
File: gawk.info, Node: This Manual, Next: Conventions, Prev: Names, Up:
Preface
@@ -981,60 +979,59 @@ File: gawk.info, Node: This Manual, Next: Conventions,
Prev: Names, Up: Pref
Using This Book
===============
-The term `awk' refers to a particular program as well as to the
-language you use to tell this program what to do. When we need to be
-careful, we call the language "the `awk' language," and the program
-"the `awk' utility." This Info file explains both how to write
-programs in the `awk' language and how to run the `awk' utility. The
-term "`awk' program" refers to a program written by you in the `awk'
-programming language.
+The term 'awk' refers to a particular program as well as to the language
+you use to tell this program what to do. When we need to be careful, we
+call the language "the 'awk' language," and the program "the 'awk'
+utility." This Info file explains both how to write programs in the
+'awk' language and how to run the 'awk' utility. The term "'awk'
+program" refers to a program written by you in the 'awk' programming
+language.
- Primarily, this Info file explains the features of `awk' as defined
-in the POSIX standard. It does so in the context of the `gawk'
+ Primarily, this Info file explains the features of 'awk' as defined
+in the POSIX standard. It does so in the context of the 'gawk'
implementation. While doing so, it also attempts to describe important
-differences between `gawk' and other `awk' implementations.(1) Finally,
-it notes any `gawk' features that are not in the POSIX standard for
-`awk'.
+differences between 'gawk' and other 'awk' implementations.(1) Finally,
+it notes any 'gawk' features that are not in the POSIX standard for
+'awk'.
There are sidebars scattered throughout the Info file. They add a
-more complete explanation of points that are relevant, but not likely
-to be of interest on first reading. All appear in the index, under the
+more complete explanation of points that are relevant, but not likely to
+be of interest on first reading. All appear in the index, under the
heading "sidebar."
- Most of the time, the examples use complete `awk' programs. Some of
-the more advanced sections show only the part of the `awk' program that
+ Most of the time, the examples use complete 'awk' programs. Some of
+the more advanced sections show only the part of the 'awk' program that
illustrates the concept being described.
Although this Info file is aimed principally at people who have not
-been exposed to `awk', there is a lot of information here that even the
-`awk' expert should find useful. In particular, the description of
-POSIX `awk' and the example programs in *note Library Functions::, and
+been exposed to 'awk', there is a lot of information here that even the
+'awk' expert should find useful. In particular, the description of
+POSIX 'awk' and the example programs in *note Library Functions::, and
in *note Sample Programs::, should be of interest.
This Info file is split into several parts, as follows:
- * Part I describes the `awk' language and the `gawk' program in
+ * Part I describes the 'awk' language and the 'gawk' program in
detail. It starts with the basics, and continues through all of
- the features of `awk'. It contains the following chapters:
+ the features of 'awk'. It contains the following chapters:
- *note Getting Started::, provides the essentials you need to
- know to begin using `awk'.
+ know to begin using 'awk'.
- - *note Invoking Gawk::, describes how to run `gawk', the
- meaning of its command-line options, and how it finds `awk'
+ - *note Invoking Gawk::, describes how to run 'gawk', the
+ meaning of its command-line options, and how it finds 'awk'
program source files.
- - *note Regexp::, introduces regular expressions in general,
- and in particular the flavors supported by POSIX `awk' and
- `gawk'.
+ - *note Regexp::, introduces regular expressions in general, and
+ in particular the flavors supported by POSIX 'awk' and 'gawk'.
- - *note Reading Files::, describes how `awk' reads your data.
+ - *note Reading Files::, describes how 'awk' reads your data.
It introduces the concepts of records and fields, as well as
- the `getline' command. I/O redirection is first described
+ the 'getline' command. I/O redirection is first described
here. Network I/O is also briefly introduced here.
- - *note Printing::, describes how `awk' programs can produce
- output with `print' and `printf'.
+ - *note Printing::, describes how 'awk' programs can produce
+ output with 'print' and 'printf'.
- *note Expressions::, describes expressions, which are the
basic building blocks for getting most things done in a
@@ -1042,88 +1039,87 @@ in *note Sample Programs::, should be of interest.
- *note Patterns and Actions::, describes how to write patterns
for matching records, actions for doing something when a
- record is matched, and the predefined variables `awk' and
- `gawk' use.
+ record is matched, and the predefined variables 'awk' and
+ 'gawk' use.
- - *note Arrays::, covers `awk''s one-and-only data structure:
+ - *note Arrays::, covers 'awk''s one-and-only data structure:
the associative array. Deleting array elements and whole
- arrays is described, as well as sorting arrays in `gawk'.
- The major node also describes how `gawk' provides arrays of
+ arrays is described, as well as sorting arrays in 'gawk'. The
+ major node also describes how 'gawk' provides arrays of
arrays.
- - *note Functions::, describes the built-in functions `awk' and
- `gawk' provide, as well as how to define your own functions.
- It also discusses how `gawk' lets you call functions
+ - *note Functions::, describes the built-in functions 'awk' and
+ 'gawk' provide, as well as how to define your own functions.
+ It also discusses how 'gawk' lets you call functions
indirectly.
- * Part II shows how to use `awk' and `gawk' for problem solving.
+ * Part II shows how to use 'awk' and 'gawk' for problem solving.
There is lots of code here for you to read and learn from. This
part contains the following chapters:
- *note Library Functions::, provides a number of functions
- meant to be used from main `awk' programs.
+ meant to be used from main 'awk' programs.
- - *note Sample Programs::, provides many sample `awk' programs.
+ - *note Sample Programs::, provides many sample 'awk' programs.
- Reading these two chapters allows you to see `awk' solving real
+ Reading these two chapters allows you to see 'awk' solving real
problems.
- * Part III focuses on features specific to `gawk'. It contains the
+ * Part III focuses on features specific to 'gawk'. It contains the
following chapters:
- *note Advanced Features::, describes a number of advanced
- features. Of particular note are the abilities to control
- the order of array traversal, have two-way communications
- with another process, perform TCP/IP networking, and profile
- your `awk' programs.
+ features. Of particular note are the abilities to control the
+ order of array traversal, have two-way communications with
+ another process, perform TCP/IP networking, and profile your
+ 'awk' programs.
- *note Internationalization::, describes special features for
translating program messages into different languages at
runtime.
- - *note Debugger::, describes the `gawk' debugger.
+ - *note Debugger::, describes the 'gawk' debugger.
- *note Arbitrary Precision Arithmetic::, describes advanced
arithmetic facilities.
- - *note Dynamic Extensions::, describes how to add new
- variables and functions to `gawk' by writing extensions in C
- or C++.
+ - *note Dynamic Extensions::, describes how to add new variables
+ and functions to 'gawk' by writing extensions in C or C++.
* Part IV provides the appendices, the Glossary, and two licenses
- that cover the `gawk' source code and this Info file, respectively.
+ that cover the 'gawk' source code and this Info file, respectively.
It contains the following appendices:
- - *note Language History::, describes how the `awk' language
- has evolved since its first release to the present. It also
- describes how `gawk' has acquired features over time.
+ - *note Language History::, describes how the 'awk' language has
+ evolved since its first release to the present. It also
+ describes how 'gawk' has acquired features over time.
- - *note Installation::, describes how to get `gawk', how to
- compile it on POSIX-compatible systems, and how to compile
- and use it on different non-POSIX systems. It also describes
- how to report bugs in `gawk' and where to get other freely
- available `awk' implementations.
+ - *note Installation::, describes how to get 'gawk', how to
+ compile it on POSIX-compatible systems, and how to compile and
+ use it on different non-POSIX systems. It also describes how
+ to report bugs in 'gawk' and where to get other freely
+ available 'awk' implementations.
- - *note Notes::, describes how to disable `gawk''s extensions,
- as well as how to contribute new code to `gawk', and some
- possible future directions for `gawk' development.
+ - *note Notes::, describes how to disable 'gawk''s extensions,
+ as well as how to contribute new code to 'gawk', and some
+ possible future directions for 'gawk' development.
- *note Basic Concepts::, provides some very cursory background
- material for those who are completely unfamiliar with
- computer programming.
+ material for those who are completely unfamiliar with computer
+ programming.
The *note Glossary::, defines most, if not all, of the
significant terms used throughout the Info file. If you find
terms that you aren't familiar with, try looking them up here.
- *note Copying::, and *note GNU Free Documentation License::,
- present the licenses that cover the `gawk' source code and
+ present the licenses that cover the 'gawk' source code and
this Info file, respectively.
---------- Footnotes ----------
(1) All such differences appear in the index under the entry
-"differences in `awk' and `gawk'."
+"differences in 'awk' and 'gawk'."
File: gawk.info, Node: Conventions, Next: Manual History, Prev: This
Manual, Up: Preface
@@ -1132,52 +1128,52 @@ Typographical Conventions
=========================
This Info file is written in Texinfo
-(http://www.gnu.org/software/texinfo/), the GNU documentation
-formatting language. A single Texinfo source file is used to produce
-both the printed and online versions of the documentation. This minor
-node briefly documents the typographical conventions used in Texinfo.
+(http://www.gnu.org/software/texinfo/), the GNU documentation formatting
+language. A single Texinfo source file is used to produce both the
+printed and online versions of the documentation. This minor node
+briefly documents the typographical conventions used in Texinfo.
Examples you would type at the command line are preceded by the
-common shell primary and secondary prompts, `$' and `>'. Input that
-you type is shown `like this'. Output from the command is preceded by
-the glyph "-|". This typically represents the command's standard
-output. Error messages and other output on the command's standard
-error are preceded by the glyph "error-->". For example:
+common shell primary and secondary prompts, '$' and '>'. Input that you
+type is shown 'like this'. Output from the command is preceded by the
+glyph "-|". This typically represents the command's standard output.
+Error messages and other output on the command's standard error are
+preceded by the glyph "error->". For example:
$ echo hi on stdout
-| hi on stdout
$ echo hello on stderr 1>&2
- error--> hello on stderr
+ error-> hello on stderr
- Characters that you type at the keyboard look `like this'. In
+ Characters that you type at the keyboard look 'like this'. In
particular, there are special characters called "control characters."
-These are characters that you type by holding down both the `CONTROL'
-key and another key, at the same time. For example, a `Ctrl-d' is typed
-by first pressing and holding the `CONTROL' key, next pressing the `d'
+These are characters that you type by holding down both the 'CONTROL'
+key and another key, at the same time. For example, a 'Ctrl-d' is typed
+by first pressing and holding the 'CONTROL' key, next pressing the 'd'
key, and finally releasing both keys.
- For the sake of brevity, throughout this Info file, we refer to
-Brian Kernighan's version of `awk' as "BWK `awk'." (*Note Other
-Versions::, for information on his and other versions.)
+ For the sake of brevity, throughout this Info file, we refer to Brian
+Kernighan's version of 'awk' as "BWK 'awk'." (*Note Other Versions::,
+for information on his and other versions.)
Dark Corners
------------
Dark corners are basically fractal--no matter how much you
- illuminate, there's always a smaller but darker one. -- Brian
- Kernighan
+ illuminate, there's always a smaller but darker one.
+ -- _Brian Kernighan_
- Until the POSIX standard (and `GAWK: Effective AWK Programming'),
-many features of `awk' were either poorly documented or not documented
-at all. Descriptions of such features (often called "dark corners")
-are noted in this Info file with "(d.c.)." They also appear in the
-index under the heading "dark corner."
+ Until the POSIX standard (and 'GAWK: Effective AWK Programming'),
+many features of 'awk' were either poorly documented or not documented
+at all. Descriptions of such features (often called "dark corners") are
+noted in this Info file with "(d.c.)." They also appear in the index
+under the heading "dark corner."
But, as noted by the opening quote, any coverage of dark corners is
by definition incomplete.
- Extensions to the standard `awk' language that are supported by more
-than one `awk' implementation are marked "(c.e.)," and listed in the
+ Extensions to the standard 'awk' language that are supported by more
+than one 'awk' implementation are marked "(c.e.)," and listed in the
index under "common extensions" and "extensions, common."
@@ -1187,57 +1183,57 @@ The GNU Project and This Book
=============================
The Free Software Foundation (FSF) is a nonprofit organization dedicated
-to the production and distribution of freely distributable software.
-It was founded by Richard M. Stallman, the author of the original Emacs
+to the production and distribution of freely distributable software. It
+was founded by Richard M. Stallman, the author of the original Emacs
editor. GNU Emacs is the most widely used version of Emacs today.
The GNU(1) Project is an ongoing effort on the part of the Free
Software Foundation to create a complete, freely distributable,
POSIX-compliant computing environment. The FSF uses the GNU General
-Public License (GPL) to ensure that its software's source code is
-always available to the end user. A copy of the GPL is included for
-your reference (*note Copying::). The GPL applies to the C language
-source code for `gawk'. To find out more about the FSF and the GNU
-Project online, see the GNU Project's home page (http://www.gnu.org).
-This Info file may also be read from GNU's website
+Public License (GPL) to ensure that its software's source code is always
+available to the end user. A copy of the GPL is included for your
+reference (*note Copying::). The GPL applies to the C language source
+code for 'gawk'. To find out more about the FSF and the GNU Project
+online, see the GNU Project's home page (http://www.gnu.org). This Info
+file may also be read from GNU's website
(http://www.gnu.org/software/gawk/manual/).
A shell, an editor (Emacs), highly portable optimizing C, C++, and
-Objective-C compilers, a symbolic debugger and dozens of large and
-small utilities (such as `gawk'), have all been completed and are
-freely available. The GNU operating system kernel (the HURD), has been
+Objective-C compilers, a symbolic debugger and dozens of large and small
+utilities (such as 'gawk'), have all been completed and are freely
+available. The GNU operating system kernel (the HURD), has been
released but remains in an early stage of development.
Until the GNU operating system is more fully developed, you should
consider using GNU/Linux, a freely distributable, Unix-like operating
system for Intel, Power Architecture, Sun SPARC, IBM S/390, and other
-systems.(2) Many GNU/Linux distributions are available for download
+systems.(2) Many GNU/Linux distributions are available for download
from the Internet.
The Info file itself has gone through multiple previous editions.
-Paul Rubin wrote the very first draft of `The GAWK Manual'; it was
+Paul Rubin wrote the very first draft of 'The GAWK Manual'; it was
around 40 pages long. Diane Close and Richard Stallman improved it,
yielding a version that was around 90 pages and barely described the
-original, "old" version of `awk'.
+original, "old" version of 'awk'.
I started working with that version in the fall of 1988. As work on
it progressed, the FSF published several preliminary versions (numbered
-0.X). In 1996, edition 1.0 was released with `gawk' 3.0.0. The FSF
-published the first two editions under the title `The GNU Awk User's
+0.X). In 1996, edition 1.0 was released with 'gawk' 3.0.0. The FSF
+published the first two editions under the title 'The GNU Awk User's
Guide'.
This edition maintains the basic structure of the previous editions.
For FSF edition 4.0, the content was thoroughly reviewed and updated.
-All references to `gawk' versions prior to 4.0 were removed. Of
+All references to 'gawk' versions prior to 4.0 were removed. Of
significant note for that edition was the addition of *note Debugger::.
- For FSF edition 4.1, the content has been reorganized into parts,
-and the major new additions are *note Arbitrary Precision Arithmetic::,
-and *note Dynamic Extensions::.
+ For FSF edition 4.1, the content has been reorganized into parts, and
+the major new additions are *note Arbitrary Precision Arithmetic::, and
+*note Dynamic Extensions::.
This Info file will undoubtedly continue to evolve. If you find an
-error in the Info file, please report it! *Note Bugs::, for
-information on submitting problem reports electronically.
+error in the Info file, please report it! *Note Bugs::, for information
+on submitting problem reports electronically.
---------- Footnotes ----------
@@ -1251,26 +1247,26 @@ File: gawk.info, Node: How To Contribute, Next:
Acknowledgments, Prev: Manual
How to Contribute
=================
-As the maintainer of GNU `awk', I once thought that I would be able to
-manage a collection of publicly available `awk' programs and I even
+As the maintainer of GNU 'awk', I once thought that I would be able to
+manage a collection of publicly available 'awk' programs and I even
solicited contributions. Making things available on the Internet helps
-keep the `gawk' distribution down to manageable size.
+keep the 'gawk' distribution down to manageable size.
The initial collection of material, such as it is, is still available
-at `ftp://ftp.freefriends.org/arnold/Awkstuff'. In the hopes of doing
-something more broad, I acquired the `awk.info' domain.
+at <ftp://ftp.freefriends.org/arnold/Awkstuff>. In the hopes of doing
+something more broad, I acquired the 'awk.info' domain.
However, I found that I could not dedicate enough time to managing
contributed code: the archive did not grow and the domain went unused
for several years.
Late in 2008, a volunteer took on the task of setting up an
-`awk'-related website--`http://awk.info'--and did a very nice job.
+'awk'-related website--<http://awk.info>--and did a very nice job.
- If you have written an interesting `awk' program, or have written a
-`gawk' extension that you would like to share with the rest of the
-world, please see `http://awk.info/?contribute' for how to contribute
-it to the website.
+ If you have written an interesting 'awk' program, or have written a
+'gawk' extension that you would like to share with the rest of the
+world, please see <http://awk.info/?contribute> for how to contribute it
+to the website.
File: gawk.info, Node: Acknowledgments, Prev: How To Contribute, Up: Preface
@@ -1278,15 +1274,15 @@ File: gawk.info, Node: Acknowledgments, Prev: How To
Contribute, Up: Preface
Acknowledgments
===============
-The initial draft of `The GAWK Manual' had the following
+The initial draft of 'The GAWK Manual' had the following
acknowledgments:
Many people need to be thanked for their assistance in producing
this manual. Jay Fenlason contributed many ideas and sample
programs. Richard Mlynarik and Robert Chassell gave helpful
- comments on drafts of this manual. The paper `A Supplemental
- Document for AWK' by John W. Pierce of the Chemistry Department
- at UC San Diego, pinpointed several issues relevant both to `awk'
+ comments on drafts of this manual. The paper 'A Supplemental
+ Document for AWK' by John W. Pierce of the Chemistry Department at
+ UC San Diego, pinpointed several issues relevant both to 'awk'
implementation and to this manual, that would otherwise have
escaped us.
@@ -1307,21 +1303,21 @@ acknowledgements:
Robert J. Chassell provided much valuable advice on the use of
Texinfo. He also deserves special thanks for convincing me _not_
- to title this Info file `How to Gawk Politely'. Karl Berry helped
+ to title this Info file 'How to Gawk Politely'. Karl Berry helped
significantly with the TeX part of Texinfo.
I would like to thank Marshall and Elaine Hartholz of Seattle and
Dr. Bert and Rita Schreiber of Detroit for large amounts of quiet
vacation time in their homes, which allowed me to make significant
- progress on this Info file and on `gawk' itself.
+ progress on this Info file and on 'gawk' itself.
Phil Hughes of SSC contributed in a very important way by loaning
me his laptop GNU/Linux system, not once, but twice, which allowed
me to do a lot of work while away from home.
David Trueman deserves special credit; he has done a yeoman job of
- evolving `gawk' so that it performs well and without bugs.
- Although he is no longer involved with `gawk', working with him on
+ evolving 'gawk' so that it performs well and without bugs.
+ Although he is no longer involved with 'gawk', working with him on
this project was a significant pleasure.
The intrepid members of the GNITS mailing list, and most notably
@@ -1330,49 +1326,48 @@ acknowledgements:
Chuck Toporek, Mary Sheehan, and Claire Cloutier of O'Reilly &
Associates contributed significant editorial help for this Info
- file for the 3.1 release of `gawk'.
+ file for the 3.1 release of 'gawk'.
Dr. Nelson Beebe, Andreas Buening, Dr. Manuel Collado, Antonio
Colombo, Stephen Davies, Scott Deifik, Akim Demaille, Darrel Hankerson,
Michal Jaegermann, Ju"rgen Kahrs, Stepan Kasal, John Malmberg, Dave
Pitts, Chet Ramey, Pat Rankin, Andrew Schorr, Corinna Vinschen, and Eli
-Zaretskii (in alphabetical order) make up the current `gawk' "crack
-portability team." Without their hard work and help, `gawk' would not
+Zaretskii (in alphabetical order) make up the current 'gawk' "crack
+portability team." Without their hard work and help, 'gawk' would not
be nearly the robust, portable program it is today. It has been and
continues to be a pleasure working with this team of fine people.
- Notable code and documentation contributions were made by a number
-of people. *Note Contributors::, for the full list.
+ Notable code and documentation contributions were made by a number of
+people. *Note Contributors::, for the full list.
Thanks to Michael Brennan for the Forewords.
- Thanks to Patrice Dumas for the new `makeinfo' program. Thanks to
+ Thanks to Patrice Dumas for the new 'makeinfo' program. Thanks to
Karl Berry, who continues to work to keep the Texinfo markup language
sane.
Robert P.J. Day, Michael Brennan, and Brian Kernighan kindly acted as
-reviewers for the 2015 edition of this Info file. Their feedback helped
+reviewers for the 2015 edition of this Info file. Their feedback helped
improve the final work.
I would also like to thank Brian Kernighan for his invaluable
-assistance during the testing and debugging of `gawk', and for his
+assistance during the testing and debugging of 'gawk', and for his
ongoing help and advice in clarifying numerous points about the
-language. We could not have done nearly as good a job on either `gawk'
+language. We could not have done nearly as good a job on either 'gawk'
or its documentation without his help.
Brian is in a class by himself as a programmer and technical author.
-I have to thank him (yet again) for his ongoing friendship and for
-being a role model to me for close to 30 years! Having him as a
-reviewer is an exciting privilege. It has also been extremely
-humbling...
+I have to thank him (yet again) for his ongoing friendship and for being
+a role model to me for close to 30 years! Having him as a reviewer is
+an exciting privilege. It has also been extremely humbling...
I must thank my wonderful wife, Miriam, for her patience through the
many versions of this project, for her proofreading, and for sharing me
-with the computer. I would like to thank my parents for their love,
-and for the grace with which they raised and educated me. Finally, I
-also must acknowledge my gratitude to G-d, for the many opportunities
-He has sent my way, as well as for the gifts He has given me with which
-to take advantage of those opportunities.
+with the computer. I would like to thank my parents for their love, and
+for the grace with which they raised and educated me. Finally, I also
+must acknowledge my gratitude to G-d, for the many opportunities He has
+sent my way, as well as for the gifts He has given me with which to take
+advantage of those opportunities.
Arnold Robbins
@@ -1383,25 +1378,25 @@ February 2015
File: gawk.info, Node: Getting Started, Next: Invoking Gawk, Prev: Preface,
Up: Top
-1 Getting Started with `awk'
+1 Getting Started with 'awk'
****************************
-The basic function of `awk' is to search files for lines (or other
-units of text) that contain certain patterns. When a line matches one
-of the patterns, `awk' performs specified actions on that line. `awk'
-continues to process input lines in this way until it reaches the end
-of the input files.
+The basic function of 'awk' is to search files for lines (or other units
+of text) that contain certain patterns. When a line matches one of the
+patterns, 'awk' performs specified actions on that line. 'awk'
+continues to process input lines in this way until it reaches the end of
+the input files.
- Programs in `awk' are different from programs in most other
-languages, because `awk' programs are "data driven" (i.e., you describe
+ Programs in 'awk' are different from programs in most other
+languages, because 'awk' programs are "data driven" (i.e., you describe
the data you want to work with and then what to do when you find it).
Most other languages are "procedural"; you have to describe, in great
detail, every step the program should take. When working with
procedural languages, it is usually much harder to clearly describe the
-data your program will process. For this reason, `awk' programs are
+data your program will process. For this reason, 'awk' programs are
often refreshingly easy to read and write.
- When you run `awk', you specify an `awk' "program" that tells `awk'
+ When you run 'awk', you specify an 'awk' "program" that tells 'awk'
what to do. The program consists of a series of "rules" (it may also
contain "function definitions", an advanced feature that we will ignore
for now; *note User-defined::). Each rule specifies one pattern to
@@ -1409,7 +1404,7 @@ search for and one action to perform upon finding the
pattern.
Syntactically, a rule consists of a "pattern" followed by an
"action". The action is enclosed in braces to separate it from the
-pattern. Newlines usually separate rules. Therefore, an `awk' program
+pattern. Newlines usually separate rules. Therefore, an 'awk' program
looks like this:
PATTERN { ACTION }
@@ -1418,9 +1413,9 @@ looks like this:
* Menu:
-* Running gawk:: How to run `gawk' programs; includes
+* Running gawk:: How to run 'gawk' programs; includes
command-line syntax.
-* Sample Data Files:: Sample data files for use in the `awk'
+* Sample Data Files:: Sample data files for use in the 'awk'
programs illustrated in this Info file.
* Very Simple:: A very simple example.
* Two Rules:: A less simple one-line example using two
@@ -1428,19 +1423,19 @@ looks like this:
* More Complex:: A more complex example.
* Statements/Lines:: Subdividing or combining statements into
lines.
-* Other Features:: Other Features of `awk'.
-* When:: When to use `gawk' and when to use
+* Other Features:: Other Features of 'awk'.
+* When:: When to use 'gawk' and when to use
other things.
* Intro Summary:: Summary of the introduction.
File: gawk.info, Node: Running gawk, Next: Sample Data Files, Up: Getting
Started
-1.1 How to Run `awk' Programs
+1.1 How to Run 'awk' Programs
=============================
-There are several ways to run an `awk' program. If the program is
-short, it is easiest to include it in the command that runs `awk', like
+There are several ways to run an 'awk' program. If the program is
+short, it is easiest to include it in the command that runs 'awk', like
this:
awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
@@ -1455,42 +1450,42 @@ variations of each.
* Menu:
-* One-shot:: Running a short throwaway `awk'
+* One-shot:: Running a short throwaway 'awk'
program.
* Read Terminal:: Using no input files (input from the keyboard
instead).
-* Long:: Putting permanent `awk' programs in
+* Long:: Putting permanent 'awk' programs in
files.
-* Executable Scripts:: Making self-contained `awk' programs.
-* Comments:: Adding documentation to `gawk'
+* Executable Scripts:: Making self-contained 'awk' programs.
+* Comments:: Adding documentation to 'gawk'
programs.
* Quoting:: More discussion of shell quoting issues.
File: gawk.info, Node: One-shot, Next: Read Terminal, Up: Running gawk
-1.1.1 One-Shot Throwaway `awk' Programs
+1.1.1 One-Shot Throwaway 'awk' Programs
---------------------------------------
-Once you are familiar with `awk', you will often type in simple
-programs the moment you want to use them. Then you can write the
-program as the first argument of the `awk' command, like this:
+Once you are familiar with 'awk', you will often type in simple programs
+the moment you want to use them. Then you can write the program as the
+first argument of the 'awk' command, like this:
awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
-where PROGRAM consists of a series of patterns and actions, as
-described earlier.
+where PROGRAM consists of a series of patterns and actions, as described
+earlier.
- This command format instructs the "shell", or command interpreter,
-to start `awk' and use the PROGRAM to process records in the input
-file(s). There are single quotes around PROGRAM so the shell won't
-interpret any `awk' characters as special shell characters. The quotes
-also cause the shell to treat all of PROGRAM as a single argument for
-`awk', and allow PROGRAM to be more than one line long.
+ This command format instructs the "shell", or command interpreter, to
+start 'awk' and use the PROGRAM to process records in the input file(s).
+There are single quotes around PROGRAM so the shell won't interpret any
+'awk' characters as special shell characters. The quotes also cause the
+shell to treat all of PROGRAM as a single argument for 'awk', and allow
+PROGRAM to be more than one line long.
- This format is also useful for running short or medium-sized `awk'
+ This format is also useful for running short or medium-sized 'awk'
programs from shell scripts, because it avoids the need for a separate
-file for the `awk' program. A self-contained shell script is more
+file for the 'awk' program. A self-contained shell script is more
reliable because there are no other files to misplace.
Later in this chapter, in *note Very Simple::, we'll see examples of
@@ -1499,44 +1494,43 @@ several short, self-contained programs.
File: gawk.info, Node: Read Terminal, Next: Long, Prev: One-shot, Up:
Running gawk
-1.1.2 Running `awk' Without Input Files
+1.1.2 Running 'awk' Without Input Files
---------------------------------------
-You can also run `awk' without any input files. If you type the
+You can also run 'awk' without any input files. If you type the
following command line:
awk 'PROGRAM'
-`awk' applies the PROGRAM to the "standard input", which usually means
+'awk' applies the PROGRAM to the "standard input", which usually means
whatever you type on the keyboard. This continues until you indicate
-end-of-file by typing `Ctrl-d'. (On non-POSIX operating systems, the
+end-of-file by typing 'Ctrl-d'. (On non-POSIX operating systems, the
end-of-file character may be different. For example, on OS/2, it is
-`Ctrl-z'.)
+'Ctrl-z'.)
As an example, the following program prints a friendly piece of
-advice (from Douglas Adams's `The Hitchhiker's Guide to the Galaxy'),
-to keep you from worrying about the complexities of computer
-programming:
+advice (from Douglas Adams's 'The Hitchhiker's Guide to the Galaxy'), to
+keep you from worrying about the complexities of computer programming:
$ awk 'BEGIN { print "Don\47t Panic!" }'
-| Don't Panic!
- `awk' executes statements associated with `BEGIN' before reading any
-input. If there are no other statements in your program, as is the
-case here, `awk' just stops, instead of trying to read input it doesn't
-know how to process. The `\47' is a magic way (explained later) of
-getting a single quote into the program, without having to engage in
-ugly shell quoting tricks.
+ 'awk' executes statements associated with 'BEGIN' before reading any
+input. If there are no other statements in your program, as is the case
+here, 'awk' just stops, instead of trying to read input it doesn't know
+how to process. The '\47' is a magic way (explained later) of getting a
+single quote into the program, without having to engage in ugly shell
+quoting tricks.
- NOTE: If you use Bash as your shell, you should execute the
- command `set +H' before running this program interactively, to
- disable the C shell-style command history, which treats `!' as a
- special character. We recommend putting this command into your
- personal startup file.
+ NOTE: If you use Bash as your shell, you should execute the command
+ 'set +H' before running this program interactively, to disable the
+ C shell-style command history, which treats '!' as a special
+ character. We recommend putting this command into your personal
+ startup file.
- This next simple `awk' program emulates the `cat' utility; it copies
-whatever you type on the keyboard to its standard output (why this
-works is explained shortly):
+ This next simple 'awk' program emulates the 'cat' utility; it copies
+whatever you type on the keyboard to its standard output (why this works
+is explained shortly):
$ awk '{ print }'
Now is the time for all good men
@@ -1555,19 +1549,19 @@ File: gawk.info, Node: Long, Next: Executable
Scripts, Prev: Read Terminal,
1.1.3 Running Long Programs
---------------------------
-Sometimes `awk' programs are very long. In these cases, it is more
+Sometimes 'awk' programs are very long. In these cases, it is more
convenient to put the program into a separate file. In order to tell
-`awk' to use that file for its program, you type:
+'awk' to use that file for its program, you type:
awk -f SOURCE-FILE INPUT-FILE1 INPUT-FILE2 ...
- The `-f' instructs the `awk' utility to get the `awk' program from
+ The '-f' instructs the 'awk' utility to get the 'awk' program from
the file SOURCE-FILE (*note Options::). Any file name can be used for
SOURCE-FILE. For example, you could put the program:
BEGIN { print "Don't Panic!" }
-into the file `advice'. Then this command:
+into the file 'advice'. Then this command:
awk -f advice
@@ -1575,93 +1569,93 @@ does the same thing as this one:
awk 'BEGIN { print "Don\47t Panic!" }'
-This was explained earlier (*note Read Terminal::). Note that you
-don't usually need single quotes around the file name that you specify
-with `-f', because most file names don't contain any of the shell's
-special characters. Notice that in `advice', the `awk' program did not
-have single quotes around it. The quotes are only needed for programs
-that are provided on the `awk' command line. (Also, placing the
-program in a file allows us to use a literal single quote in the program
-text, instead of the magic `\47'.)
+This was explained earlier (*note Read Terminal::). Note that you don't
+usually need single quotes around the file name that you specify with
+'-f', because most file names don't contain any of the shell's special
+characters. Notice that in 'advice', the 'awk' program did not have
+single quotes around it. The quotes are only needed for programs that
+are provided on the 'awk' command line. (Also, placing the program in a
+file allows us to use a literal single quote in the program text,
+instead of the magic '\47'.)
- If you want to clearly identify an `awk' program file as such, you
-can add the extension `.awk' to the file name. This doesn't affect the
-execution of the `awk' program but it does make "housekeeping" easier.
+ If you want to clearly identify an 'awk' program file as such, you
+can add the extension '.awk' to the file name. This doesn't affect the
+execution of the 'awk' program but it does make "housekeeping" easier.
File: gawk.info, Node: Executable Scripts, Next: Comments, Prev: Long, Up:
Running gawk
-1.1.4 Executable `awk' Programs
+1.1.4 Executable 'awk' Programs
-------------------------------
-Once you have learned `awk', you may want to write self-contained `awk'
-scripts, using the `#!' script mechanism. You can do this on many
-systems.(1) For example, you could update the file `advice' to look
+Once you have learned 'awk', you may want to write self-contained 'awk'
+scripts, using the '#!' script mechanism. You can do this on many
+systems.(1) For example, you could update the file 'advice' to look
like this:
#! /bin/awk -f
BEGIN { print "Don't Panic!" }
-After making this file executable (with the `chmod' utility), simply
-type `advice' at the shell and the system arranges to run `awk' as if
-you had typed `awk -f advice':
+After making this file executable (with the 'chmod' utility), simply
+type 'advice' at the shell and the system arranges to run 'awk' as if
+you had typed 'awk -f advice':
$ chmod +x advice
$ advice
-| Don't Panic!
(We assume you have the current directory in your shell's search path
-variable [typically `$PATH']. If not, you may need to type `./advice'
+variable [typically '$PATH']. If not, you may need to type './advice'
at the shell.)
- Self-contained `awk' scripts are useful when you want to write a
+ Self-contained 'awk' scripts are useful when you want to write a
program that users can invoke without their having to know that the
-program is written in `awk'.
+program is written in 'awk'.
- Understanding `#!'
+ Understanding '#!'
- `awk' is an "interpreted" language. This means that the `awk'
-utility reads your program and then processes your data according to
-the instructions in your program. (This is different from a "compiled"
+ 'awk' is an "interpreted" language. This means that the 'awk'
+utility reads your program and then processes your data according to the
+instructions in your program. (This is different from a "compiled"
language such as C, where your program is first compiled into machine
-code that is executed directly by your system's processor.) The `awk'
+code that is executed directly by your system's processor.) The 'awk'
utility is thus termed an "interpreter". Many modern languages are
interpreted.
- The line beginning with `#!' lists the full file name of an
+ The line beginning with '#!' lists the full file name of an
interpreter to run and a single optional initial command-line argument
to pass to that interpreter. The operating system then runs the
interpreter with the given argument and the full argument list of the
executed program. The first argument in the list is the full file name
-of the `awk' program. The rest of the argument list contains either
-options to `awk', or data files, or both. (Note that on many systems
-`awk' may be found in `/usr/bin' instead of in `/bin'.)
+of the 'awk' program. The rest of the argument list contains either
+options to 'awk', or data files, or both. (Note that on many systems
+'awk' may be found in '/usr/bin' instead of in '/bin'.)
Some systems limit the length of the interpreter name to 32
characters. Often, this can be dealt with by using a symbolic link.
- You should not put more than one argument on the `#!' line after the
-path to `awk'. It does not work. The operating system treats the rest
-of the line as a single argument and passes it to `awk'. Doing this
-leads to confusing behavior--most likely a usage diagnostic of some
-sort from `awk'.
+ You should not put more than one argument on the '#!' line after the
+path to 'awk'. It does not work. The operating system treats the rest
+of the line as a single argument and passes it to 'awk'. Doing this
+leads to confusing behavior--most likely a usage diagnostic of some sort
+from 'awk'.
- Finally, the value of `ARGV[0]' (*note Built-in Variables::) varies
-depending upon your operating system. Some systems put `awk' there,
-some put the full pathname of `awk' (such as `/bin/awk'), and some put
-the name of your script (`advice'). (d.c.) Don't rely on the value of
-`ARGV[0]' to provide your script name.
+ Finally, the value of 'ARGV[0]' (*note Built-in Variables::) varies
+depending upon your operating system. Some systems put 'awk' there,
+some put the full pathname of 'awk' (such as '/bin/awk'), and some put
+the name of your script ('advice'). (d.c.) Don't rely on the value of
+'ARGV[0]' to provide your script name.
---------- Footnotes ----------
- (1) The `#!' mechanism works on GNU/Linux systems, BSD-based
-systems, and commercial Unix systems.
+ (1) The '#!' mechanism works on GNU/Linux systems, BSD-based systems,
+and commercial Unix systems.
File: gawk.info, Node: Comments, Next: Quoting, Prev: Executable Scripts,
Up: Running gawk
-1.1.5 Comments in `awk' Programs
+1.1.5 Comments in 'awk' Programs
--------------------------------
A "comment" is some text that is included in a program for the sake of
@@ -1670,30 +1664,30 @@ Comments can explain what the program does and how it
works. Nearly all
programming languages have provisions for comments, as programs are
typically hard to understand without them.
- In the `awk' language, a comment starts with the number sign
-character (`#') and continues to the end of the line. The `#' does not
-have to be the first character on the line. The `awk' language ignores
+ In the 'awk' language, a comment starts with the number sign
+character ('#') and continues to the end of the line. The '#' does not
+have to be the first character on the line. The 'awk' language ignores
the rest of a line following a number sign. For example, we could have
-put the following into `advice':
+put the following into 'advice':
# This program prints a nice, friendly message. It helps
# keep novice users from being afraid of the computer.
BEGIN { print "Don't Panic!" }
- You can put comment lines into keyboard-composed throwaway `awk'
+ You can put comment lines into keyboard-composed throwaway 'awk'
programs, but this usually isn't very useful; the purpose of a comment
is to help you or another person understand the program when reading it
at a later time.
- CAUTION: As mentioned in *note One-shot::, you can enclose short
- to medium-sized programs in single quotes, in order to keep your
- shell scripts self-contained. When doing so, _don't_ put an
- apostrophe (i.e., a single quote) into a comment (or anywhere else
- in your program). The shell interprets the quote as the closing
- quote for the entire program. As a result, usually the shell
- prints a message about mismatched quotes, and if `awk' actually
- runs, it will probably print strange messages about syntax errors.
- For example, look at the following:
+ CAUTION: As mentioned in *note One-shot::, you can enclose short to
+ medium-sized programs in single quotes, in order to keep your shell
+ scripts self-contained. When doing so, _don't_ put an apostrophe
+ (i.e., a single quote) into a comment (or anywhere else in your
+ program). The shell interprets the quote as the closing quote for
+ the entire program. As a result, usually the shell prints a
+ message about mismatched quotes, and if 'awk' actually runs, it
+ will probably print strange messages about syntax errors. For
+ example, look at the following:
$ awk 'BEGIN { print "hello" } # let's be cute'
>
@@ -1701,14 +1695,14 @@ at a later time.
The shell sees that the first two quotes match, and that a new
quoted object begins at the end of the command line. It therefore
prompts with the secondary prompt, waiting for more input. With
- Unix `awk', closing the quoted string produces this result:
+ Unix 'awk', closing the quoted string produces this result:
$ awk '{ print "hello" } # let's be cute'
> '
- error--> awk: can't open file be
- error--> source line number 1
+ error-> awk: can't open file be
+ error-> source line number 1
- Putting a backslash before the single quote in `let's' wouldn't
+ Putting a backslash before the single quote in 'let's' wouldn't
help, because backslashes are not special inside single quotes.
The next node describes the shell's quoting rules.
@@ -1722,11 +1716,11 @@ File: gawk.info, Node: Quoting, Prev: Comments, Up:
Running gawk
* DOS Quoting:: Quoting in Windows Batch Files.
- For short to medium-length `awk' programs, it is most convenient to
-enter the program on the `awk' command line. This is best done by
-enclosing the entire program in single quotes. This is true whether
-you are entering the program interactively at the shell prompt, or
-writing it as part of a larger shell script:
+For short to medium-length 'awk' programs, it is most convenient to
+enter the program on the 'awk' command line. This is best done by
+enclosing the entire program in single quotes. This is true whether you
+are entering the program interactively at the shell prompt, or writing
+it as part of a larger shell script:
awk 'PROGRAM TEXT' INPUT-FILE1 INPUT-FILE2 ...
@@ -1739,16 +1733,16 @@ Shell). If you use the C shell, you're on your own.
throughout this Info file, which is that of the "null", or empty,
string.
- The null string is character data that has no value. In other
-words, it is empty. It is written in `awk' programs like this: `""'.
-In the shell, it can be written using single or double quotes: `""' or
-`'''. Although the null string has no characters in it, it does exist.
-For example, consider this command:
+ The null string is character data that has no value. In other words,
+it is empty. It is written in 'awk' programs like this: '""'. In the
+shell, it can be written using single or double quotes: '""' or ''''.
+Although the null string has no characters in it, it does exist. For
+example, consider this command:
$ echo ""
-Here, the `echo' utility receives a single argument, even though that
-argument has no characters in it. In the rest of this Info file, we use
+Here, the 'echo' utility receives a single argument, even though that
+argument has no characters in it. In the rest of this Info file, we use
the terms "null string" and "empty string" interchangeably. Now, on to
the quoting rules:
@@ -1756,15 +1750,15 @@ the quoting rules:
with other quoted items. The shell turns everything into one
argument for the command.
- * Preceding any single character with a backslash (`\') quotes that
+ * Preceding any single character with a backslash ('\') quotes that
character. The shell removes the backslash and passes the quoted
character on to the command.
* Single quotes protect everything between the opening and closing
quotes. The shell does no interpretation of the quoted text,
- passing it on verbatim to the command. It is _impossible_ to
- embed a single quote inside single-quoted text. Refer back to
- *note Comments::, for an example of what happens if you try.
+ passing it on verbatim to the command. It is _impossible_ to embed
+ a single quote inside single-quoted text. Refer back to *note
+ Comments::, for an example of what happens if you try.
* Double quotes protect most things between the opening and closing
quotes. The shell does at least variable and command substitution
@@ -1773,9 +1767,9 @@ the quoting rules:
Because certain characters within double-quoted text are processed
by the shell, they must be "escaped" within the text. Of note are
- the characters `$', ``', `\', and `"', all of which must be
- preceded by a backslash within double-quoted text if they are to
- be passed on literally to the program. (The leading backslash is
+ the characters '$', '`', '\', and '"', all of which must be
+ preceded by a backslash within double-quoted text if they are to be
+ passed on literally to the program. (The leading backslash is
stripped first.) Thus, the example seen in *note Read Terminal:::
awk 'BEGIN { print "Don\47t Panic!" }'
@@ -1789,7 +1783,7 @@ the quoting rules:
* Null strings are removed when they occur as part of a non-null
command-line argument, while explicit null objects are kept. For
- example, to specify that the field separator `FS' should be set to
+ example, to specify that the field separator 'FS' should be set to
the null string, use:
awk -F "" 'PROGRAM' FILES # correct
@@ -1798,8 +1792,8 @@ the quoting rules:
awk -F"" 'PROGRAM' FILES # wrong!
- In the second case, `awk' attempts to use the text of the program
- as the value of `FS', and the first file name as the text of the
+ In the second case, 'awk' attempts to use the text of the program
+ as the value of 'FS', and the first file name as the text of the
program! This results in syntax errors at best, and confusing
behavior at worst.
@@ -1820,17 +1814,17 @@ and the third are single-quoted, and the second is
double-quoted.
Judge for yourself which of these two is the more readable.
Another option is to use double quotes, escaping the embedded,
-`awk'-level double quotes:
+'awk'-level double quotes:
$ awk "BEGIN { print \"Here is a single quote <'>\" }"
-| Here is a single quote <'>
This option is also painful, because double quotes, backslashes, and
-dollar signs are very common in more advanced `awk' programs.
+dollar signs are very common in more advanced 'awk' programs.
- A third option is to use the octal escape sequence equivalents
-(*note Escape Sequences::) for the single- and double-quote characters,
-like so:
+ A third option is to use the octal escape sequence equivalents (*note
+Escape Sequences::) for the single- and double-quote characters, like
+so:
$ awk 'BEGIN { print "Here is a single quote <\47>" }'
-| Here is a single quote <'>
@@ -1845,10 +1839,10 @@ this:
$ awk -v sq="'" 'BEGIN { print "Here is a single quote <" sq ">" }'
-| Here is a single quote <'>
- (Here, the two string constants and the value of `sq' are
-concatenated into a single string that is printed by `print'.)
+ (Here, the two string constants and the value of 'sq' are
+concatenated into a single string that is printed by 'print'.)
- If you really need both single and double quotes in your `awk'
+ If you really need both single and double quotes in your 'awk'
program, it is probably best to move it into a separate file, where the
shell won't be part of the picture and you can say what you mean.
@@ -1877,18 +1871,18 @@ File: gawk.info, Node: Sample Data Files, Next: Very
Simple, Prev: Running ga
===============================
Many of the examples in this Info file take their input from two sample
-data files. The first, `mail-list', represents a list of peoples' names
+data files. The first, 'mail-list', represents a list of peoples' names
together with their email addresses and information about those people.
-The second data file, called `inventory-shipped', contains information
+The second data file, called 'inventory-shipped', contains information
about monthly shipments. In both files, each line is considered to be
one "record".
- In `mail-list', each record contains the name of a person, his/her
+ In 'mail-list', each record contains the name of a person, his/her
phone number, his/her email address, and a code for his/her relationship
with the author of the list. The columns are aligned using spaces. An
-`A' in the last column means that the person is an acquaintance. An
-`F' in the last column means that the person is a friend. An `R' means
-that the person is a relative:
+'A' in the last column means that the person is an acquaintance. An 'F'
+in the last column means that the person is a friend. An 'R' means that
+the person is a relative:
Amelia 555-5553 address@hidden F
Anthony 555-3412 address@hidden A
@@ -1902,7 +1896,7 @@ that the person is a relative:
Samuel 555-3430 address@hidden A
Jean-Paul 555-2127 address@hidden R
- The data file `inventory-shipped' represents information about
+ The data file 'inventory-shipped' represents information about
shipments during the year. Each record contains the month, the number
of green crates shipped, the number of red boxes shipped, the number of
orange bags shipped, and the number of blue packages shipped,
@@ -1928,8 +1922,8 @@ the data for the two years:
Mar 24 75 70 495
Apr 21 70 74 514
- The sample files are included in the `gawk' distribution, in the
-directory `awklib/eg/data'.
+ The sample files are included in the 'gawk' distribution, in the
+directory 'awklib/eg/data'.
File: gawk.info, Node: Very Simple, Next: Two Rules, Prev: Sample Data
Files, Up: Getting Started
@@ -1937,23 +1931,23 @@ File: gawk.info, Node: Very Simple, Next: Two Rules,
Prev: Sample Data Files,
1.3 Some Simple Examples
========================
-The following command runs a simple `awk' program that searches the
-input file `mail-list' for the character string `li' (a grouping of
+The following command runs a simple 'awk' program that searches the
+input file 'mail-list' for the character string 'li' (a grouping of
characters is usually called a "string"; the term "string" is based on
similar usage in English, such as "a string of pearls" or "a string of
cars in a train"):
awk '/li/ { print $0 }' mail-list
-When lines containing `li' are found, they are printed because
-`print $0' means print the current line. (Just `print' by itself means
-the same thing, so we could have written that instead.)
+When lines containing 'li' are found, they are printed because 'print $0'
+means print the current line. (Just 'print' by itself means the same
+thing, so we could have written that instead.)
- You will notice that slashes (`/') surround the string `li' in the
-`awk' program. The slashes indicate that `li' is the pattern to search
+ You will notice that slashes ('/') surround the string 'li' in the
+'awk' program. The slashes indicate that 'li' is the pattern to search
for. This type of pattern is called a "regular expression", which is
covered in more detail later (*note Regexp::). The pattern is allowed
-to match parts of words. There are single quotes around the `awk'
+to match parts of words. There are single quotes around the 'awk'
program so that the shell won't interpret any of it as special shell
characters.
@@ -1965,29 +1959,28 @@ characters.
-| Julie 555-6699 address@hidden F
-| Samuel 555-3430 address@hidden A
- In an `awk' rule, either the pattern or the action can be omitted,
+ In an 'awk' rule, either the pattern or the action can be omitted,
but not both. If the pattern is omitted, then the action is performed
-for _every_ input line. If the action is omitted, the default action
-is to print all lines that match the pattern.
-
- Thus, we could leave out the action (the `print' statement and the
-braces) in the previous example and the result would be the same: `awk'
-prints all lines matching the pattern `li'. By comparison, omitting
-the `print' statement but retaining the braces makes an empty action
-that does nothing (i.e., no lines are printed).
-
- Many practical `awk' programs are just a line or two long.
-Following is a collection of useful, short programs to get you started.
-Some of these programs contain constructs that haven't been covered
-yet. (The description of the program will give you a good idea of what
-is going on, but you'll need to read the rest of the Info file to
-become an `awk' expert!) Most of the examples use a data file named
-`data'. This is just a placeholder; if you use these programs
-yourself, substitute your own file names for `data'. For future
-reference, note that there is often more than one way to do things in
-`awk'. At some point, you may want to look back at these examples and
-see if you can come up with different ways to do the same things shown
-here:
+for _every_ input line. If the action is omitted, the default action is
+to print all lines that match the pattern.
+
+ Thus, we could leave out the action (the 'print' statement and the
+braces) in the previous example and the result would be the same: 'awk'
+prints all lines matching the pattern 'li'. By comparison, omitting the
+'print' statement but retaining the braces makes an empty action that
+does nothing (i.e., no lines are printed).
+
+ Many practical 'awk' programs are just a line or two long. Following
+is a collection of useful, short programs to get you started. Some of
+these programs contain constructs that haven't been covered yet. (The
+description of the program will give you a good idea of what is going
+on, but you'll need to read the rest of the Info file to become an 'awk'
+expert!) Most of the examples use a data file named 'data'. This is
+just a placeholder; if you use these programs yourself, substitute your
+own file names for 'data'. For future reference, note that there is
+often more than one way to do things in 'awk'. At some point, you may
+want to look back at these examples and see if you can come up with
+different ways to do the same things shown here:
* Print every line that is longer than 80 characters:
@@ -2001,16 +1994,16 @@ here:
awk '{ if (length($0) > max) max = length($0) }
END { print max }' data
- The code associated with `END' executes after all input has been
- read; it's the other side of the coin to `BEGIN'.
+ The code associated with 'END' executes after all input has been
+ read; it's the other side of the coin to 'BEGIN'.
- * Print the length of the longest line in `data':
+ * Print the length of the longest line in 'data':
expand data | awk '{ if (x < length($0)) x = length($0) }
END { print "maximum line length is " x }'
This example differs slightly from the previous one: the input is
- processed by the `expand' utility to change TABs into spaces, so
+ processed by the 'expand' utility to change TABs into spaces, so
the widths compared are actually the right-margin columns, as
opposed to the number of input characters on each line.
@@ -2049,8 +2042,8 @@ here:
awk 'NR % 2 == 0' data
- If you used the expression `NR % 2 == 1' instead, the program
- would print the odd-numbered lines.
+ If you used the expression 'NR % 2 == 1' instead, the program would
+ print the odd-numbered lines.
File: gawk.info, Node: Two Rules, Next: More Complex, Prev: Very Simple,
Up: Getting Started
@@ -2058,31 +2051,31 @@ File: gawk.info, Node: Two Rules, Next: More Complex,
Prev: Very Simple, Up:
1.4 An Example with Two Rules
=============================
-The `awk' utility reads the input files one line at a time. For each
-line, `awk' tries the patterns of each rule. If several patterns
-match, then several actions execute in the order in which they appear
-in the `awk' program. If no patterns match, then no actions run.
+The 'awk' utility reads the input files one line at a time. For each
+line, 'awk' tries the patterns of each rule. If several patterns match,
+then several actions execute in the order in which they appear in the
+'awk' program. If no patterns match, then no actions run.
- After processing all the rules that match the line (and perhaps
-there are none), `awk' reads the next line. (However, *note Next
-Statement::, and also *note Nextfile Statement::.) This continues
-until the program reaches the end of the file. For example, the
-following `awk' program contains two rules:
+ After processing all the rules that match the line (and perhaps there
+are none), 'awk' reads the next line. (However, *note Next Statement::,
+and also *note Nextfile Statement::.) This continues until the program
+reaches the end of the file. For example, the following 'awk' program
+contains two rules:
/12/ { print $0 }
/21/ { print $0 }
-The first rule has the string `12' as the pattern and `print $0' as the
-action. The second rule has the string `21' as the pattern and also
-has `print $0' as the action. Each rule's action is enclosed in its
-own pair of braces.
+The first rule has the string '12' as the pattern and 'print $0' as the
+action. The second rule has the string '21' as the pattern and also has
+'print $0' as the action. Each rule's action is enclosed in its own
+pair of braces.
- This program prints every line that contains the string `12' _or_
-the string `21'. If a line contains both strings, it is printed twice,
-once by each rule.
+ This program prints every line that contains the string '12' _or_ the
+string '21'. If a line contains both strings, it is printed twice, once
+by each rule.
This is what happens if we run this program on our two sample data
-files, `mail-list' and `inventory-shipped':
+files, 'mail-list' and 'inventory-shipped':
$ awk '/12/ { print $0 }
> /21/ { print $0 }' mail-list inventory-shipped
@@ -2094,7 +2087,7 @@ files, `mail-list' and `inventory-shipped':
-| Jan 21 36 64 620
-| Apr 21 70 74 514
-Note how the line beginning with `Jean-Paul' in `mail-list' was printed
+Note how the line beginning with 'Jean-Paul' in 'mail-list' was printed
twice, once for each rule.
@@ -2104,7 +2097,7 @@ File: gawk.info, Node: More Complex, Next:
Statements/Lines, Prev: Two Rules,
==========================
Now that we've mastered some simple tasks, let's look at what typical
-`awk' programs do. This example shows how `awk' can be used to
+'awk' programs do. This example shows how 'awk' can be used to
summarize, select, and rearrange the output of another utility. It uses
features that haven't been covered yet, so don't worry if you don't
understand all the details:
@@ -2114,9 +2107,9 @@ understand all the details:
This command prints the total number of bytes in all the files in the
current directory that were last modified in November (of any year).
-The `ls -l' part of this example is a system command that gives you a
+The 'ls -l' part of this example is a system command that gives you a
listing of the files in a directory, including each file's size and the
-date the file was last modified. Its output looks like this:
+date the file was last modified. Its output looks like this:
-rw-r--r-- 1 arnold user 1933 Nov 7 13:05 Makefile
-rw-r--r-- 1 arnold user 10809 Nov 7 13:03 awk.h
@@ -2128,46 +2121,46 @@ date the file was last modified. Its output looks like
this:
-rw-r--r-- 1 arnold user 7989 Nov 7 13:03 awk4.c
The first field contains read-write permissions, the second field
-contains the number of links to the file, and the third field
-identifies the file's owner. The fourth field identifies the file's
-group. The fifth field contains the file's size in bytes. The sixth,
-seventh, and eighth fields contain the month, day, and time,
-respectively, that the file was last modified. Finally, the ninth field
-contains the file name.
-
- The `$6 == "Nov"' in our `awk' program is an expression that tests
-whether the sixth field of the output from `ls -l' matches the string
-`Nov'. Each time a line has the string `Nov' for its sixth field,
-`awk' performs the action `sum += $5'. This adds the fifth field (the
-file's size) to the variable `sum'. As a result, when `awk' has
-finished reading all the input lines, `sum' is the total of the sizes
-of the files whose lines matched the pattern. (This works because
-`awk' variables are automatically initialized to zero.)
-
- After the last line of output from `ls' has been processed, the
-`END' rule executes and prints the value of `sum'. In this example,
-the value of `sum' is 80600.
-
- These more advanced `awk' techniques are covered in later sections
+contains the number of links to the file, and the third field identifies
+the file's owner. The fourth field identifies the file's group. The
+fifth field contains the file's size in bytes. The sixth, seventh, and
+eighth fields contain the month, day, and time, respectively, that the
+file was last modified. Finally, the ninth field contains the file
+name.
+
+ The '$6 == "Nov"' in our 'awk' program is an expression that tests
+whether the sixth field of the output from 'ls -l' matches the string
+'Nov'. Each time a line has the string 'Nov' for its sixth field, 'awk'
+performs the action 'sum += $5'. This adds the fifth field (the file's
+size) to the variable 'sum'. As a result, when 'awk' has finished
+reading all the input lines, 'sum' is the total of the sizes of the
+files whose lines matched the pattern. (This works because 'awk'
+variables are automatically initialized to zero.)
+
+ After the last line of output from 'ls' has been processed, the 'END'
+rule executes and prints the value of 'sum'. In this example, the value
+of 'sum' is 80600.
+
+ These more advanced 'awk' techniques are covered in later sections
(*note Action Overview::). Before you can move on to more advanced
-`awk' programming, you have to know how `awk' interprets your input and
-displays your output. By manipulating fields and using `print'
+'awk' programming, you have to know how 'awk' interprets your input and
+displays your output. By manipulating fields and using 'print'
statements, you can produce some very useful and impressive-looking
reports.
File: gawk.info, Node: Statements/Lines, Next: Other Features, Prev: More
Complex, Up: Getting Started
-1.6 `awk' Statements Versus Lines
+1.6 'awk' Statements Versus Lines
=================================
-Most often, each line in an `awk' program is a separate statement or
+Most often, each line in an 'awk' program is a separate statement or
separate rule, like this:
awk '/12/ { print $0 }
/21/ { print $0 }' mail-list inventory-shipped
- However, `gawk' ignores newlines after any of the following symbols
+ However, 'gawk' ignores newlines after any of the following symbols
and keywords:
, { ? : || && do else
@@ -2176,7 +2169,7 @@ A newline at any other point is considered the end of the
statement.(1)
If you would like to split a single statement into two lines at a
point where a newline would terminate it, you can "continue" it by
-ending the first line with a backslash character (`\'). The backslash
+ending the first line with a backslash character ('\'). The backslash
must be the final character on the line in order to be recognized as a
continuation character. A backslash is allowed anywhere in the
statement, even in the middle of a string or regular expression. For
@@ -2186,27 +2179,26 @@ example:
on the next line/ { print $1 }'
We have generally not used backslash continuation in our sample
-programs. `gawk' places no limit on the length of a line, so backslash
+programs. 'gawk' places no limit on the length of a line, so backslash
continuation is never strictly necessary; it just makes programs more
readable. For this same reason, as well as for clarity, we have kept
most statements short in the programs presented throughout the Info
-file. Backslash continuation is most useful when your `awk' program is
-in a separate source file instead of entered from the command line.
-You should also note that many `awk' implementations are more
-particular about where you may use backslash continuation. For example,
-they may not allow you to split a string constant using backslash
-continuation. Thus, for maximum portability of your `awk' programs, it
-is best not to split your lines in the middle of a regular expression
-or a string.
+file. Backslash continuation is most useful when your 'awk' program is
+in a separate source file instead of entered from the command line. You
+should also note that many 'awk' implementations are more particular
+about where you may use backslash continuation. For example, they may
+not allow you to split a string constant using backslash continuation.
+Thus, for maximum portability of your 'awk' programs, it is best not to
+split your lines in the middle of a regular expression or a string.
CAUTION: _Backslash continuation does not work as described with
- the C shell._ It works for `awk' programs in files and for
+ the C shell._ It works for 'awk' programs in files and for
one-shot programs, _provided_ you are using a POSIX-compliant
shell, such as the Unix Bourne shell or Bash. But the C shell
behaves differently! There you must use two backslashes in a row,
followed by a newline. Note also that when using the C shell,
- _every_ newline in your `awk' program must be escaped with a
- backslash. To illustrate:
+ _every_ newline in your 'awk' program must be escaped with a
+ backslash. To illustrate:
% awk 'BEGIN { \
? print \\
@@ -2214,8 +2206,8 @@ or a string.
? }'
-| hello, world
- Here, the `%' and `?' are the C shell's primary and secondary
- prompts, analogous to the standard shell's `$' and `>'.
+ Here, the '%' and '?' are the C shell's primary and secondary
+ prompts, analogous to the standard shell's '$' and '>'.
Compare the previous example to how it is done with a
POSIX-compliant shell:
@@ -2226,101 +2218,101 @@ or a string.
> }'
-| hello, world
- `awk' is a line-oriented language. Each rule's action has to begin
+ 'awk' is a line-oriented language. Each rule's action has to begin
on the same line as the pattern. To have the pattern and action on
-separate lines, you _must_ use backslash continuation; there is no
-other option.
+separate lines, you _must_ use backslash continuation; there is no other
+option.
Another thing to keep in mind is that backslash continuation and
-comments do not mix. As soon as `awk' sees the `#' that starts a
-comment, it ignores _everything_ on the rest of the line. For example:
+comments do not mix. As soon as 'awk' sees the '#' that starts a
+comment, it ignores _everything_ on the rest of the line. For example:
$ gawk 'BEGIN { print "dont panic" # a friendly \
> BEGIN rule
> }'
- error--> gawk: cmd. line:2: BEGIN rule
- error--> gawk: cmd. line:2: ^ syntax error
+ error-> gawk: cmd. line:2: BEGIN rule
+ error-> gawk: cmd. line:2: ^ syntax error
In this case, it looks like the backslash would continue the comment
-onto the next line. However, the backslash-newline combination is never
-even noticed because it is "hidden" inside the comment. Thus, the
-`BEGIN' is noted as a syntax error.
+onto the next line. However, the backslash-newline combination is never
+even noticed because it is "hidden" inside the comment. Thus, the
+'BEGIN' is noted as a syntax error.
- When `awk' statements within one rule are short, you might want to
-put more than one of them on a line. This is accomplished by
-separating the statements with a semicolon (`;'). This also applies to
-the rules themselves. Thus, the program shown at the start of this
-minor node could also be written this way:
+ When 'awk' statements within one rule are short, you might want to
+put more than one of them on a line. This is accomplished by separating
+the statements with a semicolon (';'). This also applies to the rules
+themselves. Thus, the program shown at the start of this minor node
+could also be written this way:
/12/ { print $0 } ; /21/ { print $0 }
NOTE: The requirement that states that rules on the same line must
- be separated with a semicolon was not in the original `awk'
+ be separated with a semicolon was not in the original 'awk'
language; it was added for consistency with the treatment of
statements within an action.
---------- Footnotes ----------
- (1) The `?' and `:' referred to here is the three-operand
-conditional expression described in *note Conditional Exp::. Splitting
-lines after `?' and `:' is a minor `gawk' extension; if `--posix' is
-specified (*note Options::), then this extension is disabled.
+ (1) The '?' and ':' referred to here is the three-operand conditional
+expression described in *note Conditional Exp::. Splitting lines after
+'?' and ':' is a minor 'gawk' extension; if '--posix' is specified
+(*note Options::), then this extension is disabled.
File: gawk.info, Node: Other Features, Next: When, Prev: Statements/Lines,
Up: Getting Started
-1.7 Other Features of `awk'
+1.7 Other Features of 'awk'
===========================
-The `awk' language provides a number of predefined, or "built-in",
-variables that your programs can use to get information from `awk'.
+The 'awk' language provides a number of predefined, or "built-in",
+variables that your programs can use to get information from 'awk'.
There are other variables your program can set as well to control how
-`awk' processes your data.
+'awk' processes your data.
- In addition, `awk' provides a number of built-in functions for doing
-common computational and string-related operations. `gawk' provides
+ In addition, 'awk' provides a number of built-in functions for doing
+common computational and string-related operations. 'gawk' provides
built-in functions for working with timestamps, performing bit
manipulation, for runtime string translation (internationalization),
determining the type of a variable, and array sorting.
- As we develop our presentation of the `awk' language, we will
-introduce most of the variables and many of the functions. They are
+ As we develop our presentation of the 'awk' language, we will
+introduce most of the variables and many of the functions. They are
described systematically in *note Built-in Variables::, and in *note
Built-in::.
File: gawk.info, Node: When, Next: Intro Summary, Prev: Other Features,
Up: Getting Started
-1.8 When to Use `awk'
+1.8 When to Use 'awk'
=====================
-Now that you've seen some of what `awk' can do, you might wonder how
-`awk' could be useful for you. By using utility programs, advanced
+Now that you've seen some of what 'awk' can do, you might wonder how
+'awk' could be useful for you. By using utility programs, advanced
patterns, field separators, arithmetic statements, and other selection
-criteria, you can produce much more complex output. The `awk' language
+criteria, you can produce much more complex output. The 'awk' language
is very useful for producing reports from large amounts of raw data,
such as summarizing information from the output of other utility
-programs like `ls'. (*Note More Complex::.)
+programs like 'ls'. (*Note More Complex::.)
- Programs written with `awk' are usually much smaller than they would
-be in other languages. This makes `awk' programs easy to compose and
-use. Often, `awk' programs can be quickly composed at your keyboard,
-used once, and thrown away. Because `awk' programs are interpreted, you
+ Programs written with 'awk' are usually much smaller than they would
+be in other languages. This makes 'awk' programs easy to compose and
+use. Often, 'awk' programs can be quickly composed at your keyboard,
+used once, and thrown away. Because 'awk' programs are interpreted, you
can avoid the (usually lengthy) compilation part of the typical
edit-compile-test-debug cycle of software development.
- Complex programs have been written in `awk', including a complete
+ Complex programs have been written in 'awk', including a complete
retargetable assembler for eight-bit microprocessors (*note Glossary::,
for more information), and a microcode assembler for a special-purpose
-Prolog computer. The original `awk''s capabilities were strained by
+Prolog computer. The original 'awk''s capabilities were strained by
tasks of such complexity, but modern versions are more capable.
- If you find yourself writing `awk' scripts of more than, say, a few
+ If you find yourself writing 'awk' scripts of more than, say, a few
hundred lines, you might consider using a different programming
language. The shell is good at string and pattern matching; in
-addition, it allows powerful use of the system utilities. Python
-offers a nice balance between high-level ease of programming and access
-to system facilities.(1)
+addition, it allows powerful use of the system utilities. Python offers
+a nice balance between high-level ease of programming and access to
+system facilities.(1)
---------- Footnotes ----------
@@ -2332,53 +2324,53 @@ File: gawk.info, Node: Intro Summary, Prev: When,
Up: Getting Started
1.9 Summary
===========
- * Programs in `awk' consist of PATTERN-ACTION pairs.
+ * Programs in 'awk' consist of PATTERN-ACTION pairs.
* An ACTION without a PATTERN always runs. The default ACTION for a
- pattern without one is `{ print $0 }'.
+ pattern without one is '{ print $0 }'.
- * Use either `awk 'PROGRAM' FILES' or `awk -f PROGRAM-FILE FILES' to
- run `awk'.
+ * Use either 'awk 'PROGRAM' FILES' or 'awk -f PROGRAM-FILE FILES' to
+ run 'awk'.
- * You may use the special `#!' header line to create `awk' programs
+ * You may use the special '#!' header line to create 'awk' programs
that are directly executable.
- * Comments in `awk' programs start with `#' and continue to the end
+ * Comments in 'awk' programs start with '#' and continue to the end
of the same line.
- * Be aware of quoting issues when writing `awk' programs as part of
- a larger shell script (or MS-Windows batch file).
+ * Be aware of quoting issues when writing 'awk' programs as part of a
+ larger shell script (or MS-Windows batch file).
* You may use backslash continuation to continue a source line.
Lines are automatically continued after a comma, open brace,
- question mark, colon, `||', `&&', `do', and `else'.
+ question mark, colon, '||', '&&', 'do', and 'else'.
File: gawk.info, Node: Invoking Gawk, Next: Regexp, Prev: Getting Started,
Up: Top
-2 Running `awk' and `gawk'
+2 Running 'awk' and 'gawk'
**************************
-This major node covers how to run `awk', both POSIX-standard and
-`gawk'-specific command-line options, and what `awk' and `gawk' do with
-nonoption arguments. It then proceeds to cover how `gawk' searches for
-source files, reading standard input along with other files, `gawk''s
-environment variables, `gawk''s exit status, using include files, and
+This major node covers how to run 'awk', both POSIX-standard and
+'gawk'-specific command-line options, and what 'awk' and 'gawk' do with
+nonoption arguments. It then proceeds to cover how 'gawk' searches for
+source files, reading standard input along with other files, 'gawk''s
+environment variables, 'gawk''s exit status, using include files, and
obsolete and undocumented options and/or features.
- Many of the options and features described here are discussed in
-more detail later in the Info file; feel free to skip over things in
-this major node that don't interest you right now.
+ Many of the options and features described here are discussed in more
+detail later in the Info file; feel free to skip over things in this
+major node that don't interest you right now.
* Menu:
-* Command Line:: How to run `awk'.
+* Command Line:: How to run 'awk'.
* Options:: Command-line options and their meanings.
* Other Arguments:: Input file names and variable assignments.
* Naming Standard Input:: How to specify standard input with other
files.
-* Environment Variables:: The environment variables `gawk' uses.
-* Exit Status:: `gawk''s exit status.
+* Environment Variables:: The environment variables 'gawk' uses.
+* Exit Status:: 'gawk''s exit status.
* Include Files:: Including other files into your program.
* Loading Shared Libraries:: Loading shared libraries into your program.
* Obsolete:: Obsolete Options and/or features.
@@ -2388,26 +2380,26 @@ this major node that don't interest you right now.
File: gawk.info, Node: Command Line, Next: Options, Up: Invoking Gawk
-2.1 Invoking `awk'
+2.1 Invoking 'awk'
==================
-There are two ways to run `awk'--with an explicit program or with one
-or more program files. Here are templates for both of them; items
-enclosed in [...] in these templates are optional:
+There are two ways to run 'awk'--with an explicit program or with one or
+more program files. Here are templates for both of them; items enclosed
+in [...] in these templates are optional:
- `awk' [OPTIONS] `-f' PROGFILE [`--'] FILE ...
- `awk' [OPTIONS] [`--'] `'PROGRAM'' FILE ...
+ 'awk' [OPTIONS] '-f' PROGFILE ['--'] FILE ...
+ 'awk' [OPTIONS] ['--'] ''PROGRAM'' FILE ...
- In addition to traditional one-letter POSIX-style options, `gawk'
+ In addition to traditional one-letter POSIX-style options, 'gawk'
also supports GNU long options.
- It is possible to invoke `awk' with an empty program:
+ It is possible to invoke 'awk' with an empty program:
awk '' datafile1 datafile2
-Doing so makes little sense, though; `awk' exits silently when given an
-empty program. (d.c.) If `--lint' has been specified on the command
-line, `gawk' issues a warning that the program is empty.
+Doing so makes little sense, though; 'awk' exits silently when given an
+empty program. (d.c.) If '--lint' has been specified on the command
+line, 'gawk' issues a warning that the program is empty.
File: gawk.info, Node: Options, Next: Other Arguments, Prev: Command Line,
Up: Invoking Gawk
@@ -2419,366 +2411,362 @@ Options begin with a dash and consist of a single
character. GNU-style
long options consist of two dashes and a keyword. The keyword can be
abbreviated, as long as the abbreviation allows the option to be
uniquely identified. If the option takes an argument, either the
-keyword is immediately followed by an equals sign (`=') and the
+keyword is immediately followed by an equals sign ('=') and the
argument's value, or the keyword and the argument's value are separated
by whitespace. If a particular option with a value is given more than
once, it is the last value that counts.
- Each long option for `gawk' has a corresponding POSIX-style short
+ Each long option for 'gawk' has a corresponding POSIX-style short
option. The long and short options are interchangeable in all contexts.
The following list describes options mandated by the POSIX standard:
-`-F FS'
-`--field-separator FS'
- Set the `FS' variable to FS (*note Field Separators::).
+'-F FS'
+'--field-separator FS'
+ Set the 'FS' variable to FS (*note Field Separators::).
-`-f SOURCE-FILE'
-`--file SOURCE-FILE'
- Read the `awk' program source from SOURCE-FILE instead of in the
- first nonoption argument. This option may be given multiple
- times; the `awk' program consists of the concatenation of the
- contents of each specified SOURCE-FILE.
+'-f SOURCE-FILE'
+'--file SOURCE-FILE'
+ Read the 'awk' program source from SOURCE-FILE instead of in the
+ first nonoption argument. This option may be given multiple times;
+ the 'awk' program consists of the concatenation of the contents of
+ each specified SOURCE-FILE.
-`-v VAR=VAL'
-`--assign VAR=VAL'
+'-v VAR=VAL'
+'--assign VAR=VAL'
Set the variable VAR to the value VAL _before_ execution of the
program begins. Such variable values are available inside the
- `BEGIN' rule (*note Other Arguments::).
+ 'BEGIN' rule (*note Other Arguments::).
- The `-v' option can only set one variable, but it can be used more
- than once, setting another variable each time, like this: `awk
- -v foo=1 -v bar=2 ...'.
+ The '-v' option can only set one variable, but it can be used more
+ than once, setting another variable each time, like this: 'awk -v foo=1
+ -v bar=2 ...'.
- CAUTION: Using `-v' to set the values of the built-in
- variables may lead to surprising results. `awk' will reset
+ CAUTION: Using '-v' to set the values of the built-in
+ variables may lead to surprising results. 'awk' will reset
the values of those variables as it needs to, possibly
ignoring any initial value you may have given.
-`-W GAWK-OPT'
+'-W GAWK-OPT'
Provide an implementation-specific option. This is the POSIX
convention for providing implementation-specific options. These
options also have corresponding GNU-style long options. Note that
the long options may be abbreviated, as long as the abbreviations
- remain unique. The full list of `gawk'-specific options is
+ remain unique. The full list of 'gawk'-specific options is
provided next.
-`--'
+'--'
Signal the end of the command-line options. The following
- arguments are not treated as options even if they begin with `-'.
- This interpretation of `--' follows the POSIX argument parsing
+ arguments are not treated as options even if they begin with '-'.
+ This interpretation of '--' follows the POSIX argument parsing
conventions.
- This is useful if you have file names that start with `-', or in
- shell scripts, if you have file names that will be specified by
- the user that could start with `-'. It is also useful for passing
- options on to the `awk' program; see *note Getopt Function::.
+ This is useful if you have file names that start with '-', or in
+ shell scripts, if you have file names that will be specified by the
+ user that could start with '-'. It is also useful for passing
+ options on to the 'awk' program; see *note Getopt Function::.
- The following list describes `gawk'-specific options:
+ The following list describes 'gawk'-specific options:
-`-b'
-`--characters-as-bytes'
- Cause `gawk' to treat all input data as single-byte characters.
- In addition, all output written with `print' or `printf' is
- treated as single-byte characters.
+'-b'
+'--characters-as-bytes'
+ Cause 'gawk' to treat all input data as single-byte characters. In
+ addition, all output written with 'print' or 'printf' is treated as
+ single-byte characters.
- Normally, `gawk' follows the POSIX standard and attempts to process
+ Normally, 'gawk' follows the POSIX standard and attempts to process
its input data according to the current locale (*note Locales::).
This can often involve converting multibyte characters into wide
characters (internally), and can lead to problems or confusion if
- the input data does not contain valid multibyte characters. This
- option is an easy way to tell `gawk', "Hands off my data!"
+ the input data does not contain valid multibyte characters. This
+ option is an easy way to tell 'gawk', "Hands off my data!"
-`-c'
-`--traditional'
+'-c'
+'--traditional'
Specify "compatibility mode", in which the GNU extensions to the
- `awk' language are disabled, so that `gawk' behaves just like BWK
- `awk'. *Note POSIX/GNU::, which summarizes the extensions. Also
+ 'awk' language are disabled, so that 'gawk' behaves just like BWK
+ 'awk'. *Note POSIX/GNU::, which summarizes the extensions. Also
see *note Compatibility Mode::.
-`-C'
-`--copyright'
+'-C'
+'--copyright'
Print the short version of the General Public License and then
exit.
-`-d'[FILE]
-`--dump-variables'[`='FILE]
+'-d'[FILE]
+'--dump-variables'['='FILE]
Print a sorted list of global variables, their types, and final
values to FILE. If no FILE is provided, print this list to a file
- named `awkvars.out' in the current directory. No space is allowed
- between the `-d' and FILE, if FILE is supplied.
+ named 'awkvars.out' in the current directory. No space is allowed
+ between the '-d' and FILE, if FILE is supplied.
Having a list of all global variables is a good way to look for
typographical errors in your programs. You would also use this
- option if you have a large program with a lot of functions, and
- you want to be sure that your functions don't inadvertently use
- global variables that you meant to be local. (This is a
- particularly easy mistake to make with simple variable names like
- `i', `j', etc.)
-
-`-D'[FILE]
-`--debug'[`='FILE]
- Enable debugging of `awk' programs (*note Debugging::). By
+ option if you have a large program with a lot of functions, and you
+ want to be sure that your functions don't inadvertently use global
+ variables that you meant to be local. (This is a particularly easy
+ mistake to make with simple variable names like 'i', 'j', etc.)
+
+'-D'[FILE]
+'--debug'['='FILE]
+ Enable debugging of 'awk' programs (*note Debugging::). By
default, the debugger reads commands interactively from the
keyboard (standard input). The optional FILE argument allows you
to specify a file with a list of commands for the debugger to
- execute noninteractively. No space is allowed between the `-D'
- and FILE, if FILE is supplied.
+ execute noninteractively. No space is allowed between the '-D' and
+ FILE, if FILE is supplied.
-`-e' PROGRAM-TEXT
-`--source' PROGRAM-TEXT
+'-e' PROGRAM-TEXT
+'--source' PROGRAM-TEXT
Provide program source code in the PROGRAM-TEXT. This option
allows you to mix source code in files with source code that you
enter on the command line. This is particularly useful when you
have library functions that you want to use from your command-line
programs (*note AWKPATH Variable::).
-`-E' FILE
-`--exec' FILE
- Similar to `-f', read `awk' program text from FILE. There are two
- differences from `-f':
+'-E' FILE
+'--exec' FILE
+ Similar to '-f', read 'awk' program text from FILE. There are two
+ differences from '-f':
- * This option terminates option processing; anything else on
- the command line is passed on directly to the `awk' program.
+ * This option terminates option processing; anything else on the
+ command line is passed on directly to the 'awk' program.
- * Command-line variable assignments of the form `VAR=VALUE' are
+ * Command-line variable assignments of the form 'VAR=VALUE' are
disallowed.
This option is particularly necessary for World Wide Web CGI
- applications that pass arguments through the URL; using this
- option prevents a malicious (or other) user from passing in
- options, assignments, or `awk' source code (via `-e') to the CGI
- application.(1) This option should be used with `#!' scripts
+ applications that pass arguments through the URL; using this option
+ prevents a malicious (or other) user from passing in options,
+ assignments, or 'awk' source code (via '-e') to the CGI
+ application.(1) This option should be used with '#!' scripts
(*note Executable Scripts::), like so:
#! /usr/local/bin/gawk -E
AWK PROGRAM HERE ...
-`-g'
-`--gen-pot'
- Analyze the source program and generate a GNU `gettext' portable
+'-g'
+'--gen-pot'
+ Analyze the source program and generate a GNU 'gettext' portable
object template file on standard output for all string constants
that have been marked for translation. *Note
Internationalization::, for information about this option.
-`-h'
-`--help'
+'-h'
+'--help'
Print a "usage" message summarizing the short- and long-style
- options that `gawk' accepts and then exit.
-
-`-i' SOURCE-FILE
-`--include' SOURCE-FILE
- Read an `awk' source library from SOURCE-FILE. This option is
- completely equivalent to using the address@hidden' directive inside
- your program. It is very similar to the `-f' option, but there
- are two important differences. First, when `-i' is used, the
- program source is not loaded if it has been previously loaded,
- whereas with `-f', `gawk' always loads the file. Second, because
- this option is intended to be used with code libraries, `gawk'
- does not recognize such files as constituting main program input.
- Thus, after processing an `-i' argument, `gawk' still expects to
- find the main source code via the `-f' option or on the command
- line.
-
-`-l' EXT
-`--load' EXT
- Load a dynamic extension named EXT. Extensions are stored as
+ options that 'gawk' accepts and then exit.
+
+'-i' SOURCE-FILE
+'--include' SOURCE-FILE
+ Read an 'awk' source library from SOURCE-FILE. This option is
+ completely equivalent to using the '@include' directive inside your
+ program. It is very similar to the '-f' option, but there are two
+ important differences. First, when '-i' is used, the program
+ source is not loaded if it has been previously loaded, whereas with
+ '-f', 'gawk' always loads the file. Second, because this option is
+ intended to be used with code libraries, 'gawk' does not recognize
+ such files as constituting main program input. Thus, after
+ processing an '-i' argument, 'gawk' still expects to find the main
+ source code via the '-f' option or on the command line.
+
+'-l' EXT
+'--load' EXT
+ Load a dynamic extension named EXT. Extensions are stored as
system shared libraries. This option searches for the library
- using the `AWKLIBPATH' environment variable. The correct library
+ using the 'AWKLIBPATH' environment variable. The correct library
suffix for your platform will be supplied by default, so it need
not be specified in the extension name. The extension
- initialization routine should be named `dl_load()'. An
- alternative is to use the address@hidden' keyword inside the program to
- load a shared library. This advanced feature is described in
- detail in *note Dynamic Extensions::.
+ initialization routine should be named 'dl_load()'. An alternative
+ is to use the '@load' keyword inside the program to load a shared
+ library. This advanced feature is described in detail in *note
+ Dynamic Extensions::.
-`-L'[VALUE]
-`--lint'[`='VALUE]
+'-L'[VALUE]
+'--lint'['='VALUE]
Warn about constructs that are dubious or nonportable to other
- `awk' implementations. No space is allowed between the `-L' and
- VALUE, if VALUE is supplied. Some warnings are issued when `gawk'
+ 'awk' implementations. No space is allowed between the '-L' and
+ VALUE, if VALUE is supplied. Some warnings are issued when 'gawk'
first reads your program. Others are issued at runtime, as your
- program executes. With an optional argument of `fatal', lint
+ program executes. With an optional argument of 'fatal', lint
warnings become fatal errors. This may be drastic, but its use
- will certainly encourage the development of cleaner `awk' programs.
- With an optional argument of `invalid', only warnings about things
- that are actually invalid are issued. (This is not fully
+ will certainly encourage the development of cleaner 'awk' programs.
+ With an optional argument of 'invalid', only warnings about things
+ that are actually invalid are issued. (This is not fully
implemented yet.)
- Some warnings are only printed once, even if the dubious
- constructs they warn about occur multiple times in your `awk'
- program. Thus, when eliminating problems pointed out by `--lint',
- you should take care to search for all occurrences of each
- inappropriate construct. As `awk' programs are usually short,
- doing so is not burdensome.
-
-`-M'
-`--bignum'
- Force arbitrary-precision arithmetic on numbers. This option has
- no effect if `gawk' is not compiled to use the GNU MPFR and MP
+ Some warnings are only printed once, even if the dubious constructs
+ they warn about occur multiple times in your 'awk' program. Thus,
+ when eliminating problems pointed out by '--lint', you should take
+ care to search for all occurrences of each inappropriate construct.
+ As 'awk' programs are usually short, doing so is not burdensome.
+
+'-M'
+'--bignum'
+ Force arbitrary-precision arithmetic on numbers. This option has
+ no effect if 'gawk' is not compiled to use the GNU MPFR and MP
libraries (*note Arbitrary Precision Arithmetic::).
-`-n'
-`--non-decimal-data'
+'-n'
+'--non-decimal-data'
Enable automatic interpretation of octal and hexadecimal values in
input data (*note Nondecimal Data::).
CAUTION: This option can severely break old programs. Use
with care. Also note that this option may disappear in a
- future version of `gawk'.
+ future version of 'gawk'.
-`-N'
-`--use-lc-numeric'
+'-N'
+'--use-lc-numeric'
Force the use of the locale's decimal point character when parsing
numeric input data (*note Locales::).
-`-o'[FILE]
-`--pretty-print'[`='FILE]
- Enable pretty-printing of `awk' programs. By default, the output
- program is created in a file named `awkprof.out' (*note
+'-o'[FILE]
+'--pretty-print'['='FILE]
+ Enable pretty-printing of 'awk' programs. By default, the output
+ program is created in a file named 'awkprof.out' (*note
Profiling::). The optional FILE argument allows you to specify a
different file name for the output. No space is allowed between
- the `-o' and FILE, if FILE is supplied.
+ the '-o' and FILE, if FILE is supplied.
- NOTE: Due to the way `gawk' has evolved, with this option
- your program still executes. This will change in the next
- major release, such that `gawk' will only pretty-print the
- program and not run it.
+ NOTE: Due to the way 'gawk' has evolved, with this option your
+ program still executes. This will change in the next major
+ release, such that 'gawk' will only pretty-print the program
+ and not run it.
-`-O'
-`--optimize'
+'-O'
+'--optimize'
Enable some optimizations on the internal representation of the
program. At the moment, this includes just simple constant
folding.
-`-p'[FILE]
-`--profile'[`='FILE]
- Enable profiling of `awk' programs (*note Profiling::). By
- default, profiles are created in a file named `awkprof.out'. The
+'-p'[FILE]
+'--profile'['='FILE]
+ Enable profiling of 'awk' programs (*note Profiling::). By
+ default, profiles are created in a file named 'awkprof.out'. The
optional FILE argument allows you to specify a different file name
- for the profile file. No space is allowed between the `-p' and
+ for the profile file. No space is allowed between the '-p' and
FILE, if FILE is supplied.
The profile contains execution counts for each statement in the
program in the left margin, and function call counts for each
function.
-`-P'
-`--posix'
- Operate in strict POSIX mode. This disables all `gawk' extensions
- (just like `--traditional') and disables all extensions not
- allowed by POSIX. *Note Common Extensions::, for a summary of the
- extensions in `gawk' that are disabled by this option. Also, the
+'-P'
+'--posix'
+ Operate in strict POSIX mode. This disables all 'gawk' extensions
+ (just like '--traditional') and disables all extensions not allowed
+ by POSIX. *Note Common Extensions::, for a summary of the
+ extensions in 'gawk' that are disabled by this option. Also, the
following additional restrictions apply:
- * Newlines do not act as whitespace to separate fields when
- `FS' is equal to a single space (*note Fields::).
+ * Newlines do not act as whitespace to separate fields when 'FS'
+ is equal to a single space (*note Fields::).
- * Newlines are not allowed after `?' or `:' (*note Conditional
+ * Newlines are not allowed after '?' or ':' (*note Conditional
Exp::).
- * Specifying `-Ft' on the command line does not set the value
- of `FS' to be a single TAB character (*note Field
- Separators::).
+ * Specifying '-Ft' on the command line does not set the value of
+ 'FS' to be a single TAB character (*note Field Separators::).
* The locale's decimal point character is used for parsing input
data (*note Locales::).
- If you supply both `--traditional' and `--posix' on the command
- line, `--posix' takes precedence. `gawk' issues a warning if both
+ If you supply both '--traditional' and '--posix' on the command
+ line, '--posix' takes precedence. 'gawk' issues a warning if both
options are supplied.
-`-r'
-`--re-interval'
+'-r'
+'--re-interval'
Allow interval expressions (*note Regexp Operators::) in regexps.
- This is now `gawk''s default behavior. Nevertheless, this option
- remains (both for backward compatibility and for use in
- combination with `--traditional').
-
-`-S'
-`--sandbox'
- Disable the `system()' function, input redirections with `getline',
- output redirections with `print' and `printf', and dynamic
- extensions. This is particularly useful when you want to run
- `awk' scripts from questionable sources and need to make sure the
- scripts can't access your system (other than the specified input
- data file).
-
-`-t'
-`--lint-old'
+ This is now 'gawk''s default behavior. Nevertheless, this option
+ remains (both for backward compatibility and for use in combination
+ with '--traditional').
+
+'-S'
+'--sandbox'
+ Disable the 'system()' function, input redirections with 'getline',
+ output redirections with 'print' and 'printf', and dynamic
+ extensions. This is particularly useful when you want to run 'awk'
+ scripts from questionable sources and need to make sure the scripts
+ can't access your system (other than the specified input data
+ file).
+
+'-t'
+'--lint-old'
Warn about constructs that are not available in the original
- version of `awk' from Version 7 Unix (*note V7/SVR3.1::).
+ version of 'awk' from Version 7 Unix (*note V7/SVR3.1::).
-`-V'
-`--version'
- Print version information for this particular copy of `gawk'.
- This allows you to determine if your copy of `gawk' is up to date
- with respect to whatever the Free Software Foundation is currently
+'-V'
+'--version'
+ Print version information for this particular copy of 'gawk'. This
+ allows you to determine if your copy of 'gawk' is up to date with
+ respect to whatever the Free Software Foundation is currently
distributing. It is also useful for bug reports (*note Bugs::).
As long as program text has been supplied, any other options are
flagged as invalid with a warning message but are otherwise ignored.
In compatibility mode, as a special case, if the value of FS supplied
-to the `-F' option is `t', then `FS' is set to the TAB character
-(`"\t"'). This is true only for `--traditional' and not for `--posix'
+to the '-F' option is 't', then 'FS' is set to the TAB character
+('"\t"'). This is true only for '--traditional' and not for '--posix'
(*note Field Separators::).
- The `-f' option may be used more than once on the command line. If
-it is, `awk' reads its program source from all of the named files, as
-if they had been concatenated together into one big file. This is
-useful for creating libraries of `awk' functions. These functions can
-be written once and then retrieved from a standard place, instead of
-having to be included in each individual program. The `-i' option is
-similar in this regard. (As mentioned in *note Definition Syntax::,
-function names must be unique.)
-
- With standard `awk', library functions can still be used, even if
-the program is entered at the keyboard, by specifying `-f /dev/tty'.
-After typing your program, type `Ctrl-d' (the end-of-file character) to
-terminate it. (You may also use `-f -' to read program source from the
+ The '-f' option may be used more than once on the command line. If
+it is, 'awk' reads its program source from all of the named files, as if
+they had been concatenated together into one big file. This is useful
+for creating libraries of 'awk' functions. These functions can be
+written once and then retrieved from a standard place, instead of having
+to be included in each individual program. The '-i' option is similar
+in this regard. (As mentioned in *note Definition Syntax::, function
+names must be unique.)
+
+ With standard 'awk', library functions can still be used, even if the
+program is entered at the keyboard, by specifying '-f /dev/tty'. After
+typing your program, type 'Ctrl-d' (the end-of-file character) to
+terminate it. (You may also use '-f -' to read program source from the
standard input, but then you will not be able to also use the standard
input as a source of data.)
- Because it is clumsy using the standard `awk' mechanisms to mix
-source file and command-line `awk' programs, `gawk' provides the `-e'
+ Because it is clumsy using the standard 'awk' mechanisms to mix
+source file and command-line 'awk' programs, 'gawk' provides the '-e'
option. This does not require you to preempt the standard input for
your source code; it allows you to easily mix command-line and library
-source code (*note AWKPATH Variable::). As with `-f', the `-e' and `-i'
+source code (*note AWKPATH Variable::). As with '-f', the '-e' and '-i'
options may also be used multiple times on the command line.
- If no `-f' or `-e' option is specified, then `gawk' uses the first
+ If no '-f' or '-e' option is specified, then 'gawk' uses the first
nonoption command-line argument as the text of the program source code.
- If the environment variable `POSIXLY_CORRECT' exists, then `gawk'
-behaves in strict POSIX mode, exactly as if you had supplied `--posix'.
+ If the environment variable 'POSIXLY_CORRECT' exists, then 'gawk'
+behaves in strict POSIX mode, exactly as if you had supplied '--posix'.
Many GNU programs look for this environment variable to suppress
-extensions that conflict with POSIX, but `gawk' behaves differently: it
+extensions that conflict with POSIX, but 'gawk' behaves differently: it
suppresses all extensions, even those that do not conflict with POSIX,
-and behaves in strict POSIX mode. If `--lint' is supplied on the
-command line and `gawk' turns on POSIX mode because of
-`POSIXLY_CORRECT', then it issues a warning message indicating that
+and behaves in strict POSIX mode. If '--lint' is supplied on the
+command line and 'gawk' turns on POSIX mode because of
+'POSIXLY_CORRECT', then it issues a warning message indicating that
POSIX mode is in effect. You would typically set this variable in your
-shell's startup file. For a Bourne-compatible shell (such as Bash),
-you would add these lines to the `.profile' file in your home directory:
+shell's startup file. For a Bourne-compatible shell (such as Bash), you
+would add these lines to the '.profile' file in your home directory:
POSIXLY_CORRECT=true
export POSIXLY_CORRECT
For a C shell-compatible shell,(2) you would add this line to the
-`.login' file in your home directory:
+'.login' file in your home directory:
setenv POSIXLY_CORRECT true
- Having `POSIXLY_CORRECT' set is not recommended for daily use, but
-it is good for testing the portability of your programs to other
+ Having 'POSIXLY_CORRECT' set is not recommended for daily use, but it
+is good for testing the portability of your programs to other
environments.
---------- Footnotes ----------
(1) For more detail, please see Section 4.4 of RFC 3875
-(http://www.ietf.org/rfc/rfc3875). Also see the explanatory note sent
-to the `gawk' bug mailing list
+(http://www.ietf.org/rfc/rfc3875). Also see the explanatory note sent
+to the 'gawk' bug mailing list
(http://lists.gnu.org/archive/html/bug-gawk/2014-11/msg00022.html).
(2) Not recommended.
@@ -2790,60 +2778,60 @@ File: gawk.info, Node: Other Arguments, Next: Naming
Standard Input, Prev: Op
================================
Any additional arguments on the command line are normally treated as
-input files to be processed in the order specified. However, an
-argument that has the form `VAR=VALUE', assigns the value VALUE to the
+input files to be processed in the order specified. However, an
+argument that has the form 'VAR=VALUE', assigns the value VALUE to the
variable VAR--it does not specify a file at all. (See *note Assignment
-Options::.) In the following example, COUNT=1 is a variable assignment,
+Options::.) In the following example, COUNT=1 is a variable assignment,
not a file name:
awk -f program.awk file1 count=1 file2
- All the command-line arguments are made available to your `awk'
-program in the `ARGV' array (*note Built-in Variables::). Command-line
-options and the program text (if present) are omitted from `ARGV'. All
-other arguments, including variable assignments, are included. As
-each element of `ARGV' is processed, `gawk' sets `ARGIND' to the index
-in `ARGV' of the current element.
+ All the command-line arguments are made available to your 'awk'
+program in the 'ARGV' array (*note Built-in Variables::). Command-line
+options and the program text (if present) are omitted from 'ARGV'. All
+other arguments, including variable assignments, are included. As each
+element of 'ARGV' is processed, 'gawk' sets 'ARGIND' to the index in
+'ARGV' of the current element.
- Changing `ARGC' and `ARGV' in your `awk' program lets you control
-how `awk' processes the input files; this is described in more detail
-in *note ARGC and ARGV::.
+ Changing 'ARGC' and 'ARGV' in your 'awk' program lets you control how
+'awk' processes the input files; this is described in more detail in
+*note ARGC and ARGV::.
The distinction between file name arguments and variable-assignment
-arguments is made when `awk' is about to open the next input file. At
+arguments is made when 'awk' is about to open the next input file. At
that point in execution, it checks the file name to see whether it is
-really a variable assignment; if so, `awk' sets the variable instead of
+really a variable assignment; if so, 'awk' sets the variable instead of
reading a file.
Therefore, the variables actually receive the given values after all
previously specified files have been read. In particular, the values of
-variables assigned in this fashion are _not_ available inside a `BEGIN'
-rule (*note BEGIN/END::), because such rules are run before `awk'
-begins scanning the argument list.
+variables assigned in this fashion are _not_ available inside a 'BEGIN'
+rule (*note BEGIN/END::), because such rules are run before 'awk' begins
+scanning the argument list.
The variable values given on the command line are processed for
escape sequences (*note Escape Sequences::). (d.c.)
- In some very early implementations of `awk', when a variable
+ In some very early implementations of 'awk', when a variable
assignment occurred before any file names, the assignment would happen
-_before_ the `BEGIN' rule was executed. `awk''s behavior was thus
+_before_ the 'BEGIN' rule was executed. 'awk''s behavior was thus
inconsistent; some command-line assignments were available inside the
-`BEGIN' rule, while others were not. Unfortunately, some applications
-came to depend upon this "feature." When `awk' was changed to be more
-consistent, the `-v' option was added to accommodate applications that
+'BEGIN' rule, while others were not. Unfortunately, some applications
+came to depend upon this "feature." When 'awk' was changed to be more
+consistent, the '-v' option was added to accommodate applications that
depended upon the old behavior.
The variable assignment feature is most useful for assigning to
-variables such as `RS', `OFS', and `ORS', which control input and
-output formats, before scanning the data files. It is also useful for
+variables such as 'RS', 'OFS', and 'ORS', which control input and output
+formats, before scanning the data files. It is also useful for
controlling state if multiple passes are needed over a data file. For
example:
awk 'pass == 1 { PASS 1 STUFF }
pass == 2 { PASS 2 STUFF }' pass=1 mydata pass=2 mydata
- Given the variable assignment feature, the `-F' option for setting
-the value of `FS' is not strictly necessary. It remains for historical
+ Given the variable assignment feature, the '-F' option for setting
+the value of 'FS' is not strictly necessary. It remains for historical
compatibility.
@@ -2856,135 +2844,135 @@ Often, you may wish to read standard input together
with other files.
For example, you may wish to read one file, read standard input coming
from a pipe, and then read another file.
- The way to name the standard input, with all versions of `awk', is
-to use a single, standalone minus sign or dash, `-'. For example:
+ The way to name the standard input, with all versions of 'awk', is to
+use a single, standalone minus sign or dash, '-'. For example:
SOME_COMMAND | awk -f myprog.awk file1 - file2
-Here, `awk' first reads `file1', then it reads the output of
-SOME_COMMAND, and finally it reads `file2'.
+Here, 'awk' first reads 'file1', then it reads the output of
+SOME_COMMAND, and finally it reads 'file2'.
- You may also use `"-"' to name standard input when reading files
-with `getline' (*note Getline/File::).
+ You may also use '"-"' to name standard input when reading files with
+'getline' (*note Getline/File::).
- In addition, `gawk' allows you to specify the special file name
-`/dev/stdin', both on the command line and with `getline'. Some other
-versions of `awk' also support this, but it is not standard. (Some
-operating systems provide a `/dev/stdin' file in the filesystem;
-however, `gawk' always processes this file name itself.)
+ In addition, 'gawk' allows you to specify the special file name
+'/dev/stdin', both on the command line and with 'getline'. Some other
+versions of 'awk' also support this, but it is not standard. (Some
+operating systems provide a '/dev/stdin' file in the filesystem;
+however, 'gawk' always processes this file name itself.)
File: gawk.info, Node: Environment Variables, Next: Exit Status, Prev:
Naming Standard Input, Up: Invoking Gawk
-2.5 The Environment Variables `gawk' Uses
+2.5 The Environment Variables 'gawk' Uses
=========================================
-A number of environment variables influence how `gawk' behaves.
+A number of environment variables influence how 'gawk' behaves.
* Menu:
-* AWKPATH Variable:: Searching directories for `awk'
+* AWKPATH Variable:: Searching directories for 'awk'
programs.
-* AWKLIBPATH Variable:: Searching directories for `awk' shared
+* AWKLIBPATH Variable:: Searching directories for 'awk' shared
libraries.
* Other Environment Variables:: The environment variables.
File: gawk.info, Node: AWKPATH Variable, Next: AWKLIBPATH Variable, Up:
Environment Variables
-2.5.1 The `AWKPATH' Environment Variable
+2.5.1 The 'AWKPATH' Environment Variable
----------------------------------------
-The previous minor node described how `awk' program files can be named
-on the command line with the `-f' option. In most `awk'
+The previous minor node described how 'awk' program files can be named
+on the command line with the '-f' option. In most 'awk'
implementations, you must supply a precise pathname for each program
-file, unless the file is in the current directory. But with `gawk', if
-the file name supplied to the `-f' or `-i' options does not contain a
-directory separator `/', then `gawk' searches a list of directories
+file, unless the file is in the current directory. But with 'gawk', if
+the file name supplied to the '-f' or '-i' options does not contain a
+directory separator '/', then 'gawk' searches a list of directories
(called the "search path") one by one, looking for a file with the
specified name.
-The search path is a string consisting of directory names separated by
-colons.(1) `gawk' gets its search path from the `AWKPATH' environment
-variable. If that variable does not exist, or if it has an empty value,
-`gawk' uses a default path (described shortly).
+ The search path is a string consisting of directory names separated
+by colons.(1) 'gawk' gets its search path from the 'AWKPATH'
+environment variable. If that variable does not exist, or if it has an
+empty value, 'gawk' uses a default path (described shortly).
The search path feature is particularly helpful for building
-libraries of useful `awk' functions. The library files can be placed
-in a standard directory in the default path and then specified on the
+libraries of useful 'awk' functions. The library files can be placed in
+a standard directory in the default path and then specified on the
command line with a short file name. Otherwise, you would have to type
the full file name for each file.
- By using the `-i' or `-f' options, your command-line `awk' programs
-can use facilities in `awk' library files (*note Library Functions::).
-Path searching is not done if `gawk' is in compatibility mode. This is
-true for both `--traditional' and `--posix'. *Note Options::.
+ By using the '-i' or '-f' options, your command-line 'awk' programs
+can use facilities in 'awk' library files (*note Library Functions::).
+Path searching is not done if 'gawk' is in compatibility mode. This is
+true for both '--traditional' and '--posix'. *Note Options::.
If the source code file is not found after the initial search, the
-path is searched again after adding the suffix `.awk' to the file name.
+path is searched again after adding the suffix '.awk' to the file name.
- `gawk''s path search mechanism is similar to the shell's. (See `The
+ 'gawk''s path search mechanism is similar to the shell's. (See 'The
Bourne-Again SHell manual' (http://www.gnu.org/software/bash/manual/).)
It treats a null entry in the path as indicating the current directory.
(A null entry is indicated by starting or ending the path with a colon
-or by placing two colons next to each other [`::'].)
+or by placing two colons next to each other ['::'].)
NOTE: To include the current directory in the path, either place
- `.' as an entry in the path or write a null entry in the path.
+ '.' as an entry in the path or write a null entry in the path.
- Different past versions of `gawk' would also look explicitly in
- the current directory, either before or after the path search. As
- of version 4.1.2, this no longer happens; if you wish to look in
- the current directory, you must include `.' either as a separate
- entry or as a null entry in the search path.
+ Different past versions of 'gawk' would also look explicitly in the
+ current directory, either before or after the path search. As of
+ version 4.1.2, this no longer happens; if you wish to look in the
+ current directory, you must include '.' either as a separate entry
+ or as a null entry in the search path.
- The default value for `AWKPATH' is `.:/usr/local/share/awk'.(2)
-Since `.' is included at the beginning, `gawk' searches first in the
-current directory and then in `/usr/local/share/awk'. In practice,
-this means that you will rarely need to change the value of `AWKPATH'.
+ The default value for 'AWKPATH' is '.:/usr/local/share/awk'.(2)
+Since '.' is included at the beginning, 'gawk' searches first in the
+current directory and then in '/usr/local/share/awk'. In practice, this
+means that you will rarely need to change the value of 'AWKPATH'.
- `gawk' places the value of the search path that it used into
-`ENVIRON["AWKPATH"]'. This provides access to the actual search path
-value from within an `awk' program.
+ 'gawk' places the value of the search path that it used into
+'ENVIRON["AWKPATH"]'. This provides access to the actual search path
+value from within an 'awk' program.
- Although you can change `ENVIRON["AWKPATH"]' within your `awk'
+ Although you can change 'ENVIRON["AWKPATH"]' within your 'awk'
program, this has no effect on the running program's behavior. This
-makes sense: the `AWKPATH' environment variable is used to find the
+makes sense: the 'AWKPATH' environment variable is used to find the
program source files. Once your program is running, all the files have
-been found, and `gawk' no longer needs to use `AWKPATH'.
+been found, and 'gawk' no longer needs to use 'AWKPATH'.
---------- Footnotes ----------
(1) Semicolons on MS-Windows and MS-DOS.
- (2) Your version of `gawk' may use a different directory; it will
-depend upon how `gawk' was built and installed. The actual directory is
-the value of `$(datadir)' generated when `gawk' was configured. You
+ (2) Your version of 'gawk' may use a different directory; it will
+depend upon how 'gawk' was built and installed. The actual directory is
+the value of '$(datadir)' generated when 'gawk' was configured. You
probably don't need to worry about this, though.
File: gawk.info, Node: AWKLIBPATH Variable, Next: Other Environment
Variables, Prev: AWKPATH Variable, Up: Environment Variables
-2.5.2 The `AWKLIBPATH' Environment Variable
+2.5.2 The 'AWKLIBPATH' Environment Variable
-------------------------------------------
-The `AWKLIBPATH' environment variable is similar to the `AWKPATH'
+The 'AWKLIBPATH' environment variable is similar to the 'AWKPATH'
variable, but it is used to search for loadable extensions (stored as
-system shared libraries) specified with the `-l' option rather than for
-source files. If the extension is not found, the path is searched
-again after adding the appropriate shared library suffix for the
-platform. For example, on GNU/Linux systems, the suffix `.so' is used.
-The search path specified is also used for extensions loaded via the
address@hidden' keyword (*note Loading Shared Libraries::).
-
- If `AWKLIBPATH' does not exist in the environment, or if it has an
-empty value, `gawk' uses a default path; this is typically
-`/usr/local/lib/gawk', although it can vary depending upon how `gawk'
+system shared libraries) specified with the '-l' option rather than for
+source files. If the extension is not found, the path is searched again
+after adding the appropriate shared library suffix for the platform.
+For example, on GNU/Linux systems, the suffix '.so' is used. The search
+path specified is also used for extensions loaded via the '@load'
+keyword (*note Loading Shared Libraries::).
+
+ If 'AWKLIBPATH' does not exist in the environment, or if it has an
+empty value, 'gawk' uses a default path; this is typically
+'/usr/local/lib/gawk', although it can vary depending upon how 'gawk'
was built.
- `gawk' places the value of the search path that it used into
-`ENVIRON["AWKLIBPATH"]'. This provides access to the actual search path
-value from within an `awk' program.
+ 'gawk' places the value of the search path that it used into
+'ENVIRON["AWKLIBPATH"]'. This provides access to the actual search path
+value from within an 'awk' program.
File: gawk.info, Node: Other Environment Variables, Prev: AWKLIBPATH
Variable, Up: Environment Variables
@@ -2992,107 +2980,107 @@ File: gawk.info, Node: Other Environment Variables,
Prev: AWKLIBPATH Variable,
2.5.3 Other Environment Variables
---------------------------------
-A number of other environment variables affect `gawk''s behavior, but
-they are more specialized. Those in the following list are meant to be
+A number of other environment variables affect 'gawk''s behavior, but
+they are more specialized. Those in the following list are meant to be
used by regular users:
-`GAWK_MSEC_SLEEP'
- Specifies the interval between connection retries, in
- milliseconds. On systems that do not support the `usleep()' system
- call, the value is rounded up to an integral number of seconds.
+'GAWK_MSEC_SLEEP'
+ Specifies the interval between connection retries, in milliseconds.
+ On systems that do not support the 'usleep()' system call, the
+ value is rounded up to an integral number of seconds.
-`GAWK_READ_TIMEOUT'
- Specifies the time, in milliseconds, for `gawk' to wait for input
+'GAWK_READ_TIMEOUT'
+ Specifies the time, in milliseconds, for 'gawk' to wait for input
before returning with an error. *Note Read Timeout::.
-`GAWK_SOCK_RETRIES'
- Controls the number of times `gawk' attempts to retry a two-way
+'GAWK_SOCK_RETRIES'
+ Controls the number of times 'gawk' attempts to retry a two-way
TCP/IP (socket) connection before giving up. *Note TCP/IP
Networking::.
-`POSIXLY_CORRECT'
- Causes `gawk' to switch to POSIX-compatibility mode, disabling all
+'POSIXLY_CORRECT'
+ Causes 'gawk' to switch to POSIX-compatibility mode, disabling all
traditional and GNU extensions. *Note Options::.
The environment variables in the following list are meant for use by
-the `gawk' developers for testing and tuning. They are subject to
-change. The variables are:
-
-`AWKBUFSIZE'
- This variable only affects `gawk' on POSIX-compliant systems.
- With a value of `exact', `gawk' uses the size of each input file
- as the size of the memory buffer to allocate for I/O. Otherwise,
- the value should be a number, and `gawk' uses that number as the
- size of the buffer to allocate. (When this variable is not set,
- `gawk' uses the smaller of the file's size and the "default"
- blocksize, which is usually the filesystem's I/O blocksize.)
-
-`AWK_HASH'
- If this variable exists with a value of `gst', `gawk' switches to
+the 'gawk' developers for testing and tuning. They are subject to
+change. The variables are:
+
+'AWKBUFSIZE'
+ This variable only affects 'gawk' on POSIX-compliant systems. With
+ a value of 'exact', 'gawk' uses the size of each input file as the
+ size of the memory buffer to allocate for I/O. Otherwise, the value
+ should be a number, and 'gawk' uses that number as the size of the
+ buffer to allocate. (When this variable is not set, 'gawk' uses
+ the smaller of the file's size and the "default" blocksize, which
+ is usually the filesystem's I/O blocksize.)
+
+'AWK_HASH'
+ If this variable exists with a value of 'gst', 'gawk' switches to
using the hash function from GNU Smalltalk for managing arrays.
This function may be marginally faster than the standard function.
-`AWKREADFUNC'
- If this variable exists, `gawk' switches to reading source files
- one line at a time, instead of reading in blocks. This exists for
+'AWKREADFUNC'
+ If this variable exists, 'gawk' switches to reading source files
+ one line at a time, instead of reading in blocks. This exists for
debugging problems on filesystems on non-POSIX operating systems
where I/O is performed in records, not in blocks.
-`GAWK_MSG_SRC'
- If this variable exists, `gawk' includes the file name and line
- number within the `gawk' source code from which warning and/or
+'GAWK_MSG_SRC'
+ If this variable exists, 'gawk' includes the file name and line
+ number within the 'gawk' source code from which warning and/or
fatal messages are generated. Its purpose is to help isolate the
source of a message, as there are multiple places that produce the
same warning or error message.
-`GAWK_NO_DFA'
- If this variable exists, `gawk' does not use the DFA regexp matcher
- for "does it match" kinds of tests. This can cause `gawk' to be
- slower. Its purpose is to help isolate differences between the two
- regexp matchers that `gawk' uses internally. (There aren't
+'GAWK_NO_DFA'
+ If this variable exists, 'gawk' does not use the DFA regexp matcher
+ for "does it match" kinds of tests. This can cause 'gawk' to be
+ slower. Its purpose is to help isolate differences between the two
+ regexp matchers that 'gawk' uses internally. (There aren't
supposed to be differences, but occasionally theory and practice
don't coordinate with each other.)
-`GAWK_NO_PP_RUN'
- When `gawk' is invoked with the `--pretty-print' option, it will
+'GAWK_NO_PP_RUN'
+ When 'gawk' is invoked with the '--pretty-print' option, it will
not run the program if this environment variable exists.
CAUTION: This variable will not survive into the next major
release.
-`GAWK_STACKSIZE'
- This specifies the amount by which `gawk' should grow its internal
+'GAWK_STACKSIZE'
+ This specifies the amount by which 'gawk' should grow its internal
evaluation stack, when needed.
-`INT_CHAIN_MAX'
- This specifies intended maximum number of items `gawk' will
+'INT_CHAIN_MAX'
+ This specifies intended maximum number of items 'gawk' will
maintain on a hash chain for managing arrays indexed by integers.
-`STR_CHAIN_MAX'
- This specifies intended maximum number of items `gawk' will
+'STR_CHAIN_MAX'
+ This specifies intended maximum number of items 'gawk' will
maintain on a hash chain for managing arrays indexed by strings.
-`TIDYMEM'
- If this variable exists, `gawk' uses the `mtrace()' library calls
+'TIDYMEM'
+ If this variable exists, 'gawk' uses the 'mtrace()' library calls
from the GNU C library to help track down possible memory leaks.
File: gawk.info, Node: Exit Status, Next: Include Files, Prev: Environment
Variables, Up: Invoking Gawk
-2.6 `gawk''s Exit Status
+2.6 'gawk''s Exit Status
========================
-If the `exit' statement is used with a value (*note Exit Statement::),
-then `gawk' exits with the numeric value given to it.
+If the 'exit' statement is used with a value (*note Exit Statement::),
+then 'gawk' exits with the numeric value given to it.
- Otherwise, if there were no problems during execution, `gawk' exits
-with the value of the C constant `EXIT_SUCCESS'. This is usually zero.
+ Otherwise, if there were no problems during execution, 'gawk' exits
+with the value of the C constant 'EXIT_SUCCESS'. This is usually zero.
- If an error occurs, `gawk' exits with the value of the C constant
-`EXIT_FAILURE'. This is usually one.
+ If an error occurs, 'gawk' exits with the value of the C constant
+'EXIT_FAILURE'. This is usually one.
- If `gawk' exits because of a fatal error, the exit status is two.
-On non-POSIX systems, this value may be mapped to `EXIT_FAILURE'.
+ If 'gawk' exits because of a fatal error, the exit status is two. On
+non-POSIX systems, this value may be mapped to 'EXIT_FAILURE'.
File: gawk.info, Node: Include Files, Next: Loading Shared Libraries, Prev:
Exit Status, Up: Invoking Gawk
@@ -3100,41 +3088,41 @@ File: gawk.info, Node: Include Files, Next: Loading
Shared Libraries, Prev: E
2.7 Including Other Files into Your Program
===========================================
-This minor node describes a feature that is specific to `gawk'.
+This minor node describes a feature that is specific to 'gawk'.
- The address@hidden' keyword can be used to read external `awk' source
-files. This gives you the ability to split large `awk' source files
+ The '@include' keyword can be used to read external 'awk' source
+files. This gives you the ability to split large 'awk' source files
into smaller, more manageable pieces, and also lets you reuse common
-`awk' code from various `awk' scripts. In other words, you can group
-together `awk' functions used to carry out specific tasks into external
-files. These files can be used just like function libraries, using the
address@hidden' keyword in conjunction with the `AWKPATH' environment
-variable. Note that source files may also be included using the `-i'
+'awk' code from various 'awk' scripts. In other words, you can group
+together 'awk' functions used to carry out specific tasks into external
+files. These files can be used just like function libraries, using the
+'@include' keyword in conjunction with the 'AWKPATH' environment
+variable. Note that source files may also be included using the '-i'
option.
- Let's see an example. We'll start with two (trivial) `awk' scripts,
-namely `test1' and `test2'. Here is the `test1' script:
+ Let's see an example. We'll start with two (trivial) 'awk' scripts,
+namely 'test1' and 'test2'. Here is the 'test1' script:
BEGIN {
print "This is script test1."
}
-and here is `test2':
+and here is 'test2':
@include "test1"
BEGIN {
print "This is script test2."
}
- Running `gawk' with `test2' produces the following result:
+ Running 'gawk' with 'test2' produces the following result:
$ gawk -f test2
-| This is script test1.
-| This is script test2.
- `gawk' runs the `test2' script, which includes `test1' using the
address@hidden' keyword. So, to include external `awk' source files, you
-just use address@hidden' followed by the name of the file to be included,
+ 'gawk' runs the 'test2' script, which includes 'test1' using the
+'@include' keyword. So, to include external 'awk' source files, you
+just use '@include' followed by the name of the file to be included,
enclosed in double quotes.
NOTE: Keep in mind that this is a language construct and the file
@@ -3142,21 +3130,21 @@ enclosed in double quotes.
constant in double quotes.
The files to be included may be nested; e.g., given a third script,
-namely `test3':
+namely 'test3':
@include "test2"
BEGIN {
print "This is script test3."
}
-Running `gawk' with the `test3' script produces the following results:
+Running 'gawk' with the 'test3' script produces the following results:
$ gawk -f test3
-| This is script test1.
-| This is script test2.
-| This is script test3.
- The file name can, of course, be a pathname. For example:
+ The file name can, of course, be a pathname. For example:
@include "../io_funcs"
@@ -3164,32 +3152,31 @@ and:
@include "/usr/awklib/network"
-are both valid. The `AWKPATH' environment variable can be of great
-value when using address@hidden'. The same rules for the use of the
-`AWKPATH' variable in command-line file searches (*note AWKPATH
-Variable::) apply to address@hidden' also.
+are both valid. The 'AWKPATH' environment variable can be of great
+value when using '@include'. The same rules for the use of the
+'AWKPATH' variable in command-line file searches (*note AWKPATH
+Variable::) apply to '@include' also.
- This is very helpful in constructing `gawk' function libraries. If
-you have a large script with useful, general-purpose `awk' functions,
+ This is very helpful in constructing 'gawk' function libraries. If
+you have a large script with useful, general-purpose 'awk' functions,
you can break it down into library files and put those files in a
special directory. You can then include those "libraries," either by
-using the full pathnames of the files, or by setting the `AWKPATH'
-environment variable accordingly and then using address@hidden' with just
-the file part of the full pathname. Of course, you can keep library
-files in more than one directory; the more complex the working
-environment is, the more directories you may need to organize the files
-to be included.
-
- Given the ability to specify multiple `-f' options, the address@hidden'
-mechanism is not strictly necessary. However, the address@hidden' keyword
-can help you in constructing self-contained `gawk' programs, thus
+using the full pathnames of the files, or by setting the 'AWKPATH'
+environment variable accordingly and then using '@include' with just the
+file part of the full pathname. Of course, you can keep library files
+in more than one directory; the more complex the working environment is,
+the more directories you may need to organize the files to be included.
+
+ Given the ability to specify multiple '-f' options, the '@include'
+mechanism is not strictly necessary. However, the '@include' keyword
+can help you in constructing self-contained 'gawk' programs, thus
reducing the need for writing complex and tedious command lines. In
-particular, address@hidden' is very useful for writing CGI scripts to be run
+particular, '@include' is very useful for writing CGI scripts to be run
from web pages.
As mentioned in *note AWKPATH Variable::, the current directory is
-always searched first for source files, before searching in `AWKPATH';
-this also applies to files named with address@hidden'.
+always searched first for source files, before searching in 'AWKPATH';
+this also applies to files named with '@include'.
File: gawk.info, Node: Loading Shared Libraries, Next: Obsolete, Prev:
Include Files, Up: Invoking Gawk
@@ -3197,19 +3184,19 @@ File: gawk.info, Node: Loading Shared Libraries,
Next: Obsolete, Prev: Includ
2.8 Loading Dynamic Extensions into Your Program
================================================
-This minor node describes a feature that is specific to `gawk'.
+This minor node describes a feature that is specific to 'gawk'.
- The address@hidden' keyword can be used to read external `awk' extensions
+ The '@load' keyword can be used to read external 'awk' extensions
(stored as system shared libraries). This allows you to link in
-compiled code that may offer superior performance and/or give you
-access to extended capabilities not supported by the `awk' language.
-The `AWKLIBPATH' variable is used to search for the extension. Using
address@hidden' is completely equivalent to using the `-l' command-line option.
+compiled code that may offer superior performance and/or give you access
+to extended capabilities not supported by the 'awk' language. The
+'AWKLIBPATH' variable is used to search for the extension. Using
+'@load' is completely equivalent to using the '-l' command-line option.
- If the extension is not initially found in `AWKLIBPATH', another
+ If the extension is not initially found in 'AWKLIBPATH', another
search is conducted after appending the platform's default shared
-library suffix to the file name. For example, on GNU/Linux systems,
-the suffix `.so' is used:
+library suffix to the file name. For example, on GNU/Linux systems, the
+suffix '.so' is used:
$ gawk '@load "ordchr"; BEGIN {print chr(65)}'
-| A
@@ -3219,13 +3206,13 @@ This is equivalent to the following example:
$ gawk -lordchr 'BEGIN {print chr(65)}'
-| A
-For command-line usage, the `-l' option is more convenient, but address@hidden'
-is useful for embedding inside an `awk' source file that requires
-access to an extension.
+For command-line usage, the '-l' option is more convenient, but '@load'
+is useful for embedding inside an 'awk' source file that requires access
+to an extension.
*note Dynamic Extensions::, describes how to write extensions (in C
-or C++) that can be loaded with either address@hidden' or the `-l' option. It
-also describes the `ordchr' extension.
+or C++) that can be loaded with either '@load' or the '-l' option. It
+also describes the 'ordchr' extension.
File: gawk.info, Node: Obsolete, Next: Undocumented, Prev: Loading Shared
Libraries, Up: Invoking Gawk
@@ -3234,14 +3221,14 @@ File: gawk.info, Node: Obsolete, Next: Undocumented,
Prev: Loading Shared Lib
====================================
This minor node describes features and/or command-line options from
-previous releases of `gawk' that either are not available in the
-current version or are still supported but deprecated (meaning that
-they will _not_ be in the next release).
+previous releases of 'gawk' that either are not available in the current
+version or are still supported but deprecated (meaning that they will
+_not_ be in the next release).
- The process-related special files `/dev/pid', `/dev/ppid',
-`/dev/pgrpid', and `/dev/user' were deprecated in `gawk' 3.1, but still
+ The process-related special files '/dev/pid', '/dev/ppid',
+'/dev/pgrpid', and '/dev/user' were deprecated in 'gawk' 3.1, but still
worked. As of version 4.0, they are no longer interpreted specially by
-`gawk'. (Use `PROCINFO' instead; see *note Auto-set::.)
+'gawk'. (Use 'PROCINFO' instead; see *note Auto-set::.)
File: gawk.info, Node: Undocumented, Next: Invoking Summary, Prev:
Obsolete, Up: Invoking Gawk
@@ -3249,7 +3236,8 @@ File: gawk.info, Node: Undocumented, Next: Invoking
Summary, Prev: Obsolete,
2.10 Undocumented Options and Features
======================================
- Use the Source, Luke! -- Obi-Wan
+ Use the Source, Luke!
+ -- _Obi-Wan_
This minor node intentionally left blank.
@@ -3259,42 +3247,41 @@ File: gawk.info, Node: Invoking Summary, Prev:
Undocumented, Up: Invoking Gaw
2.11 Summary
============
- * Use either `awk 'PROGRAM' FILES' or `awk -f PROGRAM-FILE FILES' to
- run `awk'.
+ * Use either 'awk 'PROGRAM' FILES' or 'awk -f PROGRAM-FILE FILES' to
+ run 'awk'.
- * The three standard options for all versions of `awk' are `-f',
- `-F', and `-v'. `gawk' supplies these and many others, as well as
+ * The three standard options for all versions of 'awk' are '-f',
+ '-F', and '-v'. 'gawk' supplies these and many others, as well as
corresponding GNU-style long options.
* Nonoption command-line arguments are usually treated as file names,
- unless they have the form `VAR=VALUE', in which case they are
- taken as variable assignments to be performed at that point in
- processing the input.
+ unless they have the form 'VAR=VALUE', in which case they are taken
+ as variable assignments to be performed at that point in processing
+ the input.
* All nonoption command-line arguments, excluding the program text,
- are placed in the `ARGV' array. Adjusting `ARGC' and `ARGV'
- affects how `awk' processes input.
+ are placed in the 'ARGV' array. Adjusting 'ARGC' and 'ARGV'
+ affects how 'awk' processes input.
- * You can use a single minus sign (`-') to refer to standard input
- on the command line. `gawk' also lets you use the special file
- name `/dev/stdin'.
+ * You can use a single minus sign ('-') to refer to standard input on
+ the command line. 'gawk' also lets you use the special file name
+ '/dev/stdin'.
- * `gawk' pays attention to a number of environment variables.
- `AWKPATH', `AWKLIBPATH', and `POSIXLY_CORRECT' are the most
+ * 'gawk' pays attention to a number of environment variables.
+ 'AWKPATH', 'AWKLIBPATH', and 'POSIXLY_CORRECT' are the most
important ones.
- * `gawk''s exit status conveys information to the program that
- invoked it. Use the `exit' statement from within an `awk' program
+ * 'gawk''s exit status conveys information to the program that
+ invoked it. Use the 'exit' statement from within an 'awk' program
to set the exit status.
- * `gawk' allows you to include other `awk' source files into your
- program using the address@hidden' statement and/or the `-i' and `-f'
+ * 'gawk' allows you to include other 'awk' source files into your
+ program using the '@include' statement and/or the '-i' and '-f'
command-line options.
- * `gawk' allows you to load additional functions written in C or C++
- using the address@hidden' statement and/or the `-l' option. (This
- advanced feature is described later, in *note Dynamic
- Extensions::.)
+ * 'gawk' allows you to load additional functions written in C or C++
+ using the '@load' statement and/or the '-l' option. (This advanced
+ feature is described later, in *note Dynamic Extensions::.)
File: gawk.info, Node: Regexp, Next: Reading Files, Prev: Invoking Gawk,
Up: Top
@@ -3304,15 +3291,15 @@ File: gawk.info, Node: Regexp, Next: Reading Files,
Prev: Invoking Gawk, Up:
A "regular expression", or "regexp", is a way of describing a set of
strings. Because regular expressions are such a fundamental part of
-`awk' programming, their format and use deserve a separate major node.
+'awk' programming, their format and use deserve a separate major node.
- A regular expression enclosed in slashes (`/') is an `awk' pattern
+ A regular expression enclosed in slashes ('/') is an 'awk' pattern
that matches every input record whose text belongs to that set. The
simplest regular expression is a sequence of letters, numbers, or both.
-Such a regexp matches any string that contains that sequence. Thus,
-the regexp `foo' matches any string containing `foo'. Thus, the
-pattern `/foo/' matches any input record containing the three adjacent
-characters `foo' _anywhere_ in the record. Other kinds of regexps let
+Such a regexp matches any string that contains that sequence. Thus, the
+regexp 'foo' matches any string containing 'foo'. Thus, the pattern
+'/foo/' matches any input record containing the three adjacent
+characters 'foo' _anywhere_ in the record. Other kinds of regexps let
you specify more complicated classes of strings.
* Menu:
@@ -3320,7 +3307,7 @@ you specify more complicated classes of strings.
* Regexp Usage:: How to Use Regular Expressions.
* Escape Sequences:: How to write nonprinting characters.
* Regexp Operators:: Regular Expression Operators.
-* Bracket Expressions:: What can go between `[...]'.
+* Bracket Expressions:: What can go between '[...]'.
* Leftmost Longest:: How much text matches.
* Computed Regexps:: Using Dynamic Regexps.
* GNU Regexp Operators:: Operators specific to GNU software.
@@ -3335,10 +3322,10 @@ File: gawk.info, Node: Regexp Usage, Next: Escape
Sequences, Up: Regexp
A regular expression can be used as a pattern by enclosing it in
slashes. Then the regular expression is tested against the entire text
-of each record. (Normally, it only needs to match some part of the
-text in order to succeed.) For example, the following prints the
-second field of each record where the string `li' appears anywhere in
-the record:
+of each record. (Normally, it only needs to match some part of the text
+in order to succeed.) For example, the following prints the second
+field of each record where the string 'li' appears anywhere in the
+record:
$ awk '/li/ { print $2 }' mail-list
-| 555-5553
@@ -3348,16 +3335,16 @@ the record:
Regular expressions can also be used in matching expressions. These
expressions allow you to specify the string to match against; it need
-not be the entire current input record. The two operators `~' and `!~'
+not be the entire current input record. The two operators '~' and '!~'
perform regular expression comparisons. Expressions using these
-operators can be used as patterns, or in `if', `while', `for', and `do'
+operators can be used as patterns, or in 'if', 'while', 'for', and 'do'
statements. (*Note Statements::.) For example, the following is true
if the expression EXP (taken as a string) matches REGEXP:
EXP ~ /REGEXP/
This example matches, or selects, all input records with the uppercase
-letter `J' somewhere in the first field:
+letter 'J' somewhere in the first field:
$ awk '$1 ~ /J/' inventory-shipped
-| Jan 13 25 15 115
@@ -3369,13 +3356,13 @@ letter `J' somewhere in the first field:
awk '{ if ($1 ~ /J/) print }' inventory-shipped
- This next example is true if the expression EXP (taken as a
-character string) does _not_ match REGEXP:
+ This next example is true if the expression EXP (taken as a character
+string) does _not_ match REGEXP:
EXP !~ /REGEXP/
The following example matches, or selects, all input records whose
-first field _does not_ contain the uppercase letter `J':
+first field _does not_ contain the uppercase letter 'J':
$ awk '$1 !~ /J/' inventory-shipped
-| Feb 15 32 24 226
@@ -3384,9 +3371,9 @@ first field _does not_ contain the uppercase letter `J':
-| May 16 34 29 208
...
- When a regexp is enclosed in slashes, such as `/foo/', we call it a
-"regexp constant", much like `5.27' is a numeric constant and `"foo"'
-is a string constant.
+ When a regexp is enclosed in slashes, such as '/foo/', we call it a
+"regexp constant", much like '5.27' is a numeric constant and '"foo"' is
+a string constant.
File: gawk.info, Node: Escape Sequences, Next: Regexp Operators, Prev:
Regexp Usage, Up: Regexp
@@ -3395,127 +3382,127 @@ File: gawk.info, Node: Escape Sequences, Next:
Regexp Operators, Prev: Regexp
====================
Some characters cannot be included literally in string constants
-(`"foo"') or regexp constants (`/foo/'). Instead, they should be
+('"foo"') or regexp constants ('/foo/'). Instead, they should be
represented with "escape sequences", which are character sequences
-beginning with a backslash (`\'). One use of an escape sequence is to
+beginning with a backslash ('\'). One use of an escape sequence is to
include a double-quote character in a string constant. Because a plain
-double quote ends the string, you must use `\"' to represent an actual
+double quote ends the string, you must use '\"' to represent an actual
double-quote character as a part of the string. For example:
$ awk 'BEGIN { print "He said \"hi!\" to her." }'
-| He said "hi!" to her.
- The backslash character itself is another character that cannot be
-included normally; you must write `\\' to put one backslash in the
+ The backslash character itself is another character that cannot be
+included normally; you must write '\\' to put one backslash in the
string or regexp. Thus, the string whose contents are the two
-characters `"' and `\' must be written `"\"\\"'.
+characters '"' and '\' must be written '"\"\\"'.
Other escape sequences represent unprintable characters such as TAB
-or newline. There is nothing to stop you from entering most
-unprintable characters directly in a string constant or regexp constant,
-but they may look ugly.
+or newline. There is nothing to stop you from entering most unprintable
+characters directly in a string constant or regexp constant, but they
+may look ugly.
- The following list presents all the escape sequences used in `awk'
-and what they represent. Unless noted otherwise, all these escape
+ The following list presents all the escape sequences used in 'awk'
+and what they represent. Unless noted otherwise, all these escape
sequences apply to both string constants and regexp constants:
-`\\'
- A literal backslash, `\'.
+'\\'
+ A literal backslash, '\'.
-`\a'
- The "alert" character, `Ctrl-g', ASCII code 7 (BEL). (This often
+'\a'
+ The "alert" character, 'Ctrl-g', ASCII code 7 (BEL). (This often
makes some sort of audible noise.)
-`\b'
- Backspace, `Ctrl-h', ASCII code 8 (BS).
+'\b'
+ Backspace, 'Ctrl-h', ASCII code 8 (BS).
-`\f'
- Formfeed, `Ctrl-l', ASCII code 12 (FF).
+'\f'
+ Formfeed, 'Ctrl-l', ASCII code 12 (FF).
-`\n'
- Newline, `Ctrl-j', ASCII code 10 (LF).
+'\n'
+ Newline, 'Ctrl-j', ASCII code 10 (LF).
-`\r'
- Carriage return, `Ctrl-m', ASCII code 13 (CR).
+'\r'
+ Carriage return, 'Ctrl-m', ASCII code 13 (CR).
-`\t'
- Horizontal TAB, `Ctrl-i', ASCII code 9 (HT).
+'\t'
+ Horizontal TAB, 'Ctrl-i', ASCII code 9 (HT).
-`\v'
- Vertical TAB, `Ctrl-k', ASCII code 11 (VT).
+'\v'
+ Vertical TAB, 'Ctrl-k', ASCII code 11 (VT).
-`\NNN'
- The octal value NNN, where NNN stands for 1 to 3 digits between
- `0' and `7'. For example, the code for the ASCII ESC (escape)
- character is `\033'.
+'\NNN'
+ The octal value NNN, where NNN stands for 1 to 3 digits between '0'
+ and '7'. For example, the code for the ASCII ESC (escape)
+ character is '\033'.
-`\xHH...'
+'\xHH...'
The hexadecimal value HH, where HH stands for a sequence of
- hexadecimal digits (`0'-`9', and either `A'-`F' or `a'-`f'). Like
+ hexadecimal digits ('0'-'9', and either 'A'-'F' or 'a'-'f'). Like
the same construct in ISO C, the escape sequence continues until
- the first nonhexadecimal digit is seen. (c.e.) However, using
- more than two hexadecimal digits produces undefined results. (The
- `\x' escape sequence is not allowed in POSIX `awk'.)
+ the first nonhexadecimal digit is seen. (c.e.) However, using
+ more than two hexadecimal digits produces undefined results. (The
+ '\x' escape sequence is not allowed in POSIX 'awk'.)
- CAUTION: The next major release of `gawk' will change, such
- that a maximum of two hexadecimal digits following the `\x'
+ CAUTION: The next major release of 'gawk' will change, such
+ that a maximum of two hexadecimal digits following the '\x'
will be used.
-`\/'
+'\/'
A literal slash (necessary for regexp constants only). This
sequence is used when you want to write a regexp constant that
- contains a slash (such as `/.*:\/home\/[[:alnum:]]+:.*/'; the
- `[[:alnum:]]' notation is discussed in *note Bracket
+ contains a slash (such as '/.*:\/home\/[[:alnum:]]+:.*/'; the
+ '[[:alnum:]]' notation is discussed in *note Bracket
Expressions::). Because the regexp is delimited by slashes, you
need to escape any slash that is part of the pattern, in order to
- tell `awk' to keep processing the rest of the regexp.
+ tell 'awk' to keep processing the rest of the regexp.
-`\"'
- A literal double quote (necessary for string constants only).
- This sequence is used when you want to write a string constant
- that contains a double quote (such as `"He said \"hi!\" to her."').
+'\"'
+ A literal double quote (necessary for string constants only). This
+ sequence is used when you want to write a string constant that
+ contains a double quote (such as '"He said \"hi!\" to her."').
Because the string is delimited by double quotes, you need to
- escape any quote that is part of the string, in order to tell
- `awk' to keep processing the rest of the string.
+ escape any quote that is part of the string, in order to tell 'awk'
+ to keep processing the rest of the string.
- In `gawk', a number of additional two-character sequences that begin
+ In 'gawk', a number of additional two-character sequences that begin
with a backslash have special meaning in regexps. *Note GNU Regexp
Operators::.
In a regexp, a backslash before any character that is not in the
-previous list and not listed in *note GNU Regexp Operators::, means
-that the next character should be taken literally, even if it would
-normally be a regexp operator. For example, `/a\+b/' matches the three
-characters `a+b'.
+previous list and not listed in *note GNU Regexp Operators::, means that
+the next character should be taken literally, even if it would normally
+be a regexp operator. For example, '/a\+b/' matches the three
+characters 'a+b'.
- For complete portability, do not use a backslash before any
-character not shown in the previous list or that is not an operator.
+ For complete portability, do not use a backslash before any character
+not shown in the previous list or that is not an operator.
Backslash Before Regular Characters
If you place a backslash in a string constant before something that
-is not one of the characters previously listed, POSIX `awk' purposely
+is not one of the characters previously listed, POSIX 'awk' purposely
leaves what happens as undefined. There are two choices:
Strip the backslash out
- This is what BWK `awk' and `gawk' both do. For example, `"a\qc"'
- is the same as `"aqc"'. (Because this is such an easy bug both to
- introduce and to miss, `gawk' warns you about it.) Consider `FS =
+ This is what BWK 'awk' and 'gawk' both do. For example, '"a\qc"'
+ is the same as '"aqc"'. (Because this is such an easy bug both to
+ introduce and to miss, 'gawk' warns you about it.) Consider 'FS =
"[ \t]+\|[ \t]+"' to use vertical bars surrounded by whitespace as
- the field separator. There should be two backslashes in the
- string: `FS = "[ \t]+\\|[ \t]+"'.)
+ the field separator. There should be two backslashes in the
+ string: 'FS = "[ \t]+\\|[ \t]+"'.)
Leave the backslash alone
- Some other `awk' implementations do this. In such
- implementations, typing `"a\qc"' is the same as typing `"a\\qc"'.
+ Some other 'awk' implementations do this. In such implementations,
+ typing '"a\qc"' is the same as typing '"a\\qc"'.
To summarize:
* The escape sequences in the preceding list are always processed
- first, for both string constants and regexp constants. This
- happens very early, as soon as `awk' reads your program.
+ first, for both string constants and regexp constants. This
+ happens very early, as soon as 'awk' reads your program.
- * `gawk' processes both regexp constants and dynamic regexps (*note
+ * 'gawk' processes both regexp constants and dynamic regexps (*note
Computed Regexps::), for the special operators listed in *note GNU
Regexp Operators::.
@@ -3525,15 +3512,15 @@ Leave the backslash alone
Escape Sequences for Metacharacters
Suppose you use an octal or hexadecimal escape to represent a regexp
-metacharacter. (See *note Regexp Operators::.) Does `awk' treat the
+metacharacter. (See *note Regexp Operators::.) Does 'awk' treat the
character as a literal character or as a regexp operator?
- Historically, such characters were taken literally. (d.c.)
-However, the POSIX standard indicates that they should be treated as
-real metacharacters, which is what `gawk' does. In compatibility mode
-(*note Options::), `gawk' treats the characters represented by octal
-and hexadecimal escape sequences literally when used in regexp
-constants. Thus, `/a\52b/' is equivalent to `/a\*b/'.
+ Historically, such characters were taken literally. (d.c.) However,
+the POSIX standard indicates that they should be treated as real
+metacharacters, which is what 'gawk' does. In compatibility mode (*note
+Options::), 'gawk' treats the characters represented by octal and
+hexadecimal escape sequences literally when used in regexp constants.
+Thus, '/a\52b/' is equivalent to '/a\*b/'.
File: gawk.info, Node: Regexp Operators, Next: Bracket Expressions, Prev:
Escape Sequences, Up: Regexp
@@ -3545,115 +3532,115 @@ You can combine regular expressions with special
characters, called
"regular expression operators" or "metacharacters", to increase the
power and versatility of regular expressions.
- The escape sequences described in *note Escape Sequences::, are
-valid inside a regexp. They are introduced by a `\' and are recognized
-and converted into corresponding real characters as the very first step
-in processing regexps.
+ The escape sequences described in *note Escape Sequences::, are valid
+inside a regexp. They are introduced by a '\' and are recognized and
+converted into corresponding real characters as the very first step in
+processing regexps.
Here is a list of metacharacters. All characters that are not escape
sequences and that are not listed here stand for themselves:
-`\'
+'\'
This suppresses the special meaning of a character when matching.
- For example, `\$' matches the character `$'.
+ For example, '\$' matches the character '$'.
-`^'
- This matches the beginning of a string. address@hidden' matches
- address@hidden' at the beginning of a string, for example, and can be
+'^'
+ This matches the beginning of a string. 'address@hidden' matches
+ '@chapter' at the beginning of a string, for example, and can be
used to identify chapter beginnings in Texinfo source files. The
- `^' is known as an "anchor", because it anchors the pattern to
+ '^' is known as an "anchor", because it anchors the pattern to
match only at the beginning of the string.
- It is important to realize that `^' does not match the beginning of
- a line (the point right after a `\n' newline character) embedded
- in a string. The condition is not true in the following example:
+ It is important to realize that '^' does not match the beginning of
+ a line (the point right after a '\n' newline character) embedded in
+ a string. The condition is not true in the following example:
if ("line1\nLINE 2" ~ /^L/) ...
-`$'
- This is similar to `^', but it matches only at the end of a string.
- For example, `p$' matches a record that ends with a `p'. The `$'
+'$'
+ This is similar to '^', but it matches only at the end of a string.
+ For example, 'p$' matches a record that ends with a 'p'. The '$'
is an anchor and does not match the end of a line (the point right
- before a `\n' newline character) embedded in a string. The
+ before a '\n' newline character) embedded in a string. The
condition in the following example is not true:
if ("line1\nLINE 2" ~ /1$/) ...
-`.' (period)
+'.' (period)
This matches any single character, _including_ the newline
- character. For example, `.P' matches any single character
- followed by a `P' in a string. Using concatenation, we can make a
- regular expression such as `U.A', which matches any
- three-character sequence that begins with `U' and ends with `A'.
+ character. For example, '.P' matches any single character followed
+ by a 'P' in a string. Using concatenation, we can make a regular
+ expression such as 'U.A', which matches any three-character
+ sequence that begins with 'U' and ends with 'A'.
- In strict POSIX mode (*note Options::), `.' does not match the NUL
+ In strict POSIX mode (*note Options::), '.' does not match the NUL
character, which is a character with all bits equal to zero.
- Otherwise, NUL is just another character. Other versions of `awk'
+ Otherwise, NUL is just another character. Other versions of 'awk'
may not be able to match the NUL character.
-`['...`]'
- This is called a "bracket expression".(1) It matches any _one_ of
+'['...']'
+ This is called a "bracket expression".(1) It matches any _one_ of
the characters that are enclosed in the square brackets. For
- example, `[MVX]' matches any one of the characters `M', `V', or
- `X' in a string. A full discussion of what can be inside the
- square brackets of a bracket expression is given in *note Bracket
+ example, '[MVX]' matches any one of the characters 'M', 'V', or 'X'
+ in a string. A full discussion of what can be inside the square
+ brackets of a bracket expression is given in *note Bracket
Expressions::.
-`[^'...`]'
+'[^'...']'
This is a "complemented bracket expression". The first character
- after the `[' _must_ be a `^'. It matches any characters _except_
- those in the square brackets. For example, `[^awk]' matches any
- character that is not an `a', `w', or `k'.
+ after the '[' _must_ be a '^'. It matches any characters _except_
+ those in the square brackets. For example, '[^awk]' matches any
+ character that is not an 'a', 'w', or 'k'.
-`|'
+'|'
This is the "alternation operator" and it is used to specify
- alternatives. The `|' has the lowest precedence of all the regular
- expression operators. For example, `^P|[aeiouy]' matches any
- string that matches either `^P' or `[aeiouy]'. This means it
- matches any string that starts with `P' or contains (anywhere
+ alternatives. The '|' has the lowest precedence of all the regular
+ expression operators. For example, '^P|[aeiouy]' matches any
+ string that matches either '^P' or '[aeiouy]'. This means it
+ matches any string that starts with 'P' or contains (anywhere
within it) a lowercase English vowel.
The alternation applies to the largest possible regexps on either
side.
-`('...`)'
+'('...')'
Parentheses are used for grouping in regular expressions, as in
arithmetic. They can be used to concatenate regular expressions
- containing the alternation operator, `|'. For example,
- `@(samp|code)\{[^}]+\}' matches both address@hidden' and address@hidden'.
- (These are Texinfo formatting control sequences. The `+' is
+ containing the alternation operator, '|'. For example,
+ '@(samp|code)\{[^}]+\}' matches both '@code{foo}' and '@samp{bar}'.
+ (These are Texinfo formatting control sequences. The '+' is
explained further on in this list.)
-`*'
+'*'
This symbol means that the preceding regular expression should be
repeated as many times as necessary to find a match. For example,
- `ph*' applies the `*' symbol to the preceding `h' and looks for
- matches of one `p' followed by any number of `h's. This also
- matches just `p' if no `h's are present.
-
- There are two subtle points to understand about how `*' works.
- First, the `*' applies only to the single preceding regular
- expression component (e.g., in `ph*', it applies just to the `h').
- To cause `*' to apply to a larger subexpression, use parentheses:
- `(ph)*' matches `ph', `phph', `phphph', and so on.
-
- Second, `*' finds as many repetitions as possible. If the text to
- be matched is `phhhhhhhhhhhhhhooey', `ph*' matches all of the `h's.
-
-`+'
- This symbol is similar to `*', except that the preceding
- expression must be matched at least once. This means that `wh+y'
- would match `why' and `whhy', but not `wy', whereas `wh*y' would
- match all three.
-
-`?'
- This symbol is similar to `*', except that the preceding
- expression can be matched either once or not at all. For example,
- `fe?d' matches `fed' and `fd', but nothing else.
-
-`{'N`}'
-`{'N`,}'
-`{'N`,'M`}'
+ 'ph*' applies the '*' symbol to the preceding 'h' and looks for
+ matches of one 'p' followed by any number of 'h's. This also
+ matches just 'p' if no 'h's are present.
+
+ There are two subtle points to understand about how '*' works.
+ First, the '*' applies only to the single preceding regular
+ expression component (e.g., in 'ph*', it applies just to the 'h').
+ To cause '*' to apply to a larger subexpression, use parentheses:
+ '(ph)*' matches 'ph', 'phph', 'phphph', and so on.
+
+ Second, '*' finds as many repetitions as possible. If the text to
+ be matched is 'phhhhhhhhhhhhhhooey', 'ph*' matches all of the 'h's.
+
+'+'
+ This symbol is similar to '*', except that the preceding expression
+ must be matched at least once. This means that 'wh+y' would match
+ 'why' and 'whhy', but not 'wy', whereas 'wh*y' would match all
+ three.
+
+'?'
+ This symbol is similar to '*', except that the preceding expression
+ can be matched either once or not at all. For example, 'fe?d'
+ matches 'fed' and 'fd', but nothing else.
+
+'{'N'}'
+'{'N',}'
+'{'N','M'}'
One or two numbers inside braces denote an "interval expression".
If there is one number in the braces, the preceding regexp is
repeated N times. If there are two numbers separated by a comma,
@@ -3661,54 +3648,53 @@ sequences and that are not listed here stand for
themselves:
number followed by a comma, then the preceding regexp is repeated
at least N times:
- `wh{3}y'
- Matches `whhhy', but not `why' or `whhhhy'.
+ 'wh{3}y'
+ Matches 'whhhy', but not 'why' or 'whhhhy'.
- `wh{3,5}y'
- Matches `whhhy', `whhhhy', or `whhhhhy' only.
+ 'wh{3,5}y'
+ Matches 'whhhy', 'whhhhy', or 'whhhhhy' only.
- `wh{2,}y'
- Matches `whhy', `whhhy', and so on.
+ 'wh{2,}y'
+ Matches 'whhy', 'whhhy', and so on.
- Interval expressions were not traditionally available in `awk'.
- They were added as part of the POSIX standard to make `awk' and
- `egrep' consistent with each other.
+ Interval expressions were not traditionally available in 'awk'.
+ They were added as part of the POSIX standard to make 'awk' and
+ 'egrep' consistent with each other.
- Initially, because old programs may use `{' and `}' in regexp
- constants, `gawk' did _not_ match interval expressions in regexps.
+ Initially, because old programs may use '{' and '}' in regexp
+ constants, 'gawk' did _not_ match interval expressions in regexps.
- However, beginning with version 4.0, `gawk' does match interval
+ However, beginning with version 4.0, 'gawk' does match interval
expressions by default. This is because compatibility with POSIX
- has become more important to most `gawk' users than compatibility
+ has become more important to most 'gawk' users than compatibility
with old programs.
- For programs that use `{' and `}' in regexp constants, it is good
+ For programs that use '{' and '}' in regexp constants, it is good
practice to always escape them with a backslash. Then the regexp
constants are valid and work the way you want them to, using any
- version of `awk'.(2)
+ version of 'awk'.(2)
- Finally, when `{' and `}' appear in regexp constants in a way that
- cannot be interpreted as an interval expression (such as
- `/q{a}/'), then they stand for themselves.
+ Finally, when '{' and '}' appear in regexp constants in a way that
+ cannot be interpreted as an interval expression (such as '/q{a}/'),
+ then they stand for themselves.
- In regular expressions, the `*', `+', and `?' operators, as well as
-the braces `{' and `}', have the highest precedence, followed by
-concatenation, and finally by `|'. As in arithmetic, parentheses can
+ In regular expressions, the '*', '+', and '?' operators, as well as
+the braces '{' and '}', have the highest precedence, followed by
+concatenation, and finally by '|'. As in arithmetic, parentheses can
change how operators are grouped.
- In POSIX `awk' and `gawk', the `*', `+', and `?' operators stand for
+ In POSIX 'awk' and 'gawk', the '*', '+', and '?' operators stand for
themselves when there is nothing in the regexp that precedes them. For
-example, `/+/' matches a literal plus sign. However, many other
-versions of `awk' treat such a usage as a syntax error.
+example, '/+/' matches a literal plus sign. However, many other
+versions of 'awk' treat such a usage as a syntax error.
- If `gawk' is in compatibility mode (*note Options::), interval
+ If 'gawk' is in compatibility mode (*note Options::), interval
expressions are not available in regular expressions.
---------- Footnotes ----------
- (1) In other literature, you may see a bracket expression referred
-to as either a "character set", a "character class", or a "character
-list".
+ (1) In other literature, you may see a bracket expression referred to
+as either a "character set", a "character class", or a "character list".
(2) Use two backslashes if you're using a string constant with a
regexp operator or function.
@@ -3725,96 +3711,95 @@ those listed between the opening and closing square
brackets.
Within a bracket expression, a "range expression" consists of two
characters separated by a hyphen. It matches any single character that
sorts between the two characters, based upon the system's native
-character set. For example, `[0-9]' is equivalent to `[0123456789]'.
+character set. For example, '[0-9]' is equivalent to '[0123456789]'.
(See *note Ranges and Locales::, for an explanation of how the POSIX
-standard and `gawk' have changed over time. This is mainly of
+standard and 'gawk' have changed over time. This is mainly of
historical interest.)
- To include one of the characters `\', `]', `-', or `^' in a bracket
-expression, put a `\' in front of it. For example:
+ To include one of the characters '\', ']', '-', or '^' in a bracket
+expression, put a '\' in front of it. For example:
[d\]]
-matches either `d' or `]'. Additionally, if you place `]' right after
-the opening `[', the closing bracket is treated as one of the
-characters to be matched.
+matches either 'd' or ']'. Additionally, if you place ']' right after
+the opening '[', the closing bracket is treated as one of the characters
+to be matched.
- The treatment of `\' in bracket expressions is compatible with other
-`awk' implementations and is also mandated by POSIX. The regular
-expressions in `awk' are a superset of the POSIX specification for
+ The treatment of '\' in bracket expressions is compatible with other
+'awk' implementations and is also mandated by POSIX. The regular
+expressions in 'awk' are a superset of the POSIX specification for
Extended Regular Expressions (EREs). POSIX EREs are based on the
-regular expressions accepted by the traditional `egrep' utility.
+regular expressions accepted by the traditional 'egrep' utility.
"Character classes" are a feature introduced in the POSIX standard.
A character class is a special notation for describing lists of
-characters that have a specific attribute, but the actual characters
-can vary from country to country and/or from character set to character
-set. For example, the notion of what is an alphabetic character
-differs between the United States and France.
+characters that have a specific attribute, but the actual characters can
+vary from country to country and/or from character set to character set.
+For example, the notion of what is an alphabetic character differs
+between the United States and France.
A character class is only valid in a regexp _inside_ the brackets of
-a bracket expression. Character classes consist of `[:', a keyword
-denoting the class, and `:]'. *note table-char-classes:: lists the
-character classes defined by the POSIX standard.
+a bracket expression. Character classes consist of '[:', a keyword
+denoting the class, and ':]'. *note Table 3.1: table-char-classes.
+lists the character classes defined by the POSIX standard.
Class Meaning
---------------------------------------------------------------------------
-`[:alnum:]' Alphanumeric characters
-`[:alpha:]' Alphabetic characters
-`[:blank:]' Space and TAB characters
-`[:cntrl:]' Control characters
-`[:digit:]' Numeric characters
-`[:graph:]' Characters that are both printable and visible (a space is
- printable but not visible, whereas an `a' is both)
-`[:lower:]' Lowercase alphabetic characters
-`[:print:]' Printable characters (characters that are not control
+--------------------------------------------------------------------------
+'[:alnum:]' Alphanumeric characters
+'[:alpha:]' Alphabetic characters
+'[:blank:]' Space and TAB characters
+'[:cntrl:]' Control characters
+'[:digit:]' Numeric characters
+'[:graph:]' Characters that are both printable and visible (a space is
+ printable but not visible, whereas an 'a' is both)
+'[:lower:]' Lowercase alphabetic characters
+'[:print:]' Printable characters (characters that are not control
characters)
-`[:punct:]' Punctuation characters (characters that are not letters,
+'[:punct:]' Punctuation characters (characters that are not letters,
digits, control characters, or space characters)
-`[:space:]' Space characters (such as space, TAB, and formfeed, to name
+'[:space:]' Space characters (such as space, TAB, and formfeed, to name
a few)
-`[:upper:]' Uppercase alphabetic characters
-`[:xdigit:]'Characters that are hexadecimal digits
+'[:upper:]' Uppercase alphabetic characters
+'[:xdigit:]'Characters that are hexadecimal digits
Table 3.1: POSIX character classes
For example, before the POSIX standard, you had to write
-`/[A-Za-z0-9]/' to match alphanumeric characters. If your character
-set had other alphabetic characters in it, this would not match them.
-With the POSIX character classes, you can write `/[[:alnum:]]/' to
-match the alphabetic and numeric characters in your character set.
+'/[A-Za-z0-9]/' to match alphanumeric characters. If your character set
+had other alphabetic characters in it, this would not match them. With
+the POSIX character classes, you can write '/[[:alnum:]]/' to match the
+alphabetic and numeric characters in your character set.
Some utilities that match regular expressions provide a nonstandard
-`[:ascii:]' character class; `awk' does not. However, you can simulate
-such a construct using `[\x00-\x7F]'. This matches all values
+'[:ascii:]' character class; 'awk' does not. However, you can simulate
+such a construct using '[\x00-\x7F]'. This matches all values
numerically between zero and 127, which is the defined range of the
-ASCII character set. Use a complemented character list
-(`[^\x00-\x7F]') to match any single-byte characters that are not in
-the ASCII range.
+ASCII character set. Use a complemented character list ('[^\x00-\x7F]')
+to match any single-byte characters that are not in the ASCII range.
Two additional special sequences can appear in bracket expressions.
These apply to non-ASCII character sets, which can have single symbols
(called "collating elements") that are represented with more than one
-character. They can also have several characters that are equivalent for
-"collating", or sorting, purposes. (For example, in French, a plain "e"
-and a grave-accented "e`" are equivalent.) These sequences are:
+character. They can also have several characters that are equivalent
+for "collating", or sorting, purposes. (For example, in French, a plain
+"e" and a grave-accented "e`" are equivalent.) These sequences are:
Collating symbols
- Multicharacter collating elements enclosed between `[.' and `.]'.
- For example, if `ch' is a collating element, then `[[.ch.]]' is a
- regexp that matches this collating element, whereas `[ch]' is a
- regexp that matches either `c' or `h'.
+ Multicharacter collating elements enclosed between '[.' and '.]'.
+ For example, if 'ch' is a collating element, then '[[.ch.]]' is a
+ regexp that matches this collating element, whereas '[ch]' is a
+ regexp that matches either 'c' or 'h'.
Equivalence classes
- Locale-specific names for a list of characters that are equal. The
- name is enclosed between `[=' and `=]'. For example, the name `e'
- might be used to represent all of "e," "e^," "e`," and "e'." In
- this case, `[[=e=]]' is a regexp that matches any of `e', `e^',
- `e'', or `e`'.
+ Locale-specific names for a list of characters that are equal. The
+ name is enclosed between '[=' and '=]'. For example, the name 'e'
+ might be used to represent all of "e," "e^," "e`," and "e'." In
+ this case, '[[=e=]]' is a regexp that matches any of 'e', 'e^',
+ 'e'', or 'e`'.
These features are very valuable in non-English-speaking locales.
- CAUTION: The library functions that `gawk' uses for regular
+ CAUTION: The library functions that 'gawk' uses for regular
expression matching currently recognize only POSIX character
classes; they do not recognize collating symbols or equivalence
classes.
@@ -3829,23 +3814,23 @@ Consider the following:
echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
- This example uses the `sub()' function to make a change to the input
-record. (`sub()' replaces the first instance of any text matched by
-the first argument with the string provided as the second argument;
-*note String Functions::.) Here, the regexp `/a+/' indicates "one or
-more `a' characters," and the replacement text is `<A>'.
+ This example uses the 'sub()' function to make a change to the input
+record. ('sub()' replaces the first instance of any text matched by the
+first argument with the string provided as the second argument; *note
+String Functions::.) Here, the regexp '/a+/' indicates "one or more 'a'
+characters," and the replacement text is '<A>'.
- The input contains four `a' characters. `awk' (and POSIX) regular
+ The input contains four 'a' characters. 'awk' (and POSIX) regular
expressions always match the leftmost, _longest_ sequence of input
-characters that can match. Thus, all four `a' characters are replaced
-with `<A>' in this example:
+characters that can match. Thus, all four 'a' characters are replaced
+with '<A>' in this example:
$ echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
-| <A>bcd
- For simple match/no-match tests, this is not so important. But when
-doing text matching and substitutions with the `match()', `sub()',
-`gsub()', and `gensub()' functions, it is very important. *Note String
+ For simple match/no-match tests, this is not so important. But when
+doing text matching and substitutions with the 'match()', 'sub()',
+'gsub()', and 'gensub()' functions, it is very important. *Note String
Functions::, for more information on these functions. Understanding
this principle is also important for regexp-based record and field
splitting (*note Records::, and also *note Field Separators::).
@@ -3856,7 +3841,7 @@ File: gawk.info, Node: Computed Regexps, Next: GNU
Regexp Operators, Prev: Le
3.6 Using Dynamic Regexps
=========================
-The righthand side of a `~' or `!~' operator need not be a regexp
+The righthand side of a '~' or '!~' operator need not be a regexp
constant (i.e., a string of characters between slashes). It may be any
expression. The expression is evaluated and converted to a string if
necessary; the contents of the string are then used as the regexp. A
@@ -3866,59 +3851,59 @@ regexp":
BEGIN { digits_regexp = "[[:digit:]]+" }
$0 ~ digits_regexp { print }
-This sets `digits_regexp' to a regexp that describes one or more digits,
+This sets 'digits_regexp' to a regexp that describes one or more digits,
and tests whether the input record matches this regexp.
- NOTE: When using the `~' and `!~' operators, be aware that there
- is a difference between a regexp constant enclosed in slashes and
- a string constant enclosed in double quotes. If you are going to
- use a string constant, you have to understand that the string is,
- in essence, scanned _twice_: the first time when `awk' reads your
+ NOTE: When using the '~' and '!~' operators, be aware that there is
+ a difference between a regexp constant enclosed in slashes and a
+ string constant enclosed in double quotes. If you are going to use
+ a string constant, you have to understand that the string is, in
+ essence, scanned _twice_: the first time when 'awk' reads your
program, and the second time when it goes to match the string on
the lefthand side of the operator with the pattern on the right.
This is true of any string-valued expression (such as
- `digits_regexp', shown in the previous example), not just string
+ 'digits_regexp', shown in the previous example), not just string
constants.
- What difference does it make if the string is scanned twice? The
+ What difference does it make if the string is scanned twice? The
answer has to do with escape sequences, and particularly with
backslashes. To get a backslash into a regular expression inside a
string, you have to type two backslashes.
- For example, `/\*/' is a regexp constant for a literal `*'. Only
-one backslash is needed. To do the same thing with a string, you have
-to type `"\\*"'. The first backslash escapes the second one so that
-the string actually contains the two characters `\' and `*'.
+ For example, '/\*/' is a regexp constant for a literal '*'. Only one
+backslash is needed. To do the same thing with a string, you have to
+type '"\\*"'. The first backslash escapes the second one so that the
+string actually contains the two characters '\' and '*'.
Given that you can use both regexp and string constants to describe
regular expressions, which should you use? The answer is "regexp
constants," for several reasons:
* String constants are more complicated to write and more difficult
- to read. Using regexp constants makes your programs less
+ to read. Using regexp constants makes your programs less
error-prone. Not understanding the difference between the two
kinds of constants is a common source of errors.
- * It is more efficient to use regexp constants. `awk' can note that
+ * It is more efficient to use regexp constants. 'awk' can note that
you have supplied a regexp and store it internally in a form that
makes pattern matching more efficient. When using a string
- constant, `awk' must first convert the string into this internal
+ constant, 'awk' must first convert the string into this internal
form and then perform the pattern matching.
* Using regexp constants is better form; it shows clearly that you
intend a regexp match.
- Using `\n' in Bracket Expressions of Dynamic Regexps
+ Using '\n' in Bracket Expressions of Dynamic Regexps
- Some older versions of `awk' do not allow the newline character to
-be used inside a bracket expression for a dynamic regexp:
+ Some older versions of 'awk' do not allow the newline character to be
+used inside a bracket expression for a dynamic regexp:
$ awk '$0 ~ "[ \t\n]"'
- error--> awk: newline in character class [
- error--> ]...
- error--> source line number 1
- error--> context is
- error--> $0 ~ "[ >>> \t\n]" <<<
+ error-> awk: newline in character class [
+ error-> ]...
+ error-> source line number 1
+ error-> context is
+ error-> $0 ~ "[ >>> \t\n]" <<<
But a newline in a regexp constant works with no problem:
@@ -3927,101 +3912,101 @@ be used inside a bracket expression for a dynamic
regexp:
-| here is a sample line
Ctrl-d
- `gawk' does not have this problem, and it isn't likely to occur
-often in practice, but it's worth noting for future reference.
+ 'gawk' does not have this problem, and it isn't likely to occur often
+in practice, but it's worth noting for future reference.
File: gawk.info, Node: GNU Regexp Operators, Next: Case-sensitivity, Prev:
Computed Regexps, Up: Regexp
-3.7 `gawk'-Specific Regexp Operators
+3.7 'gawk'-Specific Regexp Operators
====================================
GNU software that deals with regular expressions provides a number of
additional regexp operators. These operators are described in this
-minor node and are specific to `gawk'; they are not available in other
-`awk' implementations. Most of the additional operators deal with word
+minor node and are specific to 'gawk'; they are not available in other
+'awk' implementations. Most of the additional operators deal with word
matching. For our purposes, a "word" is a sequence of one or more
-letters, digits, or underscores (`_'):
+letters, digits, or underscores ('_'):
-`\s'
+'\s'
Matches any whitespace character. Think of it as shorthand for
- `[[:space:]]'.
+ '[[:space:]]'.
-`\S'
+'\S'
Matches any character that is not whitespace. Think of it as
- shorthand for `[^[:space:]]'.
+ shorthand for '[^[:space:]]'.
-`\w'
+'\w'
Matches any word-constituent character--that is, it matches any
- letter, digit, or underscore. Think of it as shorthand for
- `[[:alnum:]_]'.
+ letter, digit, or underscore. Think of it as shorthand for
+ '[[:alnum:]_]'.
-`\W'
- Matches any character that is not word-constituent. Think of it
- as shorthand for `[^[:alnum:]_]'.
+'\W'
+ Matches any character that is not word-constituent. Think of it as
+ shorthand for '[^[:alnum:]_]'.
-`\<'
+'\<'
Matches the empty string at the beginning of a word. For example,
- `/\<away/' matches `away' but not `stowaway'.
+ '/\<away/' matches 'away' but not 'stowaway'.
-`\>'
+'\>'
Matches the empty string at the end of a word. For example,
- `/stow\>/' matches `stow' but not `stowaway'.
+ '/stow\>/' matches 'stow' but not 'stowaway'.
-`\y'
+'\y'
Matches the empty string at either the beginning or the end of a
- word (i.e., the word boundar*y*). For example, `\yballs?\y'
- matches either `ball' or `balls', as a separate word.
+ word (i.e., the word boundar*y*). For example, '\yballs?\y'
+ matches either 'ball' or 'balls', as a separate word.
-`\B'
+'\B'
Matches the empty string that occurs between two word-constituent
- characters. For example, `/\Brat\B/' matches `crate', but it does
- not match `dirty rat'. `\B' is essentially the opposite of `\y'.
+ characters. For example, '/\Brat\B/' matches 'crate', but it does
+ not match 'dirty rat'. '\B' is essentially the opposite of '\y'.
There are two other operators that work on buffers. In Emacs, a
"buffer" is, naturally, an Emacs buffer. Other GNU programs, including
-`gawk', consider the entire string to match as the buffer. The
+'gawk', consider the entire string to match as the buffer. The
operators are:
-`\`'
+'\`'
Matches the empty string at the beginning of a buffer (string)
-`\''
+'\''
Matches the empty string at the end of a buffer (string)
- Because `^' and `$' always work in terms of the beginning and end of
-strings, these operators don't add any new capabilities for `awk'.
-They are provided for compatibility with other GNU software.
+ Because '^' and '$' always work in terms of the beginning and end of
+strings, these operators don't add any new capabilities for 'awk'. They
+are provided for compatibility with other GNU software.
- In other GNU software, the word-boundary operator is `\b'. However,
-that conflicts with the `awk' language's definition of `\b' as
-backspace, so `gawk' uses a different letter. An alternative method
+ In other GNU software, the word-boundary operator is '\b'. However,
+that conflicts with the 'awk' language's definition of '\b' as
+backspace, so 'gawk' uses a different letter. An alternative method
would have been to require two backslashes in the GNU operators, but
-this was deemed too confusing. The current method of using `\y' for the
-GNU `\b' appears to be the lesser of two evils.
+this was deemed too confusing. The current method of using '\y' for the
+GNU '\b' appears to be the lesser of two evils.
- The various command-line options (*note Options::) control how
-`gawk' interprets characters in regexps:
+ The various command-line options (*note Options::) control how 'gawk'
+interprets characters in regexps:
No options
- In the default case, `gawk' provides all the facilities of POSIX
+ In the default case, 'gawk' provides all the facilities of POSIX
regexps and the GNU regexp operators described in *note Regexp
Operators::.
-`--posix'
+'--posix'
Match only POSIX regexps; the GNU operators are not special (e.g.,
- `\w' matches a literal `w'). Interval expressions are allowed.
+ '\w' matches a literal 'w'). Interval expressions are allowed.
-`--traditional'
- Match traditional Unix `awk' regexps. The GNU operators are not
+'--traditional'
+ Match traditional Unix 'awk' regexps. The GNU operators are not
special, and interval expressions are not available. Because BWK
- `awk' supports them, the POSIX character classes (`[[:alnum:]]',
- etc.) are available. Characters described by octal and
+ 'awk' supports them, the POSIX character classes ('[[:alnum:]]',
+ etc.) are available. Characters described by octal and
hexadecimal escape sequences are treated literally, even if they
represent regexp metacharacters.
-`--re-interval'
- Allow interval expressions in regexps, if `--traditional' has been
+'--re-interval'
+ Allow interval expressions in regexps, if '--traditional' has been
provided. Otherwise, interval expressions are available by
default.
@@ -4033,32 +4018,32 @@ File: gawk.info, Node: Case-sensitivity, Next: Regexp
Summary, Prev: GNU Rege
Case is normally significant in regular expressions, both when matching
ordinary characters (i.e., not metacharacters) and inside bracket
-expressions. Thus, a `w' in a regular expression matches only a
-lowercase `w' and not an uppercase `W'.
+expressions. Thus, a 'w' in a regular expression matches only a
+lowercase 'w' and not an uppercase 'W'.
The simplest way to do a case-independent match is to use a bracket
-expression--for example, `[Ww]'. However, this can be cumbersome if
-you need to use it often, and it can make the regular expressions harder
-to read. There are two alternatives that you might prefer.
+expression--for example, '[Ww]'. However, this can be cumbersome if you
+need to use it often, and it can make the regular expressions harder to
+read. There are two alternatives that you might prefer.
One way to perform a case-insensitive match at a particular point in
the program is to convert the data to a single case, using the
-`tolower()' or `toupper()' built-in string functions (which we haven't
+'tolower()' or 'toupper()' built-in string functions (which we haven't
discussed yet; *note String Functions::). For example:
tolower($1) ~ /foo/ { ... }
converts the first field to lowercase before matching against it. This
-works in any POSIX-compliant `awk'.
+works in any POSIX-compliant 'awk'.
- Another method, specific to `gawk', is to set the variable
-`IGNORECASE' to a nonzero value (*note Built-in Variables::). When
-`IGNORECASE' is not zero, _all_ regexp and string operations ignore
+ Another method, specific to 'gawk', is to set the variable
+'IGNORECASE' to a nonzero value (*note Built-in Variables::). When
+'IGNORECASE' is not zero, _all_ regexp and string operations ignore
case.
- Changing the value of `IGNORECASE' dynamically controls the case
+ Changing the value of 'IGNORECASE' dynamically controls the case
sensitivity of the program as it runs. Case is significant by default
-because `IGNORECASE' (like most variables) is initialized to zero:
+because 'IGNORECASE' (like most variables) is initialized to zero:
x = "aB"
if (x ~ /ab/) ... # this test will fail
@@ -4066,38 +4051,38 @@ because `IGNORECASE' (like most variables) is
initialized to zero:
IGNORECASE = 1
if (x ~ /ab/) ... # now it will succeed
- In general, you cannot use `IGNORECASE' to make certain rules case
+ In general, you cannot use 'IGNORECASE' to make certain rules case
insensitive and other rules case sensitive, as there is no
-straightforward way to set `IGNORECASE' just for the pattern of a
-particular rule.(1) To do this, use either bracket expressions or
-`tolower()'. However, one thing you can do with `IGNORECASE' only is
+straightforward way to set 'IGNORECASE' just for the pattern of a
+particular rule.(1) To do this, use either bracket expressions or
+'tolower()'. However, one thing you can do with 'IGNORECASE' only is
dynamically turn case sensitivity on or off for all the rules at once.
- `IGNORECASE' can be set on the command line or in a `BEGIN' rule
+ 'IGNORECASE' can be set on the command line or in a 'BEGIN' rule
(*note Other Arguments::; also *note Using BEGIN/END::). Setting
-`IGNORECASE' from the command line is a way to make a program case
+'IGNORECASE' from the command line is a way to make a program case
insensitive without having to edit it.
In multibyte locales, the equivalences between upper- and lowercase
-characters are tested based on the wide-character values of the
-locale's character set. Otherwise, the characters are tested based on
-the ISO-8859-1 (ISO Latin-1) character set. This character set is a
+characters are tested based on the wide-character values of the locale's
+character set. Otherwise, the characters are tested based on the
+ISO-8859-1 (ISO Latin-1) character set. This character set is a
superset of the traditional 128 ASCII characters, which also provides a
number of characters suitable for use with European languages.(2)
- The value of `IGNORECASE' has no effect if `gawk' is in
-compatibility mode (*note Options::). Case is always significant in
-compatibility mode.
+ The value of 'IGNORECASE' has no effect if 'gawk' is in compatibility
+mode (*note Options::). Case is always significant in compatibility
+mode.
---------- Footnotes ----------
(1) Experienced C and C++ programmers will note that it is possible,
-using something like `IGNORECASE = 1 && /foObAr/ { ... }' and
-`IGNORECASE = 0 || /foobar/ { ... }'. However, this is somewhat
-obscure and we don't recommend it.
+using something like 'IGNORECASE = 1 && /foObAr/ { ... }' and
+'IGNORECASE = 0 || /foobar/ { ... }'. However, this is somewhat obscure
+and we don't recommend it.
- (2) If you don't understand this, don't worry about it; it just
-means that `gawk' does the right thing.
+ (2) If you don't understand this, don't worry about it; it just means
+that 'gawk' does the right thing.
File: gawk.info, Node: Regexp Summary, Prev: Case-sensitivity, Up: Regexp
@@ -4106,16 +4091,16 @@ File: gawk.info, Node: Regexp Summary, Prev:
Case-sensitivity, Up: Regexp
===========
* Regular expressions describe sets of strings to be matched. In
- `awk', regular expression constants are written enclosed between
- slashes: `/'...`/'.
+ 'awk', regular expression constants are written enclosed between
+ slashes: '/'...'/'.
* Regexp constants may be used standalone in patterns and in
conditional expressions, or as part of matching expressions using
- the `~' and `!~' operators.
+ the '~' and '!~' operators.
- * Escape sequences let you represent nonprintable characters and
- also let you represent regexp metacharacters as literal characters
- to be matched.
+ * Escape sequences let you represent nonprintable characters and also
+ let you represent regexp metacharacters as literal characters to be
+ matched.
* Regexp operators provide grouping, alternation, and repetition.
@@ -4132,10 +4117,9 @@ File: gawk.info, Node: Regexp Summary, Prev:
Case-sensitivity, Up: Regexp
* Matching expressions may use dynamic regexps (i.e., string values
treated as regular expressions).
- * `gawk''s `IGNORECASE' variable lets you control the case
- sensitivity of regexp matching. In other `awk' versions, use
- `tolower()' or `toupper()'.
-
+ * 'gawk''s 'IGNORECASE' variable lets you control the case
+ sensitivity of regexp matching. In other 'awk' versions, use
+ 'tolower()' or 'toupper()'.
File: gawk.info, Node: Reading Files, Next: Printing, Prev: Regexp, Up: Top
@@ -4143,13 +4127,13 @@ File: gawk.info, Node: Reading Files, Next: Printing,
Prev: Regexp, Up: Top
4 Reading Input Files
*********************
-In the typical `awk' program, `awk' reads all input either from the
-standard input (by default, this is the keyboard, but often it is a
-pipe from another command) or from files whose names you specify on the
-`awk' command line. If you specify input files, `awk' reads them in
-order, processing all the data from one before going on to the next.
-The name of the current input file can be found in the predefined
-variable `FILENAME' (*note Built-in Variables::).
+In the typical 'awk' program, 'awk' reads all input either from the
+standard input (by default, this is the keyboard, but often it is a pipe
+from another command) or from files whose names you specify on the 'awk'
+command line. If you specify input files, 'awk' reads them in order,
+processing all the data from one before going on to the next. The name
+of the current input file can be found in the predefined variable
+'FILENAME' (*note Built-in Variables::).
The input is read in units called "records", and is processed by the
rules of your program one record at a time. By default, each record is
@@ -4157,10 +4141,10 @@ one line. Each record is automatically split into
chunks called
"fields". This makes it more convenient for programs to work on the
parts of a record.
- On rare occasions, you may need to use the `getline' command. The
-`getline' command is valuable both because it can do explicit input
-from any number of files, and because the files used with it do not
-have to be named on the `awk' command line (*note Getline::).
+ On rare occasions, you may need to use the 'getline' command. The
+'getline' command is valuable both because it can do explicit input from
+any number of files, and because the files used with it do not have to
+be named on the 'awk' command line (*note Getline::).
* Menu:
@@ -4173,7 +4157,7 @@ have to be named on the `awk' command line (*note
Getline::).
* Splitting By Content:: Defining Fields By Content
* Multiple Line:: Reading multiline records.
* Getline:: Reading files under explicit program control
- using the `getline' function.
+ using the 'getline' function.
* Read Timeout:: Reading input with a timeout.
* Command-line directories:: What happens if you put a directory on the
command line.
@@ -4186,51 +4170,51 @@ File: gawk.info, Node: Records, Next: Fields, Up:
Reading Files
4.1 How Input Is Split into Records
===================================
-`awk' divides the input for your program into records and fields. It
-keeps track of the number of records that have been read so far from
-the current input file. This value is stored in a predefined variable
-called `FNR', which is reset to zero every time a new file is started.
-Another predefined variable, `NR', records the total number of input
+'awk' divides the input for your program into records and fields. It
+keeps track of the number of records that have been read so far from the
+current input file. This value is stored in a predefined variable
+called 'FNR', which is reset to zero every time a new file is started.
+Another predefined variable, 'NR', records the total number of input
records read so far from all data files. It starts at zero, but is
never automatically reset to zero.
* Menu:
-* awk split records:: How standard `awk' splits records.
-* gawk split records:: How `gawk' splits records.
+* awk split records:: How standard 'awk' splits records.
+* gawk split records:: How 'gawk' splits records.
File: gawk.info, Node: awk split records, Next: gawk split records, Up:
Records
-4.1.1 Record Splitting with Standard `awk'
+4.1.1 Record Splitting with Standard 'awk'
------------------------------------------
Records are separated by a character called the "record separator". By
default, the record separator is the newline character. This is why
-records are, by default, single lines. To use a different character
-for the record separator, simply assign that character to the
-predefined variable `RS'.
+records are, by default, single lines. To use a different character for
+the record separator, simply assign that character to the predefined
+variable 'RS'.
- Like any other variable, the value of `RS' can be changed in the
-`awk' program with the assignment operator, `=' (*note Assignment
+ Like any other variable, the value of 'RS' can be changed in the
+'awk' program with the assignment operator, '=' (*note Assignment
Ops::). The new record-separator character should be enclosed in
quotation marks, which indicate a string constant. Often, the right
time to do this is at the beginning of execution, before any input is
processed, so that the very first record is read with the proper
-separator. To do this, use the special `BEGIN' pattern (*note
+separator. To do this, use the special 'BEGIN' pattern (*note
BEGIN/END::). For example:
awk 'BEGIN { RS = "u" }
{ print $0 }' mail-list
-changes the value of `RS' to `u', before reading any input. The new
+changes the value of 'RS' to 'u', before reading any input. The new
value is a string whose first character is the letter "u"; as a result,
records are separated by the letter "u". Then the input file is read,
-and the second rule in the `awk' program (the action with no pattern)
-prints each record. Because each `print' statement adds a newline at
-the end of its output, this `awk' program copies the input with each
-`u' changed to a newline. Here are the results of running the program
-on `mail-list':
+and the second rule in the 'awk' program (the action with no pattern)
+prints each record. Because each 'print' statement adds a newline at
+the end of its output, this 'awk' program copies the input with each 'u'
+changed to a newline. Here are the results of running the program on
+'mail-list':
$ awk 'BEGIN { RS = "u" }
> { print $0 }' mail-list
@@ -4273,86 +4257,85 @@ on `mail-list':
-| R
-|
-Note that the entry for the name `Bill' is not split. In the original
+Note that the entry for the name 'Bill' is not split. In the original
data file (*note Sample Data Files::), the line looks like this:
Bill 555-1675 address@hidden A
-It contains no `u', so there is no reason to split the record, unlike
-the others, which each have one or more occurrences of the `u'. In
-fact, this record is treated as part of the previous record; the
-newline separating them in the output is the original newline in the
-data file, not the one added by `awk' when it printed the record!
+It contains no 'u', so there is no reason to split the record, unlike
+the others, which each have one or more occurrences of the 'u'. In
+fact, this record is treated as part of the previous record; the newline
+separating them in the output is the original newline in the data file,
+not the one added by 'awk' when it printed the record!
Another way to change the record separator is on the command line,
using the variable-assignment feature (*note Other Arguments::):
awk '{ print $0 }' RS="u" mail-list
-This sets `RS' to `u' before processing `mail-list'.
+This sets 'RS' to 'u' before processing 'mail-list'.
- Using an alphabetic character such as `u' for the record separator
-is highly likely to produce strange results. Using an unusual
-character such as `/' is more likely to produce correct behavior in the
-majority of cases, but there are no guarantees. The moral is: Know Your
-Data.
+ Using an alphabetic character such as 'u' for the record separator is
+highly likely to produce strange results. Using an unusual character
+such as '/' is more likely to produce correct behavior in the majority
+of cases, but there are no guarantees. The moral is: Know Your Data.
When using regular characters as the record separator, there is one
-unusual case that occurs when `gawk' is being fully POSIX-compliant
+unusual case that occurs when 'gawk' is being fully POSIX-compliant
(*note Options::). Then, the following (extreme) pipeline prints a
-surprising `1':
+surprising '1':
$ echo | gawk --posix 'BEGIN { RS = "a" } ; { print NF }'
-| 1
There is one field, consisting of a newline. The value of the
-built-in variable `NF' is the number of fields in the current record.
-(In the normal case, `gawk' treats the newline as whitespace, printing
-`0' as the result. Most other versions of `awk' also act this way.)
+built-in variable 'NF' is the number of fields in the current record.
+(In the normal case, 'gawk' treats the newline as whitespace, printing
+'0' as the result. Most other versions of 'awk' also act this way.)
Reaching the end of an input file terminates the current input
record, even if the last character in the file is not the character in
-`RS'. (d.c.)
+'RS'. (d.c.)
- The empty string `""' (a string without any characters) has a
-special meaning as the value of `RS'. It means that records are
-separated by one or more blank lines and nothing else. *Note Multiple
-Line::, for more details.
+ The empty string '""' (a string without any characters) has a special
+meaning as the value of 'RS'. It means that records are separated by
+one or more blank lines and nothing else. *Note Multiple Line::, for
+more details.
- If you change the value of `RS' in the middle of an `awk' run, the
+ If you change the value of 'RS' in the middle of an 'awk' run, the
new value is used to delimit subsequent records, but the record
currently being processed, as well as records already processed, are not
affected.
- After the end of the record has been determined, `gawk' sets the
-variable `RT' to the text in the input that matched `RS'.
+ After the end of the record has been determined, 'gawk' sets the
+variable 'RT' to the text in the input that matched 'RS'.
File: gawk.info, Node: gawk split records, Prev: awk split records, Up:
Records
-4.1.2 Record Splitting with `gawk'
+4.1.2 Record Splitting with 'gawk'
----------------------------------
-When using `gawk', the value of `RS' is not limited to a one-character
-string. It can be any regular expression (*note Regexp::). (c.e.) In
+When using 'gawk', the value of 'RS' is not limited to a one-character
+string. It can be any regular expression (*note Regexp::). (c.e.) In
general, each record ends at the next string that matches the regular
expression; the next record starts at the end of the matching string.
-This general rule is actually at work in the usual case, where `RS'
+This general rule is actually at work in the usual case, where 'RS'
contains just a newline: a record ends at the beginning of the next
matching string (the next newline in the input), and the following
record starts just after the end of this string (at the first character
-of the following line). The newline, because it matches `RS', is not
+of the following line). The newline, because it matches 'RS', is not
part of either record.
- When `RS' is a single character, `RT' contains the same single
-character. However, when `RS' is a regular expression, `RT' contains
+ When 'RS' is a single character, 'RT' contains the same single
+character. However, when 'RS' is a regular expression, 'RT' contains
the actual input text that matched the regular expression.
- If the input file ends without any text matching `RS', `gawk' sets
-`RT' to the null string.
+ If the input file ends without any text matching 'RS', 'gawk' sets
+'RT' to the null string.
The following example illustrates both of these features. It sets
-`RS' equal to a regular expression that matches either a newline or a
+'RS' equal to a regular expression that matches either a newline or a
series of one or more uppercase letters with optional leading and/or
trailing whitespace:
@@ -4364,64 +4347,63 @@ trailing whitespace:
-| Record = record 3 and RT = [
-| ]
-The square brackets delineate the contents of `RT', letting you see the
-leading and trailing whitespace. The final value of `RT' is a newline.
-*Note Simple Sed::, for a more useful example of `RS' as a regexp and
-`RT'.
-
- If you set `RS' to a regular expression that allows optional
-trailing text, such as `RS = "abc(XYZ)?"', it is possible, due to
-implementation constraints, that `gawk' may match the leading part of
-the regular expression, but not the trailing part, particularly if the
-input text that could match the trailing part is fairly long. `gawk'
-attempts to avoid this problem, but currently, there's no guarantee
-that this will never happen.
-
- NOTE: Remember that in `awk', the `^' and `$' anchor
- metacharacters match the beginning and end of a _string_, and not
- the beginning and end of a _line_. As a result, something like
- `RS = "^[[:upper:]]"' can only match at the beginning of a file.
- This is because `gawk' views the input file as one long string
- that happens to contain newline characters. It is thus best to
- avoid anchor metacharacters in the value of `RS'.
-
- The use of `RS' as a regular expression and the `RT' variable are
-`gawk' extensions; they are not available in compatibility mode (*note
+The square brackets delineate the contents of 'RT', letting you see the
+leading and trailing whitespace. The final value of 'RT' is a newline.
+*Note Simple Sed::, for a more useful example of 'RS' as a regexp and
+'RT'.
+
+ If you set 'RS' to a regular expression that allows optional trailing
+text, such as 'RS = "abc(XYZ)?"', it is possible, due to implementation
+constraints, that 'gawk' may match the leading part of the regular
+expression, but not the trailing part, particularly if the input text
+that could match the trailing part is fairly long. 'gawk' attempts to
+avoid this problem, but currently, there's no guarantee that this will
+never happen.
+
+ NOTE: Remember that in 'awk', the '^' and '$' anchor metacharacters
+ match the beginning and end of a _string_, and not the beginning
+ and end of a _line_. As a result, something like 'RS =
+ "^[[:upper:]]"' can only match at the beginning of a file. This is
+ because 'gawk' views the input file as one long string that happens
+ to contain newline characters. It is thus best to avoid anchor
+ metacharacters in the value of 'RS'.
+
+ The use of 'RS' as a regular expression and the 'RT' variable are
+'gawk' extensions; they are not available in compatibility mode (*note
Options::). In compatibility mode, only the first character of the
-value of `RS' determines the end of the record.
+value of 'RS' determines the end of the record.
- `RS = "\0"' Is Not Portable
+ 'RS = "\0"' Is Not Portable
There are times when you might want to treat an entire data file as a
-single record. The only way to make this happen is to give `RS' a
-value that you know doesn't occur in the input file. This is hard to
-do in a general way, such that a program always works for arbitrary
-input files.
+single record. The only way to make this happen is to give 'RS' a value
+that you know doesn't occur in the input file. This is hard to do in a
+general way, such that a program always works for arbitrary input files.
You might think that for text files, the NUL character, which
consists of a character with all bits equal to zero, is a good value to
-use for `RS' in this case:
+use for 'RS' in this case:
BEGIN { RS = "\0" } # whole file becomes one record?
- `gawk' in fact accepts this, and uses the NUL character for the
+ 'gawk' in fact accepts this, and uses the NUL character for the
record separator. This works for certain special files, such as
-`/proc/environ' on GNU/Linux systems, where the NUL character is in
-fact the record separator. However, this usage is _not_ portable to
-most other `awk' implementations.
+'/proc/environ' on GNU/Linux systems, where the NUL character is in fact
+the record separator. However, this usage is _not_ portable to most
+other 'awk' implementations.
- Almost all other `awk' implementations(1) store strings internally
-as C-style strings. C strings use the NUL character as the string
-terminator. In effect, this means that `RS = "\0"' is the same as `RS
-= ""'. (d.c.)
+ Almost all other 'awk' implementations(1) store strings internally as
+C-style strings. C strings use the NUL character as the string
+terminator. In effect, this means that 'RS = "\0"' is the same as 'RS =
+""'. (d.c.)
- It happens that recent versions of `mawk' can use the NUL character
-as a record separator. However, this is a special case: `mawk' does not
+ It happens that recent versions of 'mawk' can use the NUL character
+as a record separator. However, this is a special case: 'mawk' does not
allow embedded NUL characters in strings. (This may change in a future
-version of `mawk'.)
+version of 'mawk'.)
*Note Readfile Function::, for an interesting way to read whole
-files. If you are using `gawk', see *note Extension Sample Readfile::,
+files. If you are using 'gawk', see *note Extension Sample Readfile::,
for another option.
---------- Footnotes ----------
@@ -4434,53 +4416,53 @@ File: gawk.info, Node: Fields, Next: Nonconstant
Fields, Prev: Records, Up:
4.2 Examining Fields
====================
-When `awk' reads an input record, the record is automatically "parsed"
-or separated by the `awk' utility into chunks called "fields". By
+When 'awk' reads an input record, the record is automatically "parsed"
+or separated by the 'awk' utility into chunks called "fields". By
default, fields are separated by "whitespace", like words in a line.
-Whitespace in `awk' means any string of one or more spaces, TABs, or
+Whitespace in 'awk' means any string of one or more spaces, TABs, or
newlines;(1) other characters that are considered whitespace by other
-languages (such as formfeed, vertical tab, etc.) are _not_ considered
-whitespace by `awk'.
+languages (such as formfeed, vertical tab, etc.) are _not_ considered
+whitespace by 'awk'.
The purpose of fields is to make it more convenient for you to refer
to these pieces of the record. You don't have to use them--you can
-operate on the whole record if you want--but fields are what make
-simple `awk' programs so powerful.
+operate on the whole record if you want--but fields are what make simple
+'awk' programs so powerful.
- You use a dollar sign (`$') to refer to a field in an `awk' program,
-followed by the number of the field you want. Thus, `$1' refers to the
-first field, `$2' to the second, and so on. (Unlike in the Unix
-shells, the field numbers are not limited to single digits. `$127' is
-the 127th field in the record.) For example, suppose the following is
-a line of input:
+ You use a dollar sign ('$') to refer to a field in an 'awk' program,
+followed by the number of the field you want. Thus, '$1' refers to the
+first field, '$2' to the second, and so on. (Unlike in the Unix shells,
+the field numbers are not limited to single digits. '$127' is the 127th
+field in the record.) For example, suppose the following is a line of
+input:
This seems like a pretty nice example.
-Here the first field, or `$1', is `This', the second field, or `$2', is
-`seems', and so on. Note that the last field, `$7', is `example.'.
-Because there is no space between the `e' and the `.', the period is
+Here the first field, or '$1', is 'This', the second field, or '$2', is
+'seems', and so on. Note that the last field, '$7', is 'example.'.
+Because there is no space between the 'e' and the '.', the period is
considered part of the seventh field.
- `NF' is a predefined variable whose value is the number of fields in
-the current record. `awk' automatically updates the value of `NF' each
+ 'NF' is a predefined variable whose value is the number of fields in
+the current record. 'awk' automatically updates the value of 'NF' each
time it reads a record. No matter how many fields there are, the last
-field in a record can be represented by `$NF'. So, `$NF' is the same
-as `$7', which is `example.'. If you try to reference a field beyond
-the last one (such as `$8' when the record has only seven fields), you
-get the empty string. (If used in a numeric operation, you get zero.)
+field in a record can be represented by '$NF'. So, '$NF' is the same as
+'$7', which is 'example.'. If you try to reference a field beyond the
+last one (such as '$8' when the record has only seven fields), you get
+the empty string. (If used in a numeric operation, you get zero.)
- The use of `$0', which looks like a reference to the "zeroth" field,
-is a special case: it represents the whole input record. Use it when
+ The use of '$0', which looks like a reference to the "zeroth" field,
+is a special case: it represents the whole input record. Use it when
you are not interested in specific fields. Here are some more examples:
$ awk '$1 ~ /li/ { print $0 }' mail-list
-| Amelia 555-5553 address@hidden F
-| Julie 555-6699 address@hidden F
-This example prints each record in the file `mail-list' whose first
-field contains the string `li'.
+This example prints each record in the file 'mail-list' whose first
+field contains the string 'li'.
- By contrast, the following example looks for `li' in _the entire
+ By contrast, the following example looks for 'li' in _the entire
record_ and prints the first and last fields for each matching input
record:
@@ -4492,7 +4474,7 @@ record:
---------- Footnotes ----------
- (1) In POSIX `awk', newlines are not considered whitespace for
+ (1) In POSIX 'awk', newlines are not considered whitespace for
separating fields.
@@ -4501,15 +4483,14 @@ File: gawk.info, Node: Nonconstant Fields, Next:
Changing Fields, Prev: Field
4.3 Nonconstant Field Numbers
=============================
-A field number need not be a constant. Any expression in the `awk'
-language can be used after a `$' to refer to a field. The value of the
-expression specifies the field number. If the value is a string,
-rather than a number, it is converted to a number. Consider this
-example:
+A field number need not be a constant. Any expression in the 'awk'
+language can be used after a '$' to refer to a field. The value of the
+expression specifies the field number. If the value is a string, rather
+than a number, it is converted to a number. Consider this example:
awk '{ print $NR }'
-Recall that `NR' is the number of records read so far: one in the first
+Recall that 'NR' is the number of records read so far: one in the first
record, two in the second, and so on. So this example prints the first
field of the first record, the second field of the second record, and so
on. For the twentieth record, field number 20 is printed; most likely,
@@ -4518,33 +4499,32 @@ is another example of using expressions as field
numbers:
awk '{ print $(2*2) }' mail-list
- `awk' evaluates the expression `(2*2)' and uses its value as the
-number of the field to print. The `*' represents multiplication, so
-the expression `2*2' evaluates to four. The parentheses are used so
-that the multiplication is done before the `$' operation; they are
-necessary whenever there is a binary operator(1) in the field-number
-expression. This example, then, prints the type of relationship (the
-fourth field) for every line of the file `mail-list'. (All of the
-`awk' operators are listed, in order of decreasing precedence, in *note
-Precedence::.)
+ 'awk' evaluates the expression '(2*2)' and uses its value as the
+number of the field to print. The '*' represents multiplication, so the
+expression '2*2' evaluates to four. The parentheses are used so that
+the multiplication is done before the '$' operation; they are necessary
+whenever there is a binary operator(1) in the field-number expression.
+This example, then, prints the type of relationship (the fourth field)
+for every line of the file 'mail-list'. (All of the 'awk' operators are
+listed, in order of decreasing precedence, in *note Precedence::.)
If the field number you compute is zero, you get the entire record.
-Thus, `$(2-2)' has the same value as `$0'. Negative field numbers are
+Thus, '$(2-2)' has the same value as '$0'. Negative field numbers are
not allowed; trying to reference one usually terminates the program.
(The POSIX standard does not define what happens when you reference a
-negative field number. `gawk' notices this and terminates your
-program. Other `awk' implementations may behave differently.)
+negative field number. 'gawk' notices this and terminates your program.
+Other 'awk' implementations may behave differently.)
- As mentioned in *note Fields::, `awk' stores the current record's
-number of fields in the built-in variable `NF' (also *note Built-in
-Variables::). Thus, the expression `$NF' is not a special feature--it
-is the direct consequence of evaluating `NF' and using its value as a
+ As mentioned in *note Fields::, 'awk' stores the current record's
+number of fields in the built-in variable 'NF' (also *note Built-in
+Variables::). Thus, the expression '$NF' is not a special feature--it
+is the direct consequence of evaluating 'NF' and using its value as a
field number.
---------- Footnotes ----------
- (1) A "binary operator", such as `*' for multiplication, is one that
-takes two operands. The distinction is required because `awk' also has
+ (1) A "binary operator", such as '*' for multiplication, is one that
+takes two operands. The distinction is required because 'awk' also has
unary (one-operand) and ternary (three-operand) operators.
@@ -4553,9 +4533,9 @@ File: gawk.info, Node: Changing Fields, Next: Field
Separators, Prev: Noncons
4.4 Changing the Contents of a Field
====================================
-The contents of a field, as seen by `awk', can be changed within an
-`awk' program; this changes what `awk' perceives as the current input
-record. (The actual input is untouched; `awk' _never_ modifies the
+The contents of a field, as seen by 'awk', can be changed within an
+'awk' program; this changes what 'awk' perceives as the current input
+record. (The actual input is untouched; 'awk' _never_ modifies the
input file.) Consider the following example and its output:
$ awk '{ nboxes = $3 ; $3 = $3 - 10
@@ -4566,21 +4546,21 @@ input file.) Consider the following example and its
output:
...
The program first saves the original value of field three in the
-variable `nboxes'. The `-' sign represents subtraction, so this
-program reassigns field three, `$3', as the original value of field
-three minus ten: `$3 - 10'. (*Note Arithmetic Ops::.) Then it prints
-the original and new values for field three. (Someone in the warehouse
-made a consistent mistake while inventorying the red boxes.)
+variable 'nboxes'. The '-' sign represents subtraction, so this program
+reassigns field three, '$3', as the original value of field three minus
+ten: '$3 - 10'. (*Note Arithmetic Ops::.) Then it prints the original
+and new values for field three. (Someone in the warehouse made a
+consistent mistake while inventorying the red boxes.)
- For this to work, the text in `$3' must make sense as a number; the
+ For this to work, the text in '$3' must make sense as a number; the
string of characters must be converted to a number for the computer to
do arithmetic on it. The number resulting from the subtraction is
converted back to a string of characters that then becomes field three.
*Note Conversion::.
- When the value of a field is changed (as perceived by `awk'), the
+ When the value of a field is changed (as perceived by 'awk'), the
text of the input record is recalculated to contain the new field where
-the old one was. In other words, `$0' changes to reflect the altered
+the old one was. In other words, '$0' changes to reflect the altered
field. Thus, this program prints a copy of the input file, with 10
subtracted from the second field of each line:
@@ -4600,26 +4580,26 @@ range. For example:
-| 301
...
-We've just created `$6', whose value is the sum of fields `$2', `$3',
-`$4', and `$5'. The `+' sign represents addition. For the file
-`inventory-shipped', `$6' represents the total number of parcels
-shipped for a particular month.
+We've just created '$6', whose value is the sum of fields '$2', '$3',
+'$4', and '$5'. The '+' sign represents addition. For the file
+'inventory-shipped', '$6' represents the total number of parcels shipped
+for a particular month.
- Creating a new field changes `awk''s internal copy of the current
-input record, which is the value of `$0'. Thus, if you do `print $0'
+ Creating a new field changes 'awk''s internal copy of the current
+input record, which is the value of '$0'. Thus, if you do 'print $0'
after adding a field, the record printed includes the new field, with
the appropriate number of field separators between it and the previously
existing fields.
- This recomputation affects and is affected by `NF' (the number of
-fields; *note Fields::). For example, the value of `NF' is set to the
-number of the highest field you create. The exact format of `$0' is
+ This recomputation affects and is affected by 'NF' (the number of
+fields; *note Fields::). For example, the value of 'NF' is set to the
+number of the highest field you create. The exact format of '$0' is
also affected by a feature that has not been discussed yet: the "output
-field separator", `OFS', used to separate the fields (*note Output
+field separator", 'OFS', used to separate the fields (*note Output
Separators::).
Note, however, that merely _referencing_ an out-of-range field does
-_not_ change the value of either `$0' or `NF'. Referencing an
+_not_ change the value of either '$0' or 'NF'. Referencing an
out-of-range field only produces an empty string. For example:
if ($(NF+1) != "")
@@ -4627,13 +4607,13 @@ out-of-range field only produces an empty string. For
example:
else
print "everything is normal"
-should print `everything is normal', because `NF+1' is certain to be
-out of range. (*Note If Statement::, for more information about
-`awk''s `if-else' statements. *Note Typing and Comparison::, for more
-information about the `!=' operator.)
+should print 'everything is normal', because 'NF+1' is certain to be out
+of range. (*Note If Statement::, for more information about 'awk''s
+'if-else' statements. *Note Typing and Comparison::, for more
+information about the '!=' operator.)
It is important to note that making an assignment to an existing
-field changes the value of `$0' but does not change the value of `NF',
+field changes the value of '$0' but does not change the value of 'NF',
even when you assign the empty string to a field. For example:
$ echo a b c d | awk '{ OFS = ":"; $2 = ""
@@ -4642,7 +4622,7 @@ even when you assign the empty string to a field. For
example:
-| 4
The field is still there; it just has an empty value, delimited by the
-two colons between `a' and `c'. This example shows what happens if you
+two colons between 'a' and 'c'. This example shows what happens if you
create a new field:
$ echo a b c d | awk '{ OFS = ":"; $2 = ""; $6 = "new"
@@ -4650,51 +4630,51 @@ create a new field:
-| a::c:d::new
-| 6
-The intervening field, `$5', is created with an empty value (indicated
-by the second pair of adjacent colons), and `NF' is updated with the
+The intervening field, '$5', is created with an empty value (indicated
+by the second pair of adjacent colons), and 'NF' is updated with the
value six.
- Decrementing `NF' throws away the values of the fields after the new
-value of `NF' and recomputes `$0'. (d.c.) Here is an example:
+ Decrementing 'NF' throws away the values of the fields after the new
+value of 'NF' and recomputes '$0'. (d.c.) Here is an example:
$ echo a b c d e f | awk '{ print "NF =", NF;
> NF = 3; print $0 }'
-| NF = 6
-| a b c
- CAUTION: Some versions of `awk' don't rebuild `$0' when `NF' is
+ CAUTION: Some versions of 'awk' don't rebuild '$0' when 'NF' is
decremented.
- Finally, there are times when it is convenient to force `awk' to
+ Finally, there are times when it is convenient to force 'awk' to
rebuild the entire record, using the current values of the fields and
-`OFS'. To do this, use the seemingly innocuous assignment:
+'OFS'. To do this, use the seemingly innocuous assignment:
$1 = $1 # force record to be reconstituted
print $0 # or whatever else with $0
-This forces `awk' to rebuild the record. It does help to add a
-comment, as we've shown here.
+This forces 'awk' to rebuild the record. It does help to add a comment,
+as we've shown here.
- There is a flip side to the relationship between `$0' and the
-fields. Any assignment to `$0' causes the record to be reparsed into
-fields using the _current_ value of `FS'. This also applies to any
-built-in function that updates `$0', such as `sub()' and `gsub()'
-(*note String Functions::).
+ There is a flip side to the relationship between '$0' and the fields.
+Any assignment to '$0' causes the record to be reparsed into fields
+using the _current_ value of 'FS'. This also applies to any built-in
+function that updates '$0', such as 'sub()' and 'gsub()' (*note String
+Functions::).
- Understanding `$0'
+ Understanding '$0'
- It is important to remember that `$0' is the _full_ record, exactly
+ It is important to remember that '$0' is the _full_ record, exactly
as it was read from the input. This includes any leading or trailing
whitespace, and the exact whitespace (or other characters) that
separates the fields.
It is a common error to try to change the field separators in a
-record simply by setting `FS' and `OFS', and then expecting a plain
-`print' or `print $0' to print the modified record.
+record simply by setting 'FS' and 'OFS', and then expecting a plain
+'print' or 'print $0' to print the modified record.
But this does not work, because nothing was done to change the record
itself. Instead, you must force the record to be rebuilt, typically
-with a statement such as `$1 = $1', as described earlier.
+with a statement such as '$1 = $1', as described earlier.
File: gawk.info, Node: Field Separators, Next: Constant Size, Prev:
Changing Fields, Up: Reading Files
@@ -4707,37 +4687,36 @@ File: gawk.info, Node: Field Separators, Next:
Constant Size, Prev: Changing
* Default Field Splitting:: How fields are normally separated.
* Regexp Field Splitting:: Using regexps as the field separator.
* Single Character Fields:: Making each character a separate field.
-* Command Line Field Separator:: Setting `FS' from the command line.
+* Command Line Field Separator:: Setting 'FS' from the command line.
* Full Line Fields:: Making the full line be a single field.
* Field Splitting Summary:: Some final points and a summary table.
- The "field separator", which is either a single character or a
-regular expression, controls the way `awk' splits an input record into
-fields. `awk' scans the input record for character sequences that
-match the separator; the fields themselves are the text between the
-matches.
+The "field separator", which is either a single character or a regular
+expression, controls the way 'awk' splits an input record into fields.
+'awk' scans the input record for character sequences that match the
+separator; the fields themselves are the text between the matches.
In the examples that follow, we use the bullet symbol (*) to
-represent spaces in the output. If the field separator is `oo', then
+represent spaces in the output. If the field separator is 'oo', then
the following line:
moo goo gai pan
-is split into three fields: `m', `*g', and `*gai*pan'. Note the
-leading spaces in the values of the second and third fields.
+is split into three fields: 'm', '*g', and '*gai*pan'. Note the leading
+spaces in the values of the second and third fields.
- The field separator is represented by the predefined variable `FS'.
-Shell programmers take note: `awk' does _not_ use the name `IFS' that
-is used by the POSIX-compliant shells (such as the Unix Bourne shell,
-`sh', or Bash).
+ The field separator is represented by the predefined variable 'FS'.
+Shell programmers take note: 'awk' does _not_ use the name 'IFS' that is
+used by the POSIX-compliant shells (such as the Unix Bourne shell, 'sh',
+or Bash).
- The value of `FS' can be changed in the `awk' program with the
-assignment operator, `=' (*note Assignment Ops::). Often, the right
+ The value of 'FS' can be changed in the 'awk' program with the
+assignment operator, '=' (*note Assignment Ops::). Often, the right
time to do this is at the beginning of execution before any input has
been processed, so that the very first record is read with the proper
-separator. To do this, use the special `BEGIN' pattern (*note
-BEGIN/END::). For example, here we set the value of `FS' to the string
-`","':
+separator. To do this, use the special 'BEGIN' pattern (*note
+BEGIN/END::). For example, here we set the value of 'FS' to the string
+'","':
awk 'BEGIN { FS = "," } ; { print $2 }'
@@ -4745,7 +4724,7 @@ Given the input line:
John Q. Smith, 29 Oak St., Walamazoo, MI 42139
-this `awk' program extracts and prints the string `*29*Oak*St.'.
+this 'awk' program extracts and prints the string '*29*Oak*St.'.
Sometimes the input data contains separator characters that don't
separate fields the way you thought they would. For instance, the
@@ -4754,12 +4733,12 @@ attached, such as:
John Q. Smith, LXIX, 29 Oak St., Walamazoo, MI 42139
-The same program would extract `*LXIX' instead of `*29*Oak*St.'. If
-you were expecting the program to print the address, you would be
-surprised. The moral is to choose your data layout and separator
-characters carefully to prevent such problems. (If the data is not in
-a form that is easy to process, perhaps you can massage it first with a
-separate `awk' program.)
+The same program would extract '*LXIX' instead of '*29*Oak*St.'. If you
+were expecting the program to print the address, you would be surprised.
+The moral is to choose your data layout and separator characters
+carefully to prevent such problems. (If the data is not in a form that
+is easy to process, perhaps you can massage it first with a separate
+'awk' program.)
File: gawk.info, Node: Default Field Splitting, Next: Regexp Field
Splitting, Up: Field Separators
@@ -4767,17 +4746,16 @@ File: gawk.info, Node: Default Field Splitting, Next:
Regexp Field Splitting,
4.5.1 Whitespace Normally Separates Fields
------------------------------------------
-Fields are normally separated by whitespace sequences (spaces, TABs,
-and newlines), not by single spaces. Two spaces in a row do not
-delimit an empty field. The default value of the field separator `FS'
-is a string containing a single space, `" "'. If `awk' interpreted
-this value in the usual way, each space character would separate
-fields, so two spaces in a row would make an empty field between them.
-The reason this does not happen is that a single space as the value of
-`FS' is a special case--it is taken to specify the default manner of
-delimiting fields.
-
- If `FS' is any other single character, such as `","', then each
+Fields are normally separated by whitespace sequences (spaces, TABs, and
+newlines), not by single spaces. Two spaces in a row do not delimit an
+empty field. The default value of the field separator 'FS' is a string
+containing a single space, '" "'. If 'awk' interpreted this value in
+the usual way, each space character would separate fields, so two spaces
+in a row would make an empty field between them. The reason this does
+not happen is that a single space as the value of 'FS' is a special
+case--it is taken to specify the default manner of delimiting fields.
+
+ If 'FS' is any other single character, such as '","', then each
occurrence of that character separates two fields. Two consecutive
occurrences delimit an empty field. If the character occurs at the
beginning or the end of the line, that too delimits an empty field. The
@@ -4791,36 +4769,35 @@ File: gawk.info, Node: Regexp Field Splitting, Next:
Single Character Fields,
--------------------------------------------------
The previous node discussed the use of single characters or simple
-strings as the value of `FS'. More generally, the value of `FS' may be
-a string containing any regular expression. In this case, each match
-in the record for the regular expression separates fields. For
-example, the assignment:
+strings as the value of 'FS'. More generally, the value of 'FS' may be
+a string containing any regular expression. In this case, each match in
+the record for the regular expression separates fields. For example,
+the assignment:
FS = ", \t"
makes every area of an input line that consists of a comma followed by a
-space and a TAB into a field separator. (`\t' is an "escape sequence"
+space and a TAB into a field separator. ('\t' is an "escape sequence"
that stands for a TAB; *note Escape Sequences::, for the complete list
of similar escape sequences.)
For a less trivial example of a regular expression, try using single
-spaces to separate fields the way single commas are used. `FS' can be
-set to `"[ ]"' (left bracket, space, right bracket). This regular
+spaces to separate fields the way single commas are used. 'FS' can be
+set to '"[ ]"' (left bracket, space, right bracket). This regular
expression matches a single space and nothing else (*note Regexp::).
- There is an important difference between the two cases of `FS = " "'
-(a single space) and `FS = "[ \t\n]+"' (a regular expression matching
-one or more spaces, TABs, or newlines). For both values of `FS',
-fields are separated by "runs" (multiple adjacent occurrences) of
-spaces, TABs, and/or newlines. However, when the value of `FS' is
-`" "', `awk' first strips leading and trailing whitespace from the
-record and then decides where the fields are. For example, the
-following pipeline prints `b':
+ There is an important difference between the two cases of 'FS = " "'
+(a single space) and 'FS = "[ \t\n]+"' (a regular expression matching
+one or more spaces, TABs, or newlines). For both values of 'FS', fields
+are separated by "runs" (multiple adjacent occurrences) of spaces, TABs,
+and/or newlines. However, when the value of 'FS' is '" "', 'awk' first
+strips leading and trailing whitespace from the record and then decides
+where the fields are. For example, the following pipeline prints 'b':
$ echo ' a b c d ' | awk '{ print $2 }'
-| b
-However, this pipeline prints `a' (note the extra spaces around each
+However, this pipeline prints 'a' (note the extra spaces around each
letter):
$ echo ' a b c d ' | awk 'BEGIN { FS = "[ \t\n]+" }
@@ -4829,30 +4806,30 @@ letter):
In this case, the first field is null, or empty.
- The stripping of leading and trailing whitespace also comes into
-play whenever `$0' is recomputed. For instance, study this pipeline:
+ The stripping of leading and trailing whitespace also comes into play
+whenever '$0' is recomputed. For instance, study this pipeline:
$ echo ' a b c d' | awk '{ print; $2 = $2; print }'
-| a b c d
-| a b c d
-The first `print' statement prints the record as it was read, with
-leading whitespace intact. The assignment to `$2' rebuilds `$0' by
-concatenating `$1' through `$NF' together, separated by the value of
-`OFS' (which is a space by default). Because the leading whitespace
-was ignored when finding `$1', it is not part of the new `$0'.
-Finally, the last `print' statement prints the new `$0'.
+The first 'print' statement prints the record as it was read, with
+leading whitespace intact. The assignment to '$2' rebuilds '$0' by
+concatenating '$1' through '$NF' together, separated by the value of
+'OFS' (which is a space by default). Because the leading whitespace was
+ignored when finding '$1', it is not part of the new '$0'. Finally, the
+last 'print' statement prints the new '$0'.
There is an additional subtlety to be aware of when using regular
expressions for field splitting. It is not well specified in the POSIX
-standard, or anywhere else, what `^' means when splitting fields. Does
-the `^' match only at the beginning of the entire record? Or is each
-field separator a new string? It turns out that different `awk'
+standard, or anywhere else, what '^' means when splitting fields. Does
+the '^' match only at the beginning of the entire record? Or is each
+field separator a new string? It turns out that different 'awk'
versions answer this question differently, and you should not rely on
any specific behavior in your programs. (d.c.)
- As a point of information, BWK `awk' allows `^' to match only at the
-beginning of the record. `gawk' also works this way. For example:
+ As a point of information, BWK 'awk' allows '^' to match only at the
+beginning of the record. 'gawk' also works this way. For example:
$ echo 'xxAA xxBxx C' |
> gawk -F '(^x+)|( +)' '{ for (i = 1; i <= NF; i++)
@@ -4869,8 +4846,8 @@ File: gawk.info, Node: Single Character Fields, Next:
Command Line Field Separ
--------------------------------------------
There are times when you may want to examine each character of a record
-separately. This can be done in `gawk' by simply assigning the null
-string (`""') to `FS'. (c.e.) In this case, each individual character
+separately. This can be done in 'gawk' by simply assigning the null
+string ('""') to 'FS'. (c.e.) In this case, each individual character
in the record becomes a separate field. For example:
$ echo a b | gawk 'BEGIN { FS = "" }
@@ -4882,56 +4859,56 @@ in the record becomes a separate field. For example:
-| Field 2 is
-| Field 3 is b
- Traditionally, the behavior of `FS' equal to `""' was not defined.
-In this case, most versions of Unix `awk' simply treat the entire record
+ Traditionally, the behavior of 'FS' equal to '""' was not defined.
+In this case, most versions of Unix 'awk' simply treat the entire record
as only having one field. (d.c.) In compatibility mode (*note
-Options::), if `FS' is the null string, then `gawk' also behaves this
+Options::), if 'FS' is the null string, then 'gawk' also behaves this
way.
File: gawk.info, Node: Command Line Field Separator, Next: Full Line Fields,
Prev: Single Character Fields, Up: Field Separators
-4.5.4 Setting `FS' from the Command Line
+4.5.4 Setting 'FS' from the Command Line
----------------------------------------
-`FS' can be set on the command line. Use the `-F' option to do so.
-For example:
+'FS' can be set on the command line. Use the '-F' option to do so. For
+example:
awk -F, 'PROGRAM' INPUT-FILES
-sets `FS' to the `,' character. Notice that the option uses an
-uppercase `F' instead of a lowercase `f'. The latter option (`-f')
-specifies a file containing an `awk' program.
+sets 'FS' to the ',' character. Notice that the option uses an
+uppercase 'F' instead of a lowercase 'f'. The latter option ('-f')
+specifies a file containing an 'awk' program.
- The value used for the argument to `-F' is processed in exactly the
-same way as assignments to the predefined variable `FS'. Any special
+ The value used for the argument to '-F' is processed in exactly the
+same way as assignments to the predefined variable 'FS'. Any special
characters in the field separator must be escaped appropriately. For
-example, to use a `\' as the field separator on the command line, you
+example, to use a '\' as the field separator on the command line, you
would have to type:
# same as FS = "\\"
awk -F\\\\ '...' files ...
-Because `\' is used for quoting in the shell, `awk' sees `-F\\'. Then
-`awk' processes the `\\' for escape characters (*note Escape
-Sequences::), finally yielding a single `\' to use for the field
+Because '\' is used for quoting in the shell, 'awk' sees '-F\\'. Then
+'awk' processes the '\\' for escape characters (*note Escape
+Sequences::), finally yielding a single '\' to use for the field
separator.
As a special case, in compatibility mode (*note Options::), if the
-argument to `-F' is `t', then `FS' is set to the TAB character. If you
-type `-F\t' at the shell, without any quotes, the `\' gets deleted, so
-`awk' figures that you really want your fields to be separated with
-TABs and not `t's. Use `-v FS="t"' or `-F"[t]"' on the command line if
-you really do want to separate your fields with `t's. Use `-F '\t''
-when not in compatibility mode to specify that TABs separate fields.
+argument to '-F' is 't', then 'FS' is set to the TAB character. If you
+type '-F\t' at the shell, without any quotes, the '\' gets deleted, so
+'awk' figures that you really want your fields to be separated with TABs
+and not 't's. Use '-v FS="t"' or '-F"[t]"' on the command line if you
+really do want to separate your fields with 't's. Use '-F '\t'' when
+not in compatibility mode to specify that TABs separate fields.
- As an example, let's use an `awk' program file called `edu.awk' that
-contains the pattern `/edu/' and the action `print $1':
+ As an example, let's use an 'awk' program file called 'edu.awk' that
+contains the pattern '/edu/' and the action 'print $1':
/edu/ { print $1 }
- Let's also set `FS' to be the `-' character and run the program on
-the file `mail-list'. The following command prints a list of the names
+ Let's also set 'FS' to be the '-' character and run the program on
+the file 'mail-list'. The following command prints a list of the names
of the people that work at or attend a university, and the first three
digits of their phone numbers:
@@ -4945,19 +4922,19 @@ looked like this:
Jean-Paul 555-2127 address@hidden R
- The `-' as part of the person's name was used as the field
-separator, instead of the `-' in the phone number that was originally
-intended. This demonstrates why you have to be careful in choosing
-your field and record separators.
+ The '-' as part of the person's name was used as the field separator,
+instead of the '-' in the phone number that was originally intended.
+This demonstrates why you have to be careful in choosing your field and
+record separators.
Perhaps the most common use of a single character as the field
-separator occurs when processing the Unix system password file. On
-many Unix systems, each user has a separate entry in the system
-password file, with one line per user. The information in these lines
-is separated by colons. The first field is the user's login name and
-the second is the user's encrypted or shadow password. (A shadow
-password is indicated by the presence of a single `x' in the second
-field.) A password file entry might look like this:
+separator occurs when processing the Unix system password file. On many
+Unix systems, each user has a separate entry in the system password
+file, with one line per user. The information in these lines is
+separated by colons. The first field is the user's login name and the
+second is the user's encrypted or shadow password. (A shadow password
+is indicated by the presence of a single 'x' in the second field.) A
+password file entry might look like this:
arnold:x:2076:10:Arnold Robbins:/home/arnold:/bin/bash
@@ -4973,25 +4950,25 @@ File: gawk.info, Node: Full Line Fields, Next: Field
Splitting Summary, Prev:
--------------------------------------------
Occasionally, it's useful to treat the whole input line as a single
-field. This can be done easily and portably simply by setting `FS' to
-`"\n"' (a newline):(1)
+field. This can be done easily and portably simply by setting 'FS' to
+'"\n"' (a newline):(1)
awk -F'\n' 'PROGRAM' FILES ...
-When you do this, `$1' is the same as `$0'.
+When you do this, '$1' is the same as '$0'.
- Changing `FS' Does Not Affect the Fields
+ Changing 'FS' Does Not Affect the Fields
- According to the POSIX standard, `awk' is supposed to behave as if
-each record is split into fields at the time it is read. In
-particular, this means that if you change the value of `FS' after a
-record is read, the values of the fields (i.e., how they were split)
-should reflect the old value of `FS', not the new one.
+ According to the POSIX standard, 'awk' is supposed to behave as if
+each record is split into fields at the time it is read. In particular,
+this means that if you change the value of 'FS' after a record is read,
+the values of the fields (i.e., how they were split) should reflect the
+old value of 'FS', not the new one.
- However, many older implementations of `awk' do not work this way.
+ However, many older implementations of 'awk' do not work this way.
Instead, they defer splitting the fields until a field is actually
-referenced. The fields are split using the _current_ value of `FS'!
-(d.c.) This behavior can be difficult to diagnose. The following
+referenced. The fields are split using the _current_ value of 'FS'!
+(d.c.) This behavior can be difficult to diagnose. The following
example illustrates the difference between the two methods:
sed 1q /etc/passwd | awk '{ FS = ":" ; print $1 }'
@@ -5000,18 +4977,18 @@ which usually prints:
root
-on an incorrect implementation of `awk', while `gawk' prints the full
+on an incorrect implementation of 'awk', while 'gawk' prints the full
first line of the file, something like:
root:x:0:0:Root:/:
- (The `sed'(2) command prints just the first line of `/etc/passwd'.)
+ (The 'sed'(2) command prints just the first line of '/etc/passwd'.)
---------- Footnotes ----------
(1) Thanks to Andrew Schorr for this tip.
- (2) The `sed' utility is a "stream editor." Its behavior is also
+ (2) The 'sed' utility is a "stream editor." Its behavior is also
defined by the POSIX standard.
@@ -5021,42 +4998,41 @@ File: gawk.info, Node: Field Splitting Summary, Prev:
Full Line Fields, Up: F
-----------------------------
It is important to remember that when you assign a string constant as
-the value of `FS', it undergoes normal `awk' string processing. For
-example, with Unix `awk' and `gawk', the assignment `FS = "\.."'
-assigns the character string `".."' to `FS' (the backslash is
-stripped). This creates a regexp meaning "fields are separated by
-occurrences of any two characters." If instead you want fields to be
-separated by a literal period followed by any single character, use `FS
-= "\\.."'.
+the value of 'FS', it undergoes normal 'awk' string processing. For
+example, with Unix 'awk' and 'gawk', the assignment 'FS = "\.."' assigns
+the character string '".."' to 'FS' (the backslash is stripped). This
+creates a regexp meaning "fields are separated by occurrences of any two
+characters." If instead you want fields to be separated by a literal
+period followed by any single character, use 'FS = "\\.."'.
The following list summarizes how fields are split, based on the
-value of `FS' (`==' means "is equal to"):
+value of 'FS' ('==' means "is equal to"):
-`FS == " "'
+'FS == " "'
Fields are separated by runs of whitespace. Leading and trailing
whitespace are ignored. This is the default.
-`FS == ANY OTHER SINGLE CHARACTER'
+'FS == ANY OTHER SINGLE CHARACTER'
Fields are separated by each occurrence of the character. Multiple
successive occurrences delimit empty fields, as do leading and
trailing occurrences. The character can even be a regexp
metacharacter; it does not need to be escaped.
-`FS == REGEXP'
+'FS == REGEXP'
Fields are separated by occurrences of characters that match
REGEXP. Leading and trailing matches of REGEXP delimit empty
fields.
-`FS == ""'
+'FS == ""'
Each individual character in the record becomes a separate field.
(This is a common extension; it is not specified by the POSIX
standard.)
- `FS' and `IGNORECASE'
+ 'FS' and 'IGNORECASE'
- The `IGNORECASE' variable (*note User-modified::) affects field
-splitting _only_ when the value of `FS' is a regexp. It has no effect
-when `FS' is a single character, even if that character is a letter.
+ The 'IGNORECASE' variable (*note User-modified::) affects field
+splitting _only_ when the value of 'FS' is a regexp. It has no effect
+when 'FS' is a single character, even if that character is a letter.
Thus, in the following code:
FS = "c"
@@ -5064,9 +5040,9 @@ Thus, in the following code:
$0 = "aCa"
print $1
-The output is `aCa'. If you really want to split fields on an
+The output is 'aCa'. If you really want to split fields on an
alphabetic character while ignoring case, use a regexp that will do it
-for you (e.g., `FS = "[c]"'). In this case, `IGNORECASE' will take
+for you (e.g., 'FS = "[c]"'). In this case, 'IGNORECASE' will take
effect.
@@ -5075,31 +5051,30 @@ File: gawk.info, Node: Constant Size, Next: Splitting
By Content, Prev: Field
4.6 Reading Fixed-Width Data
============================
-This minor node discusses an advanced feature of `gawk'. If you are a
-novice `awk' user, you might want to skip it on the first reading.
+This minor node discusses an advanced feature of 'gawk'. If you are a
+novice 'awk' user, you might want to skip it on the first reading.
- `gawk' provides a facility for dealing with fixed-width fields with
-no distinctive field separator. For example, data of this nature
-arises in the input for old Fortran programs where numbers are run
-together, or in the output of programs that did not anticipate the use
-of their output as input for other programs.
+ 'gawk' provides a facility for dealing with fixed-width fields with
+no distinctive field separator. For example, data of this nature arises
+in the input for old Fortran programs where numbers are run together, or
+in the output of programs that did not anticipate the use of their
+output as input for other programs.
An example of the latter is a table where all the columns are lined
up by the use of a variable number of spaces and _empty fields are just
-spaces_. Clearly, `awk''s normal field splitting based on `FS' does
-not work well in this case. Although a portable `awk' program can use
-a series of `substr()' calls on `$0' (*note String Functions::), this
-is awkward and inefficient for a large number of fields.
-
- The splitting of an input record into fixed-width fields is
-specified by assigning a string containing space-separated numbers to
-the built-in variable `FIELDWIDTHS'. Each number specifies the width
-of the field, _including_ columns between fields. If you want to
-ignore the columns between fields, you can specify the width as a
-separate field that is subsequently ignored. It is a fatal error to
-supply a field width that has a negative value. The following data is
-the output of the Unix `w' utility. It is useful to illustrate the use
-of `FIELDWIDTHS':
+spaces_. Clearly, 'awk''s normal field splitting based on 'FS' does not
+work well in this case. Although a portable 'awk' program can use a
+series of 'substr()' calls on '$0' (*note String Functions::), this is
+awkward and inefficient for a large number of fields.
+
+ The splitting of an input record into fixed-width fields is specified
+by assigning a string containing space-separated numbers to the built-in
+variable 'FIELDWIDTHS'. Each number specifies the width of the field,
+_including_ columns between fields. If you want to ignore the columns
+between fields, you can specify the width as a separate field that is
+subsequently ignored. It is a fatal error to supply a field width that
+has a negative value. The following data is the output of the Unix 'w'
+utility. It is useful to illustrate the use of 'FIELDWIDTHS':
10:06pm up 21 days, 14:04, 23 users
User tty login idle JCPU PCPU what
@@ -5132,7 +5107,7 @@ calculated idle time:
print $1, $2, idle
}
- NOTE: The preceding program uses a number of `awk' features that
+ NOTE: The preceding program uses a number of 'awk' features that
haven't been introduced yet.
Running the program on the data produces the following results:
@@ -5152,16 +5127,16 @@ United States, voters mark their choices by punching
holes in computer
cards. These cards are then processed to count the votes for any
particular candidate or on any particular issue. Because a voter may
choose not to vote on some issue, any column on the card may be empty.
-An `awk' program for processing such data could use the `FIELDWIDTHS'
-feature to simplify reading the data. (Of course, getting `gawk' to
-run on a system with card readers is another story!)
+An 'awk' program for processing such data could use the 'FIELDWIDTHS'
+feature to simplify reading the data. (Of course, getting 'gawk' to run
+on a system with card readers is another story!)
- Assigning a value to `FS' causes `gawk' to use `FS' for field
-splitting again. Use `FS = FS' to make this happen, without having to
-know the current value of `FS'. In order to tell which kind of field
-splitting is in effect, use `PROCINFO["FS"]' (*note Auto-set::). The
-value is `"FS"' if regular field splitting is being used, or
-`"FIELDWIDTHS"' if fixed-width field splitting is being used:
+ Assigning a value to 'FS' causes 'gawk' to use 'FS' for field
+splitting again. Use 'FS = FS' to make this happen, without having to
+know the current value of 'FS'. In order to tell which kind of field
+splitting is in effect, use 'PROCINFO["FS"]' (*note Auto-set::). The
+value is '"FS"' if regular field splitting is being used, or
+'"FIELDWIDTHS"' if fixed-width field splitting is being used:
if (PROCINFO["FS"] == "FS")
REGULAR FIELD SPLITTING ...
@@ -5171,7 +5146,7 @@ value is `"FS"' if regular field splitting is being used,
or
CONTENT-BASED FIELD SPLITTING ... (see next minor node)
This information is useful when writing a function that needs to
-temporarily change `FS' or `FIELDWIDTHS', read some records, and then
+temporarily change 'FS' or 'FIELDWIDTHS', read some records, and then
restore the original settings (*note Passwd Functions::, for an example
of such a function).
@@ -5181,34 +5156,34 @@ File: gawk.info, Node: Splitting By Content, Next:
Multiple Line, Prev: Const
4.7 Defining Fields by Content
==============================
-This minor node discusses an advanced feature of `gawk'. If you are a
-novice `awk' user, you might want to skip it on the first reading.
+This minor node discusses an advanced feature of 'gawk'. If you are a
+novice 'awk' user, you might want to skip it on the first reading.
- Normally, when using `FS', `gawk' defines the fields as the parts of
-the record that occur in between each field separator. In other words,
-`FS' defines what a field _is not_, instead of what a field _is_.
+ Normally, when using 'FS', 'gawk' defines the fields as the parts of
+the record that occur in between each field separator. In other words,
+'FS' defines what a field _is not_, instead of what a field _is_.
However, there are times when you really want to define the fields by
what they are, and not by what they are not.
The most notorious such case is so-called "comma-separated values"
-(CSV) data. Many spreadsheet programs, for example, can export their
+(CSV) data. Many spreadsheet programs, for example, can export their
data into text files, where each record is terminated with a newline,
-and fields are separated by commas. If commas only separated the data,
-there wouldn't be an issue. The problem comes when one of the fields
+and fields are separated by commas. If commas only separated the data,
+there wouldn't be an issue. The problem comes when one of the fields
contains an _embedded_ comma. In such cases, most programs embed the
-field in double quotes.(1) So, we might have data like this:
+field in double quotes.(1) So, we might have data like this:
Robbins,Arnold,"1234 A Pretty Street, NE",MyTown,MyState,12345-6789,USA
- The `FPAT' variable offers a solution for cases like this. The
-value of `FPAT' should be a string that provides a regular expression.
-This regular expression describes the contents of each field.
+ The 'FPAT' variable offers a solution for cases like this. The value
+of 'FPAT' should be a string that provides a regular expression. This
+regular expression describes the contents of each field.
In the case of CSV data as presented here, each field is either
-"anything that is not a comma," or "a double quote, anything that is
-not a double quote, and a closing double quote." If written as a
-regular expression constant (*note Regexp::), we would have
-`/([^,]+)|("[^"]+")/'. Writing this as a string requires us to escape
+"anything that is not a comma," or "a double quote, anything that is not
+a double quote, and a closing double quote." If written as a regular
+expression constant (*note Regexp::), we would have
+'/([^,]+)|("[^"]+")/'. Writing this as a string requires us to escape
the double quotes, leading to:
FPAT = "([^,]+)|(\"[^\"]+\")"
@@ -5238,7 +5213,7 @@ the double quotes, leading to:
$6 = <12345-6789>
$7 = <USA>
- Note the embedded comma in the value of `$3'.
+ Note the embedded comma in the value of '$3'.
A straightforward improvement when processing CSV data of this sort
would be to remove the quotes when they occur, with something like this:
@@ -5248,33 +5223,33 @@ would be to remove the quotes when they occur, with
something like this:
$i = substr($i, 2, len - 2) # Get text within the two quotes
}
- As with `FS', the `IGNORECASE' variable (*note User-modified::)
-affects field splitting with `FPAT'.
+ As with 'FS', the 'IGNORECASE' variable (*note User-modified::)
+affects field splitting with 'FPAT'.
- Assigning a value to `FPAT' overrides field splitting with `FS' and
-with `FIELDWIDTHS'. Similar to `FIELDWIDTHS', the value of
-`PROCINFO["FS"]' will be `"FPAT"' if content-based field splitting is
+ Assigning a value to 'FPAT' overrides field splitting with 'FS' and
+with 'FIELDWIDTHS'. Similar to 'FIELDWIDTHS', the value of
+'PROCINFO["FS"]' will be '"FPAT"' if content-based field splitting is
being used.
- NOTE: Some programs export CSV data that contains embedded
- newlines between the double quotes. `gawk' provides no way to
- deal with this. Even though a formal specification for CSV data
- exists, there isn't much more to be done; the `FPAT' mechanism
- provides an elegant solution for the majority of cases, and the
- `gawk' developers are satisfied with that.
+ NOTE: Some programs export CSV data that contains embedded newlines
+ between the double quotes. 'gawk' provides no way to deal with
+ this. Even though a formal specification for CSV data exists,
+ there isn't much more to be done; the 'FPAT' mechanism provides an
+ elegant solution for the majority of cases, and the 'gawk'
+ developers are satisfied with that.
- As written, the regexp used for `FPAT' requires that each field
+ As written, the regexp used for 'FPAT' requires that each field
contain at least one character. A straightforward modification
-(changing the first `+' to `*') allows fields to be empty:
+(changing the first '+' to '*') allows fields to be empty:
FPAT = "([^,]*)|(\"[^\"]+\")"
- Finally, the `patsplit()' function makes the same functionality
+ Finally, the 'patsplit()' function makes the same functionality
available for splitting regular strings (*note String Functions::).
- To recap, `gawk' provides three independent methods to split input
+ To recap, 'gawk' provides three independent methods to split input
records into fields. The mechanism used is based on which of the three
-variables--`FS', `FIELDWIDTHS', or `FPAT'--was last assigned to.
+variables--'FS', 'FIELDWIDTHS', or 'FPAT'--was last assigned to.
---------- Footnotes ----------
@@ -5289,27 +5264,27 @@ File: gawk.info, Node: Multiple Line, Next: Getline,
Prev: Splitting By Conte
=========================
In some databases, a single line cannot conveniently hold all the
-information in one entry. In such cases, you can use multiline
-records. The first step in doing this is to choose your data format.
+information in one entry. In such cases, you can use multiline records.
+The first step in doing this is to choose your data format.
One technique is to use an unusual character or string to separate
records. For example, you could use the formfeed character (written
-`\f' in `awk', as in C) to separate them, making each record a page of
-the file. To do this, just set the variable `RS' to `"\f"' (a string
+'\f' in 'awk', as in C) to separate them, making each record a page of
+the file. To do this, just set the variable 'RS' to '"\f"' (a string
containing the formfeed character). Any other character could equally
well be used, as long as it won't be part of the data in a record.
Another technique is to have blank lines separate records. By a
-special dispensation, an empty string as the value of `RS' indicates
-that records are separated by one or more blank lines. When `RS' is set
+special dispensation, an empty string as the value of 'RS' indicates
+that records are separated by one or more blank lines. When 'RS' is set
to the empty string, each record always ends at the first blank line
encountered. The next record doesn't start until the first nonblank
line that follows. No matter how many blank lines appear in a row, they
-all act as one record separator. (Blank lines must be completely
-empty; lines that contain only whitespace do not count.)
+all act as one record separator. (Blank lines must be completely empty;
+lines that contain only whitespace do not count.)
- You can achieve the same effect as `RS = ""' by assigning the string
-`"\n\n+"' to `RS'. This regexp matches the newline at the end of the
+ You can achieve the same effect as 'RS = ""' by assigning the string
+'"\n\n+"' to 'RS'. This regexp matches the newline at the end of the
record and one or more blank lines after the record. In addition, a
regular expression always matches the longest possible sequence when
there is a choice (*note Leftmost Longest::). So, the next record
@@ -5317,37 +5292,37 @@ doesn't start until the first nonblank line that
follows--no matter how
many blank lines appear in a row, they are considered one record
separator.
- However, there is an important difference between `RS = ""' and `RS
-= "\n\n+"'. In the first case, leading newlines in the input data file
-are ignored, and if a file ends without extra blank lines after the
-last record, the final newline is removed from the record. In the
-second case, this special processing is not done. (d.c.)
+ However, there is an important difference between 'RS = ""' and 'RS =
+"\n\n+"'. In the first case, leading newlines in the input data file
+are ignored, and if a file ends without extra blank lines after the last
+record, the final newline is removed from the record. In the second
+case, this special processing is not done. (d.c.)
Now that the input is separated into records, the second step is to
separate the fields in the records. One way to do this is to divide
each of the lines into fields in the normal manner. This happens by
-default as the result of a special feature. When `RS' is set to the
-empty string _and_ `FS' is set to a single character, the newline
+default as the result of a special feature. When 'RS' is set to the
+empty string _and_ 'FS' is set to a single character, the newline
character _always_ acts as a field separator. This is in addition to
-whatever field separations result from `FS'.(1)
+whatever field separations result from 'FS'.(1)
The original motivation for this special exception was probably to
-provide useful behavior in the default case (i.e., `FS' is equal to
-`" "'). This feature can be a problem if you really don't want the
-newline character to separate fields, because there is no way to
-prevent it. However, you can work around this by using the `split()'
-function to break up the record manually (*note String Functions::).
-If you have a single-character field separator, you can work around the
-special feature in a different way, by making `FS' into a regexp for
-that single character. For example, if the field separator is a
-percent character, instead of `FS = "%"', use `FS = "[%]"'.
+provide useful behavior in the default case (i.e., 'FS' is equal to
+'" "'). This feature can be a problem if you really don't want the
+newline character to separate fields, because there is no way to prevent
+it. However, you can work around this by using the 'split()' function
+to break up the record manually (*note String Functions::). If you have
+a single-character field separator, you can work around the special
+feature in a different way, by making 'FS' into a regexp for that single
+character. For example, if the field separator is a percent character,
+instead of 'FS = "%"', use 'FS = "[%]"'.
Another way to separate fields is to put each field on a separate
-line: to do this, just set the variable `FS' to the string `"\n"'.
-(This single-character separator matches a single newline.) A
-practical example of a data file organized this way might be a mailing
-list, where blank lines separate the entries. Consider a mailing list
-in a file named `addresses', which looks like this:
+line: to do this, just set the variable 'FS' to the string '"\n"'.
+(This single-character separator matches a single newline.) A practical
+example of a data file organized this way might be a mailing list, where
+blank lines separate the entries. Consider a mailing list in a file
+named 'addresses', which looks like this:
Jane Doe
123 Main Street
@@ -5388,98 +5363,98 @@ A simple program to process this file is as follows:
*Note Labels Program::, for a more realistic program dealing with
address lists. The following list summarizes how records are split,
-based on the value of `RS'. (`==' means "is equal to.")
+based on the value of 'RS'. ('==' means "is equal to.")
-`RS == "\n"'
- Records are separated by the newline character (`\n'). In effect,
+'RS == "\n"'
+ Records are separated by the newline character ('\n'). In effect,
every line in the data file is a separate record, including blank
lines. This is the default.
-`RS == ANY SINGLE CHARACTER'
+'RS == ANY SINGLE CHARACTER'
Records are separated by each occurrence of the character.
Multiple successive occurrences delimit empty records.
-`RS == ""'
- Records are separated by runs of blank lines. When `FS' is a
+'RS == ""'
+ Records are separated by runs of blank lines. When 'FS' is a
single character, then the newline character always serves as a
- field separator, in addition to whatever value `FS' may have.
+ field separator, in addition to whatever value 'FS' may have.
Leading and trailing newlines in a file are ignored.
-`RS == REGEXP'
+'RS == REGEXP'
Records are separated by occurrences of characters that match
REGEXP. Leading and trailing matches of REGEXP delimit empty
- records. (This is a `gawk' extension; it is not specified by the
+ records. (This is a 'gawk' extension; it is not specified by the
POSIX standard.)
- If not in compatibility mode (*note Options::), `gawk' sets `RT' to
-the input text that matched the value specified by `RS'. But if the
-input file ended without any text that matches `RS', then `gawk' sets
-`RT' to the null string.
+ If not in compatibility mode (*note Options::), 'gawk' sets 'RT' to
+the input text that matched the value specified by 'RS'. But if the
+input file ended without any text that matches 'RS', then 'gawk' sets
+'RT' to the null string.
---------- Footnotes ----------
- (1) When `FS' is the null string (`""') or a regexp, this special
-feature of `RS' does not apply. It does apply to the default field
-separator of a single space: `FS = " "'.
+ (1) When 'FS' is the null string ('""') or a regexp, this special
+feature of 'RS' does not apply. It does apply to the default field
+separator of a single space: 'FS = " "'.
File: gawk.info, Node: Getline, Next: Read Timeout, Prev: Multiple Line,
Up: Reading Files
-4.9 Explicit Input with `getline'
+4.9 Explicit Input with 'getline'
=================================
-So far we have been getting our input data from `awk''s main input
+So far we have been getting our input data from 'awk''s main input
stream--either the standard input (usually your keyboard, sometimes the
-output from another program) or the files specified on the command
-line. The `awk' language has a special built-in command called
-`getline' that can be used to read input under your explicit control.
-
- The `getline' command is used in several different ways and should
-_not_ be used by beginners. The examples that follow the explanation
-of the `getline' command include material that has not been covered
-yet. Therefore, come back and study the `getline' command _after_ you
-have reviewed the rest of this Info file and have a good knowledge of
-how `awk' works.
-
- The `getline' command returns 1 if it finds a record and 0 if it
+output from another program) or the files specified on the command line.
+The 'awk' language has a special built-in command called 'getline' that
+can be used to read input under your explicit control.
+
+ The 'getline' command is used in several different ways and should
+_not_ be used by beginners. The examples that follow the explanation of
+the 'getline' command include material that has not been covered yet.
+Therefore, come back and study the 'getline' command _after_ you have
+reviewed the rest of this Info file and have a good knowledge of how
+'awk' works.
+
+ The 'getline' command returns 1 if it finds a record and 0 if it
encounters the end of the file. If there is some error in getting a
-record, such as a file that cannot be opened, then `getline' returns
--1. In this case, `gawk' sets the variable `ERRNO' to a string
-describing the error that occurred.
+record, such as a file that cannot be opened, then 'getline' returns -1.
+In this case, 'gawk' sets the variable 'ERRNO' to a string describing
+the error that occurred.
In the following examples, COMMAND stands for a string value that
represents a shell command.
- NOTE: When `--sandbox' is specified (*note Options::), reading
+ NOTE: When '--sandbox' is specified (*note Options::), reading
lines from files, pipes, and coprocesses is disabled.
* Menu:
-* Plain Getline:: Using `getline' with no arguments.
-* Getline/Variable:: Using `getline' into a variable.
-* Getline/File:: Using `getline' from a file.
-* Getline/Variable/File:: Using `getline' into a variable from a
+* Plain Getline:: Using 'getline' with no arguments.
+* Getline/Variable:: Using 'getline' into a variable.
+* Getline/File:: Using 'getline' from a file.
+* Getline/Variable/File:: Using 'getline' into a variable from a
file.
-* Getline/Pipe:: Using `getline' from a pipe.
-* Getline/Variable/Pipe:: Using `getline' into a variable from a
+* Getline/Pipe:: Using 'getline' from a pipe.
+* Getline/Variable/Pipe:: Using 'getline' into a variable from a
pipe.
-* Getline/Coprocess:: Using `getline' from a coprocess.
-* Getline/Variable/Coprocess:: Using `getline' into a variable from a
+* Getline/Coprocess:: Using 'getline' from a coprocess.
+* Getline/Variable/Coprocess:: Using 'getline' into a variable from a
coprocess.
-* Getline Notes:: Important things to know about `getline'.
-* Getline Summary:: Summary of `getline' Variants.
+* Getline Notes:: Important things to know about 'getline'.
+* Getline Summary:: Summary of 'getline' Variants.
File: gawk.info, Node: Plain Getline, Next: Getline/Variable, Up: Getline
-4.9.1 Using `getline' with No Arguments
+4.9.1 Using 'getline' with No Arguments
---------------------------------------
-The `getline' command can be used without arguments to read input from
-the current input file. All it does in this case is read the next
-input record and split it up into fields. This is useful if you've
-finished processing the current record, but want to do some special
-processing on the next record _right now_. For example:
+The 'getline' command can be used without arguments to read input from
+the current input file. All it does in this case is read the next input
+record and split it up into fields. This is useful if you've finished
+processing the current record, but want to do some special processing on
+the next record _right now_. For example:
# Remove text between /* and */, inclusive
{
@@ -5511,22 +5486,21 @@ processing on the next record _right now_. For example:
print $0
}
- This `awk' program deletes C-style comments (`/* ... */') from the
+ This 'awk' program deletes C-style comments ('/* ... */') from the
input. It uses a number of features we haven't covered yet, including
-string concatenation (*note Concatenation::) and the `index()' and
-`substr()' built-in functions (*note String Functions::). By replacing
-the `print $0' with other statements, you could perform more
-complicated processing on the decommented input, such as searching for
-matches of a regular expression. (This program has a subtle
-problem--it does not work if one comment ends and another begins on the
-same line.)
-
- This form of the `getline' command sets `NF', `NR', `FNR', `RT', and
-the value of `$0'.
-
- NOTE: The new value of `$0' is used to test the patterns of any
- subsequent rules. The original value of `$0' that triggered the
- rule that executed `getline' is lost. By contrast, the `next'
+string concatenation (*note Concatenation::) and the 'index()' and
+'substr()' built-in functions (*note String Functions::). By replacing
+the 'print $0' with other statements, you could perform more complicated
+processing on the decommented input, such as searching for matches of a
+regular expression. (This program has a subtle problem--it does not
+work if one comment ends and another begins on the same line.)
+
+ This form of the 'getline' command sets 'NF', 'NR', 'FNR', 'RT', and
+the value of '$0'.
+
+ NOTE: The new value of '$0' is used to test the patterns of any
+ subsequent rules. The original value of '$0' that triggered the
+ rule that executed 'getline' is lost. By contrast, the 'next'
statement reads a new record but immediately begins processing it
normally, starting with the first rule in the program. *Note Next
Statement::.
@@ -5534,15 +5508,15 @@ the value of `$0'.
File: gawk.info, Node: Getline/Variable, Next: Getline/File, Prev: Plain
Getline, Up: Getline
-4.9.2 Using `getline' into a Variable
+4.9.2 Using 'getline' into a Variable
-------------------------------------
-You can use `getline VAR' to read the next record from `awk''s input
+You can use 'getline VAR' to read the next record from 'awk''s input
into the variable VAR. No other processing is done. For example,
suppose the next line is a comment or a special string, and you want to
-read it without triggering any rules. This form of `getline' allows
-you to read that line and store it in a variable so that the main
-read-a-line-and-check-each-rule loop of `awk' never sees it. The
+read it without triggering any rules. This form of 'getline' allows you
+to read that line and store it in a variable so that the main
+read-a-line-and-check-each-rule loop of 'awk' never sees it. The
following example swaps every two lines of input:
{
@@ -5567,23 +5541,23 @@ and produces these results:
phore
free
- The `getline' command used in this way sets only the variables `NR',
-`FNR', and `RT' (and, of course, VAR). The record is not split into
-fields, so the values of the fields (including `$0') and the value of
-`NF' do not change.
+ The 'getline' command used in this way sets only the variables 'NR',
+'FNR', and 'RT' (and, of course, VAR). The record is not split into
+fields, so the values of the fields (including '$0') and the value of
+'NF' do not change.
File: gawk.info, Node: Getline/File, Next: Getline/Variable/File, Prev:
Getline/Variable, Up: Getline
-4.9.3 Using `getline' from a File
+4.9.3 Using 'getline' from a File
---------------------------------
-Use `getline < FILE' to read the next record from FILE. Here, FILE is
-a string-valued expression that specifies the file name. `< FILE' is
-called a "redirection" because it directs input to come from a
-different place. For example, the following program reads its input
-record from the file `secondary.input' when it encounters a first field
-with a value equal to 10 in the current input file:
+Use 'getline < FILE' to read the next record from FILE. Here, FILE is a
+string-valued expression that specifies the file name. '< FILE' is
+called a "redirection" because it directs input to come from a different
+place. For example, the following program reads its input record from
+the file 'secondary.input' when it encounters a first field with a value
+equal to 10 in the current input file:
{
if ($1 == 10) {
@@ -5593,33 +5567,33 @@ with a value equal to 10 in the current input file:
print
}
- Because the main input stream is not used, the values of `NR' and
-`FNR' are not changed. However, the record it reads is split into
-fields in the normal manner, so the values of `$0' and the other fields
-are changed, resulting in a new value of `NF'. `RT' is also set.
+ Because the main input stream is not used, the values of 'NR' and
+'FNR' are not changed. However, the record it reads is split into
+fields in the normal manner, so the values of '$0' and the other fields
+are changed, resulting in a new value of 'NF'. 'RT' is also set.
- According to POSIX, `getline < EXPRESSION' is ambiguous if
-EXPRESSION contains unparenthesized operators other than `$'; for
-example, `getline < dir "/" file' is ambiguous because the
-concatenation operator (not discussed yet; *note Concatenation::) is
-not parenthesized. You should write it as `getline < (dir "/" file)' if
-you want your program to be portable to all `awk' implementations.
+ According to POSIX, 'getline < EXPRESSION' is ambiguous if EXPRESSION
+contains unparenthesized operators other than '$'; for example, 'getline
+< dir "/" file' is ambiguous because the concatenation operator (not
+discussed yet; *note Concatenation::) is not parenthesized. You should
+write it as 'getline < (dir "/" file)' if you want your program to be
+portable to all 'awk' implementations.
File: gawk.info, Node: Getline/Variable/File, Next: Getline/Pipe, Prev:
Getline/File, Up: Getline
-4.9.4 Using `getline' into a Variable from a File
+4.9.4 Using 'getline' into a Variable from a File
-------------------------------------------------
-Use `getline VAR < FILE' to read input from the file FILE, and put it
-in the variable VAR. As earlier, FILE is a string-valued expression
-that specifies the file from which to read.
+Use 'getline VAR < FILE' to read input from the file FILE, and put it in
+the variable VAR. As earlier, FILE is a string-valued expression that
+specifies the file from which to read.
- In this version of `getline', none of the predefined variables are
+ In this version of 'getline', none of the predefined variables are
changed and the record is not split into fields. The only variable
-changed is VAR.(1) For example, the following program copies all the
+changed is VAR.(1) For example, the following program copies all the
input files to the output, except for records that say
address@hidden FILENAME'. Such a record is replaced by the contents of the
+'@include FILENAME'. Such a record is replaced by the contents of the
file FILENAME:
{
@@ -5633,37 +5607,38 @@ file FILENAME:
Note here how the name of the extra input file is not built into the
program; it is taken directly from the data, specifically from the
-second field on the address@hidden' line.
+second field on the '@include' line.
- The `close()' function is called to ensure that if two identical
address@hidden' lines appear in the input, the entire specified file is
+ The 'close()' function is called to ensure that if two identical
+'@include' lines appear in the input, the entire specified file is
included twice. *Note Close Files And Pipes::.
One deficiency of this program is that it does not process nested
address@hidden' statements (i.e., address@hidden' statements in included files)
+'@include' statements (i.e., '@include' statements in included files)
the way a true macro preprocessor would. *Note Igawk Program::, for a
-program that does handle nested address@hidden' statements.
+program that does handle nested '@include' statements.
---------- Footnotes ----------
- (1) This is not quite true. `RT' could be changed if `RS' is a
+ (1) This is not quite true. 'RT' could be changed if 'RS' is a
regular expression.
File: gawk.info, Node: Getline/Pipe, Next: Getline/Variable/Pipe, Prev:
Getline/Variable/File, Up: Getline
-4.9.5 Using `getline' from a Pipe
+4.9.5 Using 'getline' from a Pipe
---------------------------------
Omniscience has much to recommend it. Failing that, attention to
- details would be useful. -- Brian Kernighan
+ details would be useful.
+ -- _Brian Kernighan_
- The output of a command can also be piped into `getline', using
-`COMMAND | getline'. In this case, the string COMMAND is run as a
-shell command and its output is piped into `awk' to be used as input.
-This form of `getline' reads one record at a time from the pipe. For
+ The output of a command can also be piped into 'getline', using
+'COMMAND | getline'. In this case, the string COMMAND is run as a shell
+command and its output is piped into 'awk' to be used as input. This
+form of 'getline' reads one record at a time from the pipe. For
example, the following program copies its input to its output, except
-for lines that begin with address@hidden', which are replaced by the output
+for lines that begin with '@execute', which are replaced by the output
produced by running the rest of the line as a shell command:
{
@@ -5676,8 +5651,8 @@ produced by running the rest of the line as a shell
command:
print
}
-The `close()' function is called to ensure that if two identical
address@hidden' lines appear in the input, the command is run for each one.
+The 'close()' function is called to ensure that if two identical
+'@execute' lines appear in the input, the command is run for each one.
*Note Close Files And Pipes::. Given the input:
foo
@@ -5696,39 +5671,38 @@ the program might produce:
bill ttyp1 Jul 13 14:23 (murphy:0)
bletch
-Notice that this program ran the command `who' and printed the result.
+Notice that this program ran the command 'who' and printed the result.
(If you try this program yourself, you will of course get different
results, depending upon who is logged in on your system.)
- This variation of `getline' splits the record into fields, sets the
-value of `NF', and recomputes the value of `$0'. The values of `NR'
-and `FNR' are not changed. `RT' is set.
-
- According to POSIX, `EXPRESSION | getline' is ambiguous if
-EXPRESSION contains unparenthesized operators other than `$'--for
-example, `"echo " "date" | getline' is ambiguous because the
-concatenation operator is not parenthesized. You should write it as
-`("echo " "date") | getline' if you want your program to be portable to
-all `awk' implementations.
-
- NOTE: Unfortunately, `gawk' has not been consistent in its
- treatment of a construct like `"echo " "date" | getline'. Most
- versions, including the current version, treat it at as `("echo "
- "date") | getline'. (This is also how BWK `awk' behaves.) Some
- versions instead treat it as `"echo " ("date" | getline)'. (This
- is how `mawk' behaves.) In short, _always_ use explicit
+ This variation of 'getline' splits the record into fields, sets the
+value of 'NF', and recomputes the value of '$0'. The values of 'NR' and
+'FNR' are not changed. 'RT' is set.
+
+ According to POSIX, 'EXPRESSION | getline' is ambiguous if EXPRESSION
+contains unparenthesized operators other than '$'--for example, '"echo "
+"date" | getline' is ambiguous because the concatenation operator is not
+parenthesized. You should write it as '("echo " "date") | getline' if
+you want your program to be portable to all 'awk' implementations.
+
+ NOTE: Unfortunately, 'gawk' has not been consistent in its
+ treatment of a construct like '"echo " "date" | getline'. Most
+ versions, including the current version, treat it at as '("echo "
+ "date") | getline'. (This is also how BWK 'awk' behaves.) Some
+ versions instead treat it as '"echo " ("date" | getline)'. (This
+ is how 'mawk' behaves.) In short, _always_ use explicit
parentheses, and then you won't have to worry.
File: gawk.info, Node: Getline/Variable/Pipe, Next: Getline/Coprocess,
Prev: Getline/Pipe, Up: Getline
-4.9.6 Using `getline' into a Variable from a Pipe
+4.9.6 Using 'getline' into a Variable from a Pipe
-------------------------------------------------
-When you use `COMMAND | getline VAR', the output of COMMAND is sent
-through a pipe to `getline' and into the variable VAR. For example, the
+When you use 'COMMAND | getline VAR', the output of COMMAND is sent
+through a pipe to 'getline' and into the variable VAR. For example, the
following program reads the current date and time into the variable
-`current_time', using the `date' utility, and then prints it:
+'current_time', using the 'date' utility, and then prints it:
BEGIN {
"date" | getline current_time
@@ -5736,109 +5710,108 @@ following program reads the current date and time
into the variable
print "Report printed on " current_time
}
- In this version of `getline', none of the predefined variables are
-changed and the record is not split into fields. However, `RT' is set.
+ In this version of 'getline', none of the predefined variables are
+changed and the record is not split into fields. However, 'RT' is set.
- According to POSIX, `EXPRESSION | getline VAR' is ambiguous if
-EXPRESSION contains unparenthesized operators other than `$'; for
-example, `"echo " "date" | getline VAR' is ambiguous because the
-concatenation operator is not parenthesized. You should write it as
-`("echo " "date") | getline VAR' if you want your program to be
-portable to other `awk' implementations.
+ According to POSIX, 'EXPRESSION | getline VAR' is ambiguous if
+EXPRESSION contains unparenthesized operators other than '$'; for
+example, '"echo " "date" | getline VAR' is ambiguous because the
+concatenation operator is not parenthesized. You should write it as '("echo "
+"date") | getline VAR' if you want your program to be portable to other
+'awk' implementations.
File: gawk.info, Node: Getline/Coprocess, Next: Getline/Variable/Coprocess,
Prev: Getline/Variable/Pipe, Up: Getline
-4.9.7 Using `getline' from a Coprocess
+4.9.7 Using 'getline' from a Coprocess
--------------------------------------
-Reading input into `getline' from a pipe is a one-way operation. The
-command that is started with `COMMAND | getline' only sends data _to_
-your `awk' program.
+Reading input into 'getline' from a pipe is a one-way operation. The
+command that is started with 'COMMAND | getline' only sends data _to_
+your 'awk' program.
On occasion, you might want to send data to another program for
-processing and then read the results back. `gawk' allows you to start
-a "coprocess", with which two-way communications are possible. This is
-done with the `|&' operator. Typically, you write data to the
-coprocess first and then read the results back, as shown in the
-following:
+processing and then read the results back. 'gawk' allows you to start a
+"coprocess", with which two-way communications are possible. This is
+done with the '|&' operator. Typically, you write data to the coprocess
+first and then read the results back, as shown in the following:
print "SOME QUERY" |& "db_server"
"db_server" |& getline
-which sends a query to `db_server' and then reads the results.
+which sends a query to 'db_server' and then reads the results.
- The values of `NR' and `FNR' are not changed, because the main input
+ The values of 'NR' and 'FNR' are not changed, because the main input
stream is not used. However, the record is split into fields in the
-normal manner, thus changing the values of `$0', of the other fields,
-and of `NF' and `RT'.
+normal manner, thus changing the values of '$0', of the other fields,
+and of 'NF' and 'RT'.
- Coprocesses are an advanced feature. They are discussed here only
-because this is the minor node on `getline'. *Note Two-way I/O::,
-where coprocesses are discussed in more detail.
+ Coprocesses are an advanced feature. They are discussed here only
+because this is the minor node on 'getline'. *Note Two-way I/O::, where
+coprocesses are discussed in more detail.
File: gawk.info, Node: Getline/Variable/Coprocess, Next: Getline Notes,
Prev: Getline/Coprocess, Up: Getline
-4.9.8 Using `getline' into a Variable from a Coprocess
+4.9.8 Using 'getline' into a Variable from a Coprocess
------------------------------------------------------
-When you use `COMMAND |& getline VAR', the output from the coprocess
-COMMAND is sent through a two-way pipe to `getline' and into the
+When you use 'COMMAND |& getline VAR', the output from the coprocess
+COMMAND is sent through a two-way pipe to 'getline' and into the
variable VAR.
- In this version of `getline', none of the predefined variables are
+ In this version of 'getline', none of the predefined variables are
changed and the record is not split into fields. The only variable
-changed is VAR. However, `RT' is set.
+changed is VAR. However, 'RT' is set.
- Coprocesses are an advanced feature. They are discussed here only
-because this is the minor node on `getline'. *Note Two-way I/O::,
-where coprocesses are discussed in more detail.
+ Coprocesses are an advanced feature. They are discussed here only
+because this is the minor node on 'getline'. *Note Two-way I/O::, where
+coprocesses are discussed in more detail.
File: gawk.info, Node: Getline Notes, Next: Getline Summary, Prev:
Getline/Variable/Coprocess, Up: Getline
-4.9.9 Points to Remember About `getline'
+4.9.9 Points to Remember About 'getline'
----------------------------------------
-Here are some miscellaneous points about `getline' that you should bear
+Here are some miscellaneous points about 'getline' that you should bear
in mind:
- * When `getline' changes the value of `$0' and `NF', `awk' does
- _not_ automatically jump to the start of the program and start
- testing the new record against every pattern. However, the new
- record is tested against any subsequent rules.
-
- * Some very old `awk' implementations limit the number of pipelines
- that an `awk' program may have open to just one. In `gawk', there
- is no such limit. You can open as many pipelines (and
- coprocesses) as the underlying operating system permits.
-
- * An interesting side effect occurs if you use `getline' without a
- redirection inside a `BEGIN' rule. Because an unredirected
- `getline' reads from the command-line data files, the first
- `getline' command causes `awk' to set the value of `FILENAME'.
- Normally, `FILENAME' does not have a value inside `BEGIN' rules,
+ * When 'getline' changes the value of '$0' and 'NF', 'awk' does _not_
+ automatically jump to the start of the program and start testing
+ the new record against every pattern. However, the new record is
+ tested against any subsequent rules.
+
+ * Some very old 'awk' implementations limit the number of pipelines
+ that an 'awk' program may have open to just one. In 'gawk', there
+ is no such limit. You can open as many pipelines (and coprocesses)
+ as the underlying operating system permits.
+
+ * An interesting side effect occurs if you use 'getline' without a
+ redirection inside a 'BEGIN' rule. Because an unredirected
+ 'getline' reads from the command-line data files, the first
+ 'getline' command causes 'awk' to set the value of 'FILENAME'.
+ Normally, 'FILENAME' does not have a value inside 'BEGIN' rules,
because you have not yet started to process the command-line data
files. (d.c.) (See *note BEGIN/END::; also *note Auto-set::.)
- * Using `FILENAME' with `getline' (`getline < FILENAME') is likely
- to be a source of confusion. `awk' opens a separate input stream
- from the current input file. However, by not using a variable,
- `$0' and `NF' are still updated. If you're doing this, it's
- probably by accident, and you should reconsider what it is you're
- trying to accomplish.
+ * Using 'FILENAME' with 'getline' ('getline < FILENAME') is likely to
+ be a source of confusion. 'awk' opens a separate input stream from
+ the current input file. However, by not using a variable, '$0' and
+ 'NF' are still updated. If you're doing this, it's probably by
+ accident, and you should reconsider what it is you're trying to
+ accomplish.
- * *note Getline Summary::, presents a table summarizing the
- `getline' variants and which variables they can affect. It is
- worth noting that those variants that do not use redirection can
- cause `FILENAME' to be updated if they cause `awk' to start
- reading a new input file.
+ * *note Getline Summary::, presents a table summarizing the 'getline'
+ variants and which variables they can affect. It is worth noting
+ that those variants that do not use redirection can cause
+ 'FILENAME' to be updated if they cause 'awk' to start reading a new
+ input file.
* If the variable being assigned is an expression with side effects,
- different versions of `awk' behave differently upon encountering
+ different versions of 'awk' behave differently upon encountering
end-of-file. Some versions don't evaluate the expression; many
- versions (including `gawk') do. Here is an example, courtesy of
+ versions (including 'gawk') do. Here is an example, courtesy of
Duncan Moore:
BEGIN {
@@ -5847,40 +5820,41 @@ in mind:
print c
}
- Here, the side effect is the `++c'. Is `c' incremented if
- end-of-file is encountered before the element in `a' is assigned?
+ Here, the side effect is the '++c'. Is 'c' incremented if
+ end-of-file is encountered before the element in 'a' is assigned?
- `gawk' treats `getline' like a function call, and evaluates the
- expression `a[++c]' before attempting to read from `f'. However,
- some versions of `awk' only evaluate the expression once they know
+ 'gawk' treats 'getline' like a function call, and evaluates the
+ expression 'a[++c]' before attempting to read from 'f'. However,
+ some versions of 'awk' only evaluate the expression once they know
that there is a string value to be assigned.
File: gawk.info, Node: Getline Summary, Prev: Getline Notes, Up: Getline
-4.9.10 Summary of `getline' Variants
+4.9.10 Summary of 'getline' Variants
------------------------------------
-*note table-getline-variants:: summarizes the eight variants of
-`getline', listing which predefined variables are set by each one, and
-whether the variant is standard or a `gawk' extension. Note: for each
-variant, `gawk' sets the `RT' predefined variable.
-
-Variant Effect `awk' / `gawk'
--------------------------------------------------------------------------
-`getline' Sets `$0', `NF', `FNR', `awk'
- `NR', and `RT'
-`getline' VAR Sets VAR, `FNR', `NR', and `awk'
- `RT'
-`getline <' FILE Sets `$0', `NF', and `RT' `awk'
-`getline VAR < FILE' Sets VAR and `RT' `awk'
-COMMAND `| getline' Sets `$0', `NF', and `RT' `awk'
-COMMAND `| getline' VAR Sets VAR and `RT' `awk'
-COMMAND `|& getline' Sets `$0', `NF', and `RT' `gawk'
-COMMAND `|& getline' Sets VAR and `RT' `gawk'
-VAR
-
-Table 4.1: `getline' variants and what they set
+*note Table 4.1: table-getline-variants. summarizes the eight variants
+of 'getline', listing which predefined variables are set by each one,
+and whether the variant is standard or a 'gawk' extension. Note: for
+each variant, 'gawk' sets the 'RT' predefined variable.
+
+Variant Effect 'awk' / 'gawk'
+-------------------------------------------------------------------------
+'getline' Sets '$0', 'NF', 'FNR', 'awk'
+ 'NR', and 'RT'
+'getline' VAR Sets VAR, 'FNR', 'NR', 'awk'
+ and 'RT'
+'getline <' FILE Sets '$0', 'NF', and 'RT' 'awk'
+'getline VAR < FILE' Sets VAR and 'RT' 'awk'
+COMMAND '| getline' Sets '$0', 'NF', and 'RT' 'awk'
+COMMAND '| getline' Sets VAR and 'RT' 'awk'
+VAR
+COMMAND '|& getline' Sets '$0', 'NF', and 'RT' 'gawk'
+COMMAND '|& getline' Sets VAR and 'RT' 'gawk'
+VAR
+
+Table 4.1: 'getline' variants and what they set
File: gawk.info, Node: Read Timeout, Next: Command-line directories, Prev:
Getline, Up: Reading Files
@@ -5888,16 +5862,16 @@ File: gawk.info, Node: Read Timeout, Next:
Command-line directories, Prev: Ge
4.10 Reading Input with a Timeout
=================================
-This minor node describes a feature that is specific to `gawk'.
+This minor node describes a feature that is specific to 'gawk'.
You may specify a timeout in milliseconds for reading input from the
keyboard, a pipe, or two-way communication, including TCP/IP sockets.
This can be done on a per-input, per-command, or per-connection basis,
-by setting a special element in the `PROCINFO' array (*note Auto-set::):
+by setting a special element in the 'PROCINFO' array (*note Auto-set::):
PROCINFO["input_name", "READ_TIMEOUT"] = TIMEOUT IN MILLISECONDS
- When set, this causes `gawk' to time out and return failure if no
+ When set, this causes 'gawk' to time out and return failure if no
data is available to read within the specified timeout period. For
example, a TCP client can decide to give up on receiving any response
from the server after a certain amount of time:
@@ -5916,8 +5890,8 @@ for more than five seconds:
while ((getline < "/dev/stdin") > 0)
print $0
- `gawk' terminates the read operation if input does not arrive after
-waiting for the timeout period, returns failure, and sets `ERRNO' to an
+ 'gawk' terminates the read operation if input does not arrive after
+waiting for the timeout period, returns failure, and sets 'ERRNO' to an
appropriate string value. A negative or zero value for the timeout is
the same as specifying no timeout at all.
@@ -5933,10 +5907,10 @@ patterns, like so:
In this case, failure to respond within five seconds results in the
following error message:
- error--> gawk: cmd. line:2: (FILENAME=- FNR=1) fatal: error reading input
file `-': Connection timed out
+ error-> gawk: cmd. line:2: (FILENAME=- FNR=1) fatal: error reading input
file `-': Connection timed out
The timeout can be set or changed at any time, and will take effect
-on the next attempt to read from the input device. In the following
+on the next attempt to read from the input device. In the following
example, we start with a timeout value of one second, and progressively
reduce it by one-tenth of a second until we wait indefinitely for the
input to arrive:
@@ -5948,29 +5922,28 @@ input to arrive:
}
NOTE: You should not assume that the read operation will block
- exactly after the tenth record has been printed. It is possible
- that `gawk' will read and buffer more than one record's worth of
- data the first time. Because of this, changing the value of
+ exactly after the tenth record has been printed. It is possible
+ that 'gawk' will read and buffer more than one record's worth of
+ data the first time. Because of this, changing the value of
timeout like in the preceding example is not very useful.
- If the `PROCINFO' element is not present and the `GAWK_READ_TIMEOUT'
-environment variable exists, `gawk' uses its value to initialize the
-timeout value. The exclusive use of the environment variable to
-specify timeout has the disadvantage of not being able to control it on
-a per-command or per-connection basis.
+ If the 'PROCINFO' element is not present and the 'GAWK_READ_TIMEOUT'
+environment variable exists, 'gawk' uses its value to initialize the
+timeout value. The exclusive use of the environment variable to specify
+timeout has the disadvantage of not being able to control it on a
+per-command or per-connection basis.
- `gawk' considers a timeout event to be an error even though the
+ 'gawk' considers a timeout event to be an error even though the
attempt to read from the underlying device may succeed in a later
-attempt. This is a limitation, and it also means that you cannot use
+attempt. This is a limitation, and it also means that you cannot use
this to multiplex input from two or more sources.
Assigning a timeout value prevents read operations from blocking
-indefinitely. But bear in mind that there are other ways `gawk' can
+indefinitely. But bear in mind that there are other ways 'gawk' can
stall waiting for an input device to be ready. A network client can
-sometimes take a long time to establish a connection before it can
-start reading any data, or the attempt to open a FIFO special file for
-reading can block indefinitely until some other process opens it for
-writing.
+sometimes take a long time to establish a connection before it can start
+reading any data, or the attempt to open a FIFO special file for reading
+can block indefinitely until some other process opens it for writing.
---------- Footnotes ----------
@@ -5982,22 +5955,22 @@ File: gawk.info, Node: Command-line directories,
Next: Input Summary, Prev: R
4.11 Directories on the Command Line
====================================
-According to the POSIX standard, files named on the `awk' command line
+According to the POSIX standard, files named on the 'awk' command line
must be text files; it is a fatal error if they are not. Most versions
-of `awk' treat a directory on the command line as a fatal error.
+of 'awk' treat a directory on the command line as a fatal error.
- By default, `gawk' produces a warning for a directory on the command
+ By default, 'gawk' produces a warning for a directory on the command
line, but otherwise ignores it. This makes it easier to use shell
-wildcards with your `awk' program:
+wildcards with your 'awk' program:
$ gawk -f whizprog.awk * Directories could kill this program
- If either of the `--posix' or `--traditional' options is given, then
-`gawk' reverts to treating a directory on the command line as a fatal
+ If either of the '--posix' or '--traditional' options is given, then
+'gawk' reverts to treating a directory on the command line as a fatal
error.
*Note Extension Sample Readdir::, for a way to treat directories as
-usable data from an `awk' program.
+usable data from an 'awk' program.
File: gawk.info, Node: Input Summary, Next: Input Exercises, Prev:
Command-line directories, Up: Reading Files
@@ -6005,73 +5978,71 @@ File: gawk.info, Node: Input Summary, Next: Input
Exercises, Prev: Command-li
4.12 Summary
============
- * Input is split into records based on the value of `RS'. The
+ * Input is split into records based on the value of 'RS'. The
possibilities are as follows:
- Value of `RS' Records are split on `awk' / `gawk'
- ...
- ----------------------------------------------------------------------
- Any single That character `awk'
- character
- The empty string Runs of two or more `awk'
- (`""') newlines
- A regexp Text that matches the `gawk'
- regexp
-
- * `FNR' indicates how many records have been read from the current
- input file; `NR' indicates how many records have been read in
+ Value of 'RS' Records are split on 'awk' / 'gawk'
+ ...
+
---------------------------------------------------------------------------
+ Any single That character 'awk'
+ character
+ The empty string Runs of two or more 'awk'
+ ('""') newlines
+ A regexp Text that matches the 'gawk'
+ regexp
+
+ * 'FNR' indicates how many records have been read from the current
+ input file; 'NR' indicates how many records have been read in
total.
- * `gawk' sets `RT' to the text matched by `RS'.
+ * 'gawk' sets 'RT' to the text matched by 'RS'.
- * After splitting the input into records, `awk' further splits the
- records into individual fields, named `$1', `$2', and so on. `$0'
- is the whole record, and `NF' indicates how many fields there are.
+ * After splitting the input into records, 'awk' further splits the
+ records into individual fields, named '$1', '$2', and so on. '$0'
+ is the whole record, and 'NF' indicates how many fields there are.
The default way to split fields is between whitespace characters.
- * Fields may be referenced using a variable, as in `$NF'. Fields
- may also be assigned values, which causes the value of `$0' to be
- recomputed when it is later referenced. Assigning to a field with
- a number greater than `NF' creates the field and rebuilds the
- record, using `OFS' to separate the fields. Incrementing `NF'
- does the same thing. Decrementing `NF' throws away fields and
- rebuilds the record.
+ * Fields may be referenced using a variable, as in '$NF'. Fields may
+ also be assigned values, which causes the value of '$0' to be
+ recomputed when it is later referenced. Assigning to a field with
+ a number greater than 'NF' creates the field and rebuilds the
+ record, using 'OFS' to separate the fields. Incrementing 'NF' does
+ the same thing. Decrementing 'NF' throws away fields and rebuilds
+ the record.
* Field splitting is more complicated than record splitting:
- Field separator value Fields are split ... `awk' /
- `gawk'
- ----------------------------------------------------------------------
- `FS == " "' On runs of whitespace `awk'
- `FS == ANY SINGLE On that character `awk'
- CHARACTER'
- `FS == REGEXP' On text matching the `awk'
- regexp
- `FS == ""' Such that each individual `gawk'
- character is a separate
- field
- `FIELDWIDTHS == LIST OF Based on character `gawk'
- COLUMNS' position
- `FPAT == REGEXP' On the text surrounding `gawk'
- text matching the regexp
-
- * Using `FS = "\n"' causes the entire record to be a single field
+ Field separator value Fields are split ... 'awk' /
+ 'gawk'
+
---------------------------------------------------------------------------
+ 'FS == " "' On runs of whitespace 'awk'
+ 'FS == ANY SINGLE On that character 'awk'
+ CHARACTER'
+ 'FS == REGEXP' On text matching the regexp 'awk'
+ 'FS == ""' Such that each individual 'gawk'
+ character is a separate
+ field
+ 'FIELDWIDTHS == LIST OF Based on character position 'gawk'
+ COLUMNS'
+ 'FPAT == REGEXP' On the text surrounding 'gawk'
+ text matching the regexp
+
+ * Using 'FS = "\n"' causes the entire record to be a single field
(assuming that newlines separate records).
- * `FS' may be set from the command line using the `-F' option. This
+ * 'FS' may be set from the command line using the '-F' option. This
can also be done using command-line variable assignment.
- * Use `PROCINFO["FS"]' to see how fields are being split.
+ * Use 'PROCINFO["FS"]' to see how fields are being split.
- * Use `getline' in its various forms to read additional records from
+ * Use 'getline' in its various forms to read additional records from
the default input stream, from a file, or from a pipe or coprocess.
- * Use `PROCINFO[FILE, "READ_TIMEOUT"]' to cause reads to time out
- for FILE.
-
- * Directories on the command line are fatal for standard `awk';
- `gawk' ignores them if not in POSIX mode.
+ * Use 'PROCINFO[FILE, "READ_TIMEOUT"]' to cause reads to time out for
+ FILE.
+ * Directories on the command line are fatal for standard 'awk';
+ 'gawk' ignores them if not in POSIX mode.
File: gawk.info, Node: Input Exercises, Prev: Input Summary, Up: Reading
Files
@@ -6079,18 +6050,17 @@ File: gawk.info, Node: Input Exercises, Prev: Input
Summary, Up: Reading File
4.13 Exercises
==============
- 1. Using the `FIELDWIDTHS' variable (*note Constant Size::), write a
+ 1. Using the 'FIELDWIDTHS' variable (*note Constant Size::), write a
program to read election data, where each record represents one
voter's votes. Come up with a way to define which columns are
associated with each ballot item, and print the total votes,
including abstentions, for each item.
2. *note Plain Getline::, presented a program to remove C-style
- comments (`/* ... */') from the input. That program does not work
- if one comment ends on one line and another one starts later on
- the same line. That can be fixed by making one simple change.
- What is it?
-
+ comments ('/* ... */') from the input. That program does not work
+ if one comment ends on one line and another one starts later on the
+ same line. That can be fixed by making one simple change. What is
+ it?
File: gawk.info, Node: Printing, Next: Expressions, Prev: Reading Files,
Up: Top
@@ -6099,32 +6069,32 @@ File: gawk.info, Node: Printing, Next: Expressions,
Prev: Reading Files, Up:
*****************
One of the most common programming actions is to "print", or output,
-some or all of the input. Use the `print' statement for simple output,
-and the `printf' statement for fancier formatting. The `print'
+some or all of the input. Use the 'print' statement for simple output,
+and the 'printf' statement for fancier formatting. The 'print'
statement is not limited when computing _which_ values to print.
However, with two exceptions, you cannot specify _how_ to print
them--how many columns, whether to use exponential notation or not, and
so on. (For the exceptions, *note Output Separators::, and *note
-OFMT::.) For printing with specifications, you need the `printf'
+OFMT::.) For printing with specifications, you need the 'printf'
statement (*note Printf::).
- Besides basic and formatted printing, this major node also covers
-I/O redirections to files and pipes, introduces the special file names
-that `gawk' processes internally, and discusses the `close()' built-in
+ Besides basic and formatted printing, this major node also covers I/O
+redirections to files and pipes, introduces the special file names that
+'gawk' processes internally, and discusses the 'close()' built-in
function.
* Menu:
-* Print:: The `print' statement.
-* Print Examples:: Simple examples of `print' statements.
+* Print:: The 'print' statement.
+* Print Examples:: Simple examples of 'print' statements.
* Output Separators:: The output separators and how to change them.
-* OFMT:: Controlling Numeric Output With `print'.
-* Printf:: The `printf' statement.
+* OFMT:: Controlling Numeric Output With 'print'.
+* Printf:: The 'printf' statement.
* Redirection:: How to redirect output to multiple files and
pipes.
* Special FD:: Special files for I/O.
-* Special Files:: File name interpretation in `gawk'.
- `gawk' allows access to inherited file
+* Special Files:: File name interpretation in 'gawk'.
+ 'gawk' allows access to inherited file
descriptors.
* Close Files And Pipes:: Closing Input and Output Files and Pipes.
* Output Summary:: Output summary.
@@ -6133,59 +6103,58 @@ function.
File: gawk.info, Node: Print, Next: Print Examples, Up: Printing
-5.1 The `print' Statement
+5.1 The 'print' Statement
=========================
-Use the `print' statement to produce output with simple, standardized
-formatting. You specify only the strings or numbers to print, in a
-list separated by commas. They are output, separated by single spaces,
+Use the 'print' statement to produce output with simple, standardized
+formatting. You specify only the strings or numbers to print, in a list
+separated by commas. They are output, separated by single spaces,
followed by a newline. The statement looks like this:
print ITEM1, ITEM2, ...
The entire list of items may be optionally enclosed in parentheses. The
-parentheses are necessary if any of the item expressions uses the `>'
+parentheses are necessary if any of the item expressions uses the '>'
relational operator; otherwise it could be confused with an output
redirection (*note Redirection::).
The items to print can be constant strings or numbers, fields of the
-current record (such as `$1'), variables, or any `awk' expression.
+current record (such as '$1'), variables, or any 'awk' expression.
Numeric values are converted to strings and then printed.
- The simple statement `print' with no items is equivalent to `print
+ The simple statement 'print' with no items is equivalent to 'print
$0': it prints the entire current record. To print a blank line, use
-`print ""'. To print a fixed piece of text, use a string constant,
-such as `"Don't Panic"', as one item. If you forget to use the
-double-quote characters, your text is taken as an `awk' expression, and
-you will probably get an error. Keep in mind that a space is printed
-between any two items.
+'print ""'. To print a fixed piece of text, use a string constant, such
+as '"Don't Panic"', as one item. If you forget to use the double-quote
+characters, your text is taken as an 'awk' expression, and you will
+probably get an error. Keep in mind that a space is printed between any
+two items.
- Note that the `print' statement is a statement and not an
+ Note that the 'print' statement is a statement and not an
expression--you can't use it in the pattern part of a pattern-action
statement, for example.
File: gawk.info, Node: Print Examples, Next: Output Separators, Prev:
Print, Up: Printing
-5.2 `print' Statement Examples
+5.2 'print' Statement Examples
==============================
-Each `print' statement makes at least one line of output. However, it
-isn't limited to only one line. If an item value is a string
-containing a newline, the newline is output along with the rest of the
-string. A single `print' statement can make any number of lines this
-way.
+Each 'print' statement makes at least one line of output. However, it
+isn't limited to only one line. If an item value is a string containing
+a newline, the newline is output along with the rest of the string. A
+single 'print' statement can make any number of lines this way.
The following is an example of printing a string that contains
-embedded newlines (the `\n' is an escape sequence, used to represent
-the newline character; *note Escape Sequences::):
+embedded newlines (the '\n' is an escape sequence, used to represent the
+newline character; *note Escape Sequences::):
$ awk 'BEGIN { print "line one\nline two\nline three" }'
-| line one
-| line two
-| line three
- The next example, which is run on the `inventory-shipped' file,
+ The next example, which is run on the 'inventory-shipped' file,
prints the first two fields of each input record, with a space between
them:
@@ -6195,10 +6164,10 @@ them:
-| Mar 15
...
- A common mistake in using the `print' statement is to omit the comma
+ A common mistake in using the 'print' statement is to omit the comma
between two items. This often has the effect of making the items run
together in the output, with no space. The reason for this is that
-juxtaposing two string expressions in `awk' means to concatenate them.
+juxtaposing two string expressions in 'awk' means to concatenate them.
Here is the same program, without the comma:
$ awk '{ print $1 $2 }' inventory-shipped
@@ -6207,11 +6176,11 @@ Here is the same program, without the comma:
-| Mar15
...
- To someone unfamiliar with the `inventory-shipped' file, neither
+ To someone unfamiliar with the 'inventory-shipped' file, neither
example's output makes much sense. A heading line at the beginning
would make it clearer. Let's add some headings to our table of months
-(`$1') and green crates shipped (`$2'). We do this using a `BEGIN'
-rule (*note BEGIN/END::) so that the headings are only printed once:
+('$1') and green crates shipped ('$2'). We do this using a 'BEGIN' rule
+(*note BEGIN/END::) so that the headings are only printed once:
awk 'BEGIN { print "Month Crates"
print "----- ------" }
@@ -6226,8 +6195,8 @@ When run, the program prints the following:
Mar 15
...
-The only problem, however, is that the headings and the table data
-don't line up! We can fix this by printing some spaces between the two
+The only problem, however, is that the headings and the table data don't
+line up! We can fix this by printing some spaces between the two
fields:
awk 'BEGIN { print "Month Crates"
@@ -6236,11 +6205,11 @@ fields:
Lining up columns this way can get pretty complicated when there are
many columns to fix. Counting spaces for two or three columns is
-simple, but any more than this can take up a lot of time. This is why
-the `printf' statement was created (*note Printf::); one of its
+simple, but any more than this can take up a lot of time. This is why
+the 'printf' statement was created (*note Printf::); one of its
specialties is lining up columns of data.
- NOTE: You can continue either a `print' or `printf' statement
+ NOTE: You can continue either a 'print' or 'printf' statement
simply by putting a newline after any comma (*note
Statements/Lines::).
@@ -6250,29 +6219,28 @@ File: gawk.info, Node: Output Separators, Next: OFMT,
Prev: Print Examples,
5.3 Output Separators
=====================
-As mentioned previously, a `print' statement contains a list of items
-separated by commas. In the output, the items are normally separated
-by single spaces. However, this doesn't need to be the case; a single
+As mentioned previously, a 'print' statement contains a list of items
+separated by commas. In the output, the items are normally separated by
+single spaces. However, this doesn't need to be the case; a single
space is simply the default. Any string of characters may be used as
-the "output field separator" by setting the predefined variable `OFS'.
-The initial value of this variable is the string `" "' (i.e., a single
+the "output field separator" by setting the predefined variable 'OFS'.
+The initial value of this variable is the string '" "' (i.e., a single
space).
- The output from an entire `print' statement is called an "output
-record". Each `print' statement outputs one output record, and then
-outputs a string called the "output record separator" (or `ORS'). The
-initial value of `ORS' is the string `"\n"' (i.e., a newline
-character). Thus, each `print' statement normally makes a separate
-line.
+ The output from an entire 'print' statement is called an "output
+record". Each 'print' statement outputs one output record, and then
+outputs a string called the "output record separator" (or 'ORS'). The
+initial value of 'ORS' is the string '"\n"' (i.e., a newline character).
+Thus, each 'print' statement normally makes a separate line.
In order to change how output fields and records are separated,
-assign new values to the variables `OFS' and `ORS'. The usual place to
-do this is in the `BEGIN' rule (*note BEGIN/END::), so that it happens
+assign new values to the variables 'OFS' and 'ORS'. The usual place to
+do this is in the 'BEGIN' rule (*note BEGIN/END::), so that it happens
before any input is processed. It can also be done with assignments on
-the command line, before the names of the input files, or using the
-`-v' command-line option (*note Options::). The following example
-prints the first and second fields of each input record, separated by a
-semicolon, with a blank line added after each newline:
+the command line, before the names of the input files, or using the '-v'
+command-line option (*note Options::). The following example prints the
+first and second fields of each input record, separated by a semicolon,
+with a blank line added after each newline:
$ awk 'BEGIN { OFS = ";"; ORS = "\n\n" }
> { print $1, $2 }' mail-list
@@ -6299,29 +6267,29 @@ semicolon, with a blank line added after each newline:
-| Jean-Paul;555-2127
-|
- If the value of `ORS' does not contain a newline, the program's
+ If the value of 'ORS' does not contain a newline, the program's
output runs together on a single line.
File: gawk.info, Node: OFMT, Next: Printf, Prev: Output Separators, Up:
Printing
-5.4 Controlling Numeric Output with `print'
+5.4 Controlling Numeric Output with 'print'
===========================================
-When printing numeric values with the `print' statement, `awk'
+When printing numeric values with the 'print' statement, 'awk'
internally converts each number to a string of characters and prints
-that string. `awk' uses the `sprintf()' function to do this conversion
+that string. 'awk' uses the 'sprintf()' function to do this conversion
(*note String Functions::). For now, it suffices to say that the
-`sprintf()' function accepts a "format specification" that tells it how
-to format numbers (or strings), and that there are a number of
-different ways in which numbers can be formatted. The different format
+'sprintf()' function accepts a "format specification" that tells it how
+to format numbers (or strings), and that there are a number of different
+ways in which numbers can be formatted. The different format
specifications are discussed more fully in *note Control Letters::.
- The predefined variable `OFMT' contains the format specification
-that `print' uses with `sprintf()' when it wants to convert a number to
-a string for printing. The default value of `OFMT' is `"%.6g"'. The
-way `print' prints numbers can be changed by supplying a different
-format specification for the value of `OFMT', as shown in the following
+ The predefined variable 'OFMT' contains the format specification that
+'print' uses with 'sprintf()' when it wants to convert a number to a
+string for printing. The default value of 'OFMT' is '"%.6g"'. The way
+'print' prints numbers can be changed by supplying a different format
+specification for the value of 'OFMT', as shown in the following
example:
$ awk 'BEGIN {
@@ -6329,25 +6297,24 @@ example:
> print 17.23, 17.54 }'
-| 17 18
-According to the POSIX standard, `awk''s behavior is undefined if
-`OFMT' contains anything but a floating-point conversion specification.
-(d.c.)
+According to the POSIX standard, 'awk''s behavior is undefined if 'OFMT'
+contains anything but a floating-point conversion specification. (d.c.)
File: gawk.info, Node: Printf, Next: Redirection, Prev: OFMT, Up: Printing
-5.5 Using `printf' Statements for Fancier Printing
+5.5 Using 'printf' Statements for Fancier Printing
==================================================
-For more precise control over the output format than what is provided
-by `print', use `printf'. With `printf' you can specify the width to
-use for each item, as well as various formatting choices for numbers
-(such as what output base to use, whether to print an exponent, whether
-to print a sign, and how many digits to print after the decimal point).
+For more precise control over the output format than what is provided by
+'print', use 'printf'. With 'printf' you can specify the width to use
+for each item, as well as various formatting choices for numbers (such
+as what output base to use, whether to print an exponent, whether to
+print a sign, and how many digits to print after the decimal point).
* Menu:
-* Basic Printf:: Syntax of the `printf' statement.
+* Basic Printf:: Syntax of the 'printf' statement.
* Control Letters:: Format-control letters.
* Format Modifiers:: Format-specification modifiers.
* Printf Examples:: Several examples.
@@ -6355,34 +6322,34 @@ to print a sign, and how many digits to print after the
decimal point).
File: gawk.info, Node: Basic Printf, Next: Control Letters, Up: Printf
-5.5.1 Introduction to the `printf' Statement
+5.5.1 Introduction to the 'printf' Statement
--------------------------------------------
-A simple `printf' statement looks like this:
+A simple 'printf' statement looks like this:
printf FORMAT, ITEM1, ITEM2, ...
-As for `print', the entire list of arguments may optionally be enclosed
-in parentheses. Here too, the parentheses are necessary if any of the
-item expressions uses the `>' relational operator; otherwise, it can be
+As for 'print', the entire list of arguments may optionally be enclosed
+in parentheses. Here too, the parentheses are necessary if any of the
+item expressions uses the '>' relational operator; otherwise, it can be
confused with an output redirection (*note Redirection::).
- The difference between `printf' and `print' is the FORMAT argument.
-This is an expression whose value is taken as a string; it specifies
-how to output each of the other arguments. It is called the "format
+ The difference between 'printf' and 'print' is the FORMAT argument.
+This is an expression whose value is taken as a string; it specifies how
+to output each of the other arguments. It is called the "format
string".
The format string is very similar to that in the ISO C library
-function `printf()'. Most of FORMAT is text to output verbatim.
+function 'printf()'. Most of FORMAT is text to output verbatim.
Scattered among this text are "format specifiers"--one per item. Each
format specifier says to output the next item in the argument list at
that place in the format.
- The `printf' statement does not automatically append a newline to
-its output. It outputs only what the format string specifies. So if a
+ The 'printf' statement does not automatically append a newline to its
+output. It outputs only what the format string specifies. So if a
newline is needed, you must include one in the format string. The
-output separator variables `OFS' and `ORS' have no effect on `printf'
-statements. For example:
+output separator variables 'OFS' and 'ORS' have no effect on 'printf'
+statements. For example:
$ awk 'BEGIN {
> ORS = "\nOUCH!\n"; OFS = "+"
@@ -6391,7 +6358,7 @@ statements. For example:
> }'
-| Don't Panic!
-Here, neither the `+' nor the `OUCH!' appears in the output message.
+Here, neither the '+' nor the 'OUCH!' appears in the output message.
File: gawk.info, Node: Control Letters, Next: Format Modifiers, Prev: Basic
Printf, Up: Printf
@@ -6399,120 +6366,120 @@ File: gawk.info, Node: Control Letters, Next:
Format Modifiers, Prev: Basic P
5.5.2 Format-Control Letters
----------------------------
-A format specifier starts with the character `%' and ends with a
-"format-control letter"--it tells the `printf' statement how to output
+A format specifier starts with the character '%' and ends with a
+"format-control letter"--it tells the 'printf' statement how to output
one item. The format-control letter specifies what _kind_ of value to
print. The rest of the format specifier is made up of optional
"modifiers" that control _how_ to print the value, such as the field
width. Here is a list of the format-control letters:
-`%c'
- Print a number as a character; thus, `printf "%c", 65' outputs the
- letter `A'. The output for a string value is the first character
+'%c'
+ Print a number as a character; thus, 'printf "%c", 65' outputs the
+ letter 'A'. The output for a string value is the first character
of the string.
NOTE: The POSIX standard says the first character of a string
- is printed. In locales with multibyte characters, `gawk'
+ is printed. In locales with multibyte characters, 'gawk'
attempts to convert the leading bytes of the string into a
valid wide character and then to print the multibyte encoding
of that character. Similarly, when printing a numeric value,
- `gawk' allows the value to be within the numeric range of
+ 'gawk' allows the value to be within the numeric range of
values that can be held in a wide character. If the
- conversion to multibyte encoding fails, `gawk' uses the low
+ conversion to multibyte encoding fails, 'gawk' uses the low
eight bits of the value as the character to print.
- Other `awk' versions generally restrict themselves to printing
+ Other 'awk' versions generally restrict themselves to printing
the first byte of a string or to numeric values within the
range of a single byte (0-255).
-`%d', `%i'
+'%d', '%i'
Print a decimal integer. The two control letters are equivalent.
- (The `%i' specification is for compatibility with ISO C.)
+ (The '%i' specification is for compatibility with ISO C.)
-`%e', `%E'
+'%e', '%E'
Print a number in scientific (exponential) notation. For example:
printf "%4.3e\n", 1950
- prints `1.950e+03', with a total of four significant figures,
- three of which follow the decimal point. (The `4.3' represents
- two modifiers, discussed in the next node.) `%E' uses `E' instead
- of `e' in the output.
+ prints '1.950e+03', with a total of four significant figures, three
+ of which follow the decimal point. (The '4.3' represents two
+ modifiers, discussed in the next node.) '%E' uses 'E' instead of
+ 'e' in the output.
-`%f'
+'%f'
Print a number in floating-point notation. For example:
printf "%4.3f", 1950
- prints `1950.000', with a total of four significant figures, three
- of which follow the decimal point. (The `4.3' represents two
+ prints '1950.000', with a total of four significant figures, three
+ of which follow the decimal point. (The '4.3' represents two
modifiers, discussed in the next node.)
On systems supporting IEEE 754 floating-point format, values
- representing negative infinity are formatted as `-inf' or
- `-infinity', and positive infinity as `inf' or `infinity'. The
- special "not a number" value formats as `-nan' or `nan' (*note
- Math Definitions::).
+ representing negative infinity are formatted as '-inf' or
+ '-infinity', and positive infinity as 'inf' or 'infinity'. The
+ special "not a number" value formats as '-nan' or 'nan' (*note Math
+ Definitions::).
-`%F'
- Like `%f', but the infinity and "not a number" values are spelled
+'%F'
+ Like '%f', but the infinity and "not a number" values are spelled
using uppercase letters.
- The `%F' format is a POSIX extension to ISO C; not all systems
- support it. On those that don't, `gawk' uses `%f' instead.
+ The '%F' format is a POSIX extension to ISO C; not all systems
+ support it. On those that don't, 'gawk' uses '%f' instead.
-`%g', `%G'
+'%g', '%G'
Print a number in either scientific notation or in floating-point
- notation, whichever uses fewer characters; if the result is
- printed in scientific notation, `%G' uses `E' instead of `e'.
+ notation, whichever uses fewer characters; if the result is printed
+ in scientific notation, '%G' uses 'E' instead of 'e'.
-`%o'
+'%o'
Print an unsigned octal integer (*note Nondecimal-numbers::).
-`%s'
+'%s'
Print a string.
-`%u'
+'%u'
Print an unsigned decimal integer. (This format is of marginal
- use, because all numbers in `awk' are floating point; it is
+ use, because all numbers in 'awk' are floating point; it is
provided primarily for compatibility with C.)
-`%x', `%X'
- Print an unsigned hexadecimal integer; `%X' uses the letters `A'
- through `F' instead of `a' through `f' (*note
+'%x', '%X'
+ Print an unsigned hexadecimal integer; '%X' uses the letters 'A'
+ through 'F' instead of 'a' through 'f' (*note
Nondecimal-numbers::).
-`%%'
- Print a single `%'. This does not consume an argument and it
+'%%'
+ Print a single '%'. This does not consume an argument and it
ignores any modifiers.
- NOTE: When using the integer format-control letters for values
- that are outside the range of the widest C integer type, `gawk'
- switches to the `%g' format specifier. If `--lint' is provided on
- the command line (*note Options::), `gawk' warns about this.
- Other versions of `awk' may print invalid values or do something
- else entirely. (d.c.)
+ NOTE: When using the integer format-control letters for values that
+ are outside the range of the widest C integer type, 'gawk' switches
+ to the '%g' format specifier. If '--lint' is provided on the
+ command line (*note Options::), 'gawk' warns about this. Other
+ versions of 'awk' may print invalid values or do something else
+ entirely. (d.c.)
File: gawk.info, Node: Format Modifiers, Next: Printf Examples, Prev:
Control Letters, Up: Printf
-5.5.3 Modifiers for `printf' Formats
+5.5.3 Modifiers for 'printf' Formats
------------------------------------
-A format specification can also include "modifiers" that can control
-how much of the item's value is printed, as well as how much space it
-gets. The modifiers come between the `%' and the format-control letter.
-We use the bullet symbol "*" in the following examples to represent
-spaces in the output. Here are the possible modifiers, in the order in
-which they may appear:
+A format specification can also include "modifiers" that can control how
+much of the item's value is printed, as well as how much space it gets.
+The modifiers come between the '%' and the format-control letter. We
+use the bullet symbol "*" in the following examples to represent spaces
+in the output. Here are the possible modifiers, in the order in which
+they may appear:
-`N$'
- An integer constant followed by a `$' is a "positional specifier".
+'N$'
+ An integer constant followed by a '$' is a "positional specifier".
Normally, format specifications are applied to arguments in the
- order given in the format string. With a positional specifier,
- the format specification is applied to a specific argument,
- instead of what would be the next argument in the list.
- Positional specifiers begin counting with one. Thus:
+ order given in the format string. With a positional specifier, the
+ format specification is applied to a specific argument, instead of
+ what would be the next argument in the list. Positional specifiers
+ begin counting with one. Thus:
printf "%s %s\n", "don't", "panic"
printf "%2$s %1$s\n", "panic", "don't"
@@ -6520,11 +6487,11 @@ which they may appear:
prints the famous friendly message twice.
At first glance, this feature doesn't seem to be of much use. It
- is in fact a `gawk' extension, intended for use in translating
+ is in fact a 'gawk' extension, intended for use in translating
messages at runtime. *Note Printf Ordering::, which describes how
and why to use positional specifiers. For now, we ignore them.
-`-' (Minus)
+'-' (Minus)
The minus sign, used before the width modifier (see later on in
this list), says to left-justify the argument within its specified
width. Normally, the argument is printed right-justified in the
@@ -6532,35 +6499,35 @@ which they may appear:
printf "%-4s", "foo"
- prints `foo*'.
+ prints 'foo*'.
SPACE
For numeric conversions, prefix positive values with a space and
negative values with a minus sign.
-`+'
- The plus sign, used before the width modifier (see later on in
- this list), says to always supply a sign for numeric conversions,
- even if the data to format is positive. The `+' overrides the
- space modifier.
-
-`#'
- Use an "alternative form" for certain control letters. For `%o',
- supply a leading zero. For `%x' and `%X', supply a leading `0x'
- or `0X' for a nonzero result. For `%e', `%E', `%f', and `%F', the
- result always contains a decimal point. For `%g' and `%G',
+'+'
+ The plus sign, used before the width modifier (see later on in this
+ list), says to always supply a sign for numeric conversions, even
+ if the data to format is positive. The '+' overrides the space
+ modifier.
+
+'#'
+ Use an "alternative form" for certain control letters. For '%o',
+ supply a leading zero. For '%x' and '%X', supply a leading '0x' or
+ '0X' for a nonzero result. For '%e', '%E', '%f', and '%F', the
+ result always contains a decimal point. For '%g' and '%G',
trailing zeros are not removed from the result.
-`0'
- A leading `0' (zero) acts as a flag indicating that output should
+'0'
+ A leading '0' (zero) acts as a flag indicating that output should
be padded with zeros instead of spaces. This applies only to the
numeric output formats. This flag only has an effect when the
field width is wider than the value to print.
-`''
+'''
A single quote or apostrophe character is a POSIX extension to ISO
- C. It indicates that the integer part of a floating-point value,
- or the entire part of an integer decimal value, should have a
+ C. It indicates that the integer part of a floating-point value, or
+ the entire part of an integer decimal value, should have a
thousands-separator character in it. This only works in locales
that support such characters. For example:
@@ -6574,20 +6541,20 @@ SPACE
For more information about locales and internationalization issues,
see *note Locales::.
- NOTE: The `'' flag is a nice feature, but its use complicates
+ NOTE: The ''' flag is a nice feature, but its use complicates
things: it becomes difficult to use it in command-line
programs. For information on appropriate quoting tricks, see
*note Quoting::.
WIDTH
This is a number specifying the desired minimum width of a field.
- Inserting any number between the `%' sign and the format-control
+ Inserting any number between the '%' sign and the format-control
character forces the field to expand to this width. The default
way to do this is to pad with spaces on the left. For example:
printf "%4s", "foo"
- prints `*foo'.
+ prints '*foo'.
The value of WIDTH is a minimum width, not a maximum. If the item
value requires more than WIDTH characters, it can be as wide as
@@ -6595,26 +6562,26 @@ WIDTH
printf "%4s", "foobar"
- prints `foobar'.
+ prints 'foobar'.
Preceding the WIDTH with a minus sign causes the output to be
padded with spaces on the right, instead of on the left.
-`.PREC'
- A period followed by an integer constant specifies the precision
- to use when printing. The meaning of the precision varies by
- control letter:
+'.PREC'
+ A period followed by an integer constant specifies the precision to
+ use when printing. The meaning of the precision varies by control
+ letter:
- `%d', `%i', `%o', `%u', `%x', `%X'
+ '%d', '%i', '%o', '%u', '%x', '%X'
Minimum number of digits to print.
- `%e', `%E', `%f', `%F'
+ '%e', '%E', '%f', '%F'
Number of digits to the right of the decimal point.
- `%g', `%G'
+ '%g', '%G'
Maximum number of significant digits.
- `%s'
+ '%s'
Maximum number of characters from the string that should
print.
@@ -6622,10 +6589,10 @@ WIDTH
printf "%.4s", "foobar"
- prints `foob'.
+ prints 'foob'.
- The C library `printf''s dynamic WIDTH and PREC capability (e.g.,
-`"%*.*s"') is supported. Instead of supplying explicit WIDTH and/or
+ The C library 'printf''s dynamic WIDTH and PREC capability (e.g.,
+'"%*.*s"') is supported. Instead of supplying explicit WIDTH and/or
PREC values in the format string, they are passed in the argument list.
For example:
@@ -6639,10 +6606,9 @@ is exactly equivalent to:
s = "abcdefg"
printf "%5.3s\n", s
-Both programs output `**abc'. Earlier versions of `awk' did not
-support this capability. If you must use such a version, you may
-simulate this feature by using concatenation to build up the format
-string, like so:
+Both programs output '**abc'. Earlier versions of 'awk' did not support
+this capability. If you must use such a version, you may simulate this
+feature by using concatenation to build up the format string, like so:
w = 5
p = 3
@@ -6651,28 +6617,27 @@ string, like so:
This is not particularly easy to read, but it does work.
- C programmers may be used to supplying additional modifiers (`h',
-`j', `l', `L', `t', and `z') in `printf' format strings. These are not
-valid in `awk'. Most `awk' implementations silently ignore them. If
-`--lint' is provided on the command line (*note Options::), `gawk'
-warns about their use. If `--posix' is supplied, their use is a fatal
-error.
+ C programmers may be used to supplying additional modifiers ('h',
+'j', 'l', 'L', 't', and 'z') in 'printf' format strings. These are not
+valid in 'awk'. Most 'awk' implementations silently ignore them. If
+'--lint' is provided on the command line (*note Options::), 'gawk' warns
+about their use. If '--posix' is supplied, their use is a fatal error.
File: gawk.info, Node: Printf Examples, Prev: Format Modifiers, Up: Printf
-5.5.4 Examples Using `printf'
+5.5.4 Examples Using 'printf'
-----------------------------
-The following simple example shows how to use `printf' to make an
+The following simple example shows how to use 'printf' to make an
aligned table:
awk '{ printf "%-10s %s\n", $1, $2 }' mail-list
-This command prints the names of the people (`$1') in the file
-`mail-list' as a string of 10 characters that are left-justified. It
-also prints the phone numbers (`$2') next on the line. This produces
-an aligned two-column table of names and phone numbers, as shown here:
+This command prints the names of the people ('$1') in the file
+'mail-list' as a string of 10 characters that are left-justified. It
+also prints the phone numbers ('$2') next on the line. This produces an
+aligned two-column table of names and phone numbers, as shown here:
$ awk '{ printf "%-10s %s\n", $1, $2 }' mail-list
-| Amelia 555-5553
@@ -6689,7 +6654,7 @@ an aligned two-column table of names and phone numbers,
as shown here:
In this case, the phone numbers had to be printed as strings because
the numbers are separated by dashes. Printing the phone numbers as
-numbers would have produced just the first three digits: `555'. This
+numbers would have produced just the first three digits: '555'. This
would have been pretty confusing.
It wasn't necessary to specify a width for the phone numbers because
@@ -6697,25 +6662,25 @@ they are last on their lines. They don't need to have
spaces after
them.
The table could be made to look even nicer by adding headings to the
-tops of the columns. This is done using a `BEGIN' rule (*note
-BEGIN/END::) so that the headers are only printed once, at the
-beginning of the `awk' program:
+tops of the columns. This is done using a 'BEGIN' rule (*note
+BEGIN/END::) so that the headers are only printed once, at the beginning
+of the 'awk' program:
awk 'BEGIN { print "Name Number"
print "---- ------" }
{ printf "%-10s %s\n", $1, $2 }' mail-list
- The preceding example mixes `print' and `printf' statements in the
-same program. Using just `printf' statements can produce the same
+ The preceding example mixes 'print' and 'printf' statements in the
+same program. Using just 'printf' statements can produce the same
results:
awk 'BEGIN { printf "%-10s %s\n", "Name", "Number"
printf "%-10s %s\n", "----", "------" }
{ printf "%-10s %s\n", $1, $2 }' mail-list
-Printing each column heading with the same format specification used
-for the column elements ensures that the headings are aligned just like
-the columns.
+Printing each column heading with the same format specification used for
+the column elements ensures that the headings are aligned just like the
+columns.
The fact that the same format specification is used three times can
be emphasized by storing it in a variable, like this:
@@ -6728,39 +6693,39 @@ be emphasized by storing it in a variable, like this:
File: gawk.info, Node: Redirection, Next: Special FD, Prev: Printf, Up:
Printing
-5.6 Redirecting Output of `print' and `printf'
+5.6 Redirecting Output of 'print' and 'printf'
==============================================
-So far, the output from `print' and `printf' has gone to the standard
-output, usually the screen. Both `print' and `printf' can also send
+So far, the output from 'print' and 'printf' has gone to the standard
+output, usually the screen. Both 'print' and 'printf' can also send
their output to other places. This is called "redirection".
- NOTE: When `--sandbox' is specified (*note Options::), redirecting
+ NOTE: When '--sandbox' is specified (*note Options::), redirecting
output to files, pipes, and coprocesses is disabled.
- A redirection appears after the `print' or `printf' statement.
-Redirections in `awk' are written just like redirections in shell
-commands, except that they are written inside the `awk' program.
+ A redirection appears after the 'print' or 'printf' statement.
+Redirections in 'awk' are written just like redirections in shell
+commands, except that they are written inside the 'awk' program.
There are four forms of output redirection: output to a file, output
appended to a file, output through a pipe to another command, and output
-to a coprocess. We show them all for the `print' statement, but they
-work identically for `printf':
+to a coprocess. We show them all for the 'print' statement, but they
+work identically for 'printf':
-`print ITEMS > OUTPUT-FILE'
+'print ITEMS > OUTPUT-FILE'
This redirection prints the items into the output file named
- OUTPUT-FILE. The file name OUTPUT-FILE can be any expression.
- Its value is changed to a string and then used as a file name
- (*note Expressions::).
+ OUTPUT-FILE. The file name OUTPUT-FILE can be any expression. Its
+ value is changed to a string and then used as a file name (*note
+ Expressions::).
When this type of redirection is used, the OUTPUT-FILE is erased
- before the first output is written to it. Subsequent writes to
- the same OUTPUT-FILE do not erase OUTPUT-FILE, but append to it.
- (This is different from how you use redirections in shell scripts.)
- If OUTPUT-FILE does not exist, it is created. For example, here
- is how an `awk' program can write a list of peoples' names to one
- file named `name-list', and a list of phone numbers to another file
- named `phone-list':
+ before the first output is written to it. Subsequent writes to the
+ same OUTPUT-FILE do not erase OUTPUT-FILE, but append to it. (This
+ is different from how you use redirections in shell scripts.) If
+ OUTPUT-FILE does not exist, it is created. For example, here is
+ how an 'awk' program can write a list of peoples' names to one file
+ named 'name-list', and a list of phone numbers to another file
+ named 'phone-list':
$ awk '{ print $2 > "phone-list"
> print $1 > "name-list" }' mail-list
@@ -6775,20 +6740,20 @@ work identically for `printf':
Each output file contains one name or number per line.
-`print ITEMS >> OUTPUT-FILE'
+'print ITEMS >> OUTPUT-FILE'
This redirection prints the items into the preexisting output file
- named OUTPUT-FILE. The difference between this and the single-`>'
+ named OUTPUT-FILE. The difference between this and the single-'>'
redirection is that the old contents (if any) of OUTPUT-FILE are
- not erased. Instead, the `awk' output is appended to the file.
- If OUTPUT-FILE does not exist, then it is created.
+ not erased. Instead, the 'awk' output is appended to the file. If
+ OUTPUT-FILE does not exist, then it is created.
-`print ITEMS | COMMAND'
+'print ITEMS | COMMAND'
It is possible to send output to another program through a pipe
- instead of into a file. This redirection opens a pipe to
- COMMAND, and writes the values of ITEMS through this pipe to
- another process created to execute COMMAND.
+ instead of into a file. This redirection opens a pipe to COMMAND,
+ and writes the values of ITEMS through this pipe to another process
+ created to execute COMMAND.
- The redirection argument COMMAND is actually an `awk' expression.
+ The redirection argument COMMAND is actually an 'awk' expression.
Its value is converted to a string whose contents give the shell
command to be run. For example, the following produces two files,
one unsorted list of peoples' names, and one list sorted in reverse
@@ -6799,11 +6764,11 @@ work identically for `printf':
print $1 | command }' mail-list
The unsorted list is written with an ordinary redirection, while
- the sorted list is written by piping through the `sort' utility.
+ the sorted list is written by piping through the 'sort' utility.
The next example uses redirection to mail a message to the mailing
- list `bug-system'. This might be useful when trouble is
- encountered in an `awk' script run periodically for system
+ list 'bug-system'. This might be useful when trouble is
+ encountered in an 'awk' script run periodically for system
maintenance:
report = "mail bug-system"
@@ -6811,34 +6776,34 @@ work identically for `printf':
print("at record number", FNR, "of", FILENAME) | report
close(report)
- The `close()' function is called here because it's a good idea to
+ The 'close()' function is called here because it's a good idea to
close the pipe as soon as all the intended output has been sent to
it. *Note Close Files And Pipes::, for more information.
This example also illustrates the use of a variable to represent a
FILE or COMMAND--it is not necessary to always use a string
constant. Using a variable is generally a good idea, because (if
- you mean to refer to that same file or command) `awk' requires
- that the string value be written identically every time.
+ you mean to refer to that same file or command) 'awk' requires that
+ the string value be written identically every time.
-`print ITEMS |& COMMAND'
+'print ITEMS |& COMMAND'
This redirection prints the items to the input of COMMAND. The
- difference between this and the single-`|' redirection is that the
- output from COMMAND can be read with `getline'. Thus, COMMAND is
- a "coprocess", which works together with but is subsidiary to the
- `awk' program.
+ difference between this and the single-'|' redirection is that the
+ output from COMMAND can be read with 'getline'. Thus, COMMAND is a
+ "coprocess", which works together with but is subsidiary to the
+ 'awk' program.
- This feature is a `gawk' extension, and is not available in POSIX
- `awk'. *Note Getline/Coprocess::, for a brief discussion. *Note
+ This feature is a 'gawk' extension, and is not available in POSIX
+ 'awk'. *Note Getline/Coprocess::, for a brief discussion. *Note
Two-way I/O::, for a more complete discussion.
- Redirecting output using `>', `>>', `|', or `|&' asks the system to
+ Redirecting output using '>', '>>', '|', or '|&' asks the system to
open a file, pipe, or coprocess only if the particular FILE or COMMAND
-you specify has not already been written to by your program or if it
-has been closed since it was last written to.
+you specify has not already been written to by your program or if it has
+been closed since it was last written to.
- It is a common error to use `>' redirection for the first `print' to
-a file, and then to use `>>' for subsequent output:
+ It is a common error to use '>' redirection for the first 'print' to
+a file, and then to use '>>' for subsequent output:
# clear the file
print "Don't panic" > "guide.txt"
@@ -6847,34 +6812,34 @@ a file, and then to use `>>' for subsequent output:
print "Avoid improbability generators" >> "guide.txt"
This is indeed how redirections must be used from the shell. But in
-`awk', it isn't necessary. In this kind of case, a program should use
-`>' for all the `print' statements, because the output file is only
-opened once. (It happens that if you mix `>' and `>>' output is
-produced in the expected order. However, mixing the operators for the
+'awk', it isn't necessary. In this kind of case, a program should use
+'>' for all the 'print' statements, because the output file is only
+opened once. (It happens that if you mix '>' and '>>' output is
+produced in the expected order. However, mixing the operators for the
same file is definitely poor style, and is confusing to readers of your
program.)
- Many older `awk' implementations limit the number of pipelines that
-an `awk' program may have open to just one! In `gawk', there is no
-such limit. `gawk' allows a program to open as many pipelines as the
+ Many older 'awk' implementations limit the number of pipelines that
+an 'awk' program may have open to just one! In 'gawk', there is no such
+limit. 'gawk' allows a program to open as many pipelines as the
underlying operating system permits.
- Piping into `sh'
+ Piping into 'sh'
A particularly powerful way to use redirection is to build command
-lines and pipe them into the shell, `sh'. For example, suppose you
-have a list of files brought over from a system where all the file names
-are stored in uppercase, and you wish to rename them to have names in
-all lowercase. The following program is both simple and efficient:
+lines and pipe them into the shell, 'sh'. For example, suppose you have
+a list of files brought over from a system where all the file names are
+stored in uppercase, and you wish to rename them to have names in all
+lowercase. The following program is both simple and efficient:
{ printf("mv %s %s\n", $0, tolower($0)) | "sh" }
END { close("sh") }
- The `tolower()' function returns its argument string with all
+ The 'tolower()' function returns its argument string with all
uppercase characters converted to lowercase (*note String Functions::).
-The program builds up a list of command lines, using the `mv' utility
-to rename the files. It then sends the list to the shell for execution.
+The program builds up a list of command lines, using the 'mv' utility to
+rename the files. It then sends the list to the shell for execution.
*Note Shell Quoting::, for a function that can help in generating
command lines to be fed to the shell.
@@ -6891,49 +6856,49 @@ the "standard input", "standard output", and "standard
error output".
These open streams (and any other open files or pipes) are often
referred to by the technical term "file descriptors".
- These streams are, by default, connected to your keyboard and
-screen, but they are often redirected with the shell, via the `<', `<<',
-`>', `>>', `>&', and `|' operators. Standard error is typically used
-for writing error messages; the reason there are two separate streams,
+ These streams are, by default, connected to your keyboard and screen,
+but they are often redirected with the shell, via the '<', '<<', '>',
+'>>', '>&', and '|' operators. Standard error is typically used for
+writing error messages; the reason there are two separate streams,
standard output and standard error, is so that they can be redirected
separately.
- In traditional implementations of `awk', the only way to write an
-error message to standard error in an `awk' program is as follows:
+ In traditional implementations of 'awk', the only way to write an
+error message to standard error in an 'awk' program is as follows:
print "Serious error detected!" | "cat 1>&2"
This works by opening a pipeline to a shell command that can access the
-standard error stream that it inherits from the `awk' process. This is
+standard error stream that it inherits from the 'awk' process. This is
far from elegant, and it also requires a separate process. So people
-writing `awk' programs often don't do this. Instead, they send the
+writing 'awk' programs often don't do this. Instead, they send the
error messages to the screen, like this:
print "Serious error detected!" > "/dev/tty"
-(`/dev/tty' is a special file supplied by the operating system that is
-connected to your keyboard and screen. It represents the "terminal,"(1)
+('/dev/tty' is a special file supplied by the operating system that is
+connected to your keyboard and screen. It represents the "terminal,"(1)
which on modern systems is a keyboard and screen, not a serial console.)
This generally has the same effect, but not always: although the
standard error stream is usually the screen, it can be redirected; when
-that happens, writing to the screen is not correct. In fact, if `awk'
+that happens, writing to the screen is not correct. In fact, if 'awk'
is run from a background job, it may not have a terminal at all. Then
-opening `/dev/tty' fails.
+opening '/dev/tty' fails.
- `gawk', BWK `awk', and `mawk' provide special file names for
+ 'gawk', BWK 'awk', and 'mawk' provide special file names for
accessing the three standard streams. If the file name matches one of
-these special names when `gawk' (or one of the others) redirects input
+these special names when 'gawk' (or one of the others) redirects input
or output, then it directly uses the descriptor that the file name
stands for. These special file names work for all operating systems
-that `gawk' has been ported to, not just those that are POSIX-compliant:
+that 'gawk' has been ported to, not just those that are POSIX-compliant:
-`/dev/stdin'
+'/dev/stdin'
The standard input (file descriptor 0).
-`/dev/stdout'
+'/dev/stdout'
The standard output (file descriptor 1).
-`/dev/stderr'
+'/dev/stderr'
The standard error output (file descriptor 2).
With these facilities, the proper way to write an error message then
@@ -6945,53 +6910,53 @@ becomes:
redirection, the value must be a string. It is a common error to omit
the quotes, which leads to confusing results.
- `gawk' does not treat these file names as special when in
-POSIX-compatibility mode. However, because BWK `awk' supports them,
-`gawk' does support them even when invoked with the `--traditional'
+ 'gawk' does not treat these file names as special when in
+POSIX-compatibility mode. However, because BWK 'awk' supports them,
+'gawk' does support them even when invoked with the '--traditional'
option (*note Options::).
---------- Footnotes ----------
- (1) The "tty" in `/dev/tty' stands for "Teletype," a serial terminal.
+ (1) The "tty" in '/dev/tty' stands for "Teletype," a serial terminal.
File: gawk.info, Node: Special Files, Next: Close Files And Pipes, Prev:
Special FD, Up: Printing
-5.8 Special File names in `gawk'
+5.8 Special File names in 'gawk'
================================
Besides access to standard input, standard output, and standard error,
-`gawk' provides access to any open file descriptor. Additionally,
-there are special file names reserved for TCP/IP networking.
+'gawk' provides access to any open file descriptor. Additionally, there
+are special file names reserved for TCP/IP networking.
* Menu:
* Other Inherited Files:: Accessing other open files with
- `gawk'.
+ 'gawk'.
* Special Network:: Special files for network communications.
* Special Caveats:: Things to watch out for.
File: gawk.info, Node: Other Inherited Files, Next: Special Network, Up:
Special Files
-5.8.1 Accessing Other Open Files with `gawk'
+5.8.1 Accessing Other Open Files with 'gawk'
--------------------------------------------
-Besides the `/dev/stdin', `/dev/stdout', and `/dev/stderr' special file
-names mentioned earlier, `gawk' provides syntax for accessing any other
+Besides the '/dev/stdin', '/dev/stdout', and '/dev/stderr' special file
+names mentioned earlier, 'gawk' provides syntax for accessing any other
inherited open file:
-`/dev/fd/N'
+'/dev/fd/N'
The file associated with file descriptor N. Such a file must be
- opened by the program initiating the `awk' execution (typically
- the shell). Unless special pains are taken in the shell from which
- `gawk' is invoked, only descriptors 0, 1, and 2 are available.
+ opened by the program initiating the 'awk' execution (typically the
+ shell). Unless special pains are taken in the shell from which
+ 'gawk' is invoked, only descriptors 0, 1, and 2 are available.
- The file names `/dev/stdin', `/dev/stdout', and `/dev/stderr' are
-essentially aliases for `/dev/fd/0', `/dev/fd/1', and `/dev/fd/2',
-respectively. However, those names are more self-explanatory.
+ The file names '/dev/stdin', '/dev/stdout', and '/dev/stderr' are
+essentially aliases for '/dev/fd/0', '/dev/fd/1', and '/dev/fd/2',
+respectively. However, those names are more self-explanatory.
- Note that using `close()' on a file name of the form `"/dev/fd/N"',
+ Note that using 'close()' on a file name of the form '"/dev/fd/N"',
for file descriptor numbers above two, does actually close the given
file descriptor.
@@ -7001,16 +6966,15 @@ File: gawk.info, Node: Special Network, Next: Special
Caveats, Prev: Other In
5.8.2 Special Files for Network Communications
----------------------------------------------
-`gawk' programs can open a two-way TCP/IP connection, acting as either
-a client or a server. This is done using a special file name of the
-form:
+'gawk' programs can open a two-way TCP/IP connection, acting as either a
+client or a server. This is done using a special file name of the form:
- `/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT'
+ /NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT
- The NET-TYPE is one of `inet', `inet4', or `inet6'. The PROTOCOL is
-one of `tcp' or `udp', and the other fields represent the other
+ The NET-TYPE is one of 'inet', 'inet4', or 'inet6'. The PROTOCOL is
+one of 'tcp' or 'udp', and the other fields represent the other
essential pieces of information for making a networking connection.
-These file names are used with the `|&' operator for communicating with
+These file names are used with the '|&' operator for communicating with
a coprocess (*note Two-way I/O::). This is an advanced feature,
mentioned here only for completeness. Full discussion is delayed until
*note TCP/IP Networking::.
@@ -7022,18 +6986,18 @@ File: gawk.info, Node: Special Caveats, Prev: Special
Network, Up: Special Fi
-------------------------------
Here are some things to bear in mind when using the special file names
-that `gawk' provides:
+that 'gawk' provides:
* Recognition of the file names for the three standard preopened
files is disabled only in POSIX mode.
- * Recognition of the other special file names is disabled if `gawk'
- is in compatibility mode (either `--traditional' or `--posix';
+ * Recognition of the other special file names is disabled if 'gawk'
+ is in compatibility mode (either '--traditional' or '--posix';
*note Options::).
- * `gawk' _always_ interprets these special file names. For example,
- using `/dev/fd/4' for output actually writes on file descriptor 4,
- and not on a new file descriptor that is `dup()'ed from file
+ * 'gawk' _always_ interprets these special file names. For example,
+ using '/dev/fd/4' for output actually writes on file descriptor 4,
+ and not on a new file descriptor that is 'dup()'ed from file
descriptor 4. Most of the time this does not matter; however, it
is important to _not_ close any of the files related to file
descriptors 0, 1, and 2. Doing so results in unpredictable
@@ -7045,21 +7009,21 @@ File: gawk.info, Node: Close Files And Pipes, Next:
Output Summary, Prev: Spe
5.9 Closing Input and Output Redirections
=========================================
-If the same file name or the same shell command is used with `getline'
-more than once during the execution of an `awk' program (*note
+If the same file name or the same shell command is used with 'getline'
+more than once during the execution of an 'awk' program (*note
Getline::), the file is opened (or the command is executed) the first
time only. At that time, the first record of input is read from that
file or command. The next time the same file or command is used with
-`getline', another record is read from it, and so on.
+'getline', another record is read from it, and so on.
- Similarly, when a file or pipe is opened for output, `awk' remembers
+ Similarly, when a file or pipe is opened for output, 'awk' remembers
the file name or command associated with it, and subsequent writes to
the same file or command are appended to the previous writes. The file
-or pipe stays open until `awk' exits.
+or pipe stays open until 'awk' exits.
This implies that special steps are necessary in order to read the
same file again from the beginning, or to rerun a shell command (rather
-than reading more output from the same command). The `close()' function
+than reading more output from the same command). The 'close()' function
makes these things possible:
close(FILENAME)
@@ -7070,7 +7034,7 @@ or:
The argument FILENAME or COMMAND can be any expression. Its value
must _exactly_ match the string that was used to open the file or start
-the command (spaces and other "irrelevant" characters included). For
+the command (spaces and other "irrelevant" characters included). For
example, if you open a pipe with this:
"sort -r names" | getline foo
@@ -7079,28 +7043,28 @@ then you must close it with this:
close("sort -r names")
- Once this function call is executed, the next `getline' from that
-file or command, or the next `print' or `printf' to that file or
-command, reopens the file or reruns the command. Because the
-expression that you use to close a file or pipeline must exactly match
-the expression used to open the file or run the command, it is good
-practice to use a variable to store the file name or command. The
-previous example becomes the following:
+ Once this function call is executed, the next 'getline' from that
+file or command, or the next 'print' or 'printf' to that file or
+command, reopens the file or reruns the command. Because the expression
+that you use to close a file or pipeline must exactly match the
+expression used to open the file or run the command, it is good practice
+to use a variable to store the file name or command. The previous
+example becomes the following:
sortcom = "sort -r names"
sortcom | getline foo
...
close(sortcom)
-This helps avoid hard-to-find typographical errors in your `awk'
+This helps avoid hard-to-find typographical errors in your 'awk'
programs. Here are some of the reasons for closing an output file:
- * To write a file and read it back later on in the same `awk'
+ * To write a file and read it back later on in the same 'awk'
program. Close the file after writing it, then begin reading it
- with `getline'.
+ with 'getline'.
- * To write numerous files, successively, in the same `awk' program.
- If the files aren't closed, eventually `awk' may exceed a system
+ * To write numerous files, successively, in the same 'awk' program.
+ If the files aren't closed, eventually 'awk' may exceed a system
limit on the number of open files in one process. It is best to
close each one when the program has finished writing it.
@@ -7108,25 +7072,25 @@ programs. Here are some of the reasons for closing an
output file:
pipe, the command reading the pipe normally continues to try to
read input as long as the pipe is open. Often this means the
command cannot really do its work until the pipe is closed. For
- example, if output is redirected to the `mail' program, the
- message is not actually sent until the pipe is closed.
+ example, if output is redirected to the 'mail' program, the message
+ is not actually sent until the pipe is closed.
* To run the same program a second time, with the same arguments.
This is not the same thing as giving more input to the first run!
- For example, suppose a program pipes output to the `mail' program.
+ For example, suppose a program pipes output to the 'mail' program.
If it outputs several lines redirected to this pipe without closing
it, they make a single message of several lines. By contrast, if
the program closes the pipe after each line of output, then each
line makes a separate message.
- If you use more files than the system allows you to have open,
-`gawk' attempts to multiplex the available open files among your data
-files. `gawk''s ability to do this depends upon the facilities of your
+ If you use more files than the system allows you to have open, 'gawk'
+attempts to multiplex the available open files among your data files.
+'gawk''s ability to do this depends upon the facilities of your
operating system, so it may not always work. It is therefore both good
-practice and good portability advice to always use `close()' on your
+practice and good portability advice to always use 'close()' on your
files when you are done with them. In fact, if you are using a lot of
-pipes, it is essential that you close commands when done. For example,
+pipes, it is essential that you close commands when done. For example,
consider something like this:
{
@@ -7139,64 +7103,63 @@ consider something like this:
}
This example creates a new pipeline based on data in _each_ record.
-Without the call to `close()' indicated in the comment, `awk' creates
+Without the call to 'close()' indicated in the comment, 'awk' creates
child processes to run the commands, until it eventually runs out of
file descriptors for more pipelines.
Even though each command has finished (as indicated by the
-end-of-file return status from `getline'), the child process is not
-terminated;(1) more importantly, the file descriptor for the pipe is
-not closed and released until `close()' is called or `awk' exits.
-
- `close()' silently does nothing if given an argument that does not
-represent a file, pipe, or coprocess that was opened with a
-redirection. In such a case, it returns a negative value, indicating
-an error. In addition, `gawk' sets `ERRNO' to a string indicating the
-error.
+end-of-file return status from 'getline'), the child process is not
+terminated;(1) more importantly, the file descriptor for the pipe is not
+closed and released until 'close()' is called or 'awk' exits.
- Note also that `close(FILENAME)' has no "magic" effects on the
+ 'close()' silently does nothing if given an argument that does not
+represent a file, pipe, or coprocess that was opened with a redirection.
+In such a case, it returns a negative value, indicating an error. In
+addition, 'gawk' sets 'ERRNO' to a string indicating the error.
+
+ Note also that 'close(FILENAME)' has no "magic" effects on the
implicit loop that reads through the files named on the command line.
It is, more likely, a close of a file that was never opened with a
-redirection, so `awk' silently does nothing, except return a negative
+redirection, so 'awk' silently does nothing, except return a negative
value.
- When using the `|&' operator to communicate with a coprocess, it is
+ When using the '|&' operator to communicate with a coprocess, it is
occasionally useful to be able to close one end of the two-way pipe
without closing the other. This is done by supplying a second argument
-to `close()'. As in any other call to `close()', the first argument is
+to 'close()'. As in any other call to 'close()', the first argument is
the name of the command or special file used to start the coprocess.
-The second argument should be a string, with either of the values
-`"to"' or `"from"'. Case does not matter. As this is an advanced
-feature, discussion is delayed until *note Two-way I/O::, which
-describes it in more detail and gives an example.
+The second argument should be a string, with either of the values '"to"'
+or '"from"'. Case does not matter. As this is an advanced feature,
+discussion is delayed until *note Two-way I/O::, which describes it in
+more detail and gives an example.
- Using `close()''s Return Value
+ Using 'close()''s Return Value
- In many older versions of Unix `awk', the `close()' function is
+ In many older versions of Unix 'awk', the 'close()' function is
actually a statement. (d.c.) It is a syntax error to try and use the
-return value from `close()':
+return value from 'close()':
command = "..."
command | getline info
retval = close(command) # syntax error in many Unix awks
- `gawk' treats `close()' as a function. The return value is -1 if
-the argument names something that was never opened with a redirection,
-or if there is a system problem closing the file or process. In these
-cases, `gawk' sets the predefined variable `ERRNO' to a string
-describing the problem.
+ 'gawk' treats 'close()' as a function. The return value is -1 if the
+argument names something that was never opened with a redirection, or if
+there is a system problem closing the file or process. In these cases,
+'gawk' sets the predefined variable 'ERRNO' to a string describing the
+problem.
- In `gawk', when closing a pipe or coprocess (input or output), the
-return value is the exit status of the command.(2) Otherwise, it is the
-return value from the system's `close()' or `fclose()' C functions when
+ In 'gawk', when closing a pipe or coprocess (input or output), the
+return value is the exit status of the command.(2) Otherwise, it is the
+return value from the system's 'close()' or 'fclose()' C functions when
closing input or output files, respectively. This value is zero if the
close succeeds, or -1 if it fails.
- The POSIX standard is very vague; it says that `close()' returns
-zero on success and a nonzero value otherwise. In general, different
+ The POSIX standard is very vague; it says that 'close()' returns zero
+on success and a nonzero value otherwise. In general, different
implementations vary in what they report when closing pipes; thus, the
return value cannot be used portably. (d.c.) In POSIX mode (*note
-Options::), `gawk' just returns zero when closing a pipe.
+Options::), 'gawk' just returns zero when closing a pipe.
---------- Footnotes ----------
@@ -7204,8 +7167,8 @@ Options::), `gawk' just returns zero when closing a pipe.
is called a "zombie," and cleaning up after it is referred to as
"reaping."
- (2) This is a full 16-bit value as returned by the `wait()' system
-call. See the system manual pages for information on how to decode this
+ (2) This is a full 16-bit value as returned by the 'wait()' system
+call. See the system manual pages for information on how to decode this
value.
@@ -7214,26 +7177,25 @@ File: gawk.info, Node: Output Summary, Next: Output
Exercises, Prev: Close Fi
5.10 Summary
============
- * The `print' statement prints comma-separated expressions. Each
- expression is separated by the value of `OFS' and terminated by
- the value of `ORS'. `OFMT' provides the conversion format for
- numeric values for the `print' statement.
+ * The 'print' statement prints comma-separated expressions. Each
+ expression is separated by the value of 'OFS' and terminated by the
+ value of 'ORS'. 'OFMT' provides the conversion format for numeric
+ values for the 'print' statement.
- * The `printf' statement provides finer-grained control over output,
+ * The 'printf' statement provides finer-grained control over output,
with format-control letters for different data types and various
flags that modify the behavior of the format-control letters.
- * Output from both `print' and `printf' may be redirected to files,
+ * Output from both 'print' and 'printf' may be redirected to files,
pipes, and coprocesses.
- * `gawk' provides special file names for access to standard input,
+ * 'gawk' provides special file names for access to standard input,
output, and error, and for network communications.
- * Use `close()' to close open file, pipe, and coprocess redirections.
+ * Use 'close()' to close open file, pipe, and coprocess redirections.
For coprocesses, it is possible to close only one direction of the
communications.
-
File: gawk.info, Node: Output Exercises, Prev: Output Summary, Up: Printing
@@ -7246,10 +7208,10 @@ File: gawk.info, Node: Output Exercises, Prev: Output
Summary, Up: Printing
print "----- ------" }
{ print $1, " ", $2 }' inventory-shipped
- from *note Output Separators::, by using a new value of `OFS'.
+ from *note Output Separators::, by using a new value of 'OFS'.
- 2. Use the `printf' statement to line up the headings and table data
- for the `inventory-shipped' example that was covered in *note
+ 2. Use the 'printf' statement to line up the headings and table data
+ for the 'inventory-shipped' example that was covered in *note
Print::.
3. What happens if you forget the double quotes when redirecting
@@ -7257,29 +7219,28 @@ File: gawk.info, Node: Output Exercises, Prev: Output
Summary, Up: Printing
BEGIN { print "Serious error detected!" > /dev/stderr }
-
File: gawk.info, Node: Expressions, Next: Patterns and Actions, Prev:
Printing, Up: Top
6 Expressions
*************
-Expressions are the basic building blocks of `awk' patterns and
-actions. An expression evaluates to a value that you can print, test,
-or pass to a function. Additionally, an expression can assign a new
-value to a variable or a field by using an assignment operator.
+Expressions are the basic building blocks of 'awk' patterns and actions.
+An expression evaluates to a value that you can print, test, or pass to
+a function. Additionally, an expression can assign a new value to a
+variable or a field by using an assignment operator.
An expression can serve as a pattern or action statement on its own.
Most other kinds of statements contain one or more expressions that
specify the data on which to operate. As in other languages,
-expressions in `awk' can include variables, array references,
-constants, and function calls, as well as combinations of these with
-various operators.
+expressions in 'awk' can include variables, array references, constants,
+and function calls, as well as combinations of these with various
+operators.
* Menu:
* Values:: Constants, Variables, and Regular Expressions.
-* All Operators:: `gawk''s operators.
+* All Operators:: 'gawk''s operators.
* Truth Values and Conditions:: Testing for true and false.
* Function Calls:: A function call is an expression.
* Precedence:: How various operators nest.
@@ -7293,7 +7254,7 @@ File: gawk.info, Node: Values, Next: All Operators,
Up: Expressions
=========================================
Expressions are built up from values and the operations performed upon
-them. This minor node describes the elementary objects that provide the
+them. This minor node describes the elementary objects that provide the
values used in expressions.
* Menu:
@@ -7315,8 +7276,8 @@ same value. There are three types of constants: numeric,
string, and
regular expression.
Each is used in the appropriate context when you need a data value
-that isn't going to change. Numeric constants can have different
-forms, but are internally stored in an identical manner.
+that isn't going to change. Numeric constants can have different forms,
+but are internally stored in an identical manner.
* Menu:
@@ -7332,7 +7293,7 @@ File: gawk.info, Node: Scalar Constants, Next:
Nondecimal-numbers, Up: Consta
A "numeric constant" stands for a number. This number can be an
integer, a decimal fraction, or a number in scientific (exponential)
-notation.(1) Here are some examples of numeric constants that all have
+notation.(1) Here are some examples of numeric constants that all have
the same value:
105
@@ -7344,11 +7305,10 @@ double quotation marks. For example:
"parrot"
-represents the string whose contents are `parrot'. Strings in `gawk'
-can be of any length, and they can contain any of the possible
-eight-bit ASCII characters, including ASCII NUL (character code zero).
-Other `awk' implementations may have difficulty with some character
-codes.
+represents the string whose contents are 'parrot'. Strings in 'gawk'
+can be of any length, and they can contain any of the possible eight-bit
+ASCII characters, including ASCII NUL (character code zero). Other
+'awk' implementations may have difficulty with some character codes.
---------- Footnotes ----------
@@ -7363,30 +7323,29 @@ File: gawk.info, Node: Nondecimal-numbers, Next:
Regexp Constants, Prev: Scal
6.1.1.2 Octal and Hexadecimal Numbers
.....................................
-In `awk', all numbers are in decimal (i.e., base 10). Many other
+In 'awk', all numbers are in decimal (i.e., base 10). Many other
programming languages allow you to specify numbers in other bases, often
octal (base 8) and hexadecimal (base 16). In octal, the numbers go 0,
-1, 2, 3, 4, 5, 6, 7, 10, 11, 12, and so on. Just as `11' in decimal is
-1 times 10 plus 1, so `11' in octal is 1 times 8 plus 1. This equals 9
-in decimal. In hexadecimal, there are 16 digits. Because the everyday
-decimal number system only has ten digits (`0'-`9'), the letters `a'
-through `f' are used to represent the rest. (Case in the letters is
-usually irrelevant; hexadecimal `a' and `A' have the same value.)
-Thus, `11' in hexadecimal is 1 times 16 plus 1, which equals 17 in
-decimal.
-
- Just by looking at plain `11', you can't tell what base it's in.
-So, in C, C++, and other languages derived from C, there is a special
-notation to signify the base. Octal numbers start with a leading `0',
-and hexadecimal numbers start with a leading `0x' or `0X':
-
-`11'
+1, 2, 3, 4, 5, 6, 7, 10, 11, 12, and so on. Just as '11' in decimal is
+1 times 10 plus 1, so '11' in octal is 1 times 8 plus 1. This equals 9
+in decimal. In hexadecimal, there are 16 digits. Because the everyday
+decimal number system only has ten digits ('0'-'9'), the letters 'a'
+through 'f' are used to represent the rest. (Case in the letters is
+usually irrelevant; hexadecimal 'a' and 'A' have the same value.) Thus,
+'11' in hexadecimal is 1 times 16 plus 1, which equals 17 in decimal.
+
+ Just by looking at plain '11', you can't tell what base it's in. So,
+in C, C++, and other languages derived from C, there is a special
+notation to signify the base. Octal numbers start with a leading '0',
+and hexadecimal numbers start with a leading '0x' or '0X':
+
+'11'
Decimal value 11
-`011'
+'011'
Octal 11, decimal value 9
-`0x11'
+'0x11'
Hexadecimal 11, decimal value 17
This example shows the difference:
@@ -7394,39 +7353,39 @@ and hexadecimal numbers start with a leading `0x' or
`0X':
$ gawk 'BEGIN { printf "%d, %d, %d\n", 011, 11, 0x11 }'
-| 9, 11, 17
- Being able to use octal and hexadecimal constants in your programs
-is most useful when working with data that cannot be represented
-conveniently as characters or as regular numbers, such as binary data
-of various sorts.
+ Being able to use octal and hexadecimal constants in your programs is
+most useful when working with data that cannot be represented
+conveniently as characters or as regular numbers, such as binary data of
+various sorts.
- `gawk' allows the use of octal and hexadecimal constants in your
+ 'gawk' allows the use of octal and hexadecimal constants in your
program text. However, such numbers in the input data are not treated
differently; doing so by default would break old programs. (If you
-really need to do this, use the `--non-decimal-data' command-line
+really need to do this, use the '--non-decimal-data' command-line
option; *note Nondecimal Data::.) If you have octal or hexadecimal
-data, you can use the `strtonum()' function (*note String Functions::)
+data, you can use the 'strtonum()' function (*note String Functions::)
to convert the data into a number. Most of the time, you will want to
use octal or hexadecimal constants when working with the built-in
bit-manipulation functions; see *note Bitwise Functions::, for more
information.
- Unlike in some early C implementations, `8' and `9' are not valid in
-octal constants. For example, `gawk' treats `018' as decimal 18:
+ Unlike in some early C implementations, '8' and '9' are not valid in
+octal constants. For example, 'gawk' treats '018' as decimal 18:
$ gawk 'BEGIN { print "021 is", 021 ; print 018 }'
-| 021 is 17
-| 18
- Octal and hexadecimal source code constants are a `gawk' extension.
-If `gawk' is in compatibility mode (*note Options::), they are not
+ Octal and hexadecimal source code constants are a 'gawk' extension.
+If 'gawk' is in compatibility mode (*note Options::), they are not
available.
A Constant's Base Does Not Affect Its Value
Once a numeric constant has been converted internally into a number,
-`gawk' no longer remembers what the original form of the constant was;
-the internal value is always used. This has particular consequences
-for conversion of numbers to strings:
+'gawk' no longer remembers what the original form of the constant was;
+the internal value is always used. This has particular consequences for
+conversion of numbers to strings:
$ gawk 'BEGIN { printf "0x11 is <%s>\n", 0x11 }'
-| 0x11 is <17>
@@ -7438,8 +7397,8 @@ File: gawk.info, Node: Regexp Constants, Prev:
Nondecimal-numbers, Up: Consta
....................................
A "regexp constant" is a regular expression description enclosed in
-slashes, such as `/^beginning and end$/'. Most regexps used in `awk'
-programs are constant, but the `~' and `!~' matching operators can also
+slashes, such as '/^beginning and end$/'. Most regexps used in 'awk'
+programs are constant, but the '~' and '!~' matching operators can also
match computed or dynamic regexps (which are typically just ordinary
strings or variables that contain a regexp, but could be more complex
expressions).
@@ -7450,11 +7409,11 @@ File: gawk.info, Node: Using Constant Regexps, Next:
Variables, Prev: Constan
6.1.2 Using Regular Expression Constants
----------------------------------------
-When used on the righthand side of the `~' or `!~' operators, a regexp
+When used on the righthand side of the '~' or '!~' operators, a regexp
constant merely stands for the regexp that is to be matched. However,
-regexp constants (such as `/foo/') may be used like simple expressions.
+regexp constants (such as '/foo/') may be used like simple expressions.
When a regexp constant appears by itself, it has the same meaning as if
-it appeared in a pattern (i.e., `($0 ~ /foo/)'). (d.c.) *Note
+it appeared in a pattern (i.e., '($0 ~ /foo/)'). (d.c.) *Note
Expression Patterns::. This means that the following two code segments:
if ($0 ~ /barfly/ || $0 ~ /camelot/)
@@ -7466,37 +7425,37 @@ and:
print "found"
are exactly equivalent. One rather bizarre consequence of this rule is
-that the following Boolean expression is valid, but does not do what
-its author probably intended:
+that the following Boolean expression is valid, but does not do what its
+author probably intended:
# Note that /foo/ is on the left of the ~
if (/foo/ ~ $1) print "found foo"
-This code is "obviously" testing `$1' for a match against the regexp
-`/foo/'. But in fact, the expression `/foo/ ~ $1' really means `($0 ~
+This code is "obviously" testing '$1' for a match against the regexp
+'/foo/'. But in fact, the expression '/foo/ ~ $1' really means '($0 ~
/foo/) ~ $1'. In other words, first match the input record against the
-regexp `/foo/'. The result is either zero or one, depending upon the
+regexp '/foo/'. The result is either zero or one, depending upon the
success or failure of the match. That result is then matched against
the first field in the record. Because it is unlikely that you would
-ever really want to make this kind of test, `gawk' issues a warning
-when it sees this construct in a program. Another consequence of this
-rule is that the assignment statement:
+ever really want to make this kind of test, 'gawk' issues a warning when
+it sees this construct in a program. Another consequence of this rule
+is that the assignment statement:
matches = /foo/
-assigns either zero or one to the variable `matches', depending upon
-the contents of the current input record.
+assigns either zero or one to the variable 'matches', depending upon the
+contents of the current input record.
Constant regular expressions are also used as the first argument for
-the `gensub()', `sub()', and `gsub()' functions, as the second argument
-of the `match()' function, and as the third argument of the `split()'
-and `patsplit()' functions (*note String Functions::). Modern
-implementations of `awk', including `gawk', allow the third argument of
-`split()' to be a regexp constant, but some older implementations do
-not. (d.c.) Because some built-in functions accept regexp constants
-as arguments, confusion can arise when attempting to use regexp
-constants as arguments to user-defined functions (*note
-User-defined::). For example:
+the 'gensub()', 'sub()', and 'gsub()' functions, as the second argument
+of the 'match()' function, and as the third argument of the 'split()'
+and 'patsplit()' functions (*note String Functions::). Modern
+implementations of 'awk', including 'gawk', allow the third argument of
+'split()' to be a regexp constant, but some older implementations do
+not. (d.c.) Because some built-in functions accept regexp constants as
+arguments, confusion can arise when attempting to use regexp constants
+as arguments to user-defined functions (*note User-defined::). For
+example:
function mysub(pat, repl, str, global)
{
@@ -7515,13 +7474,13 @@ User-defined::). For example:
}
In this example, the programmer wants to pass a regexp constant to
-the user-defined function `mysub()', which in turn passes it on to
-either `sub()' or `gsub()'. However, what really happens is that the
-`pat' parameter is assigned a value of either one or zero, depending
-upon whether or not `$0' matches `/hi/'. `gawk' issues a warning when
+the user-defined function 'mysub()', which in turn passes it on to
+either 'sub()' or 'gsub()'. However, what really happens is that the
+'pat' parameter is assigned a value of either one or zero, depending
+upon whether or not '$0' matches '/hi/'. 'gawk' issues a warning when
it sees a regexp constant used as a parameter to a user-defined
-function, because passing a truth value in this way is probably not
-what was intended.
+function, because passing a truth value in this way is probably not what
+was intended.
File: gawk.info, Node: Variables, Next: Conversion, Prev: Using Constant
Regexps, Up: Values
@@ -7532,7 +7491,7 @@ File: gawk.info, Node: Variables, Next: Conversion,
Prev: Using Constant Rege
"Variables" are ways of storing values at one point in your program for
use later in another part of your program. They can be manipulated
entirely within the program text, and they can also be assigned values
-on the `awk' command line.
+on the 'awk' command line.
* Menu:
@@ -7548,35 +7507,35 @@ File: gawk.info, Node: Using Variables, Next:
Assignment Options, Up: Variabl
....................................
Variables let you give names to values and refer to them later.
-Variables have already been used in many of the examples. The name of
-a variable must be a sequence of letters, digits, or underscores, and
-it may not begin with a digit. Here, a "letter" is any one of the 52
+Variables have already been used in many of the examples. The name of a
+variable must be a sequence of letters, digits, or underscores, and it
+may not begin with a digit. Here, a "letter" is any one of the 52
upper- and lowercase English letters. Other characters that may be
defined as letters in non-English locales are not valid in variable
-names. Case is significant in variable names; `a' and `A' are distinct
+names. Case is significant in variable names; 'a' and 'A' are distinct
variables.
A variable name is a valid expression by itself; it represents the
variable's current value. Variables are given new values with
"assignment operators", "increment operators", and "decrement operators"
-(*note Assignment Ops::). In addition, the `sub()' and `gsub()'
-functions can change a variable's value, and the `match()', `split()',
-and `patsplit()' functions can change the contents of their array
+(*note Assignment Ops::). In addition, the 'sub()' and 'gsub()'
+functions can change a variable's value, and the 'match()', 'split()',
+and 'patsplit()' functions can change the contents of their array
parameters (*note String Functions::).
- A few variables have special built-in meanings, such as `FS' (the
-field separator) and `NF' (the number of fields in the current input
+ A few variables have special built-in meanings, such as 'FS' (the
+field separator) and 'NF' (the number of fields in the current input
record). *Note Built-in Variables::, for a list of the predefined
variables. These predefined variables can be used and assigned just
like all other variables, but their values are also used or changed
-automatically by `awk'. All predefined variables' names are entirely
+automatically by 'awk'. All predefined variables' names are entirely
uppercase.
- Variables in `awk' can be assigned either numeric or string values.
+ Variables in 'awk' can be assigned either numeric or string values.
The kind of value a variable holds can change over the life of a
program. By default, variables are initialized to the empty string,
which is zero if converted to a number. There is no need to explicitly
-initialize a variable in `awk', which is what you would do in C and in
+initialize a variable in 'awk', which is what you would do in C and in
most other traditional languages.
@@ -7585,34 +7544,34 @@ File: gawk.info, Node: Assignment Options, Prev:
Using Variables, Up: Variabl
6.1.3.2 Assigning Variables on the Command Line
...............................................
-Any `awk' variable can be set by including a "variable assignment"
-among the arguments on the command line when `awk' is invoked (*note
-Other Arguments::). Such an assignment has the following form:
+Any 'awk' variable can be set by including a "variable assignment" among
+the arguments on the command line when 'awk' is invoked (*note Other
+Arguments::). Such an assignment has the following form:
VARIABLE=TEXT
-With it, a variable is set either at the beginning of the `awk' run or
-in between input files. When the assignment is preceded with the `-v'
+With it, a variable is set either at the beginning of the 'awk' run or
+in between input files. When the assignment is preceded with the '-v'
option, as in the following:
-v VARIABLE=TEXT
-the variable is set at the very beginning, even before the `BEGIN'
-rules execute. The `-v' option and its assignment must precede all the
-file name arguments, as well as the program text. (*Note Options::,
-for more information about the `-v' option.) Otherwise, the variable
-assignment is performed at a time determined by its position among the
-input file arguments--after the processing of the preceding input file
-argument. For example:
+the variable is set at the very beginning, even before the 'BEGIN' rules
+execute. The '-v' option and its assignment must precede all the file
+name arguments, as well as the program text. (*Note Options::, for more
+information about the '-v' option.) Otherwise, the variable assignment
+is performed at a time determined by its position among the input file
+arguments--after the processing of the preceding input file argument.
+For example:
awk '{ print $n }' n=4 inventory-shipped n=2 mail-list
-prints the value of field number `n' for all input records. Before the
-first file is read, the command line sets the variable `n' equal to
+prints the value of field number 'n' for all input records. Before the
+first file is read, the command line sets the variable 'n' equal to
four. This causes the fourth field to be printed in lines from
-`inventory-shipped'. After the first file has finished, but before the
-second file is started, `n' is set to two, so that the second field is
-printed in lines from `mail-list':
+'inventory-shipped'. After the first file has finished, but before the
+second file is started, 'n' is set to two, so that the second field is
+printed in lines from 'mail-list':
$ awk '{ print $n }' n=4 inventory-shipped n=2 mail-list
-| 15
@@ -7623,7 +7582,7 @@ printed in lines from `mail-list':
...
Command-line arguments are made available for explicit examination by
-the `awk' program in the `ARGV' array (*note ARGC and ARGV::). `awk'
+the 'awk' program in the 'ARGV' array (*note ARGC and ARGV::). 'awk'
processes the values of command-line assignments for escape sequences
(*note Escape Sequences::). (d.c.)
@@ -7635,23 +7594,23 @@ File: gawk.info, Node: Conversion, Prev: Variables,
Up: Values
Number-to-string and string-to-number conversion are generally
straightforward. There can be subtleties to be aware of; this minor
-node discusses this important facet of `awk'.
+node discusses this important facet of 'awk'.
* Menu:
-* Strings And Numbers:: How `awk' Converts Between Strings And
+* Strings And Numbers:: How 'awk' Converts Between Strings And
Numbers.
* Locale influences conversions:: How the locale may affect conversions.
File: gawk.info, Node: Strings And Numbers, Next: Locale influences
conversions, Up: Conversion
-6.1.4.1 How `awk' Converts Between Strings and Numbers
+6.1.4.1 How 'awk' Converts Between Strings and Numbers
......................................................
Strings are converted to numbers and numbers are converted to strings,
-if the context of the `awk' program demands it. For example, if the
-value of either `foo' or `bar' in the expression `foo + bar' happens to
+if the context of the 'awk' program demands it. For example, if the
+value of either 'foo' or 'bar' in the expression 'foo + bar' happens to
be a string, it is converted to a number before the addition is
performed. If numeric values appear in string concatenation, they are
converted to strings. Consider the following:
@@ -7659,60 +7618,59 @@ converted to strings. Consider the following:
two = 2; three = 3
print (two three) + 4
-This prints the (numeric) value 27. The numeric values of the
-variables `two' and `three' are converted to strings and concatenated
-together. The resulting string is converted back to the number 23, to
-which 4 is then added.
+This prints the (numeric) value 27. The numeric values of the variables
+'two' and 'three' are converted to strings and concatenated together.
+The resulting string is converted back to the number 23, to which 4 is
+then added.
If, for some reason, you need to force a number to be converted to a
-string, concatenate that number with the empty string, `""'. To force
-a string to be converted to a number, add zero to that string. A
-string is converted to a number by interpreting any numeric prefix of
-the string as numerals: `"2.5"' converts to 2.5, `"1e3"' converts to
-1,000, and `"25fix"' has a numeric value of 25. Strings that can't be
+string, concatenate that number with the empty string, '""'. To force a
+string to be converted to a number, add zero to that string. A string
+is converted to a number by interpreting any numeric prefix of the
+string as numerals: '"2.5"' converts to 2.5, '"1e3"' converts to 1,000,
+and '"25fix"' has a numeric value of 25. Strings that can't be
interpreted as valid numbers convert to zero.
The exact manner in which numbers are converted into strings is
-controlled by the `awk' predefined variable `CONVFMT' (*note Built-in
-Variables::). Numbers are converted using the `sprintf()' function
-with `CONVFMT' as the format specifier (*note String Functions::).
+controlled by the 'awk' predefined variable 'CONVFMT' (*note Built-in
+Variables::). Numbers are converted using the 'sprintf()' function with
+'CONVFMT' as the format specifier (*note String Functions::).
- `CONVFMT''s default value is `"%.6g"', which creates a value with at
+ 'CONVFMT''s default value is '"%.6g"', which creates a value with at
most six significant digits. For some applications, you might want to
-change it to specify more precision. On most modern machines, 17
-digits is usually enough to capture a floating-point number's value
-exactly.(1)
+change it to specify more precision. On most modern machines, 17 digits
+is usually enough to capture a floating-point number's value exactly.(1)
- Strange results can occur if you set `CONVFMT' to a string that
-doesn't tell `sprintf()' how to format floating-point numbers in a
-useful way. For example, if you forget the `%' in the format, `awk'
+ Strange results can occur if you set 'CONVFMT' to a string that
+doesn't tell 'sprintf()' how to format floating-point numbers in a
+useful way. For example, if you forget the '%' in the format, 'awk'
converts all numbers to the same constant string.
As a special case, if a number is an integer, then the result of
converting it to a string is _always_ an integer, no matter what the
-value of `CONVFMT' may be. Given the following code fragment:
+value of 'CONVFMT' may be. Given the following code fragment:
CONVFMT = "%2.2f"
a = 12
b = a ""
-`b' has the value `"12"', not `"12.00"'. (d.c.)
+'b' has the value '"12"', not '"12.00"'. (d.c.)
- Pre-POSIX `awk' Used `OFMT' for String Conversion
+ Pre-POSIX 'awk' Used 'OFMT' for String Conversion
- Prior to the POSIX standard, `awk' used the value of `OFMT' for
-converting numbers to strings. `OFMT' specifies the output format to
-use when printing numbers with `print'. `CONVFMT' was introduced in
+ Prior to the POSIX standard, 'awk' used the value of 'OFMT' for
+converting numbers to strings. 'OFMT' specifies the output format to
+use when printing numbers with 'print'. 'CONVFMT' was introduced in
order to separate the semantics of conversion from the semantics of
-printing. Both `CONVFMT' and `OFMT' have the same default value:
-`"%.6g"'. In the vast majority of cases, old `awk' programs do not
+printing. Both 'CONVFMT' and 'OFMT' have the same default value:
+'"%.6g"'. In the vast majority of cases, old 'awk' programs do not
change their behavior. *Note Print::, for more information on the
-`print' statement.
+'print' statement.
---------- Footnotes ----------
- (1) Pathological cases can require up to 752 digits (!), but we
-doubt that you need to worry about this.
+ (1) Pathological cases can require up to 752 digits (!), but we doubt
+that you need to worry about this.
File: gawk.info, Node: Locale influences conversions, Prev: Strings And
Numbers, Up: Conversion
@@ -7721,22 +7679,22 @@ File: gawk.info, Node: Locale influences conversions,
Prev: Strings And Number
........................................
Where you are can matter when it comes to converting between numbers and
-strings. The local character set and language--the "locale"--can
-affect numeric formats. In particular, for `awk' programs, it affects
-the decimal point character and the thousands-separator character. The
-`"C"' locale, and most English-language locales, use the period
-character (`.') as the decimal point and don't have a thousands
-separator. However, many (if not most) European and non-English
-locales use the comma (`,') as the decimal point character. European
-locales often use either a space or a period as the thousands
-separator, if they have one.
-
- The POSIX standard says that `awk' always uses the period as the
-decimal point when reading the `awk' program source code, and for
+strings. The local character set and language--the "locale"--can affect
+numeric formats. In particular, for 'awk' programs, it affects the
+decimal point character and the thousands-separator character. The
+'"C"' locale, and most English-language locales, use the period
+character ('.') as the decimal point and don't have a thousands
+separator. However, many (if not most) European and non-English locales
+use the comma (',') as the decimal point character. European locales
+often use either a space or a period as the thousands separator, if they
+have one.
+
+ The POSIX standard says that 'awk' always uses the period as the
+decimal point when reading the 'awk' program source code, and for
command-line variable assignments (*note Other Arguments::). However,
-when interpreting input data, for `print' and `printf' output, and for
+when interpreting input data, for 'print' and 'printf' output, and for
number-to-string conversion, the local decimal point character is used.
-(d.c.) In all cases, numbers in source code and in input data cannot
+(d.c.) In all cases, numbers in source code and in input data cannot
have a thousands separator. Here are some examples indicating the
difference in behavior, on a GNU/Linux system:
@@ -7750,37 +7708,38 @@ difference in behavior, on a GNU/Linux system:
$ echo 4,321 | LC_ALL=en_DK.utf-8 gawk '{ print $1 + 1 }'
-| 5,321
-The `en_DK.utf-8' locale is for English in Denmark, where the comma
-acts as the decimal point separator. In the normal `"C"' locale, `gawk'
-treats `4,321' as 4, while in the Danish locale, it's treated as the
+The 'en_DK.utf-8' locale is for English in Denmark, where the comma acts
+as the decimal point separator. In the normal '"C"' locale, 'gawk'
+treats '4,321' as 4, while in the Danish locale, it's treated as the
full number including the fractional part, 4.321.
- Some earlier versions of `gawk' fully complied with this aspect of
+ Some earlier versions of 'gawk' fully complied with this aspect of
the standard. However, many users in non-English locales complained
about this behavior, because their data used a period as the decimal
point, so the default behavior was restored to use a period as the
-decimal point character. You can use the `--use-lc-numeric' option
-(*note Options::) to force `gawk' to use the locale's decimal point
-character. (`gawk' also uses the locale's decimal point character when
-in POSIX mode, either via `--posix' or the `POSIXLY_CORRECT'
-environment variable, as shown previously.)
-
- *note table-locale-affects:: describes the cases in which the
-locale's decimal point character is used and when a period is used.
+decimal point character. You can use the '--use-lc-numeric' option
+(*note Options::) to force 'gawk' to use the locale's decimal point
+character. ('gawk' also uses the locale's decimal point character when
+in POSIX mode, either via '--posix' or the 'POSIXLY_CORRECT' environment
+variable, as shown previously.)
+
+ *note Table 6.1: table-locale-affects. describes the cases in which
+the locale's decimal point character is used and when a period is used.
Some of these features have not been described yet.
-Feature Default `--posix' or `--use-lc-numeric'
-------------------------------------------------------------
-`%'g' Use locale Use locale
-`%g' Use period Use locale
+Feature Default '--posix' or
+ '--use-lc-numeric'
+------------------------------------------------------------
+'%'g' Use locale Use locale
+'%g' Use period Use locale
Input Use period Use locale
-`strtonum()'Use period Use locale
+'strtonum()'Use period Use locale
Table 6.1: Locale decimal point versus a period
Finally, modern-day formal standards and the IEEE standard
floating-point representation can have an unusual but important effect
-on the way `gawk' converts some special string values to numbers. The
+on the way 'gawk' converts some special string values to numbers. The
details are presented in *note POSIX Floating Point Problems::.
@@ -7794,7 +7753,7 @@ provided by constants and variables.
* Menu:
-* Arithmetic Ops:: Arithmetic operations (`+', `-',
+* Arithmetic Ops:: Arithmetic operations ('+', '-',
etc.)
* Concatenation:: Concatenating strings.
* Assignment Ops:: Changing the value of a variable or a field.
@@ -7806,11 +7765,11 @@ File: gawk.info, Node: Arithmetic Ops, Next:
Concatenation, Up: All Operators
6.2.1 Arithmetic Operators
--------------------------
-The `awk' language uses the common arithmetic operators when evaluating
-expressions. All of these arithmetic operators follow normal
-precedence rules and work as you would expect them to.
+The 'awk' language uses the common arithmetic operators when evaluating
+expressions. All of these arithmetic operators follow normal precedence
+rules and work as you would expect them to.
- The following example uses a file named `grades', which contains a
+ The following example uses a file named 'grades', which contains a
list of student names as well as three test scores per student (it's a
small class):
@@ -7818,7 +7777,7 @@ small class):
Sandy 84 72 93
Chris 72 92 89
-This program takes the file `grades' and prints the average of the
+This program takes the file 'grades' and prints the average of the
scores:
$ awk '{ sum = $2 + $3 + $4 ; avg = sum / 3
@@ -7827,62 +7786,62 @@ scores:
-| Sandy 83
-| Chris 84.3333
- The following list provides the arithmetic operators in `awk', in
+ The following list provides the arithmetic operators in 'awk', in
order from the highest precedence to the lowest:
-`X ^ Y'
-`X ** Y'
- Exponentiation; X raised to the Y power. `2 ^ 3' has the value
- eight; the character sequence `**' is equivalent to `^'. (c.e.)
+'X ^ Y'
+'X ** Y'
+ Exponentiation; X raised to the Y power. '2 ^ 3' has the value
+ eight; the character sequence '**' is equivalent to '^'. (c.e.)
-`- X'
+'- X'
Negation.
-`+ X'
+'+ X'
Unary plus; the expression is converted to a number.
-`X * Y'
+'X * Y'
Multiplication.
-`X / Y'
- Division; because all numbers in `awk' are floating-point
- numbers, the result is _not_ rounded to an integer--`3 / 4' has
- the value 0.75. (It is a common mistake, especially for C
- programmers, to forget that _all_ numbers in `awk' are floating
- point, and that division of integer-looking constants produces a
- real number, not an integer.)
+'X / Y'
+ Division; because all numbers in 'awk' are floating-point numbers,
+ the result is _not_ rounded to an integer--'3 / 4' has the value
+ 0.75. (It is a common mistake, especially for C programmers, to
+ forget that _all_ numbers in 'awk' are floating point, and that
+ division of integer-looking constants produces a real number, not
+ an integer.)
-`X % Y'
+'X % Y'
Remainder; further discussion is provided in the text, just after
this list.
-`X + Y'
+'X + Y'
Addition.
-`X - Y'
+'X - Y'
Subtraction.
Unary plus and minus have the same precedence, the multiplication
operators all have the same precedence, and addition and subtraction
have the same precedence.
- When computing the remainder of `X % Y', the quotient is rounded
-toward zero to an integer and multiplied by Y. This result is
+ When computing the remainder of 'X % Y', the quotient is rounded
+toward zero to an integer and multiplied by Y. This result is
subtracted from X; this operation is sometimes known as "trunc-mod."
The following relation always holds:
b * int(a / b) + (a % b) == a
One possibly undesirable effect of this definition of remainder is
-that `X % Y' is negative if X is negative. Thus:
+that 'X % Y' is negative if X is negative. Thus:
-17 % 8 = -1
- In other `awk' implementations, the signedness of the remainder may
+ In other 'awk' implementations, the signedness of the remainder may
be machine-dependent.
- NOTE: The POSIX standard only specifies the use of `^' for
- exponentiation. For maximum portability, do not use the `**'
+ NOTE: The POSIX standard only specifies the use of '^' for
+ exponentiation. For maximum portability, do not use the '**'
operator.
@@ -7891,7 +7850,8 @@ File: gawk.info, Node: Concatenation, Next: Assignment
Ops, Prev: Arithmetic
6.2.2 String Concatenation
--------------------------
- It seemed like a good idea at the time. -- Brian Kernighan
+ It seemed like a good idea at the time.
+ -- _Brian Kernighan_
There is only one string operation: concatenation. It does not have
a specific operator to represent it. Instead, concatenation is
@@ -7903,8 +7863,8 @@ For example:
-| Field number one: Anthony
...
- Without the space in the string constant after the `:', the line
-runs together. For example:
+ Without the space in the string constant after the ':', the line runs
+together. For example:
$ awk '{ print "Field number one:" $1 }' mail-list
-| Field number one:Amelia
@@ -7913,34 +7873,32 @@ runs together. For example:
Because string concatenation does not have an explicit operator, it
is often necessary to ensure that it happens at the right time by using
-parentheses to enclose the items to concatenate. For example, you
-might expect that the following code fragment concatenates `file' and
-`name':
+parentheses to enclose the items to concatenate. For example, you might
+expect that the following code fragment concatenates 'file' and 'name':
file = "file"
name = "name"
print "something meaningful" > file name
-This produces a syntax error with some versions of Unix `awk'.(1) It is
+This produces a syntax error with some versions of Unix 'awk'.(1) It is
necessary to use the following:
print "something meaningful" > (file name)
Parentheses should be used around concatenation in all but the most
-common contexts, such as on the righthand side of `='. Be careful
-about the kinds of expressions used in string concatenation. In
-particular, the order of evaluation of expressions used for
-concatenation is undefined in the `awk' language. Consider this
-example:
+common contexts, such as on the righthand side of '='. Be careful about
+the kinds of expressions used in string concatenation. In particular,
+the order of evaluation of expressions used for concatenation is
+undefined in the 'awk' language. Consider this example:
BEGIN {
a = "don't"
print (a " " (a = "panic"))
}
-It is not defined whether the second assignment to `a' happens before
-or after the value of `a' is retrieved for producing the concatenated
-value. The result could be either `don't panic', or `panic panic'.
+It is not defined whether the second assignment to 'a' happens before or
+after the value of 'a' is retrieved for producing the concatenated
+value. The result could be either 'don't panic', or 'panic panic'.
The precedence of concatenation, when mixed with other operators, is
often counter-intuitive. Consider this example:
@@ -7950,27 +7908,26 @@ often counter-intuitive. Consider this example:
This "obviously" is concatenating -12, a space, and -24. But where
did the space disappear to? The answer lies in the combination of
-operator precedences and `awk''s automatic conversion rules. To get
-the desired result, write the program this way:
+operator precedences and 'awk''s automatic conversion rules. To get the
+desired result, write the program this way:
$ awk 'BEGIN { print -12 " " (-24) }'
-| -12 -24
- This forces `awk' to treat the `-' on the `-24' as unary.
-Otherwise, it's parsed as follows:
+ This forces 'awk' to treat the '-' on the '-24' as unary. Otherwise,
+it's parsed as follows:
- -12 (`" "' - 24)
+ -12 ('" "' - 24)
=> -12 (0 - 24)
=> -12 (-24)
=> -12-24
- As mentioned earlier, when mixing concatenation with other
-operators, _parenthesize_. Otherwise, you're never quite sure what
-you'll get.
+ As mentioned earlier, when mixing concatenation with other operators,
+_parenthesize_. Otherwise, you're never quite sure what you'll get.
---------- Footnotes ----------
- (1) It happens that BWK `awk', `gawk', and `mawk' all "get it right,"
+ (1) It happens that BWK 'awk', 'gawk', and 'mawk' all "get it right,"
but you should not rely on this.
@@ -7979,24 +7936,23 @@ File: gawk.info, Node: Assignment Ops, Next:
Increment Ops, Prev: Concatenati
6.2.3 Assignment Expressions
----------------------------
-An "assignment" is an expression that stores a (usually different)
-value into a variable. For example, let's assign the value one to the
-variable `z':
+An "assignment" is an expression that stores a (usually different) value
+into a variable. For example, let's assign the value one to the
+variable 'z':
z = 1
- After this expression is executed, the variable `z' has the value
-one. Whatever old value `z' had before the assignment is forgotten.
+ After this expression is executed, the variable 'z' has the value
+one. Whatever old value 'z' had before the assignment is forgotten.
- Assignments can also store string values. For example, the
-following stores the value `"this food is good"' in the variable
-`message':
+ Assignments can also store string values. For example, the following
+stores the value '"this food is good"' in the variable 'message':
thing = "food"
predicate = "good"
message = "this " thing " is " predicate
-This also illustrates string concatenation. The `=' sign is called an
+This also illustrates string concatenation. The '=' sign is called an
"assignment operator". It is the simplest assignment operator because
the value of the righthand operand is stored unchanged. Most operators
(addition, concatenation, and so on) have no effect except to compute a
@@ -8011,11 +7967,11 @@ array element (*note Arrays::). These are all called
"lvalues", which
means they can appear on the lefthand side of an assignment operator.
The righthand operand may be any expression; it produces the new value
that the assignment stores in the specified variable, field, or array
-element. (Such values are called "rvalues".)
+element. (Such values are called "rvalues".)
It is important to note that variables do _not_ have permanent types.
A variable's type is simply the type of whatever value was last assigned
-to it. In the following program fragment, the variable `foo' has a
+to it. In the following program fragment, the variable 'foo' has a
numeric value at first, and a string value later on:
foo = 1
@@ -8023,43 +7979,43 @@ numeric value at first, and a string value later on:
foo = "bar"
print foo
-When the second assignment gives `foo' a string value, the fact that it
+When the second assignment gives 'foo' a string value, the fact that it
previously had a numeric value is forgotten.
String values that do not begin with a digit have a numeric value of
-zero. After executing the following code, the value of `foo' is five:
+zero. After executing the following code, the value of 'foo' is five:
foo = "a string"
foo = foo + 5
NOTE: Using a variable as a number and then later as a string can
be confusing and is poor programming style. The previous two
- examples illustrate how `awk' works, _not_ how you should write
+ examples illustrate how 'awk' works, _not_ how you should write
your programs!
An assignment is an expression, so it has a value--the same value
-that is assigned. Thus, `z = 1' is an expression with the value one.
+that is assigned. Thus, 'z = 1' is an expression with the value one.
One consequence of this is that you can write multiple assignments
together, such as:
x = y = z = 5
-This example stores the value five in all three variables (`x', `y',
-and `z'). It does so because the value of `z = 5', which is five, is
-stored into `y' and then the value of `y = z = 5', which is five, is
-stored into `x'.
+This example stores the value five in all three variables ('x', 'y', and
+'z'). It does so because the value of 'z = 5', which is five, is stored
+into 'y' and then the value of 'y = z = 5', which is five, is stored
+into 'x'.
Assignments may be used anywhere an expression is called for. For
-example, it is valid to write `x != (y = 1)' to set `y' to one, and
-then test whether `x' equals one. But this style tends to make
-programs hard to read; such nesting of assignments should be avoided,
-except perhaps in a one-shot program.
+example, it is valid to write 'x != (y = 1)' to set 'y' to one, and then
+test whether 'x' equals one. But this style tends to make programs hard
+to read; such nesting of assignments should be avoided, except perhaps
+in a one-shot program.
- Aside from `=', there are several other assignment operators that do
+ Aside from '=', there are several other assignment operators that do
arithmetic with the old value of the variable. For example, the
-operator `+=' computes a new value by adding the righthand value to the
+operator '+=' computes a new value by adding the righthand value to the
old value of the variable. Thus, the following assignment adds five to
-the value of `foo':
+the value of 'foo':
foo += 5
@@ -8069,9 +8025,9 @@ This is equivalent to the following:
Use whichever makes the meaning of your program clearer.
- There are situations where using `+=' (or any assignment operator)
-is _not_ the same as simply repeating the lefthand operand in the
-righthand expression. For example:
+ There are situations where using '+=' (or any assignment operator) is
+_not_ the same as simply repeating the lefthand operand in the righthand
+expression. For example:
# Thanks to Pat Rankin for this example
BEGIN {
@@ -8084,9 +8040,9 @@ righthand expression. For example:
print x, bar[x]
}
-The indices of `bar' are practically guaranteed to be different, because
-`rand()' returns different values each time it is called. (Arrays and
-the `rand()' function haven't been covered yet. *Note Arrays::, and
+The indices of 'bar' are practically guaranteed to be different, because
+'rand()' returns different values each time it is called. (Arrays and
+the 'rand()' function haven't been covered yet. *Note Arrays::, and
*note Numeric Functions::, for more information.) This example
illustrates an important fact about assignment operators: the lefthand
expression is only evaluated _once_.
@@ -8097,45 +8053,47 @@ first, the lefthand or the righthand. Consider this
example:
i = 1
a[i += 2] = i + 1
-The value of `a[3]' could be either two or four.
+The value of 'a[3]' could be either two or four.
- *note table-assign-ops:: lists the arithmetic assignment operators.
-In each case, the righthand operand is an expression whose value is
-converted to a number.
+ *note Table 6.2: table-assign-ops. lists the arithmetic assignment
+operators. In each case, the righthand operand is an expression whose
+value is converted to a number.
Operator Effect
---------------------------------------------------------------------------
-LVALUE `+=' INCREMENT Add INCREMENT to the value of LVALUE.
-LVALUE `-=' DECREMENT Subtract DECREMENT from the value of LVALUE.
-LVALUE `*=' Multiply the value of LVALUE by COEFFICIENT.
-COEFFICIENT
-LVALUE `/=' DIVISOR Divide the value of LVALUE by DIVISOR.
-LVALUE `%=' MODULUS Set LVALUE to its remainder by MODULUS.
-LVALUE `^=' POWER Raise LVALUE to the power POWER.
-LVALUE `**=' POWER Raise LVALUE to the power POWER. (c.e.)
+--------------------------------------------------------------------------
+LVALUE '+=' Add INCREMENT to the value of LVALUE.
+INCREMENT
+LVALUE '-=' Subtract DECREMENT from the value of LVALUE.
+DECREMENT
+LVALUE '*=' Multiply the value of LVALUE by COEFFICIENT.
+COEFFICIENT
+LVALUE '/=' DIVISOR Divide the value of LVALUE by DIVISOR.
+LVALUE '%=' MODULUS Set LVALUE to its remainder by MODULUS.
+LVALUE '^=' POWER Raise LVALUE to the power POWER.
+LVALUE '**=' POWER Raise LVALUE to the power POWER. (c.e.)
Table 6.2: Arithmetic assignment operators
- NOTE: Only the `^=' operator is specified by POSIX. For maximum
- portability, do not use the `**=' operator.
+ NOTE: Only the '^=' operator is specified by POSIX. For maximum
+ portability, do not use the '**=' operator.
- Syntactic Ambiguities Between `/=' and Regular Expressions
+ Syntactic Ambiguities Between '/=' and Regular Expressions
- There is a syntactic ambiguity between the `/=' assignment operator
-and regexp constants whose first character is an `='. (d.c.) This is
-most notable in some commercial `awk' versions. For example:
+ There is a syntactic ambiguity between the '/=' assignment operator
+and regexp constants whose first character is an '='. (d.c.) This is
+most notable in some commercial 'awk' versions. For example:
$ awk /==/ /dev/null
- error--> awk: syntax error at source line 1
- error--> context is
- error--> >>> /= <<<
- error--> awk: bailing out at source line 1
+ error-> awk: syntax error at source line 1
+ error-> context is
+ error-> >>> /= <<<
+ error-> awk: bailing out at source line 1
A workaround is:
awk '/[=]=/' /dev/null
- `gawk' does not have this problem; BWK `awk' and `mawk' also do not.
+ 'gawk' does not have this problem; BWK 'awk' and 'mawk' also do not.
File: gawk.info, Node: Increment Ops, Prev: Assignment Ops, Up: All
Operators
@@ -8144,61 +8102,62 @@ File: gawk.info, Node: Increment Ops, Prev:
Assignment Ops, Up: All Operators
---------------------------------------
"Increment" and "decrement operators" increase or decrease the value of
-a variable by one. An assignment operator can do the same thing, so
-the increment operators add no power to the `awk' language; however,
-they are convenient abbreviations for very common operations.
+a variable by one. An assignment operator can do the same thing, so the
+increment operators add no power to the 'awk' language; however, they
+are convenient abbreviations for very common operations.
- The operator used for adding one is written `++'. It can be used to
+ The operator used for adding one is written '++'. It can be used to
increment a variable either before or after taking its value. To
-"pre-increment" a variable `v', write `++v'. This adds one to the
-value of `v'--that new value is also the value of the expression. (The
-assignment expression `v += 1' is completely equivalent.) Writing the
-`++' after the variable specifies "post-increment". This increments
-the variable value just the same; the difference is that the value of
-the increment expression itself is the variable's _old_ value. Thus,
-if `foo' has the value four, then the expression `foo++' has the value
-four, but it changes the value of `foo' to five. In other words, the
-operator returns the old value of the variable, but with the side
-effect of incrementing it.
-
- The post-increment `foo++' is nearly the same as writing `(foo += 1)
-- 1'. It is not perfectly equivalent because all numbers in `awk' are
-floating point--in floating point, `foo + 1 - 1' does not necessarily
-equal `foo'. But the difference is minute as long as you stick to
+"pre-increment" a variable 'v', write '++v'. This adds one to the value
+of 'v'--that new value is also the value of the expression. (The
+assignment expression 'v += 1' is completely equivalent.) Writing the
+'++' after the variable specifies "post-increment". This increments the
+variable value just the same; the difference is that the value of the
+increment expression itself is the variable's _old_ value. Thus, if
+'foo' has the value four, then the expression 'foo++' has the value
+four, but it changes the value of 'foo' to five. In other words, the
+operator returns the old value of the variable, but with the side effect
+of incrementing it.
+
+ The post-increment 'foo++' is nearly the same as writing '(foo += 1)
+- 1'. It is not perfectly equivalent because all numbers in 'awk' are
+floating point--in floating point, 'foo + 1 - 1' does not necessarily
+equal 'foo'. But the difference is minute as long as you stick to
numbers that are fairly small (less than 10e12).
Fields and array elements are incremented just like variables. (Use
-`$(i++)' when you want to do a field reference and a variable increment
+'$(i++)' when you want to do a field reference and a variable increment
at the same time. The parentheses are necessary because of the
-precedence of the field reference operator `$'.)
+precedence of the field reference operator '$'.)
- The decrement operator `--' works just like `++', except that it
-subtracts one instead of adding it. As with `++', it can be used before
-the lvalue to pre-decrement or after it to post-decrement. Following
-is a summary of increment and decrement expressions:
+ The decrement operator '--' works just like '++', except that it
+subtracts one instead of adding it. As with '++', it can be used before
+the lvalue to pre-decrement or after it to post-decrement. Following is
+a summary of increment and decrement expressions:
-`++LVALUE'
+'++LVALUE'
Increment LVALUE, returning the new value as the value of the
expression.
-`LVALUE++'
+'LVALUE++'
Increment LVALUE, returning the _old_ value of LVALUE as the value
of the expression.
-`--LVALUE'
+'--LVALUE'
Decrement LVALUE, returning the new value as the value of the
- expression. (This expression is like `++LVALUE', but instead of
+ expression. (This expression is like '++LVALUE', but instead of
adding, it subtracts.)
-`LVALUE--'
+'LVALUE--'
Decrement LVALUE, returning the _old_ value of LVALUE as the value
- of the expression. (This expression is like `LVALUE++', but
+ of the expression. (This expression is like 'LVALUE++', but
instead of adding, it subtracts.)
Operator Evaluation Order
Doctor, it hurts when I do this!
- Then don't do that! -- Groucho Marx
+ Then don't do that!
+ -- _Groucho Marx_
What happens for something like the following?
@@ -8212,10 +8171,10 @@ Or something even stranger?
print b
In other words, when do the various side effects prescribed by the
-postfix operators (`b++') take effect? When side effects happen is
+postfix operators ('b++') take effect? When side effects happen is
"implementation-defined". In other words, it is up to the particular
-version of `awk'. The result for the first example may be 12 or 13,
-and for the second, it may be 22 or 23.
+version of 'awk'. The result for the first example may be 12 or 13, and
+for the second, it may be 22 or 23.
In short, doing things like this is not recommended and definitely
not anything that you can rely upon for portability. You should avoid
@@ -8228,19 +8187,19 @@ File: gawk.info, Node: Truth Values and Conditions,
Next: Function Calls, Pre
===============================
In certain contexts, expression values also serve as "truth values";
-i.e., they determine what should happen next as the program runs. This
-minor node describes how `awk' defines "true" and "false" and how
-values are compared.
+i.e., they determine what should happen next as the program runs. This
+minor node describes how 'awk' defines "true" and "false" and how values
+are compared.
* Menu:
-* Truth Values:: What is ``true'' and what is ``false''.
+* Truth Values:: What is "true" and what is "false".
* Typing and Comparison:: How variables acquire types and how this
affects comparison of numbers and strings with
- `<', etc.
+ '<', etc.
* Boolean Ops:: Combining comparison expressions using boolean
- operators `||' (``or''), `&&'
- (``and'') and `!' (``not'').
+ operators '||' ("or"), '&&'
+ ("and") and '!' ("not").
* Conditional Exp:: Conditional expressions select between two
subexpressions under control of a third
subexpression.
@@ -8248,17 +8207,17 @@ values are compared.
File: gawk.info, Node: Truth Values, Next: Typing and Comparison, Up: Truth
Values and Conditions
-6.3.1 True and False in `awk'
+6.3.1 True and False in 'awk'
-----------------------------
Many programming languages have a special representation for the
concepts of "true" and "false." Such languages usually use the special
-constants `true' and `false', or perhaps their uppercase equivalents.
-However, `awk' is different. It borrows a very simple concept of true
-and false from C. In `awk', any nonzero numeric value _or_ any
-nonempty string value is true. Any other value (zero or the null
-string, `""') is false. The following program prints `A strange truth
-value' three times:
+constants 'true' and 'false', or perhaps their uppercase equivalents.
+However, 'awk' is different. It borrows a very simple concept of true
+and false from C. In 'awk', any nonzero numeric value _or_ any nonempty
+string value is true. Any other value (zero or the null string, '""')
+is false. The following program prints 'A strange truth value' three
+times:
BEGIN {
if (3.1415927)
@@ -8270,7 +8229,7 @@ value' three times:
}
There is a surprising consequence of the "nonzero or non-null" rule:
-the string constant `"0"' is actually true, because it is non-null.
+the string constant '"0"' is actually true, because it is non-null.
(d.c.)
@@ -8279,13 +8238,13 @@ File: gawk.info, Node: Typing and Comparison, Next:
Boolean Ops, Prev: Truth
6.3.2 Variable Typing and Comparison Expressions
------------------------------------------------
- The Guide is definitive. Reality is frequently inaccurate. --
- Douglas Adams, `The Hitchhiker's Guide to the Galaxy'
+ The Guide is definitive. Reality is frequently inaccurate.
+ -- _Douglas Adams, 'The Hitchhiker's Guide to the Galaxy'_
- Unlike in other programming languages, in `awk' variables do not
-have a fixed type. Instead, they can be either a number or a string,
+ Unlike in other programming languages, in 'awk' variables do not have
+a fixed type. Instead, they can be either a number or a string,
depending upon the value that is assigned to them. We look now at how
-variables are typed, and how `awk' compares variables.
+variables are typed, and how 'awk' compares variables.
* Menu:
@@ -8300,10 +8259,10 @@ File: gawk.info, Node: Variable Typing, Next:
Comparison Operators, Up: Typin
.......................................
The POSIX standard introduced the concept of a "numeric string", which
-is simply a string that looks like a number--for example, `" +2"'.
-This concept is used for determining the type of a variable. The type
-of the variable is important because the types of two variables
-determine how they are compared. Variable typing follows these rules:
+is simply a string that looks like a number--for example, '" +2"'. This
+concept is used for determining the type of a variable. The type of the
+variable is important because the types of two variables determine how
+they are compared. Variable typing follows these rules:
* A numeric constant or the result of a numeric operation has the
"numeric" attribute.
@@ -8311,17 +8270,17 @@ determine how they are compared. Variable typing
follows these rules:
* A string constant or the result of a string operation has the
"string" attribute.
- * Fields, `getline' input, `FILENAME', `ARGV' elements, `ENVIRON'
- elements, and the elements of an array created by `match()',
- `split()', and `patsplit()' that are numeric strings have the
+ * Fields, 'getline' input, 'FILENAME', 'ARGV' elements, 'ENVIRON'
+ elements, and the elements of an array created by 'match()',
+ 'split()', and 'patsplit()' that are numeric strings have the
"strnum" attribute. Otherwise, they have the "string" attribute.
Uninitialized variables also have the "strnum" attribute.
* Attributes propagate across assignments but are not changed by any
use.
- The last rule is particularly important. In the following program,
-`a' has numeric type, even though it is later used in a string
+ The last rule is particularly important. In the following program,
+'a' has numeric type, even though it is later used in a string
operation:
BEGIN {
@@ -8331,26 +8290,26 @@ operation:
}
When two operands are compared, either string comparison or numeric
-comparison may be used. This depends upon the attributes of the
+comparison may be used. This depends upon the attributes of the
operands, according to the following symmetric matrix:
- +---------------------------------------------
+ +-------------------------------
| STRING NUMERIC STRNUM
- -------+---------------------------------------------
+ -----+-------------------------------
|
STRING | string string string
|
NUMERIC | string numeric numeric
|
STRNUM | string numeric numeric
- -------+---------------------------------------------
+ -----+-------------------------------
- The basic idea is that user input that looks numeric--and _only_
-user input--should be treated as numeric, even though it is actually
-made of characters and is therefore also a string. Thus, for example,
-the string constant `" +3.14"', when it appears in program source code,
-is a string--even though it looks numeric--and is _never_ treated as a
-number for comparison purposes.
+ The basic idea is that user input that looks numeric--and _only_ user
+input--should be treated as numeric, even though it is actually made of
+characters and is therefore also a string. Thus, for example, the
+string constant '" +3.14"', when it appears in program source code, is a
+string--even though it looks numeric--and is _never_ treated as a number
+for comparison purposes.
In short, when one operand is a "pure" string, such as a string
constant, then a string comparison is performed. Otherwise, a numeric
@@ -8359,10 +8318,10 @@ comparison is performed.
This point bears additional emphasis: All user input is made of
characters, and so is first and foremost of string type; input strings
that look numeric are additionally given the strnum attribute. Thus,
-the six-character input string ` +3.14' receives the strnum attribute.
-In contrast, the eight characters `" +3.14"' appearing in program text
-comprise a string constant. The following examples print `1' when the
-comparison between the two different constants is true, and `0'
+the six-character input string ' +3.14' receives the strnum attribute.
+In contrast, the eight characters '" +3.14"' appearing in program text
+comprise a string constant. The following examples print '1' when the
+comparison between the two different constants is true, and '0'
otherwise:
$ echo ' +3.14' | awk '{ print($0 == " +3.14") }' True
@@ -8390,37 +8349,37 @@ File: gawk.info, Node: Comparison Operators, Next:
POSIX String Comparison, P
"Comparison expressions" compare strings or numbers for relationships
such as equality. They are written using "relational operators", which
-are a superset of those in C. *note table-relational-ops:: describes
-them.
+are a superset of those in C. *note Table 6.3: table-relational-ops.
+describes them.
Expression Result
---------------------------------------------------------------------------
-X `<' Y True if X is less than Y
-X `<=' Y True if X is less than or equal to Y
-X `>' Y True if X is greater than Y
-X `>=' Y True if X is greater than or equal to Y
-X `==' Y True if X is equal to Y
-X `!=' Y True if X is not equal to Y
-X `~' Y True if the string X matches the regexp denoted by Y
-X `!~' Y True if the string X does not match the regexp
+--------------------------------------------------------------------------
+X '<' Y True if X is less than Y
+X '<=' Y True if X is less than or equal to Y
+X '>' Y True if X is greater than Y
+X '>=' Y True if X is greater than or equal to Y
+X '==' Y True if X is equal to Y
+X '!=' Y True if X is not equal to Y
+X '~' Y True if the string X matches the regexp denoted by Y
+X '!~' Y True if the string X does not match the regexp
denoted by Y
-SUBSCRIPT `in' True if the array ARRAY has an element with the
+SUBSCRIPT 'in' True if the array ARRAY has an element with the
ARRAY subscript SUBSCRIPT
Table 6.3: Relational operators
Comparison expressions have the value one if true and zero if false.
When comparing operands of mixed types, numeric operands are converted
-to strings using the value of `CONVFMT' (*note Conversion::).
+to strings using the value of 'CONVFMT' (*note Conversion::).
Strings are compared by comparing the first character of each, then
-the second character of each, and so on. Thus, `"10"' is less than
-`"9"'. If there are two strings where one is a prefix of the other,
-the shorter string is less than the longer one. Thus, `"abc"' is less
-than `"abcd"'.
+the second character of each, and so on. Thus, '"10"' is less than
+'"9"'. If there are two strings where one is a prefix of the other, the
+shorter string is less than the longer one. Thus, '"abc"' is less than
+'"abcd"'.
- It is very easy to accidentally mistype the `==' operator and leave
-off one of the `=' characters. The result is still valid `awk' code,
+ It is very easy to accidentally mistype the '==' operator and leave
+off one of the '=' characters. The result is still valid 'awk' code,
but the program does not do what is intended:
if (a = b) # oops! should be a == b
@@ -8428,32 +8387,32 @@ but the program does not do what is intended:
else
...
-Unless `b' happens to be zero or the null string, the `if' part of the
+Unless 'b' happens to be zero or the null string, the 'if' part of the
test always succeeds. Because the operators are so similar, this kind
of error is very difficult to spot when scanning the source code.
The following list of expressions illustrates the kinds of
-comparisons `awk' performs, as well as what the result of each
+comparisons 'awk' performs, as well as what the result of each
comparison is:
-`1.5 <= 2.0'
+'1.5 <= 2.0'
Numeric comparison (true)
-`"abc" >= "xyz"'
+'"abc" >= "xyz"'
String comparison (false)
-`1.5 != " +2"'
+'1.5 != " +2"'
String comparison (true)
-`"1e2" < "3"'
+'"1e2" < "3"'
String comparison (true)
-`a = 2; b = "2"'
-`a == b'
+'a = 2; b = "2"'
+'a == b'
String comparison (true)
-`a = 2; b = " +2"'
-`a == b'
+'a = 2; b = " +2"'
+'a == b'
String comparison (false)
In this example:
@@ -8461,38 +8420,38 @@ comparison is:
$ echo 1e2 3 | awk '{ print ($1 < $2) ? "true" : "false" }'
-| false
-the result is `false' because both `$1' and `$2' are user input. They
-are numeric strings--therefore both have the strnum attribute,
-dictating a numeric comparison. The purpose of the comparison rules
-and the use of numeric strings is to attempt to produce the behavior
-that is "least surprising," while still "doing the right thing."
+the result is 'false' because both '$1' and '$2' are user input. They
+are numeric strings--therefore both have the strnum attribute, dictating
+a numeric comparison. The purpose of the comparison rules and the use
+of numeric strings is to attempt to produce the behavior that is "least
+surprising," while still "doing the right thing."
String comparisons and regular expression comparisons are very
different. For example:
x == "foo"
-has the value one, or is true if the variable `x' is precisely `foo'.
+has the value one, or is true if the variable 'x' is precisely 'foo'.
By contrast:
x ~ /foo/
-has the value one if `x' contains `foo', such as `"Oh, what a fool am
+has the value one if 'x' contains 'foo', such as '"Oh, what a fool am
I!"'.
- The righthand operand of the `~' and `!~' operators may be either a
-regexp constant (`/'...`/') or an ordinary expression. In the latter
+ The righthand operand of the '~' and '!~' operators may be either a
+regexp constant ('/'...'/') or an ordinary expression. In the latter
case, the value of the expression as a string is used as a dynamic
regexp (*note Regexp Usage::; also *note Computed Regexps::).
A constant regular expression in slashes by itself is also an
-expression. `/REGEXP/' is an abbreviation for the following comparison
+expression. '/REGEXP/' is an abbreviation for the following comparison
expression:
$0 ~ /REGEXP/
- One special place where `/foo/' is _not_ an abbreviation for `$0 ~
-/foo/' is when it is the righthand operand of `~' or `!~'. *Note Using
+ One special place where '/foo/' is _not_ an abbreviation for '$0 ~
+/foo/' is when it is the righthand operand of '~' or '!~'. *Note Using
Constant Regexps::, where this is discussed in more detail.
@@ -8501,15 +8460,15 @@ File: gawk.info, Node: POSIX String Comparison, Prev:
Comparison Operators, U
6.3.2.3 String Comparison with POSIX Rules
..........................................
-The POSIX standard says that string comparison is performed based on
-the locale's "collating order". This is the order in which characters
-sort, as defined by the locale (for more discussion, *note Locales::).
-This order is usually very different from the results obtained when
-doing straight character-by-character comparison.(1)
+The POSIX standard says that string comparison is performed based on the
+locale's "collating order". This is the order in which characters sort,
+as defined by the locale (for more discussion, *note Locales::). This
+order is usually very different from the results obtained when doing
+straight character-by-character comparison.(1)
Because this behavior differs considerably from existing practice,
-`gawk' only implements it when in POSIX mode (*note Options::). Here
-is an example to illustrate the difference, in an `en_US.UTF-8' locale:
+'gawk' only implements it when in POSIX mode (*note Options::). Here is
+an example to illustrate the difference, in an 'en_US.UTF-8' locale:
$ gawk 'BEGIN { printf("ABC < abc = %s\n",
> ("ABC" < "abc" ? "TRUE" : "FALSE")) }'
@@ -8520,8 +8479,8 @@ is an example to illustrate the difference, in an
`en_US.UTF-8' locale:
---------- Footnotes ----------
- (1) Technically, string comparison is supposed to behave the same
-way as if the strings were compared with the C `strcoll()' function.
+ (1) Technically, string comparison is supposed to behave the same way
+as if the strings were compared with the C 'strcoll()' function.
File: gawk.info, Node: Boolean Ops, Next: Conditional Exp, Prev: Typing and
Comparison, Up: Truth Values and Conditions
@@ -8530,72 +8489,72 @@ File: gawk.info, Node: Boolean Ops, Next: Conditional
Exp, Prev: Typing and C
-------------------------
A "Boolean expression" is a combination of comparison expressions or
-matching expressions, using the Boolean operators "or" (`||'), "and"
-(`&&'), and "not" (`!'), along with parentheses to control nesting.
-The truth value of the Boolean expression is computed by combining the
-truth values of the component expressions. Boolean expressions are
-also referred to as "logical expressions". The terms are equivalent.
+matching expressions, using the Boolean operators "or" ('||'), "and"
+('&&'), and "not" ('!'), along with parentheses to control nesting. The
+truth value of the Boolean expression is computed by combining the truth
+values of the component expressions. Boolean expressions are also
+referred to as "logical expressions". The terms are equivalent.
Boolean expressions can be used wherever comparison and matching
-expressions can be used. They can be used in `if', `while', `do', and
-`for' statements (*note Statements::). They have numeric values (one
-if true, zero if false) that come into play if the result of the
-Boolean expression is stored in a variable or used in arithmetic.
+expressions can be used. They can be used in 'if', 'while', 'do', and
+'for' statements (*note Statements::). They have numeric values (one if
+true, zero if false) that come into play if the result of the Boolean
+expression is stored in a variable or used in arithmetic.
- In addition, every Boolean expression is also a valid pattern, so
-you can use one as a pattern to control the execution of rules. The
-Boolean operators are:
+ In addition, every Boolean expression is also a valid pattern, so you
+can use one as a pattern to control the execution of rules. The Boolean
+operators are:
-`BOOLEAN1 && BOOLEAN2'
+'BOOLEAN1 && BOOLEAN2'
True if both BOOLEAN1 and BOOLEAN2 are true. For example, the
following statement prints the current input record if it contains
- both `edu' and `li':
+ both 'edu' and 'li':
if ($0 ~ /edu/ && $0 ~ /li/) print
The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is true.
This can make a difference when BOOLEAN2 contains expressions that
- have side effects. In the case of `$0 ~ /foo/ && ($2 == bar++)',
- the variable `bar' is not incremented if there is no substring
- `foo' in the record.
+ have side effects. In the case of '$0 ~ /foo/ && ($2 == bar++)',
+ the variable 'bar' is not incremented if there is no substring
+ 'foo' in the record.
-`BOOLEAN1 || BOOLEAN2'
- True if at least one of BOOLEAN1 or BOOLEAN2 is true. For
- example, the following statement prints all records in the input
- that contain _either_ `edu' or `li':
+'BOOLEAN1 || BOOLEAN2'
+ True if at least one of BOOLEAN1 or BOOLEAN2 is true. For example,
+ the following statement prints all records in the input that
+ contain _either_ 'edu' or 'li':
if ($0 ~ /edu/ || $0 ~ /li/) print
The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is false.
This can make a difference when BOOLEAN2 contains expressions that
have side effects. (Thus, this test never really distinguishes
- records that contain both `edu' and `li'--as soon as `edu' is
+ records that contain both 'edu' and 'li'--as soon as 'edu' is
matched, the full test succeeds.)
-`! BOOLEAN'
+'! BOOLEAN'
True if BOOLEAN is false. For example, the following program
- prints `no home!' in the unusual event that the `HOME' environment
+ prints 'no home!' in the unusual event that the 'HOME' environment
variable is not defined:
BEGIN { if (! ("HOME" in ENVIRON))
print "no home!" }
- (The `in' operator is described in *note Reference to Elements::.)
+ (The 'in' operator is described in *note Reference to Elements::.)
- The `&&' and `||' operators are called "short-circuit" operators
+ The '&&' and '||' operators are called "short-circuit" operators
because of the way they work. Evaluation of the full expression is
"short-circuited" if the result can be determined partway through its
evaluation.
- Statements that end with `&&' or `||' can be continued simply by
+ Statements that end with '&&' or '||' can be continued simply by
putting a newline after them. But you cannot put a newline in front of
either of these operators without using backslash continuation (*note
Statements/Lines::).
- The actual value of an expression using the `!' operator is either
+ The actual value of an expression using the '!' operator is either
one or zero, depending upon the truth value of the expression it is
-applied to. The `!' operator is often useful for changing the sense of
-a flag variable from false to true and back again. For example, the
+applied to. The '!' operator is often useful for changing the sense of
+a flag variable from false to true and back again. For example, the
following program is one way to print lines in between special
bracketing lines:
@@ -8603,30 +8562,30 @@ bracketing lines:
interested { print }
$1 == "END" { interested = ! interested; next }
-The variable `interested', as with all `awk' variables, starts out
+The variable 'interested', as with all 'awk' variables, starts out
initialized to zero, which is also false. When a line is seen whose
-first field is `START', the value of `interested' is toggled to true,
-using `!'. The next rule prints lines as long as `interested' is true.
-When a line is seen whose first field is `END', `interested' is toggled
+first field is 'START', the value of 'interested' is toggled to true,
+using '!'. The next rule prints lines as long as 'interested' is true.
+When a line is seen whose first field is 'END', 'interested' is toggled
back to false.(1)
- Most commonly, the `!' operator is used in the conditions of `if'
-and `while' statements, where it often makes more sense to phrase the
-logic in the negative:
+ Most commonly, the '!' operator is used in the conditions of 'if' and
+'while' statements, where it often makes more sense to phrase the logic
+in the negative:
if (! SOME CONDITION || SOME OTHER CONDITION) {
... DO WHATEVER PROCESSING ...
}
- NOTE: The `next' statement is discussed in *note Next Statement::.
- `next' tells `awk' to skip the rest of the rules, get the next
+ NOTE: The 'next' statement is discussed in *note Next Statement::.
+ 'next' tells 'awk' to skip the rest of the rules, get the next
record, and start processing the rules over again at the top. The
- reason it's there is to avoid printing the bracketing `START' and
- `END' lines.
+ reason it's there is to avoid printing the bracketing 'START' and
+ 'END' lines.
---------- Footnotes ----------
- (1) This program has a bug; it prints lines starting with `END'. How
+ (1) This program has a bug; it prints lines starting with 'END'. How
would you fix it?
@@ -8637,36 +8596,36 @@ File: gawk.info, Node: Conditional Exp, Prev: Boolean
Ops, Up: Truth Values a
A "conditional expression" is a special kind of expression that has
three operands. It allows you to use one expression's value to select
-one of two other expressions. The conditional expression in `awk' is
+one of two other expressions. The conditional expression in 'awk' is
the same as in the C language, as shown here:
SELECTOR ? IF-TRUE-EXP : IF-FALSE-EXP
-There are three subexpressions. The first, SELECTOR, is always
-computed first. If it is "true" (not zero or not null), then
-IF-TRUE-EXP is computed next, and its value becomes the value of the
-whole expression. Otherwise, IF-FALSE-EXP is computed next, and its
-value becomes the value of the whole expression. For example, the
-following expression produces the absolute value of `x':
+There are three subexpressions. The first, SELECTOR, is always computed
+first. If it is "true" (not zero or not null), then IF-TRUE-EXP is
+computed next, and its value becomes the value of the whole expression.
+Otherwise, IF-FALSE-EXP is computed next, and its value becomes the
+value of the whole expression. For example, the following expression
+produces the absolute value of 'x':
x >= 0 ? x : -x
Each time the conditional expression is computed, only one of
IF-TRUE-EXP and IF-FALSE-EXP is used; the other is ignored. This is
important when the expressions have side effects. For example, this
-conditional expression examines element `i' of either array `a' or
-array `b', and increments `i':
+conditional expression examines element 'i' of either array 'a' or array
+'b', and increments 'i':
x == y ? a[i++] : b[i++]
-This is guaranteed to increment `i' exactly once, because each time
-only one of the two increment expressions is executed and the other is
-not. *Note Arrays::, for more information about arrays.
+This is guaranteed to increment 'i' exactly once, because each time only
+one of the two increment expressions is executed and the other is not.
+*Note Arrays::, for more information about arrays.
- As a minor `gawk' extension, a statement that uses `?:' can be
+ As a minor 'gawk' extension, a statement that uses '?:' can be
continued simply by putting a newline after either character. However,
putting a newline in front of either character does not work without
-using backslash continuation (*note Statements/Lines::). If `--posix'
+using backslash continuation (*note Statements/Lines::). If '--posix'
is specified (*note Options::), this extension is disabled.
@@ -8677,22 +8636,22 @@ File: gawk.info, Node: Function Calls, Next:
Precedence, Prev: Truth Values a
A "function" is a name for a particular calculation. This enables you
to ask for it by name at any point in the program. For example, the
-function `sqrt()' computes the square root of a number.
+function 'sqrt()' computes the square root of a number.
A fixed set of functions are "built in", which means they are
-available in every `awk' program. The `sqrt()' function is one of
+available in every 'awk' program. The 'sqrt()' function is one of
these. *Note Built-in::, for a list of built-in functions and their
descriptions. In addition, you can define functions for use in your
program. *Note User-defined::, for instructions on how to do this.
-Finally, `gawk' lets you write functions in C or C++ that may be called
+Finally, 'gawk' lets you write functions in C or C++ that may be called
from your program (*note Dynamic Extensions::).
- The way to use a function is with a "function call" expression,
-which consists of the function name followed immediately by a list of
+ The way to use a function is with a "function call" expression, which
+consists of the function name followed immediately by a list of
"arguments" in parentheses. The arguments are expressions that provide
the raw materials for the function's calculations. When there is more
than one argument, they are separated by commas. If there are no
-arguments, just write `()' after the function name. The following
+arguments, just write '()' after the function name. The following
examples show function calls with and without arguments:
sqrt(x^2 + y^2) one argument
@@ -8701,15 +8660,15 @@ examples show function calls with and without arguments:
CAUTION: Do not put any space between the function name and the
opening parenthesis! A user-defined function name looks just like
- the name of a variable--a space would make the expression look
- like concatenation of a variable with an expression inside
- parentheses. With built-in functions, space before the
- parenthesis is harmless, but it is best not to get into the habit
- of using space to avoid mistakes with user-defined functions.
+ the name of a variable--a space would make the expression look like
+ concatenation of a variable with an expression inside parentheses.
+ With built-in functions, space before the parenthesis is harmless,
+ but it is best not to get into the habit of using space to avoid
+ mistakes with user-defined functions.
- Each function expects a particular number of arguments. For
-example, the `sqrt()' function must be called with a single argument,
-the number of which to take the square root:
+ Each function expects a particular number of arguments. For example,
+the 'sqrt()' function must be called with a single argument, the number
+of which to take the square root:
sqrt(ARGUMENT)
@@ -8717,19 +8676,19 @@ the number of which to take the square root:
If those arguments are not supplied, the functions use a reasonable
default value. *Note Built-in::, for full details. If arguments are
omitted in calls to user-defined functions, then those arguments are
-treated as local variables. Such local variables act like the empty
+treated as local variables. Such local variables act like the empty
string if referenced where a string value is required, and like zero if
referenced where a numeric value is required (*note User-defined::).
- As an advanced feature, `gawk' provides indirect function calls,
+ As an advanced feature, 'gawk' provides indirect function calls,
which is a way to choose the function to call at runtime, instead of
-when you write the source code to your program. We defer discussion of
+when you write the source code to your program. We defer discussion of
this feature until later; see *note Indirect Calls::.
Like every other expression, the function call has a value, often
called the "return value", which is computed by the function based on
the arguments you give it. In this example, the return value of
-`sqrt(ARGUMENT)' is the square root of ARGUMENT. The following program
+'sqrt(ARGUMENT)' is the square root of ARGUMENT. The following program
reads numbers, one number per line, and prints the square root of each
one:
@@ -8743,9 +8702,9 @@ one:
Ctrl-d
A function can also have side effects, such as assigning values to
-certain variables or doing I/O. This program shows how the `match()'
-function (*note String Functions::) changes the variables `RSTART' and
-`RLENGTH':
+certain variables or doing I/O. This program shows how the 'match()'
+function (*note String Functions::) changes the variables 'RSTART' and
+'RLENGTH':
{
if (match($1, $2))
@@ -8771,9 +8730,9 @@ File: gawk.info, Node: Precedence, Next: Locales,
Prev: Function Calls, Up:
============================================
"Operator precedence" determines how operators are grouped when
-different operators appear close by in one expression. For example,
-`*' has higher precedence than `+'; thus, `a + b * c' means to multiply
-`b' and `c', and then add `a' to the product (i.e., `a + (b * c)').
+different operators appear close by in one expression. For example, '*'
+has higher precedence than '+'; thus, 'a + b * c' means to multiply 'b'
+and 'c', and then add 'a' to the product (i.e., 'a + (b * c)').
The normal precedence of the operators can be overruled by using
parentheses. Think of the precedence rules as saying where the
@@ -8786,84 +8745,83 @@ help prevent any such mistakes.
When operators of equal precedence are used together, the leftmost
operator groups first, except for the assignment, conditional, and
-exponentiation operators, which group in the opposite order. Thus, `a
-- b + c' groups as `(a - b) + c' and `a = b = c' groups as `a = (b =
-c)'.
+exponentiation operators, which group in the opposite order. Thus, 'a -
+b + c' groups as '(a - b) + c' and 'a = b = c' groups as 'a = (b = c)'.
Normally the precedence of prefix unary operators does not matter,
-because there is only one way to interpret them: innermost first.
-Thus, `$++i' means `$(++i)' and `++$x' means `++($x)'. However, when
-another operator follows the operand, then the precedence of the unary
-operators can matter. `$x^2' means `($x)^2', but `-x^2' means
-`-(x^2)', because `-' has lower precedence than `^', whereas `$' has
-higher precedence. Also, operators cannot be combined in a way that
-violates the precedence rules; for example, `$$0++--' is not a valid
-expression because the first `$' has higher precedence than the `++';
-to avoid the problem the expression can be rewritten as `$($0++)--'.
-
- This list presents `awk''s operators, in order of highest to lowest
+because there is only one way to interpret them: innermost first. Thus,
+'$++i' means '$(++i)' and '++$x' means '++($x)'. However, when another
+operator follows the operand, then the precedence of the unary operators
+can matter. '$x^2' means '($x)^2', but '-x^2' means '-(x^2)', because
+'-' has lower precedence than '^', whereas '$' has higher precedence.
+Also, operators cannot be combined in a way that violates the precedence
+rules; for example, '$$0++--' is not a valid expression because the
+first '$' has higher precedence than the '++'; to avoid the problem the
+expression can be rewritten as '$($0++)--'.
+
+ This list presents 'awk''s operators, in order of highest to lowest
precedence:
-`('...`)'
+'('...')'
Grouping.
-`$'
+'$'
Field reference.
-`++ --'
+'++ --'
Increment, decrement.
-`^ **'
+'^ **'
Exponentiation. These operators group right to left.
-`+ - !'
+'+ - !'
Unary plus, minus, logical "not."
-`* / %'
+'* / %'
Multiplication, division, remainder.
-`+ -'
+'+ -'
Addition, subtraction.
String concatenation
There is no special symbol for concatenation. The operands are
simply written side by side (*note Concatenation::).
-`< <= == != > >= >> | |&'
+'< <= == != > >= >> | |&'
Relational and redirection. The relational operators and the
redirections have the same precedence level. Characters such as
- `>' serve both as relationals and as redirections; the context
+ '>' serve both as relationals and as redirections; the context
distinguishes between the two meanings.
- Note that the I/O redirection operators in `print' and `printf'
+ Note that the I/O redirection operators in 'print' and 'printf'
statements belong to the statement level, not to expressions. The
redirection does not produce an expression that could be the
operand of another operator. As a result, it does not make sense
to use a redirection operator near another operator of lower
- precedence without parentheses. Such combinations (e.g., `print
+ precedence without parentheses. Such combinations (e.g., 'print
foo > a ? b : c') result in syntax errors. The correct way to
- write this statement is `print foo > (a ? b : c)'.
+ write this statement is 'print foo > (a ? b : c)'.
-`~ !~'
+'~ !~'
Matching, nonmatching.
-`in'
+'in'
Array membership.
-`&&'
+'&&'
Logical "and."
-`||'
+'||'
Logical "or."
-`?:'
+'?:'
Conditional. This operator groups right to left.
-`= += -= *= /= %= ^= **='
+'= += -= *= /= %= ^= **='
Assignment. These operators group right to left.
- NOTE: The `|&', `**', and `**=' operators are not specified by
- POSIX. For maximum portability, do not use them.
+ NOTE: The '|&', '**', and '**=' operators are not specified by
+ POSIX. For maximum portability, do not use them.
File: gawk.info, Node: Locales, Next: Expressions Summary, Prev:
Precedence, Up: Expressions
@@ -8871,34 +8829,34 @@ File: gawk.info, Node: Locales, Next: Expressions
Summary, Prev: Precedence,
6.6 Where You Are Makes a Difference
====================================
-Modern systems support the notion of "locales": a way to tell the
-system about the local character set and language. The ISO C standard
-defines a default `"C"' locale, which is an environment that is typical
-of what many C programmers are used to.
+Modern systems support the notion of "locales": a way to tell the system
+about the local character set and language. The ISO C standard defines
+a default '"C"' locale, which is an environment that is typical of what
+many C programmers are used to.
Once upon a time, the locale setting used to affect regexp matching,
but this is no longer true (*note Ranges and Locales::).
- Locales can affect record splitting. For the normal case of `RS =
+ Locales can affect record splitting. For the normal case of 'RS =
"\n"', the locale is largely irrelevant. For other single-character
-record separators, setting `LC_ALL=C' in the environment will give you
-much better performance when reading records. Otherwise, `gawk' has to
+record separators, setting 'LC_ALL=C' in the environment will give you
+much better performance when reading records. Otherwise, 'gawk' has to
make several function calls, _per input character_, to find the record
terminator.
Locales can affect how dates and times are formatted (*note Time
Functions::). For example, a common way to abbreviate the date
September 4, 2015, in the United States is "9/4/15." In many countries
-in Europe, however, it is abbreviated "4.9.15." Thus, the `%x'
-specification in a `"US"' locale might produce `9/4/15', while in a
-`"EUROPE"' locale, it might produce `4.9.15'.
+in Europe, however, it is abbreviated "4.9.15." Thus, the '%x'
+specification in a '"US"' locale might produce '9/4/15', while in a
+'"EUROPE"' locale, it might produce '4.9.15'.
According to POSIX, string comparison is also affected by locales
(similar to regular expressions). The details are presented in *note
POSIX String Comparison::.
Finally, the locale affects the value of the decimal point character
-used when `gawk' parses input data. This is discussed in detail in
+used when 'gawk' parses input data. This is discussed in detail in
*note Conversion::.
@@ -8911,35 +8869,35 @@ File: gawk.info, Node: Expressions Summary, Prev:
Locales, Up: Expressions
They are built from constants, variables, function calls, and
combinations of the various kinds of values with operators.
- * `awk' supplies three kinds of constants: numeric, string, and
- regexp. `gawk' lets you specify numeric constants in octal and
+ * 'awk' supplies three kinds of constants: numeric, string, and
+ regexp. 'gawk' lets you specify numeric constants in octal and
hexadecimal (bases 8 and 16) as well as decimal (base 10). In
- certain contexts, a standalone regexp constant such as `/foo/' has
- the same meaning as `$0 ~ /foo/'.
+ certain contexts, a standalone regexp constant such as '/foo/' has
+ the same meaning as '$0 ~ /foo/'.
- * Variables hold values between uses in computations. A number of
- built-in variables provide information to your `awk' program, and
- a number of others let you control how `awk' behaves.
+ * Variables hold values between uses in computations. A number of
+ built-in variables provide information to your 'awk' program, and a
+ number of others let you control how 'awk' behaves.
* Numbers are automatically converted to strings, and strings to
- numbers, as needed by `awk'. Numeric values are converted as if
- they were formatted with `sprintf()' using the format in `CONVFMT'.
+ numbers, as needed by 'awk'. Numeric values are converted as if
+ they were formatted with 'sprintf()' using the format in 'CONVFMT'.
Locales can influence the conversions.
- * `awk' provides the usual arithmetic operators (addition,
- subtraction, multiplication, division, modulus), and unary plus
- and minus. It also provides comparison operators, Boolean
- operators, an array membership testing operator, and regexp
- matching operators. String concatenation is accomplished by
- placing two expressions next to each other; there is no explicit
- operator. The three-operand `?:' operator provides an "if-else"
- test within expressions.
+ * 'awk' provides the usual arithmetic operators (addition,
+ subtraction, multiplication, division, modulus), and unary plus and
+ minus. It also provides comparison operators, Boolean operators,
+ an array membership testing operator, and regexp matching
+ operators. String concatenation is accomplished by placing two
+ expressions next to each other; there is no explicit operator. The
+ three-operand '?:' operator provides an "if-else" test within
+ expressions.
* Assignment operators provide convenient shorthands for common
arithmetic operations.
- * In `awk', a value is considered to be true if it is nonzero _or_
- non-null. Otherwise, the value is false.
+ * In 'awk', a value is considered to be true if it is nonzero _or_
+ non-null. Otherwise, the value is false.
* A variable's type is set upon each assignment and may change over
its lifetime. The type determines how it behaves in comparisons
@@ -8947,37 +8905,36 @@ File: gawk.info, Node: Expressions Summary, Prev:
Locales, Up: Expressions
* Function calls return a value that may be used as part of a larger
expression. Expressions used to pass parameter values are fully
- evaluated before the function is called. `awk' provides built-in
+ evaluated before the function is called. 'awk' provides built-in
and user-defined functions; this is described in *note Functions::.
* Operator precedence specifies the order in which operations are
- performed, unless explicitly overridden by parentheses. `awk''s
+ performed, unless explicitly overridden by parentheses. 'awk''s
operator precedence is compatible with that of C.
- * Locales can affect the format of data as output by an `awk'
+ * Locales can affect the format of data as output by an 'awk'
program, and occasionally the format for data read as input.
-
File: gawk.info, Node: Patterns and Actions, Next: Arrays, Prev:
Expressions, Up: Top
7 Patterns, Actions, and Variables
**********************************
-As you have already seen, each `awk' statement consists of a pattern
+As you have already seen, each 'awk' statement consists of a pattern
with an associated action. This major node describes how you build
patterns and actions, what kinds of things you can do within actions,
-and `awk''s predefined variables.
+and 'awk''s predefined variables.
The pattern-action rules and the statements available for use within
-actions form the core of `awk' programming. In a sense, everything
+actions form the core of 'awk' programming. In a sense, everything
covered up to here has been the foundation that programs are built on
top of. Now it's time to start building something useful.
* Menu:
* Pattern Overview:: What goes into a pattern.
-* Using Shell Variables:: How to use shell variables with `awk'.
+* Using Shell Variables:: How to use shell variables with 'awk'.
* Action Overview:: What goes into an action.
* Statements:: Describes the various control statements in
detail.
@@ -8999,34 +8956,34 @@ File: gawk.info, Node: Pattern Overview, Next: Using
Shell Variables, Up: Pat
* BEGINFILE/ENDFILE:: Two special patterns for advanced control.
* Empty:: The empty pattern, which matches every record.
- Patterns in `awk' control the execution of rules--a rule is executed
+Patterns in 'awk' control the execution of rules--a rule is executed
when its pattern matches the current input record. The following is a
-summary of the types of `awk' patterns:
+summary of the types of 'awk' patterns:
-`/REGULAR EXPRESSION/'
- A regular expression. It matches when the text of the input record
+'/REGULAR EXPRESSION/'
+ A regular expression. It matches when the text of the input record
fits the regular expression. (*Note Regexp::.)
-`EXPRESSION'
+'EXPRESSION'
A single expression. It matches when its value is nonzero (if a
number) or non-null (if a string). (*Note Expression Patterns::.)
-`BEGPAT, ENDPAT'
+'BEGPAT, ENDPAT'
A pair of patterns separated by a comma, specifying a "range" of
records. The range includes both the initial record that matches
BEGPAT and the final record that matches ENDPAT. (*Note Ranges::.)
-`BEGIN'
-`END'
+'BEGIN'
+'END'
Special patterns for you to supply startup or cleanup actions for
- your `awk' program. (*Note BEGIN/END::.)
+ your 'awk' program. (*Note BEGIN/END::.)
-`BEGINFILE'
-`ENDFILE'
+'BEGINFILE'
+'ENDFILE'
Special patterns for you to supply startup or cleanup actions to be
done on a per-file basis. (*Note BEGINFILE/ENDFILE::.)
-`EMPTY'
+'EMPTY'
The empty pattern matches every input record. (*Note Empty::.)
@@ -9037,7 +8994,7 @@ File: gawk.info, Node: Regexp Patterns, Next:
Expression Patterns, Up: Patter
Regular expressions are one of the first kinds of patterns presented in
this book. This kind of pattern is simply a regexp constant in the
-pattern part of a rule. Its meaning is `$0 ~ /PATTERN/'. The pattern
+pattern part of a rule. Its meaning is '$0 ~ /PATTERN/'. The pattern
matches when the input record matches the regexp. For example:
/foo|bar|baz/ { buzzwords++ }
@@ -9049,49 +9006,49 @@ File: gawk.info, Node: Expression Patterns, Next:
Ranges, Prev: Regexp Patter
7.1.2 Expressions as Patterns
-----------------------------
-Any `awk' expression is valid as an `awk' pattern. The pattern matches
+Any 'awk' expression is valid as an 'awk' pattern. The pattern matches
if the expression's value is nonzero (if a number) or non-null (if a
string). The expression is reevaluated each time the rule is tested
-against a new input record. If the expression uses fields such as
-`$1', the value depends directly on the new input record's text;
-otherwise, it depends on only what has happened so far in the execution
-of the `awk' program.
+against a new input record. If the expression uses fields such as '$1',
+the value depends directly on the new input record's text; otherwise, it
+depends on only what has happened so far in the execution of the 'awk'
+program.
Comparison expressions, using the comparison operators described in
*note Typing and Comparison::, are a very common kind of pattern.
Regexp matching and nonmatching are also very common expressions. The
-left operand of the `~' and `!~' operators is a string. The right
+left operand of the '~' and '!~' operators is a string. The right
operand is either a constant regular expression enclosed in slashes
-(`/REGEXP/'), or any expression whose string value is used as a dynamic
+('/REGEXP/'), or any expression whose string value is used as a dynamic
regular expression (*note Computed Regexps::). The following example
prints the second field of each input record whose first field is
-precisely `li':
+precisely 'li':
$ awk '$1 == "li" { print $2 }' mail-list
(There is no output, because there is no person with the exact name
-`li'.) Contrast this with the following regular expression match, which
-accepts any record with a first field that contains `li':
+'li'.) Contrast this with the following regular expression match, which
+accepts any record with a first field that contains 'li':
$ awk '$1 ~ /li/ { print $2 }' mail-list
-| 555-5553
-| 555-6699
A regexp constant as a pattern is also a special case of an
-expression pattern. The expression `/li/' has the value one if `li'
-appears in the current input record. Thus, as a pattern, `/li/' matches
-any record containing `li'.
+expression pattern. The expression '/li/' has the value one if 'li'
+appears in the current input record. Thus, as a pattern, '/li/' matches
+any record containing 'li'.
Boolean expressions are also commonly used as patterns. Whether the
pattern matches an input record depends on whether its subexpressions
match. For example, the following command prints all the records in
-`mail-list' that contain both `edu' and `li':
+'mail-list' that contain both 'edu' and 'li':
$ awk '/edu/ && /li/' mail-list
-| Samuel 555-3430 address@hidden A
- The following command prints all records in `mail-list' that contain
-_either_ `edu' or `li' (or both, of course):
+ The following command prints all records in 'mail-list' that contain
+_either_ 'edu' or 'li' (or both, of course):
$ awk '/edu/ || /li/' mail-list
-| Amelia 555-5553 address@hidden F
@@ -9101,8 +9058,8 @@ _either_ `edu' or `li' (or both, of course):
-| Samuel 555-3430 address@hidden A
-| Jean-Paul 555-2127 address@hidden R
- The following command prints all records in `mail-list' that do
-_not_ contain the string `li':
+ The following command prints all records in 'mail-list' that do _not_
+contain the string 'li':
$ awk '! /li/' mail-list
-| Anthony 555-3412 address@hidden A
@@ -9113,15 +9070,15 @@ _not_ contain the string `li':
-| Martin 555-6480 address@hidden A
-| Jean-Paul 555-2127 address@hidden R
- The subexpressions of a Boolean operator in a pattern can be
-constant regular expressions, comparisons, or any other `awk'
-expressions. Range patterns are not expressions, so they cannot appear
-inside Boolean patterns. Likewise, the special patterns `BEGIN', `END',
-`BEGINFILE', and `ENDFILE', which never match any input record, are not
-expressions and cannot appear inside Boolean patterns.
+ The subexpressions of a Boolean operator in a pattern can be constant
+regular expressions, comparisons, or any other 'awk' expressions. Range
+patterns are not expressions, so they cannot appear inside Boolean
+patterns. Likewise, the special patterns 'BEGIN', 'END', 'BEGINFILE',
+and 'ENDFILE', which never match any input record, are not expressions
+and cannot appear inside Boolean patterns.
- The precedence of the different operators that can appear in
-patterns is described in *note Precedence::.
+ The precedence of the different operators that can appear in patterns
+is described in *note Precedence::.
File: gawk.info, Node: Ranges, Next: BEGIN/END, Prev: Expression Patterns,
Up: Pattern Overview
@@ -9130,80 +9087,78 @@ File: gawk.info, Node: Ranges, Next: BEGIN/END,
Prev: Expression Patterns, U
--------------------------------------------
A "range pattern" is made of two patterns separated by a comma, in the
-form `BEGPAT, ENDPAT'. It is used to match ranges of consecutive input
+form 'BEGPAT, ENDPAT'. It is used to match ranges of consecutive input
records. The first pattern, BEGPAT, controls where the range begins,
while ENDPAT controls where the pattern ends. For example, the
following:
awk '$1 == "on", $1 == "off"' myfile
-prints every record in `myfile' between `on'/`off' pairs, inclusive.
+prints every record in 'myfile' between 'on'/'off' pairs, inclusive.
A range pattern starts out by matching BEGPAT against every input
-record. When a record matches BEGPAT, the range pattern is "turned
-on", and the range pattern matches this record as well. As long as the
-range pattern stays turned on, it automatically matches every input
-record read. The range pattern also matches ENDPAT against every input
-record; when this succeeds, the range pattern is "turned off" again for
-the following record. Then the range pattern goes back to checking
-BEGPAT against each record.
+record. When a record matches BEGPAT, the range pattern is "turned on",
+and the range pattern matches this record as well. As long as the range
+pattern stays turned on, it automatically matches every input record
+read. The range pattern also matches ENDPAT against every input record;
+when this succeeds, the range pattern is "turned off" again for the
+following record. Then the range pattern goes back to checking BEGPAT
+against each record.
The record that turns on the range pattern and the one that turns it
-off both match the range pattern. If you don't want to operate on
-these records, you can write `if' statements in the rule's action to
+off both match the range pattern. If you don't want to operate on these
+records, you can write 'if' statements in the rule's action to
distinguish them from the records you are interested in.
It is possible for a pattern to be turned on and off by the same
-record. If the record satisfies both conditions, then the action is
+record. If the record satisfies both conditions, then the action is
executed for just that record. For example, suppose there is text
-between two identical markers (e.g., the `%' symbol), each on its own
+between two identical markers (e.g., the '%' symbol), each on its own
line, that should be ignored. A first attempt would be to combine a
-range pattern that describes the delimited text with the `next'
+range pattern that describes the delimited text with the 'next'
statement (not discussed yet, *note Next Statement::). This causes
-`awk' to skip any further processing of the current record and start
-over again with the next input record. Such a program looks like this:
+'awk' to skip any further processing of the current record and start
+over again with the next input record. Such a program looks like this:
/^%$/,/^%$/ { next }
{ print }
This program fails because the range pattern is both turned on and
-turned off by the first line, which just has a `%' on it. To
-accomplish this task, write the program in the following manner, using
-a flag:
+turned off by the first line, which just has a '%' on it. To accomplish
+this task, write the program in the following manner, using a flag:
/^%$/ { skip = ! skip; next }
skip == 1 { next } # skip lines with `skip' set
- In a range pattern, the comma (`,') has the lowest precedence of all
-the operators (i.e., it is evaluated last). Thus, the following
-program attempts to combine a range pattern with another, simpler test:
+ In a range pattern, the comma (',') has the lowest precedence of all
+the operators (i.e., it is evaluated last). Thus, the following program
+attempts to combine a range pattern with another, simpler test:
echo Yes | awk '/1/,/2/ || /Yes/'
- The intent of this program is `(/1/,/2/) || /Yes/'. However, `awk'
-interprets this as `/1/, (/2/ || /Yes/)'. This cannot be changed or
+ The intent of this program is '(/1/,/2/) || /Yes/'. However, 'awk'
+interprets this as '/1/, (/2/ || /Yes/)'. This cannot be changed or
worked around; range patterns do not combine with other patterns:
$ echo Yes | gawk '(/1/,/2/) || /Yes/'
- error--> gawk: cmd. line:1: (/1/,/2/) || /Yes/
- error--> gawk: cmd. line:1: ^ syntax error
+ error-> gawk: cmd. line:1: (/1/,/2/) || /Yes/
+ error-> gawk: cmd. line:1: ^ syntax error
- As a minor point of interest, although it is poor style, POSIX
-allows you to put a newline after the comma in a range pattern.
-(d.c.)
+ As a minor point of interest, although it is poor style, POSIX allows
+you to put a newline after the comma in a range pattern. (d.c.)
File: gawk.info, Node: BEGIN/END, Next: BEGINFILE/ENDFILE, Prev: Ranges,
Up: Pattern Overview
-7.1.4 The `BEGIN' and `END' Special Patterns
+7.1.4 The 'BEGIN' and 'END' Special Patterns
--------------------------------------------
All the patterns described so far are for matching input records. The
-`BEGIN' and `END' special patterns are different. They supply startup
-and cleanup actions for `awk' programs. `BEGIN' and `END' rules must
+'BEGIN' and 'END' special patterns are different. They supply startup
+and cleanup actions for 'awk' programs. 'BEGIN' and 'END' rules must
have actions; there is no default action for these rules because there
-is no current record when they run. `BEGIN' and `END' rules are often
-referred to as "`BEGIN' and `END' blocks" by longtime `awk' programmers.
+is no current record when they run. 'BEGIN' and 'END' rules are often
+referred to as "'BEGIN' and 'END' blocks" by longtime 'awk' programmers.
* Menu:
@@ -9216,8 +9171,8 @@ File: gawk.info, Node: Using BEGIN/END, Next: I/O And
BEGIN/END, Up: BEGIN/EN
7.1.4.1 Startup and Cleanup Actions
...................................
-A `BEGIN' rule is executed once only, before the first input record is
-read. Likewise, an `END' rule is executed once only, after all the
+A 'BEGIN' rule is executed once only, before the first input record is
+read. Likewise, an 'END' rule is executed once only, after all the
input is read. For example:
$ awk '
@@ -9228,110 +9183,109 @@ input is read. For example:
-| "li" appears in 4 records.
This program finds the number of records in the input file
-`mail-list' that contain the string `li'. The `BEGIN' rule prints a
-title for the report. There is no need to use the `BEGIN' rule to
-initialize the counter `n' to zero, as `awk' does this automatically
-(*note Variables::). The second rule increments the variable `n' every
-time a record containing the pattern `li' is read. The `END' rule
-prints the value of `n' at the end of the run.
-
- The special patterns `BEGIN' and `END' cannot be used in ranges or
+'mail-list' that contain the string 'li'. The 'BEGIN' rule prints a
+title for the report. There is no need to use the 'BEGIN' rule to
+initialize the counter 'n' to zero, as 'awk' does this automatically
+(*note Variables::). The second rule increments the variable 'n' every
+time a record containing the pattern 'li' is read. The 'END' rule
+prints the value of 'n' at the end of the run.
+
+ The special patterns 'BEGIN' and 'END' cannot be used in ranges or
with Boolean operators (indeed, they cannot be used with any operators).
-An `awk' program may have multiple `BEGIN' and/or `END' rules. They
-are executed in the order in which they appear: all the `BEGIN' rules
-at startup and all the `END' rules at termination. `BEGIN' and `END'
-rules may be intermixed with other rules. This feature was added in
-the 1987 version of `awk' and is included in the POSIX standard. The
-original (1978) version of `awk' required the `BEGIN' rule to be placed
-at the beginning of the program, the `END' rule to be placed at the
-end, and only allowed one of each. This is no longer required, but it
-is a good idea to follow this template in terms of program organization
-and readability.
-
- Multiple `BEGIN' and `END' rules are useful for writing library
-functions, because each library file can have its own `BEGIN' and/or
-`END' rule to do its own initialization and/or cleanup. The order in
-which library functions are named on the command line controls the
-order in which their `BEGIN' and `END' rules are executed. Therefore,
-you have to be careful when writing such rules in library files so that
-the order in which they are executed doesn't matter. *Note Options::,
-for more information on using library functions. *Note Library
-Functions::, for a number of useful library functions.
-
- If an `awk' program has only `BEGIN' rules and no other rules, then
-the program exits after the `BEGIN' rules are run.(1) However, if an
-`END' rule exists, then the input is read, even if there are no other
-rules in the program. This is necessary in case the `END' rule checks
-the `FNR' and `NR' variables.
+An 'awk' program may have multiple 'BEGIN' and/or 'END' rules. They are
+executed in the order in which they appear: all the 'BEGIN' rules at
+startup and all the 'END' rules at termination. 'BEGIN' and 'END' rules
+may be intermixed with other rules. This feature was added in the 1987
+version of 'awk' and is included in the POSIX standard. The original
+(1978) version of 'awk' required the 'BEGIN' rule to be placed at the
+beginning of the program, the 'END' rule to be placed at the end, and
+only allowed one of each. This is no longer required, but it is a good
+idea to follow this template in terms of program organization and
+readability.
+
+ Multiple 'BEGIN' and 'END' rules are useful for writing library
+functions, because each library file can have its own 'BEGIN' and/or
+'END' rule to do its own initialization and/or cleanup. The order in
+which library functions are named on the command line controls the order
+in which their 'BEGIN' and 'END' rules are executed. Therefore, you
+have to be careful when writing such rules in library files so that the
+order in which they are executed doesn't matter. *Note Options::, for
+more information on using library functions. *Note Library Functions::,
+for a number of useful library functions.
+
+ If an 'awk' program has only 'BEGIN' rules and no other rules, then
+the program exits after the 'BEGIN' rules are run.(1) However, if an
+'END' rule exists, then the input is read, even if there are no other
+rules in the program. This is necessary in case the 'END' rule checks
+the 'FNR' and 'NR' variables.
---------- Footnotes ----------
- (1) The original version of `awk' kept reading and ignoring input
+ (1) The original version of 'awk' kept reading and ignoring input
until the end of the file was seen.
File: gawk.info, Node: I/O And BEGIN/END, Prev: Using BEGIN/END, Up:
BEGIN/END
-7.1.4.2 Input/Output from `BEGIN' and `END' Rules
+7.1.4.2 Input/Output from 'BEGIN' and 'END' Rules
.................................................
There are several (sometimes subtle) points to be aware of when doing
-I/O from a `BEGIN' or `END' rule. The first has to do with the value
-of `$0' in a `BEGIN' rule. Because `BEGIN' rules are executed before
-any input is read, there simply is no input record, and therefore no
-fields, when executing `BEGIN' rules. References to `$0' and the fields
-yield a null string or zero, depending upon the context. One way to
-give `$0' a real value is to execute a `getline' command without a
-variable (*note Getline::). Another way is simply to assign a value to
-`$0'.
+I/O from a 'BEGIN' or 'END' rule. The first has to do with the value of
+'$0' in a 'BEGIN' rule. Because 'BEGIN' rules are executed before any
+input is read, there simply is no input record, and therefore no fields,
+when executing 'BEGIN' rules. References to '$0' and the fields yield a
+null string or zero, depending upon the context. One way to give '$0' a
+real value is to execute a 'getline' command without a variable (*note
+Getline::). Another way is simply to assign a value to '$0'.
The second point is similar to the first, but from the other
-direction. Traditionally, due largely to implementation issues, `$0'
-and `NF' were _undefined_ inside an `END' rule. The POSIX standard
-specifies that `NF' is available in an `END' rule. It contains the
+direction. Traditionally, due largely to implementation issues, '$0'
+and 'NF' were _undefined_ inside an 'END' rule. The POSIX standard
+specifies that 'NF' is available in an 'END' rule. It contains the
number of fields from the last input record. Most probably due to an
-oversight, the standard does not say that `$0' is also preserved,
+oversight, the standard does not say that '$0' is also preserved,
although logically one would think that it should be. In fact, all of
-BWK `awk', `mawk', and `gawk' preserve the value of `$0' for use in
-`END' rules. Be aware, however, that some other implementations and
-many older versions of Unix `awk' do not.
-
- The third point follows from the first two. The meaning of `print'
-inside a `BEGIN' or `END' rule is the same as always: `print $0'. If
-`$0' is the null string, then this prints an empty record. Many
-longtime `awk' programmers use an unadorned `print' in `BEGIN' and
-`END' rules, to mean `print ""', relying on `$0' being null. Although
-one might generally get away with this in `BEGIN' rules, it is a very
-bad idea in `END' rules, at least in `gawk'. It is also poor style,
-because if an empty line is needed in the output, the program should
-print one explicitly.
-
- Finally, the `next' and `nextfile' statements are not allowed in a
-`BEGIN' rule, because the implicit
+BWK 'awk', 'mawk', and 'gawk' preserve the value of '$0' for use in
+'END' rules. Be aware, however, that some other implementations and
+many older versions of Unix 'awk' do not.
+
+ The third point follows from the first two. The meaning of 'print'
+inside a 'BEGIN' or 'END' rule is the same as always: 'print $0'. If
+'$0' is the null string, then this prints an empty record. Many
+longtime 'awk' programmers use an unadorned 'print' in 'BEGIN' and 'END'
+rules, to mean 'print ""', relying on '$0' being null. Although one
+might generally get away with this in 'BEGIN' rules, it is a very bad
+idea in 'END' rules, at least in 'gawk'. It is also poor style, because
+if an empty line is needed in the output, the program should print one
+explicitly.
+
+ Finally, the 'next' and 'nextfile' statements are not allowed in a
+'BEGIN' rule, because the implicit
read-a-record-and-match-against-the-rules loop has not started yet.
-Similarly, those statements are not valid in an `END' rule, because all
+Similarly, those statements are not valid in an 'END' rule, because all
the input has been read. (*Note Next Statement::, and *note Nextfile
Statement::,.)
File: gawk.info, Node: BEGINFILE/ENDFILE, Next: Empty, Prev: BEGIN/END,
Up: Pattern Overview
-7.1.5 The `BEGINFILE' and `ENDFILE' Special Patterns
+7.1.5 The 'BEGINFILE' and 'ENDFILE' Special Patterns
----------------------------------------------------
-This minor node describes a `gawk'-specific feature.
+This minor node describes a 'gawk'-specific feature.
- Two special kinds of rule, `BEGINFILE' and `ENDFILE', give you
-"hooks" into `gawk''s command-line file processing loop. As with the
-`BEGIN' and `END' rules (*note BEGIN/END::), all `BEGINFILE' rules in a
-program are merged, in the order they are read by `gawk', and all
-`ENDFILE' rules are merged as well.
+ Two special kinds of rule, 'BEGINFILE' and 'ENDFILE', give you
+"hooks" into 'gawk''s command-line file processing loop. As with the
+'BEGIN' and 'END' rules (*note BEGIN/END::), all 'BEGINFILE' rules in a
+program are merged, in the order they are read by 'gawk', and all
+'ENDFILE' rules are merged as well.
- The body of the `BEGINFILE' rules is executed just before `gawk'
-reads the first record from a file. `FILENAME' is set to the name of
-the current file, and `FNR' is set to zero.
+ The body of the 'BEGINFILE' rules is executed just before 'gawk'
+reads the first record from a file. 'FILENAME' is set to the name of
+the current file, and 'FNR' is set to zero.
- The `BEGINFILE' rule provides you the opportunity to accomplish two
+ The 'BEGINFILE' rule provides you the opportunity to accomplish two
tasks that would otherwise be difficult or impossible to perform:
* You can test if the file is readable. Normally, it is a fatal
@@ -9339,39 +9293,39 @@ tasks that would otherwise be difficult or impossible
to perform:
reading. However, you can bypass the fatal error and move on to
the next file on the command line.
- You do this by checking if the `ERRNO' variable is not the empty
- string; if so, then `gawk' was not able to open the file. In this
- case, your program can execute the `nextfile' statement (*note
- Nextfile Statement::). This causes `gawk' to skip the file
- entirely. Otherwise, `gawk' exits with the usual fatal error.
+ You do this by checking if the 'ERRNO' variable is not the empty
+ string; if so, then 'gawk' was not able to open the file. In this
+ case, your program can execute the 'nextfile' statement (*note
+ Nextfile Statement::). This causes 'gawk' to skip the file
+ entirely. Otherwise, 'gawk' exits with the usual fatal error.
* If you have written extensions that modify the record handling (by
inserting an "input parser"; *note Input Parsers::), you can invoke
- them at this point, before `gawk' has started processing the file.
+ them at this point, before 'gawk' has started processing the file.
(This is a _very_ advanced feature, currently used only by the
- `gawkextlib' project (http://sourceforge.net/projects/gawkextlib).)
+ 'gawkextlib' project (http://sourceforge.net/projects/gawkextlib).)
- The `ENDFILE' rule is called when `gawk' has finished processing the
+ The 'ENDFILE' rule is called when 'gawk' has finished processing the
last record in an input file. For the last input file, it will be
-called before any `END' rules. The `ENDFILE' rule is executed even for
+called before any 'END' rules. The 'ENDFILE' rule is executed even for
empty input files.
Normally, when an error occurs when reading input in the normal
-input-processing loop, the error is fatal. However, if an `ENDFILE'
-rule is present, the error becomes non-fatal, and instead `ERRNO' is
+input-processing loop, the error is fatal. However, if an 'ENDFILE'
+rule is present, the error becomes non-fatal, and instead 'ERRNO' is
set. This makes it possible to catch and process I/O errors at the
-level of the `awk' program.
+level of the 'awk' program.
- The `next' statement (*note Next Statement::) is not allowed inside
-either a `BEGINFILE' or an `ENDFILE' rule. The `nextfile' statement is
-allowed only inside a `BEGINFILE' rule, not inside an `ENDFILE' rule.
+ The 'next' statement (*note Next Statement::) is not allowed inside
+either a 'BEGINFILE' or an 'ENDFILE' rule. The 'nextfile' statement is
+allowed only inside a 'BEGINFILE' rule, not inside an 'ENDFILE' rule.
- The `getline' statement (*note Getline::) is restricted inside both
-`BEGINFILE' and `ENDFILE': only redirected forms of `getline' are
+ The 'getline' statement (*note Getline::) is restricted inside both
+'BEGINFILE' and 'ENDFILE': only redirected forms of 'getline' are
allowed.
- `BEGINFILE' and `ENDFILE' are `gawk' extensions. In most other
-`awk' implementations, or if `gawk' is in compatibility mode (*note
+ 'BEGINFILE' and 'ENDFILE' are 'gawk' extensions. In most other 'awk'
+implementations, or if 'gawk' is in compatibility mode (*note
Options::), they are not special.
@@ -9393,10 +9347,10 @@ File: gawk.info, Node: Using Shell Variables, Next:
Action Overview, Prev: Pa
7.2 Using Shell Variables in Programs
=====================================
-`awk' programs are often used as components in larger programs written
+'awk' programs are often used as components in larger programs written
in shell. For example, it is very common to use a shell variable to
-hold a pattern that the `awk' program searches for. There are two ways
-to get the value of the shell variable into the body of the `awk'
+hold a pattern that the 'awk' program searches for. There are two ways
+to get the value of the shell variable into the body of the 'awk'
program.
A common method is to use shell quoting to substitute the variable's
@@ -9408,35 +9362,35 @@ following program:
awk "/$pattern/ "'{ nmatches++ }
END { print nmatches, "found" }' /path/to/data
-The `awk' program consists of two pieces of quoted text that are
+The 'awk' program consists of two pieces of quoted text that are
concatenated together to form the program. The first part is
-double-quoted, which allows substitution of the `pattern' shell
-variable inside the quotes. The second part is single-quoted.
+double-quoted, which allows substitution of the 'pattern' shell variable
+inside the quotes. The second part is single-quoted.
Variable substitution via quoting works, but can potentially be
messy. It requires a good understanding of the shell's quoting rules
(*note Quoting::), and it's often difficult to correctly match up the
quotes when reading the program.
- A better method is to use `awk''s variable assignment feature (*note
-Assignment Options::) to assign the shell variable's value to an `awk'
-variable. Then use dynamic regexps to match the pattern (*note
-Computed Regexps::). The following shows how to redo the previous
-example using this technique:
+ A better method is to use 'awk''s variable assignment feature (*note
+Assignment Options::) to assign the shell variable's value to an 'awk'
+variable. Then use dynamic regexps to match the pattern (*note Computed
+Regexps::). The following shows how to redo the previous example using
+this technique:
printf "Enter search pattern: "
read pattern
awk -v pat="$pattern" '$0 ~ pat { nmatches++ }
END { print nmatches, "found" }' /path/to/data
-Now, the `awk' program is just one single-quoted string. The
-assignment `-v pat="$pattern"' still requires double quotes, in case
-there is whitespace in the value of `$pattern'. The `awk' variable
-`pat' could be named `pattern' too, but that would be more confusing.
-Using a variable also provides more flexibility, as the variable can be
-used anywhere inside the program--for printing, as an array subscript,
-or for any other use--without requiring the quoting tricks at every
-point in the program.
+Now, the 'awk' program is just one single-quoted string. The assignment
+'-v pat="$pattern"' still requires double quotes, in case there is
+whitespace in the value of '$pattern'. The 'awk' variable 'pat' could
+be named 'pattern' too, but that would be more confusing. Using a
+variable also provides more flexibility, as the variable can be used
+anywhere inside the program--for printing, as an array subscript, or for
+any other use--without requiring the quoting tricks at every point in
+the program.
File: gawk.info, Node: Action Overview, Next: Statements, Prev: Using Shell
Variables, Up: Patterns and Actions
@@ -9444,55 +9398,55 @@ File: gawk.info, Node: Action Overview, Next:
Statements, Prev: Using Shell V
7.3 Actions
===========
-An `awk' program or script consists of a series of rules and function
+An 'awk' program or script consists of a series of rules and function
definitions interspersed. (Functions are described later. *Note
User-defined::.) A rule contains a pattern and an action, either of
which (but not both) may be omitted. The purpose of the "action" is to
-tell `awk' what to do once a match for the pattern is found. Thus, in
-outline, an `awk' program generally looks like this:
+tell 'awk' what to do once a match for the pattern is found. Thus, in
+outline, an 'awk' program generally looks like this:
- [PATTERN] `{ ACTION }'
- PATTERN [`{ ACTION }']
+ [PATTERN] '{ ACTION }'
+ PATTERN ['{ ACTION }']
...
- `function NAME(ARGS) { ... }'
+ 'function NAME(ARGS) { ... }'
...
- An action consists of one or more `awk' "statements", enclosed in
-braces (`{...}'). Each statement specifies one thing to do. The
+ An action consists of one or more 'awk' "statements", enclosed in
+braces ('{...}'). Each statement specifies one thing to do. The
statements are separated by newlines or semicolons. The braces around
an action must be used even if the action contains only one statement,
-or if it contains no statements at all. However, if you omit the
-action entirely, omit the braces as well. An omitted action is
-equivalent to `{ print $0 }':
+or if it contains no statements at all. However, if you omit the action
+entirely, omit the braces as well. An omitted action is equivalent to
+'{ print $0 }':
- /foo/ { } match `foo', do nothing -- empty action
- /foo/ match `foo', print the record -- omitted action
+ /foo/ { } match 'foo', do nothing -- empty action
+ /foo/ match 'foo', print the record -- omitted action
- The following types of statements are supported in `awk':
+ The following types of statements are supported in 'awk':
Expressions
- Call functions or assign values to variables (*note
- Expressions::). Executing this kind of statement simply computes
- the value of the expression. This is useful when the expression
- has side effects (*note Assignment Ops::).
+ Call functions or assign values to variables (*note Expressions::).
+ Executing this kind of statement simply computes the value of the
+ expression. This is useful when the expression has side effects
+ (*note Assignment Ops::).
Control statements
- Specify the control flow of `awk' programs. The `awk' language
- gives you C-like constructs (`if', `for', `while', and `do') as
+ Specify the control flow of 'awk' programs. The 'awk' language
+ gives you C-like constructs ('if', 'for', 'while', and 'do') as
well as a few special ones (*note Statements::).
Compound statements
Enclose one or more statements in braces. A compound statement is
used in order to put several statements together in the body of an
- `if', `while', `do', or `for' statement.
+ 'if', 'while', 'do', or 'for' statement.
Input statements
- Use the `getline' command (*note Getline::). Also supplied in
- `awk' are the `next' statement (*note Next Statement::) and the
- `nextfile' statement (*note Nextfile Statement::).
+ Use the 'getline' command (*note Getline::). Also supplied in
+ 'awk' are the 'next' statement (*note Next Statement::) and the
+ 'nextfile' statement (*note Nextfile Statement::).
Output statements
- Such as `print' and `printf'. *Note Printing::.
+ Such as 'print' and 'printf'. *Note Printing::.
Deletion statements
For deleting array elements. *Note Delete::.
@@ -9503,13 +9457,13 @@ File: gawk.info, Node: Statements, Next: Built-in
Variables, Prev: Action Ove
7.4 Control Statements in Actions
=================================
-"Control statements", such as `if', `while', and so on, control the
-flow of execution in `awk' programs. Most of `awk''s control
-statements are patterned after similar statements in C.
+"Control statements", such as 'if', 'while', and so on, control the flow
+of execution in 'awk' programs. Most of 'awk''s control statements are
+patterned after similar statements in C.
- All the control statements start with special keywords, such as `if'
-and `while', to distinguish them from simple expressions. Many control
-statements contain other statements. For example, the `if' statement
+ All the control statements start with special keywords, such as 'if'
+and 'while', to distinguish them from simple expressions. Many control
+statements contain other statements. For example, the 'if' statement
contains another statement that may or may not be executed. The
contained statement is called the "body". To include more than one
statement in the body, group them into a single "compound statement"
@@ -9517,7 +9471,7 @@ with braces, separating them with newlines or semicolons.
* Menu:
-* If Statement:: Conditionally execute some `awk'
+* If Statement:: Conditionally execute some 'awk'
statements.
* While Statement:: Loop until some condition is satisfied.
* Do Statement:: Do specified action while looping until some
@@ -9531,56 +9485,55 @@ with braces, separating them with newlines or
semicolons.
loop.
* Next Statement:: Stop processing the current input record.
* Nextfile Statement:: Stop processing the current file.
-* Exit Statement:: Stop execution of `awk'.
+* Exit Statement:: Stop execution of 'awk'.
File: gawk.info, Node: If Statement, Next: While Statement, Up: Statements
-7.4.1 The `if'-`else' Statement
+7.4.1 The 'if'-'else' Statement
-------------------------------
-The `if'-`else' statement is `awk''s decision-making statement. It
+The 'if'-'else' statement is 'awk''s decision-making statement. It
looks like this:
- `if (CONDITION) THEN-BODY' [`else ELSE-BODY']
+ 'if (CONDITION) THEN-BODY' ['else ELSE-BODY']
The CONDITION is an expression that controls what the rest of the
statement does. If the CONDITION is true, THEN-BODY is executed;
-otherwise, ELSE-BODY is executed. The `else' part of the statement is
-optional. The condition is considered false if its value is zero or
-the null string; otherwise, the condition is true. Refer to the
-following:
+otherwise, ELSE-BODY is executed. The 'else' part of the statement is
+optional. The condition is considered false if its value is zero or the
+null string; otherwise, the condition is true. Refer to the following:
if (x % 2 == 0)
print "x is even"
else
print "x is odd"
- In this example, if the expression `x % 2 == 0' is true (i.e., if
-the value of `x' is evenly divisible by two), then the first `print'
-statement is executed; otherwise, the second `print' statement is
-executed. If the `else' keyword appears on the same line as THEN-BODY
+ In this example, if the expression 'x % 2 == 0' is true (i.e., if the
+value of 'x' is evenly divisible by two), then the first 'print'
+statement is executed; otherwise, the second 'print' statement is
+executed. If the 'else' keyword appears on the same line as THEN-BODY
and THEN-BODY is not a compound statement (i.e., not surrounded by
-braces), then a semicolon must separate THEN-BODY from the `else'. To
+braces), then a semicolon must separate THEN-BODY from the 'else'. To
illustrate this, the previous example can be rewritten as:
if (x % 2 == 0) print "x is even"; else
print "x is odd"
-If the `;' is left out, `awk' can't interpret the statement and it
+If the ';' is left out, 'awk' can't interpret the statement and it
produces a syntax error. Don't actually write programs this way,
-because a human reader might fail to see the `else' if it is not the
+because a human reader might fail to see the 'else' if it is not the
first thing on its line.
File: gawk.info, Node: While Statement, Next: Do Statement, Prev: If
Statement, Up: Statements
-7.4.2 The `while' Statement
+7.4.2 The 'while' Statement
---------------------------
-In programming, a "loop" is a part of a program that can be executed
-two or more times in succession. The `while' statement is the simplest
-looping statement in `awk'. It repeatedly executes a statement as long
+In programming, a "loop" is a part of a program that can be executed two
+or more times in succession. The 'while' statement is the simplest
+looping statement in 'awk'. It repeatedly executes a statement as long
as a condition is true. For example:
while (CONDITION)
@@ -9588,13 +9541,13 @@ as a condition is true. For example:
BODY is a statement called the "body" of the loop, and CONDITION is an
expression that controls how long the loop keeps running. The first
-thing the `while' statement does is test the CONDITION. If the
+thing the 'while' statement does is test the CONDITION. If the
CONDITION is true, it executes the statement BODY. (The CONDITION is
true when the value is not zero and not a null string.) After BODY has
been executed, CONDITION is tested again, and if it is still true, BODY
executes again. This process repeats until the CONDITION is no longer
true. If the CONDITION is initially false, the body of the loop never
-executes and `awk' continues with the statement following the loop.
+executes and 'awk' continues with the statement following the loop.
This example prints the first three fields of each record, one per line:
awk '
@@ -9608,11 +9561,11 @@ This example prints the first three fields of each
record, one per line:
The body of this loop is a compound statement enclosed in braces,
containing two statements. The loop works in the following manner:
-first, the value of `i' is set to one. Then, the `while' statement
-tests whether `i' is less than or equal to three. This is true when
-`i' equals one, so the `i'th field is printed. Then the `i++'
-increments the value of `i' and the loop repeats. The loop terminates
-when `i' reaches four.
+first, the value of 'i' is set to one. Then, the 'while' statement
+tests whether 'i' is less than or equal to three. This is true when 'i'
+equals one, so the 'i'th field is printed. Then the 'i++' increments
+the value of 'i' and the loop repeats. The loop terminates when 'i'
+reaches four.
A newline is not required between the condition and the body;
however, using one makes the program clearer unless the body is a
@@ -9623,12 +9576,12 @@ program is harder to read without it.
File: gawk.info, Node: Do Statement, Next: For Statement, Prev: While
Statement, Up: Statements
-7.4.3 The `do'-`while' Statement
+7.4.3 The 'do'-'while' Statement
--------------------------------
-The `do' loop is a variation of the `while' looping statement. The
-`do' loop executes the BODY once and then repeats the BODY as long as
-the CONDITION is true. It looks like this:
+The 'do' loop is a variation of the 'while' looping statement. The 'do'
+loop executes the BODY once and then repeats the BODY as long as the
+CONDITION is true. It looks like this:
do
BODY
@@ -9636,13 +9589,13 @@ the CONDITION is true. It looks like this:
Even if the CONDITION is false at the start, the BODY executes at
least once (and only once, unless executing BODY makes CONDITION true).
-Contrast this with the corresponding `while' statement:
+Contrast this with the corresponding 'while' statement:
while (CONDITION)
BODY
This statement does not execute the BODY even once if the CONDITION is
-false to begin with. The following is an example of a `do' statement:
+false to begin with. The following is an example of a 'do' statement:
{
i = 1
@@ -9653,26 +9606,26 @@ false to begin with. The following is an example of a
`do' statement:
}
This program prints each input record 10 times. However, it isn't a
-very realistic example, because in this case an ordinary `while' would
+very realistic example, because in this case an ordinary 'while' would
do just as well. This situation reflects actual experience; only
-occasionally is there a real use for a `do' statement.
+occasionally is there a real use for a 'do' statement.
File: gawk.info, Node: For Statement, Next: Switch Statement, Prev: Do
Statement, Up: Statements
-7.4.4 The `for' Statement
+7.4.4 The 'for' Statement
-------------------------
-The `for' statement makes it more convenient to count iterations of a
-loop. The general form of the `for' statement looks like this:
+The 'for' statement makes it more convenient to count iterations of a
+loop. The general form of the 'for' statement looks like this:
for (INITIALIZATION; CONDITION; INCREMENT)
BODY
-The INITIALIZATION, CONDITION, and INCREMENT parts are arbitrary `awk'
-expressions, and BODY stands for any `awk' statement.
+The INITIALIZATION, CONDITION, and INCREMENT parts are arbitrary 'awk'
+expressions, and BODY stands for any 'awk' statement.
- The `for' statement starts by executing INITIALIZATION. Then, as
+ The 'for' statement starts by executing INITIALIZATION. Then, as
long as the CONDITION is true, it repeatedly executes BODY and then
INCREMENT. Typically, INITIALIZATION sets a variable to either zero or
one, INCREMENT adds one to it, and CONDITION compares it against the
@@ -9687,34 +9640,33 @@ desired number of iterations. For example:
This prints the first three fields of each input record, with one field
per line.
- It isn't possible to set more than one variable in the
-INITIALIZATION part without using a multiple assignment statement such
-as `x = y = 0'. This makes sense only if all the initial values are
-equal. (But it is possible to initialize additional variables by
-writing their assignments as separate statements preceding the `for'
-loop.)
+ It isn't possible to set more than one variable in the INITIALIZATION
+part without using a multiple assignment statement such as 'x = y = 0'.
+This makes sense only if all the initial values are equal. (But it is
+possible to initialize additional variables by writing their assignments
+as separate statements preceding the 'for' loop.)
- The same is true of the INCREMENT part. Incrementing additional
+ The same is true of the INCREMENT part. Incrementing additional
variables requires separate statements at the end of the loop. The C
compound expression, using C's comma operator, is useful in this
-context, but it is not supported in `awk'.
+context, but it is not supported in 'awk'.
Most often, INCREMENT is an increment expression, as in the previous
-example. But this is not required; it can be any expression
-whatsoever. For example, the following statement prints all the powers
-of two between 1 and 100:
+example. But this is not required; it can be any expression whatsoever.
+For example, the following statement prints all the powers of two
+between 1 and 100:
for (i = 1; i <= 100; i *= 2)
print i
If there is nothing to be done, any of the three expressions in the
-parentheses following the `for' keyword may be omitted. Thus,
-`for (; x > 0;)' is equivalent to `while (x > 0)'. If the CONDITION is
-omitted, it is treated as true, effectively yielding an "infinite loop"
-(i.e., a loop that never terminates).
+parentheses following the 'for' keyword may be omitted. Thus, 'for (; x > 0;)'
+is equivalent to 'while (x > 0)'. If the CONDITION is omitted, it is
+treated as true, effectively yielding an "infinite loop" (i.e., a loop
+that never terminates).
- In most cases, a `for' loop is an abbreviation for a `while' loop,
-as shown here:
+ In most cases, a 'for' loop is an abbreviation for a 'while' loop, as
+shown here:
INITIALIZATION
while (CONDITION) {
@@ -9722,46 +9674,46 @@ as shown here:
INCREMENT
}
-The only exception is when the `continue' statement (*note Continue
-Statement::) is used inside the loop. Changing a `for' statement to a
-`while' statement in this way can change the effect of the `continue'
+The only exception is when the 'continue' statement (*note Continue
+Statement::) is used inside the loop. Changing a 'for' statement to a
+'while' statement in this way can change the effect of the 'continue'
statement inside the loop.
- The `awk' language has a `for' statement in addition to a `while'
-statement because a `for' loop is often both less work to type and more
+ The 'awk' language has a 'for' statement in addition to a 'while'
+statement because a 'for' loop is often both less work to type and more
natural to think of. Counting the number of iterations is very common
-in loops. It can be easier to think of this counting as part of
-looping rather than as something to do inside the loop.
+in loops. It can be easier to think of this counting as part of looping
+rather than as something to do inside the loop.
- There is an alternative version of the `for' loop, for iterating over
+ There is an alternative version of the 'for' loop, for iterating over
all the indices of an array:
for (i in array)
DO SOMETHING WITH array[i]
*Note Scanning an Array::, for more information on this version of the
-`for' loop.
+'for' loop.
File: gawk.info, Node: Switch Statement, Next: Break Statement, Prev: For
Statement, Up: Statements
-7.4.5 The `switch' Statement
+7.4.5 The 'switch' Statement
----------------------------
-This minor node describes a `gawk'-specific feature. If `gawk' is in
+This minor node describes a 'gawk'-specific feature. If 'gawk' is in
compatibility mode (*note Options::), it is not available.
- The `switch' statement allows the evaluation of an expression and
-the execution of statements based on a `case' match. Case statements
-are checked for a match in the order they are defined. If no suitable
-`case' is found, the `default' section is executed, if supplied.
+ The 'switch' statement allows the evaluation of an expression and the
+execution of statements based on a 'case' match. Case statements are
+checked for a match in the order they are defined. If no suitable
+'case' is found, the 'default' section is executed, if supplied.
- Each `case' contains a single constant, be it numeric, string, or
-regexp. The `switch' expression is evaluated, and then each `case''s
-constant is compared against the result in turn. The type of constant
+ Each 'case' contains a single constant, be it numeric, string, or
+regexp. The 'switch' expression is evaluated, and then each 'case''s
+constant is compared against the result in turn. The type of constant
determines the comparison: numeric or string do the usual comparisons.
A regexp constant does a regular expression match against the string
-value of the original expression. The general form of the `switch'
+value of the original expression. The general form of the 'switch'
statement looks like this:
switch (EXPRESSION) {
@@ -9771,10 +9723,10 @@ statement looks like this:
DEFAULT-BODY
}
- Control flow in the `switch' statement works as it does in C. Once a
-match to a given case is made, the case statement bodies execute until
-a `break', `continue', `next', `nextfile', or `exit' is encountered, or
-the end of the `switch' statement itself. For example:
+ Control flow in the 'switch' statement works as it does in C. Once a
+match to a given case is made, the case statement bodies execute until a
+'break', 'continue', 'next', 'nextfile', or 'exit' is encountered, or
+the end of the 'switch' statement itself. For example:
while ((c = getopt(ARGC, ARGV, "aksx")) != -1) {
switch (c) {
@@ -9801,21 +9753,21 @@ the end of the `switch' statement itself. For example:
}
Note that if none of the statements specified here halt execution of
-a matched `case' statement, execution falls through to the next `case'
-until execution halts. In this example, the `case' for `"?"' falls
-through to the `default' case, which is to call a function named
-`usage()'. (The `getopt()' function being called here is described in
+a matched 'case' statement, execution falls through to the next 'case'
+until execution halts. In this example, the 'case' for '"?"' falls
+through to the 'default' case, which is to call a function named
+'usage()'. (The 'getopt()' function being called here is described in
*note Getopt Function::.)
File: gawk.info, Node: Break Statement, Next: Continue Statement, Prev:
Switch Statement, Up: Statements
-7.4.6 The `break' Statement
+7.4.6 The 'break' Statement
---------------------------
-The `break' statement jumps out of the innermost `for', `while', or
-`do' loop that encloses it. The following example finds the smallest
-divisor of any integer, and also identifies prime numbers:
+The 'break' statement jumps out of the innermost 'for', 'while', or 'do'
+loop that encloses it. The following example finds the smallest divisor
+of any integer, and also identifies prime numbers:
# find smallest divisor of num
{
@@ -9830,15 +9782,15 @@ divisor of any integer, and also identifies prime
numbers:
printf "%d is prime\n", num
}
- When the remainder is zero in the first `if' statement, `awk'
-immediately "breaks out" of the containing `for' loop. This means that
-`awk' proceeds immediately to the statement following the loop and
-continues processing. (This is very different from the `exit'
-statement, which stops the entire `awk' program. *Note Exit
+ When the remainder is zero in the first 'if' statement, 'awk'
+immediately "breaks out" of the containing 'for' loop. This means that
+'awk' proceeds immediately to the statement following the loop and
+continues processing. (This is very different from the 'exit'
+statement, which stops the entire 'awk' program. *Note Exit
Statement::.)
- The following program illustrates how the CONDITION of a `for' or
-`while' statement could be replaced with a `break' inside an `if':
+ The following program illustrates how the CONDITION of a 'for' or
+'while' statement could be replaced with a 'break' inside an 'if':
# find smallest divisor of num
{
@@ -9855,30 +9807,30 @@ Statement::.)
}
}
- The `break' statement is also used to break out of the `switch'
+ The 'break' statement is also used to break out of the 'switch'
statement. This is discussed in *note Switch Statement::.
- The `break' statement has no meaning when used outside the body of a
-loop or `switch'. However, although it was never documented,
-historical implementations of `awk' treated the `break' statement
-outside of a loop as if it were a `next' statement (*note Next
-Statement::). (d.c.) Recent versions of BWK `awk' no longer allow
-this usage, nor does `gawk'.
+ The 'break' statement has no meaning when used outside the body of a
+loop or 'switch'. However, although it was never documented, historical
+implementations of 'awk' treated the 'break' statement outside of a loop
+as if it were a 'next' statement (*note Next Statement::). (d.c.)
+Recent versions of BWK 'awk' no longer allow this usage, nor does
+'gawk'.
File: gawk.info, Node: Continue Statement, Next: Next Statement, Prev:
Break Statement, Up: Statements
-7.4.7 The `continue' Statement
+7.4.7 The 'continue' Statement
------------------------------
-Similar to `break', the `continue' statement is used only inside `for',
-`while', and `do' loops. It skips over the rest of the loop body,
+Similar to 'break', the 'continue' statement is used only inside 'for',
+'while', and 'do' loops. It skips over the rest of the loop body,
causing the next cycle around the loop to begin immediately. Contrast
-this with `break', which jumps out of the loop altogether.
+this with 'break', which jumps out of the loop altogether.
- The `continue' statement in a `for' loop directs `awk' to skip the
+ The 'continue' statement in a 'for' loop directs 'awk' to skip the
rest of the body of the loop and resume execution with the
-increment-expression of the `for' statement. The following program
+increment-expression of the 'for' statement. The following program
illustrates this fact:
BEGIN {
@@ -9891,9 +9843,9 @@ illustrates this fact:
}
This program prints all the numbers from 0 to 20--except for 5, for
-which the `printf' is skipped. Because the increment `x++' is not
-skipped, `x' does not remain stuck at 5. Contrast the `for' loop from
-the previous example with the following `while' loop:
+which the 'printf' is skipped. Because the increment 'x++' is not
+skipped, 'x' does not remain stuck at 5. Contrast the 'for' loop from
+the previous example with the following 'while' loop:
BEGIN {
x = 0
@@ -9906,42 +9858,42 @@ the previous example with the following `while' loop:
print ""
}
-This program loops forever once `x' reaches 5, because the increment
-(`x++') is never reached.
+This program loops forever once 'x' reaches 5, because the increment
+('x++') is never reached.
- The `continue' statement has no special meaning with respect to the
-`switch' statement, nor does it have any meaning when used outside the
-body of a loop. Historical versions of `awk' treated a `continue'
-statement outside a loop the same way they treated a `break' statement
-outside a loop: as if it were a `next' statement (*note Next
-Statement::). (d.c.) Recent versions of BWK `awk' no longer work this
-way, nor does `gawk'.
+ The 'continue' statement has no special meaning with respect to the
+'switch' statement, nor does it have any meaning when used outside the
+body of a loop. Historical versions of 'awk' treated a 'continue'
+statement outside a loop the same way they treated a 'break' statement
+outside a loop: as if it were a 'next' statement (*note Next
+Statement::). (d.c.) Recent versions of BWK 'awk' no longer work this
+way, nor does 'gawk'.
File: gawk.info, Node: Next Statement, Next: Nextfile Statement, Prev:
Continue Statement, Up: Statements
-7.4.8 The `next' Statement
+7.4.8 The 'next' Statement
--------------------------
-The `next' statement forces `awk' to immediately stop processing the
-current record and go on to the next record. This means that no
-further rules are executed for the current record, and the rest of the
-current rule's action isn't executed.
+The 'next' statement forces 'awk' to immediately stop processing the
+current record and go on to the next record. This means that no further
+rules are executed for the current record, and the rest of the current
+rule's action isn't executed.
- Contrast this with the effect of the `getline' function (*note
-Getline::). That also causes `awk' to read the next record
-immediately, but it does not alter the flow of control in any way
-(i.e., the rest of the current action executes with a new input record).
+ Contrast this with the effect of the 'getline' function (*note
+Getline::). That also causes 'awk' to read the next record immediately,
+but it does not alter the flow of control in any way (i.e., the rest of
+the current action executes with a new input record).
- At the highest level, `awk' program execution is a loop that reads
-an input record and then tests each rule's pattern against it. If you
-think of this loop as a `for' statement whose body contains the rules,
-then the `next' statement is analogous to a `continue' statement. It
+ At the highest level, 'awk' program execution is a loop that reads an
+input record and then tests each rule's pattern against it. If you
+think of this loop as a 'for' statement whose body contains the rules,
+then the 'next' statement is analogous to a 'continue' statement. It
skips to the end of the body of this implicit loop and executes the
increment (which reads another record).
- For example, suppose an `awk' program works only on records with
-four fields, and it shouldn't fail when given bad input. To avoid
+ For example, suppose an 'awk' program works only on records with four
+fields, and it shouldn't fail when given bad input. To avoid
complicating the rest of the program, write a "weed out" rule near the
beginning, in the following manner:
@@ -9950,119 +9902,119 @@ beginning, in the following manner:
next
}
-Because of the `next' statement, the program's subsequent rules won't
+Because of the 'next' statement, the program's subsequent rules won't
see the bad record. The error message is redirected to the standard
error output stream, as error messages should be. For more detail, see
*note Special Files::.
- If the `next' statement causes the end of the input to be reached,
-then the code in any `END' rules is executed. *Note BEGIN/END::.
+ If the 'next' statement causes the end of the input to be reached,
+then the code in any 'END' rules is executed. *Note BEGIN/END::.
- The `next' statement is not allowed inside `BEGINFILE' and `ENDFILE'
-rules. *Note BEGINFILE/ENDFILE::.
+ The 'next' statement is not allowed inside 'BEGINFILE' and 'ENDFILE'
+rules. *Note BEGINFILE/ENDFILE::.
According to the POSIX standard, the behavior is undefined if the
-`next' statement is used in a `BEGIN' or `END' rule. `gawk' treats it
+'next' statement is used in a 'BEGIN' or 'END' rule. 'gawk' treats it
as a syntax error. Although POSIX does not disallow it, most other
-`awk' implementations don't allow the `next' statement inside function
-bodies (*note User-defined::). Just as with any other `next'
-statement, a `next' statement inside a function body reads the next
-record and starts processing it with the first rule in the program.
+'awk' implementations don't allow the 'next' statement inside function
+bodies (*note User-defined::). Just as with any other 'next' statement,
+a 'next' statement inside a function body reads the next record and
+starts processing it with the first rule in the program.
File: gawk.info, Node: Nextfile Statement, Next: Exit Statement, Prev: Next
Statement, Up: Statements
-7.4.9 The `nextfile' Statement
+7.4.9 The 'nextfile' Statement
------------------------------
-The `nextfile' statement is similar to the `next' statement. However,
-instead of abandoning processing of the current record, the `nextfile'
-statement instructs `awk' to stop processing the current data file.
+The 'nextfile' statement is similar to the 'next' statement. However,
+instead of abandoning processing of the current record, the 'nextfile'
+statement instructs 'awk' to stop processing the current data file.
- Upon execution of the `nextfile' statement, `FILENAME' is updated to
-the name of the next data file listed on the command line, `FNR' is
+ Upon execution of the 'nextfile' statement, 'FILENAME' is updated to
+the name of the next data file listed on the command line, 'FNR' is
reset to one, and processing starts over with the first rule in the
-program. If the `nextfile' statement causes the end of the input to be
-reached, then the code in any `END' rules is executed. An exception to
-this is when `nextfile' is invoked during execution of any statement in
-an `END' rule; in this case, it causes the program to stop immediately.
+program. If the 'nextfile' statement causes the end of the input to be
+reached, then the code in any 'END' rules is executed. An exception to
+this is when 'nextfile' is invoked during execution of any statement in
+an 'END' rule; in this case, it causes the program to stop immediately.
*Note BEGIN/END::.
- The `nextfile' statement is useful when there are many data files to
+ The 'nextfile' statement is useful when there are many data files to
process but it isn't necessary to process every record in every file.
-Without `nextfile', in order to move on to the next data file, a program
-would have to continue scanning the unwanted records. The `nextfile'
+Without 'nextfile', in order to move on to the next data file, a program
+would have to continue scanning the unwanted records. The 'nextfile'
statement accomplishes this much more efficiently.
- In `gawk', execution of `nextfile' causes additional things to
-happen: any `ENDFILE' rules are executed if `gawk' is not currently in
-an `END' or `BEGINFILE' rule, `ARGIND' is incremented, and any
-`BEGINFILE' rules are executed. (`ARGIND' hasn't been introduced yet.
+ In 'gawk', execution of 'nextfile' causes additional things to
+happen: any 'ENDFILE' rules are executed if 'gawk' is not currently in
+an 'END' or 'BEGINFILE' rule, 'ARGIND' is incremented, and any
+'BEGINFILE' rules are executed. ('ARGIND' hasn't been introduced yet.
*Note Built-in Variables::.)
- With `gawk', `nextfile' is useful inside a `BEGINFILE' rule to skip
-over a file that would otherwise cause `gawk' to exit with a fatal
-error. In this case, `ENDFILE' rules are not executed. *Note
+ With 'gawk', 'nextfile' is useful inside a 'BEGINFILE' rule to skip
+over a file that would otherwise cause 'gawk' to exit with a fatal
+error. In this case, 'ENDFILE' rules are not executed. *Note
BEGINFILE/ENDFILE::.
- Although it might seem that `close(FILENAME)' would accomplish the
-same as `nextfile', this isn't true. `close()' is reserved for closing
+ Although it might seem that 'close(FILENAME)' would accomplish the
+same as 'nextfile', this isn't true. 'close()' is reserved for closing
files, pipes, and coprocesses that are opened with redirections. It is
-not related to the main processing that `awk' does with the files
-listed in `ARGV'.
+not related to the main processing that 'awk' does with the files listed
+in 'ARGV'.
- NOTE: For many years, `nextfile' was a common extension. In
+ NOTE: For many years, 'nextfile' was a common extension. In
September 2012, it was accepted for inclusion into the POSIX
standard. See the Austin Group website
(http://austingroupbugs.net/view.php?id=607).
- The current version of BWK `awk' and `mawk' also support `nextfile'.
-However, they don't allow the `nextfile' statement inside function
-bodies (*note User-defined::). `gawk' does; a `nextfile' inside a
+ The current version of BWK 'awk' and 'mawk' also support 'nextfile'.
+However, they don't allow the 'nextfile' statement inside function
+bodies (*note User-defined::). 'gawk' does; a 'nextfile' inside a
function body reads the next record and starts processing it with the
-first rule in the program, just as any other `nextfile' statement.
+first rule in the program, just as any other 'nextfile' statement.
File: gawk.info, Node: Exit Statement, Prev: Nextfile Statement, Up:
Statements
-7.4.10 The `exit' Statement
+7.4.10 The 'exit' Statement
---------------------------
-The `exit' statement causes `awk' to immediately stop executing the
+The 'exit' statement causes 'awk' to immediately stop executing the
current rule and to stop processing input; any remaining input is
-ignored. The `exit' statement is written as follows:
-
- `exit' [RETURN CODE]
-
- When an `exit' statement is executed from a `BEGIN' rule, the
-program stops processing everything immediately. No input records are
-read. However, if an `END' rule is present, as part of executing the
-`exit' statement, the `END' rule is executed (*note BEGIN/END::). If
-`exit' is used in the body of an `END' rule, it causes the program to
-stop immediately.
-
- An `exit' statement that is not part of a `BEGIN' or `END' rule
-stops the execution of any further automatic rules for the current
-record, skips reading any remaining input records, and executes the
-`END' rule if there is one. `gawk' also skips any `ENDFILE' rules;
-they do not execute.
-
- In such a case, if you don't want the `END' rule to do its job, set
-a variable to a nonzero value before the `exit' statement and check
-that variable in the `END' rule. *Note Assert Function::, for an
-example that does this.
-
- If an argument is supplied to `exit', its value is used as the exit
-status code for the `awk' process. If no argument is supplied, `exit'
-causes `awk' to return a "success" status. In the case where an
-argument is supplied to a first `exit' statement, and then `exit' is
-called a second time from an `END' rule with no argument, `awk' uses
-the previously supplied exit value. (d.c.) *Note Exit Status::, for
-more information.
+ignored. The 'exit' statement is written as follows:
+
+ 'exit' [RETURN CODE]
+
+ When an 'exit' statement is executed from a 'BEGIN' rule, the program
+stops processing everything immediately. No input records are read.
+However, if an 'END' rule is present, as part of executing the 'exit'
+statement, the 'END' rule is executed (*note BEGIN/END::). If 'exit' is
+used in the body of an 'END' rule, it causes the program to stop
+immediately.
+
+ An 'exit' statement that is not part of a 'BEGIN' or 'END' rule stops
+the execution of any further automatic rules for the current record,
+skips reading any remaining input records, and executes the 'END' rule
+if there is one. 'gawk' also skips any 'ENDFILE' rules; they do not
+execute.
+
+ In such a case, if you don't want the 'END' rule to do its job, set a
+variable to a nonzero value before the 'exit' statement and check that
+variable in the 'END' rule. *Note Assert Function::, for an example
+that does this.
+
+ If an argument is supplied to 'exit', its value is used as the exit
+status code for the 'awk' process. If no argument is supplied, 'exit'
+causes 'awk' to return a "success" status. In the case where an
+argument is supplied to a first 'exit' statement, and then 'exit' is
+called a second time from an 'END' rule with no argument, 'awk' uses the
+previously supplied exit value. (d.c.) *Note Exit Status::, for more
+information.
For example, suppose an error condition occurs that is difficult or
impossible to handle. Conventionally, programs report this by exiting
-with a nonzero status. An `awk' program can do this using an `exit'
+with a nonzero status. An 'awk' program can do this using an 'exit'
statement with a nonzero argument, as shown in the following example:
BEGIN {
@@ -10075,9 +10027,8 @@ statement with a nonzero argument, as shown in the
following example:
}
NOTE: For full portability, exit values should be between zero and
- 126, inclusive. Negative values, and values of 127 or greater,
- may not produce consistent results across different operating
- systems.
+ 126, inclusive. Negative values, and values of 127 or greater, may
+ not produce consistent results across different operating systems.
File: gawk.info, Node: Built-in Variables, Next: Pattern Action Summary,
Prev: Statements, Up: Patterns and Actions
@@ -10085,159 +10036,159 @@ File: gawk.info, Node: Built-in Variables, Next:
Pattern Action Summary, Prev
7.5 Predefined Variables
========================
-Most `awk' variables are available to use for your own purposes; they
+Most 'awk' variables are available to use for your own purposes; they
never change unless your program assigns values to them, and they never
affect anything unless your program examines them. However, a few
-variables in `awk' have special built-in meanings. `awk' examines some
-of these automatically, so that they enable you to tell `awk' how to do
-certain things. Others are set automatically by `awk', so that they
-carry information from the internal workings of `awk' to your program.
+variables in 'awk' have special built-in meanings. 'awk' examines some
+of these automatically, so that they enable you to tell 'awk' how to do
+certain things. Others are set automatically by 'awk', so that they
+carry information from the internal workings of 'awk' to your program.
- This minor node documents all of `gawk''s predefined variables, most
+ This minor node documents all of 'gawk''s predefined variables, most
of which are also documented in the major nodes describing their areas
of activity.
* Menu:
* User-modified:: Built-in variables that you change to control
- `awk'.
-* Auto-set:: Built-in variables where `awk' gives
+ 'awk'.
+* Auto-set:: Built-in variables where 'awk' gives
you information.
-* ARGC and ARGV:: Ways to use `ARGC' and `ARGV'.
+* ARGC and ARGV:: Ways to use 'ARGC' and 'ARGV'.
File: gawk.info, Node: User-modified, Next: Auto-set, Up: Built-in Variables
-7.5.1 Built-in Variables That Control `awk'
+7.5.1 Built-in Variables That Control 'awk'
-------------------------------------------
The following is an alphabetical list of variables that you can change
-to control how `awk' does certain things.
+to control how 'awk' does certain things.
- The variables that are specific to `gawk' are marked with a pound
-sign (`#'). These variables are `gawk' extensions. In other `awk'
-implementations or if `gawk' is in compatibility mode (*note
-Options::), they are not special. (Any exceptions are noted in the
-description of each variable.)
+ The variables that are specific to 'gawk' are marked with a pound
+sign ('#'). These variables are 'gawk' extensions. In other 'awk'
+implementations or if 'gawk' is in compatibility mode (*note Options::),
+they are not special. (Any exceptions are noted in the description of
+each variable.)
-`BINMODE #'
+'BINMODE #'
On non-POSIX systems, this variable specifies use of binary mode
- for all I/O. Numeric values of one, two, or three specify that
+ for all I/O. Numeric values of one, two, or three specify that
input files, output files, or all files, respectively, should use
- binary I/O. A numeric value less than zero is treated as zero,
- and a numeric value greater than three is treated as three.
- Alternatively, string values of `"r"' or `"w"' specify that input
- files and output files, respectively, should use binary I/O. A
- string value of `"rw"' or `"wr"' indicates that all files should
- use binary I/O. Any other string value is treated the same as
- `"rw"', but causes `gawk' to generate a warning message.
- `BINMODE' is described in more detail in *note PC Using::. `mawk'
- (*note Other Versions::) also supports this variable, but only
- using numeric values.
-
-``CONVFMT''
+ binary I/O. A numeric value less than zero is treated as zero, and
+ a numeric value greater than three is treated as three.
+ Alternatively, string values of '"r"' or '"w"' specify that input
+ files and output files, respectively, should use binary I/O. A
+ string value of '"rw"' or '"wr"' indicates that all files should
+ use binary I/O. Any other string value is treated the same as
+ '"rw"', but causes 'gawk' to generate a warning message. 'BINMODE'
+ is described in more detail in *note PC Using::. 'mawk' (*note
+ Other Versions::) also supports this variable, but only using
+ numeric values.
+
+'CONVFMT'
A string that controls the conversion of numbers to strings (*note
Conversion::). It works by being passed, in effect, as the first
- argument to the `sprintf()' function (*note String Functions::).
- Its default value is `"%.6g"'. `CONVFMT' was introduced by the
+ argument to the 'sprintf()' function (*note String Functions::).
+ Its default value is '"%.6g"'. 'CONVFMT' was introduced by the
POSIX standard.
-`FIELDWIDTHS #'
- A space-separated list of columns that tells `gawk' how to split
+'FIELDWIDTHS #'
+ A space-separated list of columns that tells 'gawk' how to split
input with fixed columnar boundaries. Assigning a value to
- `FIELDWIDTHS' overrides the use of `FS' and `FPAT' for field
+ 'FIELDWIDTHS' overrides the use of 'FS' and 'FPAT' for field
splitting. *Note Constant Size::, for more information.
-`FPAT #'
- A regular expression (as a string) that tells `gawk' to create the
+'FPAT #'
+ A regular expression (as a string) that tells 'gawk' to create the
fields based on text that matches the regular expression.
- Assigning a value to `FPAT' overrides the use of `FS' and
- `FIELDWIDTHS' for field splitting. *Note Splitting By Content::,
+ Assigning a value to 'FPAT' overrides the use of 'FS' and
+ 'FIELDWIDTHS' for field splitting. *Note Splitting By Content::,
for more information.
-`FS'
- The input field separator (*note Field Separators::). The value
- is a single-character string or a multicharacter regular
- expression that matches the separations between fields in an input
- record. If the value is the null string (`""'), then each
- character in the record becomes a separate field. (This behavior
- is a `gawk' extension. POSIX `awk' does not specify the behavior
- when `FS' is the null string. Nonetheless, some other versions of
- `awk' also treat `""' specially.)
-
- The default value is `" "', a string consisting of a single space.
+'FS'
+ The input field separator (*note Field Separators::). The value is
+ a single-character string or a multicharacter regular expression
+ that matches the separations between fields in an input record. If
+ the value is the null string ('""'), then each character in the
+ record becomes a separate field. (This behavior is a 'gawk'
+ extension. POSIX 'awk' does not specify the behavior when 'FS' is
+ the null string. Nonetheless, some other versions of 'awk' also
+ treat '""' specially.)
+
+ The default value is '" "', a string consisting of a single space.
As a special exception, this value means that any sequence of
spaces, TABs, and/or newlines is a single separator.(1) It also
causes spaces, TABs, and newlines at the beginning and end of a
record to be ignored.
- You can set the value of `FS' on the command line using the `-F'
+ You can set the value of 'FS' on the command line using the '-F'
option:
awk -F, 'PROGRAM' INPUT-FILES
- If `gawk' is using `FIELDWIDTHS' or `FPAT' for field splitting,
- assigning a value to `FS' causes `gawk' to return to the normal,
- `FS'-based field splitting. An easy way to do this is to simply
- say `FS = FS', perhaps with an explanatory comment.
+ If 'gawk' is using 'FIELDWIDTHS' or 'FPAT' for field splitting,
+ assigning a value to 'FS' causes 'gawk' to return to the normal,
+ 'FS'-based field splitting. An easy way to do this is to simply
+ say 'FS = FS', perhaps with an explanatory comment.
-`IGNORECASE #'
- If `IGNORECASE' is nonzero or non-null, then all string comparisons
+'IGNORECASE #'
+ If 'IGNORECASE' is nonzero or non-null, then all string comparisons
and all regular expression matching are case-independent. This
- applies to regexp matching with `~' and `!~', the `gensub()',
- `gsub()', `index()', `match()', `patsplit()', `split()', and
- `sub()' functions, record termination with `RS', and field
- splitting with `FS' and `FPAT'. However, the value of
- `IGNORECASE' does _not_ affect array subscripting and it does not
- affect field splitting when using a single-character field
- separator. *Note Case-sensitivity::.
-
-`LINT #'
- When this variable is true (nonzero or non-null), `gawk' behaves
- as if the `--lint' command-line option is in effect (*note
- Options::). With a value of `"fatal"', lint warnings become fatal
- errors. With a value of `"invalid"', only warnings about things
- that are actually invalid are issued. (This is not fully
- implemented yet.) Any other true value prints nonfatal warnings.
- Assigning a false value to `LINT' turns off the lint warnings.
-
- This variable is a `gawk' extension. It is not special in other
- `awk' implementations. Unlike with the other special variables,
- changing `LINT' does affect the production of lint warnings, even
- if `gawk' is in compatibility mode. Much as the `--lint' and
- `--traditional' options independently control different aspects of
- `gawk''s behavior, the control of lint warnings during program
- execution is independent of the flavor of `awk' being executed.
-
-`OFMT'
+ applies to regexp matching with '~' and '!~', the 'gensub()',
+ 'gsub()', 'index()', 'match()', 'patsplit()', 'split()', and
+ 'sub()' functions, record termination with 'RS', and field
+ splitting with 'FS' and 'FPAT'. However, the value of 'IGNORECASE'
+ does _not_ affect array subscripting and it does not affect field
+ splitting when using a single-character field separator. *Note
+ Case-sensitivity::.
+
+'LINT #'
+ When this variable is true (nonzero or non-null), 'gawk' behaves as
+ if the '--lint' command-line option is in effect (*note Options::).
+ With a value of '"fatal"', lint warnings become fatal errors. With
+ a value of '"invalid"', only warnings about things that are
+ actually invalid are issued. (This is not fully implemented yet.)
+ Any other true value prints nonfatal warnings. Assigning a false
+ value to 'LINT' turns off the lint warnings.
+
+ This variable is a 'gawk' extension. It is not special in other
+ 'awk' implementations. Unlike with the other special variables,
+ changing 'LINT' does affect the production of lint warnings, even
+ if 'gawk' is in compatibility mode. Much as the '--lint' and
+ '--traditional' options independently control different aspects of
+ 'gawk''s behavior, the control of lint warnings during program
+ execution is independent of the flavor of 'awk' being executed.
+
+'OFMT'
A string that controls conversion of numbers to strings (*note
- Conversion::) for printing with the `print' statement. It works
- by being passed as the first argument to the `sprintf()' function
- (*note String Functions::). Its default value is `"%.6g"'.
- Earlier versions of `awk' used `OFMT' to specify the format for
+ Conversion::) for printing with the 'print' statement. It works by
+ being passed as the first argument to the 'sprintf()' function
+ (*note String Functions::). Its default value is '"%.6g"'.
+ Earlier versions of 'awk' used 'OFMT' to specify the format for
converting numbers to strings in general expressions; this is now
- done by `CONVFMT'.
+ done by 'CONVFMT'.
-`OFS'
+'OFS'
The output field separator (*note Output Separators::). It is
- output between the fields printed by a `print' statement. Its
- default value is `" "', a string consisting of a single space.
+ output between the fields printed by a 'print' statement. Its
+ default value is '" "', a string consisting of a single space.
-`ORS'
+'ORS'
The output record separator. It is output at the end of every
- `print' statement. Its default value is `"\n"', the newline
+ 'print' statement. Its default value is '"\n"', the newline
character. (*Note Output Separators::.)
-`PREC #'
+'PREC #'
The working precision of arbitrary-precision floating-point
numbers, 53 bits by default (*note Setting precision::).
-`ROUNDMODE #'
+'ROUNDMODE #'
The rounding mode to use for arbitrary-precision arithmetic on
- numbers, by default `"N"' (`roundTiesToEven' in the IEEE 754
+ numbers, by default '"N"' ('roundTiesToEven' in the IEEE 754
standard; *note Setting the rounding mode::).
-``RS''
+'RS'
The input record separator. Its default value is a string
containing a single newline character, which means that an input
record consists of a single line of text. It can also be the null
@@ -10245,28 +10196,28 @@ description of each variable.)
If it is a regexp, records are separated by matches of the regexp
in the input text. (*Note Records::.)
- The ability for `RS' to be a regular expression is a `gawk'
- extension. In most other `awk' implementations, or if `gawk' is
- in compatibility mode (*note Options::), just the first character
- of `RS''s value is used.
+ The ability for 'RS' to be a regular expression is a 'gawk'
+ extension. In most other 'awk' implementations, or if 'gawk' is in
+ compatibility mode (*note Options::), just the first character of
+ 'RS''s value is used.
-``SUBSEP''
- The subscript separator. It has the default value of `"\034"' and
+'SUBSEP'
+ The subscript separator. It has the default value of '"\034"' and
is used to separate the parts of the indices of a multidimensional
- array. Thus, the expression `foo["A", "B"]' really accesses
- `foo["A\034B"]' (*note Multidimensional::).
+ array. Thus, the expression 'foo["A", "B"]' really accesses
+ 'foo["A\034B"]' (*note Multidimensional::).
-`TEXTDOMAIN #'
- Used for internationalization of programs at the `awk' level. It
+'TEXTDOMAIN #'
+ Used for internationalization of programs at the 'awk' level. It
sets the default text domain for specially marked string constants
- in the source text, as well as for the `dcgettext()',
- `dcngettext()', and `bindtextdomain()' functions (*note
- Internationalization::). The default value of `TEXTDOMAIN' is
- `"messages"'.
+ in the source text, as well as for the 'dcgettext()',
+ 'dcngettext()', and 'bindtextdomain()' functions (*note
+ Internationalization::). The default value of 'TEXTDOMAIN' is
+ '"messages"'.
---------- Footnotes ----------
- (1) In POSIX `awk', newline does not count as whitespace.
+ (1) In POSIX 'awk', newline does not count as whitespace.
File: gawk.info, Node: Auto-set, Next: ARGC and ARGV, Prev: User-modified,
Up: Built-in Variables
@@ -10274,20 +10225,20 @@ File: gawk.info, Node: Auto-set, Next: ARGC and
ARGV, Prev: User-modified, U
7.5.2 Built-in Variables That Convey Information
------------------------------------------------
-The following is an alphabetical list of variables that `awk' sets
+The following is an alphabetical list of variables that 'awk' sets
automatically on certain occasions in order to provide information to
your program.
- The variables that are specific to `gawk' are marked with a pound
-sign (`#'). These variables are `gawk' extensions. In other `awk'
-implementations or if `gawk' is in compatibility mode (*note
-Options::), they are not special:
+ The variables that are specific to 'gawk' are marked with a pound
+sign ('#'). These variables are 'gawk' extensions. In other 'awk'
+implementations or if 'gawk' is in compatibility mode (*note Options::),
+they are not special:
-`ARGC', `ARGV'
- The command-line arguments available to `awk' programs are stored
- in an array called `ARGV'. `ARGC' is the number of command-line
- arguments present. *Note Other Arguments::. Unlike most `awk'
- arrays, `ARGV' is indexed from 0 to `ARGC' - 1. In the following
+'ARGC', 'ARGV'
+ The command-line arguments available to 'awk' programs are stored
+ in an array called 'ARGV'. 'ARGC' is the number of command-line
+ arguments present. *Note Other Arguments::. Unlike most 'awk'
+ arrays, 'ARGV' is indexed from 0 to 'ARGC' - 1. In the following
example:
$ awk 'BEGIN {
@@ -10298,251 +10249,249 @@ Options::), they are not special:
-| inventory-shipped
-| mail-list
- `ARGV[0]' contains `awk', `ARGV[1]' contains `inventory-shipped',
- and `ARGV[2]' contains `mail-list'. The value of `ARGC' is three,
- one more than the index of the last element in `ARGV', because the
+ 'ARGV[0]' contains 'awk', 'ARGV[1]' contains 'inventory-shipped',
+ and 'ARGV[2]' contains 'mail-list'. The value of 'ARGC' is three,
+ one more than the index of the last element in 'ARGV', because the
elements are numbered from zero.
- The names `ARGC' and `ARGV', as well as the convention of indexing
- the array from 0 to `ARGC' - 1, are derived from the C language's
+ The names 'ARGC' and 'ARGV', as well as the convention of indexing
+ the array from 0 to 'ARGC' - 1, are derived from the C language's
method of accessing command-line arguments.
- The value of `ARGV[0]' can vary from system to system. Also, you
- should note that the program text is _not_ included in `ARGV', nor
- are any of `awk''s command-line options. *Note ARGC and ARGV::,
- for information about how `awk' uses these variables. (d.c.)
+ The value of 'ARGV[0]' can vary from system to system. Also, you
+ should note that the program text is _not_ included in 'ARGV', nor
+ are any of 'awk''s command-line options. *Note ARGC and ARGV::,
+ for information about how 'awk' uses these variables. (d.c.)
-`ARGIND #'
- The index in `ARGV' of the current file being processed. Every
- time `gawk' opens a new data file for processing, it sets `ARGIND'
- to the index in `ARGV' of the file name. When `gawk' is
- processing the input files, `FILENAME == ARGV[ARGIND]' is always
- true.
+'ARGIND #'
+ The index in 'ARGV' of the current file being processed. Every
+ time 'gawk' opens a new data file for processing, it sets 'ARGIND'
+ to the index in 'ARGV' of the file name. When 'gawk' is processing
+ the input files, 'FILENAME == ARGV[ARGIND]' is always true.
This variable is useful in file processing; it allows you to tell
how far along you are in the list of data files as well as to
distinguish between successive instances of the same file name on
the command line.
- While you can change the value of `ARGIND' within your `awk'
- program, `gawk' automatically sets it to a new value when it opens
+ While you can change the value of 'ARGIND' within your 'awk'
+ program, 'gawk' automatically sets it to a new value when it opens
the next file.
-`ENVIRON'
- An associative array containing the values of the environment.
- The array indices are the environment variable names; the elements
- are the values of the particular environment variables. For
- example, `ENVIRON["HOME"]' might be `"/home/arnold"'. Changing
- this array does not affect the environment passed on to any
- programs that `awk' may spawn via redirection or the `system()'
- function. (In a future version of `gawk', it may do so.)
-
- Some operating systems may not have environment variables. On
- such systems, the `ENVIRON' array is empty (except for
- `ENVIRON["AWKPATH"]' and `ENVIRON["AWKLIBPATH"]'; *note AWKPATH
- Variable::, and *note AWKLIBPATH Variable::).
-
-`ERRNO #'
- If a system error occurs during a redirection for `getline', during
- a read for `getline', or during a `close()' operation, then
- `ERRNO' contains a string describing the error.
-
- In addition, `gawk' clears `ERRNO' before opening each
- command-line input file. This enables checking if the file is
- readable inside a `BEGINFILE' pattern (*note BEGINFILE/ENDFILE::).
-
- Otherwise, `ERRNO' works similarly to the C variable `errno'.
- Except for the case just mentioned, `gawk' _never_ clears it (sets
- it to zero or `""'). Thus, you should only expect its value to be
+'ENVIRON'
+ An associative array containing the values of the environment. The
+ array indices are the environment variable names; the elements are
+ the values of the particular environment variables. For example,
+ 'ENVIRON["HOME"]' might be '"/home/arnold"'. Changing this array
+ does not affect the environment passed on to any programs that
+ 'awk' may spawn via redirection or the 'system()' function. (In a
+ future version of 'gawk', it may do so.)
+
+ Some operating systems may not have environment variables. On such
+ systems, the 'ENVIRON' array is empty (except for 'ENVIRON["AWKPATH"]'
+ and 'ENVIRON["AWKLIBPATH"]'; *note AWKPATH Variable::, and *note
+ AWKLIBPATH Variable::).
+
+'ERRNO #'
+ If a system error occurs during a redirection for 'getline', during
+ a read for 'getline', or during a 'close()' operation, then 'ERRNO'
+ contains a string describing the error.
+
+ In addition, 'gawk' clears 'ERRNO' before opening each command-line
+ input file. This enables checking if the file is readable inside a
+ 'BEGINFILE' pattern (*note BEGINFILE/ENDFILE::).
+
+ Otherwise, 'ERRNO' works similarly to the C variable 'errno'.
+ Except for the case just mentioned, 'gawk' _never_ clears it (sets
+ it to zero or '""'). Thus, you should only expect its value to be
meaningful when an I/O operation returns a failure value, such as
- `getline' returning -1. You are, of course, free to clear it
+ 'getline' returning -1. You are, of course, free to clear it
yourself before doing an I/O operation.
-`FILENAME'
+'FILENAME'
The name of the current input file. When no data files are listed
- on the command line, `awk' reads from the standard input and
- `FILENAME' is set to `"-"'. `FILENAME' changes each time a new
- file is read (*note Reading Files::). Inside a `BEGIN' rule, the
- value of `FILENAME' is `""', because there are no input files
- being processed yet.(1) (d.c.) Note, though, that using `getline'
- (*note Getline::) inside a `BEGIN' rule can give `FILENAME' a
+ on the command line, 'awk' reads from the standard input and
+ 'FILENAME' is set to '"-"'. 'FILENAME' changes each time a new
+ file is read (*note Reading Files::). Inside a 'BEGIN' rule, the
+ value of 'FILENAME' is '""', because there are no input files being
+ processed yet.(1) (d.c.) Note, though, that using 'getline'
+ (*note Getline::) inside a 'BEGIN' rule can give 'FILENAME' a
value.
-`FNR'
- The current record number in the current file. `awk' increments
- `FNR' each time it reads a new record (*note Records::). `awk'
- resets `FNR' to zero each time it starts a new input file.
+'FNR'
+ The current record number in the current file. 'awk' increments
+ 'FNR' each time it reads a new record (*note Records::). 'awk'
+ resets 'FNR' to zero each time it starts a new input file.
-`NF'
- The number of fields in the current input record. `NF' is set
- each time a new record is read, when a new field is created, or
- when `$0' changes (*note Fields::).
+'NF'
+ The number of fields in the current input record. 'NF' is set each
+ time a new record is read, when a new field is created, or when
+ '$0' changes (*note Fields::).
Unlike most of the variables described in this node, assigning a
- value to `NF' has the potential to affect `awk''s internal
- workings. In particular, assignments to `NF' can be used to
- create fields in or remove fields from the current record. *Note
- Changing Fields::.
+ value to 'NF' has the potential to affect 'awk''s internal
+ workings. In particular, assignments to 'NF' can be used to create
+ fields in or remove fields from the current record. *Note Changing
+ Fields::.
-`FUNCTAB #'
+'FUNCTAB #'
An array whose indices and corresponding values are the names of
all the built-in, user-defined, and extension functions in the
program.
- NOTE: Attempting to use the `delete' statement with the
- `FUNCTAB' array causes a fatal error. Any attempt to assign
- to an element of `FUNCTAB' also causes a fatal error.
+ NOTE: Attempting to use the 'delete' statement with the
+ 'FUNCTAB' array causes a fatal error. Any attempt to assign
+ to an element of 'FUNCTAB' also causes a fatal error.
-`NR'
- The number of input records `awk' has processed since the
- beginning of the program's execution (*note Records::). `awk'
- increments `NR' each time it reads a new record.
+'NR'
+ The number of input records 'awk' has processed since the beginning
+ of the program's execution (*note Records::). 'awk' increments
+ 'NR' each time it reads a new record.
-`PROCINFO #'
+'PROCINFO #'
The elements of this array provide access to information about the
- running `awk' program. The following elements (listed
+ running 'awk' program. The following elements (listed
alphabetically) are guaranteed to be available:
- `PROCINFO["egid"]'
- The value of the `getegid()' system call.
+ 'PROCINFO["egid"]'
+ The value of the 'getegid()' system call.
- `PROCINFO["euid"]'
- The value of the `geteuid()' system call.
+ 'PROCINFO["euid"]'
+ The value of the 'geteuid()' system call.
- `PROCINFO["FS"]'
- This is `"FS"' if field splitting with `FS' is in effect,
- `"FIELDWIDTHS"' if field splitting with `FIELDWIDTHS' is in
- effect, or `"FPAT"' if field matching with `FPAT' is in
+ 'PROCINFO["FS"]'
+ This is '"FS"' if field splitting with 'FS' is in effect,
+ '"FIELDWIDTHS"' if field splitting with 'FIELDWIDTHS' is in
+ effect, or '"FPAT"' if field matching with 'FPAT' is in
effect.
- `PROCINFO["identifiers"]'
+ 'PROCINFO["identifiers"]'
A subarray, indexed by the names of all identifiers used in
- the text of the `awk' program. An "identifier" is simply the
- name of a variable (be it scalar or array), built-in
- function, user-defined function, or extension function. For
- each identifier, the value of the element is one of the
- following:
+ the text of the 'awk' program. An "identifier" is simply the
+ name of a variable (be it scalar or array), built-in function,
+ user-defined function, or extension function. For each
+ identifier, the value of the element is one of the following:
- `"array"'
+ '"array"'
The identifier is an array.
- `"builtin"'
+ '"builtin"'
The identifier is a built-in function.
- `"extension"'
+ '"extension"'
The identifier is an extension function loaded via
- address@hidden' or `-l'.
+ '@load' or '-l'.
- `"scalar"'
+ '"scalar"'
The identifier is a scalar.
- `"untyped"'
+ '"untyped"'
The identifier is untyped (could be used as a scalar or
- an array; `gawk' doesn't know yet).
+ an array; 'gawk' doesn't know yet).
- `"user"'
+ '"user"'
The identifier is a user-defined function.
- The values indicate what `gawk' knows about the identifiers
+ The values indicate what 'gawk' knows about the identifiers
after it has finished parsing the program; they are _not_
updated while the program runs.
- `PROCINFO["gid"]'
- The value of the `getgid()' system call.
+ 'PROCINFO["gid"]'
+ The value of the 'getgid()' system call.
- `PROCINFO["pgrpid"]'
+ 'PROCINFO["pgrpid"]'
The process group ID of the current process.
- `PROCINFO["pid"]'
+ 'PROCINFO["pid"]'
The process ID of the current process.
- `PROCINFO["ppid"]'
+ 'PROCINFO["ppid"]'
The parent process ID of the current process.
- `PROCINFO["sorted_in"]'
- If this element exists in `PROCINFO', its value controls the
- order in which array indices will be processed by `for (INDX
+ 'PROCINFO["sorted_in"]'
+ If this element exists in 'PROCINFO', its value controls the
+ order in which array indices will be processed by 'for (INDX
in ARRAY)' loops. This is an advanced feature, so we defer
the full description until later; see *note Scanning an
Array::.
- `PROCINFO["strftime"]'
- The default time format string for `strftime()'. Assigning a
+ 'PROCINFO["strftime"]'
+ The default time format string for 'strftime()'. Assigning a
new value to this element changes the default. *Note Time
Functions::.
- `PROCINFO["uid"]'
- The value of the `getuid()' system call.
+ 'PROCINFO["uid"]'
+ The value of the 'getuid()' system call.
- `PROCINFO["version"]'
- The version of `gawk'.
+ 'PROCINFO["version"]'
+ The version of 'gawk'.
The following additional elements in the array are available to
provide information about the MPFR and GMP libraries if your
- version of `gawk' supports arbitrary-precision arithmetic (*note
+ version of 'gawk' supports arbitrary-precision arithmetic (*note
Arbitrary Precision Arithmetic::):
- `PROCINFO["mpfr_version"]'
+ 'PROCINFO["mpfr_version"]'
The version of the GNU MPFR library.
- `PROCINFO["gmp_version"]'
+ 'PROCINFO["gmp_version"]'
The version of the GNU MP library.
- `PROCINFO["prec_max"]'
+ 'PROCINFO["prec_max"]'
The maximum precision supported by MPFR.
- `PROCINFO["prec_min"]'
+ 'PROCINFO["prec_min"]'
The minimum precision required by MPFR.
The following additional elements in the array are available to
- provide information about the version of the extension API, if
- your version of `gawk' supports dynamic loading of extension
- functions (*note Dynamic Extensions::):
+ provide information about the version of the extension API, if your
+ version of 'gawk' supports dynamic loading of extension functions
+ (*note Dynamic Extensions::):
- `PROCINFO["api_major"]'
+ 'PROCINFO["api_major"]'
The major version of the extension API.
- `PROCINFO["api_minor"]'
+ 'PROCINFO["api_minor"]'
The minor version of the extension API.
- On some systems, there may be elements in the array, `"group1"'
- through `"groupN"' for some N. N is the number of supplementary
- groups that the process has. Use the `in' operator to test for
+ On some systems, there may be elements in the array, '"group1"'
+ through '"groupN"' for some N. N is the number of supplementary
+ groups that the process has. Use the 'in' operator to test for
these elements (*note Reference to Elements::).
- The `PROCINFO' array has the following additional uses:
+ The 'PROCINFO' array has the following additional uses:
- * It may be used to provide a timeout when reading from any
- open input file, pipe, or coprocess. *Note Read Timeout::,
- for more information.
+ * It may be used to provide a timeout when reading from any open
+ input file, pipe, or coprocess. *Note Read Timeout::, for
+ more information.
* It may be used to cause coprocesses to communicate over
pseudo-ttys instead of through two-way pipes; this is
discussed further in *note Two-way I/O::.
-`RLENGTH'
- The length of the substring matched by the `match()' function
- (*note String Functions::). `RLENGTH' is set by invoking the
- `match()' function. Its value is the length of the matched
- string, or -1 if no match is found.
+'RLENGTH'
+ The length of the substring matched by the 'match()' function
+ (*note String Functions::). 'RLENGTH' is set by invoking the
+ 'match()' function. Its value is the length of the matched string,
+ or -1 if no match is found.
-`RSTART'
+'RSTART'
The start index in characters of the substring that is matched by
- the `match()' function (*note String Functions::). `RSTART' is
- set by invoking the `match()' function. Its value is the position
- of the string where the matched substring starts, or zero if no
- match was found.
+ the 'match()' function (*note String Functions::). 'RSTART' is set
+ by invoking the 'match()' function. Its value is the position of
+ the string where the matched substring starts, or zero if no match
+ was found.
-`RT #'
- The input text that matched the text denoted by `RS', the record
+'RT #'
+ The input text that matched the text denoted by 'RS', the record
separator. It is set every time a record is read.
-`SYMTAB #'
+'SYMTAB #'
An array whose indices are the names of all defined global
- variables and arrays in the program. `SYMTAB' makes `gawk''s
- symbol table visible to the `awk' programmer. It is built as
- `gawk' parses the program and is complete before the program
- starts to run.
+ variables and arrays in the program. 'SYMTAB' makes 'gawk''s
+ symbol table visible to the 'awk' programmer. It is built as
+ 'gawk' parses the program and is complete before the program starts
+ to run.
The array may be used for indirect access to read or write the
value of a variable:
@@ -10551,23 +10500,23 @@ Options::), they are not special:
SYMTAB["foo"] = 4
print foo # prints 4
- The `isarray()' function (*note Type Functions::) may be used to
- test if an element in `SYMTAB' is an array. Also, you may not use
- the `delete' statement with the `SYMTAB' array.
+ The 'isarray()' function (*note Type Functions::) may be used to
+ test if an element in 'SYMTAB' is an array. Also, you may not use
+ the 'delete' statement with the 'SYMTAB' array.
- You may use an index for `SYMTAB' that is not a predefined
+ You may use an index for 'SYMTAB' that is not a predefined
identifier:
SYMTAB["xxx"] = 5
print SYMTAB["xxx"]
- This works as expected: in this case `SYMTAB' acts just like a
+ This works as expected: in this case 'SYMTAB' acts just like a
regular array. The only difference is that you can't then delete
- `SYMTAB["xxx"]'.
+ 'SYMTAB["xxx"]'.
- The `SYMTAB' array is more interesting than it looks. Andrew Schorr
- points out that it effectively gives `awk' data pointers. Consider
- his example:
+ The 'SYMTAB' array is more interesting than it looks. Andrew
+ Schorr points out that it effectively gives 'awk' data pointers.
+ Consider his example:
# Indirect multiply of any variable by amount, return result
@@ -10577,12 +10526,12 @@ Options::), they are not special:
}
NOTE: In order to avoid severe time-travel paradoxes,(2)
- neither `FUNCTAB' nor `SYMTAB' is available as an element
- within the `SYMTAB' array.
+ neither 'FUNCTAB' nor 'SYMTAB' is available as an element
+ within the 'SYMTAB' array.
- Changing `NR' and `FNR'
+ Changing 'NR' and 'FNR'
- `awk' increments `NR' and `FNR' each time it reads a record, instead
+ 'awk' increments 'NR' and 'FNR' each time it reads a record, instead
of setting them to the absolute value of the number of records read.
This means that a program can change these variables and their new
values are incremented for each record. (d.c.) The following example
@@ -10598,14 +10547,14 @@ shows this:
-| 18
-| 19
-Before `FNR' was added to the `awk' language (*note V7/SVR3.1::), many
-`awk' programs used this feature to track the number of records in a
-file by resetting `NR' to zero when `FILENAME' changed.
+Before 'FNR' was added to the 'awk' language (*note V7/SVR3.1::), many
+'awk' programs used this feature to track the number of records in a
+file by resetting 'NR' to zero when 'FILENAME' changed.
---------- Footnotes ----------
- (1) Some early implementations of Unix `awk' initialized `FILENAME'
-to `"-"', even if there were data files to be processed. This behavior
+ (1) Some early implementations of Unix 'awk' initialized 'FILENAME'
+to '"-"', even if there were data files to be processed. This behavior
was incorrect and should not be relied upon in your programs.
(2) Not to mention difficult implementation issues.
@@ -10613,11 +10562,11 @@ was incorrect and should not be relied upon in your
programs.
File: gawk.info, Node: ARGC and ARGV, Prev: Auto-set, Up: Built-in Variables
-7.5.3 Using `ARGC' and `ARGV'
+7.5.3 Using 'ARGC' and 'ARGV'
-----------------------------
*note Auto-set::, presented the following program describing the
-information contained in `ARGC' and `ARGV':
+information contained in 'ARGC' and 'ARGV':
$ awk 'BEGIN {
> for (i = 0; i < ARGC; i++)
@@ -10627,14 +10576,14 @@ information contained in `ARGC' and `ARGV':
-| inventory-shipped
-| mail-list
-In this example, `ARGV[0]' contains `awk', `ARGV[1]' contains
-`inventory-shipped', and `ARGV[2]' contains `mail-list'. Notice that
-the `awk' program is not entered in `ARGV'. The other command-line
+In this example, 'ARGV[0]' contains 'awk', 'ARGV[1]' contains
+'inventory-shipped', and 'ARGV[2]' contains 'mail-list'. Notice that
+the 'awk' program is not entered in 'ARGV'. The other command-line
options, with their arguments, are also not entered. This includes
-variable assignments done with the `-v' option (*note Options::).
+variable assignments done with the '-v' option (*note Options::).
Normal variable assignments on the command line _are_ treated as
-arguments and do show up in the `ARGV' array. Given the following
-program in a file named `showargs.awk':
+arguments and do show up in the 'ARGV' array. Given the following
+program in a file named 'showargs.awk':
BEGIN {
printf "A=%d, B=%d\n", A, B
@@ -10652,37 +10601,37 @@ Running it produces the following:
-| ARGV[2] = /dev/null
-| A=1, B=2
- A program can alter `ARGC' and the elements of `ARGV'. Each time
-`awk' reaches the end of an input file, it uses the next element of
-`ARGV' as the name of the next input file. By storing a different
-string there, a program can change which files are read. Use `"-"' to
+ A program can alter 'ARGC' and the elements of 'ARGV'. Each time
+'awk' reaches the end of an input file, it uses the next element of
+'ARGV' as the name of the next input file. By storing a different
+string there, a program can change which files are read. Use '"-"' to
represent the standard input. Storing additional elements and
-incrementing `ARGC' causes additional files to be read.
+incrementing 'ARGC' causes additional files to be read.
- If the value of `ARGC' is decreased, that eliminates input files
-from the end of the list. By recording the old value of `ARGC'
-elsewhere, a program can treat the eliminated arguments as something
-other than file names.
+ If the value of 'ARGC' is decreased, that eliminates input files from
+the end of the list. By recording the old value of 'ARGC' elsewhere, a
+program can treat the eliminated arguments as something other than file
+names.
To eliminate a file from the middle of the list, store the null
-string (`""') into `ARGV' in place of the file's name. As a special
-feature, `awk' ignores file names that have been replaced with the null
-string. Another option is to use the `delete' statement to remove
-elements from `ARGV' (*note Delete::).
-
- All of these actions are typically done in the `BEGIN' rule, before
-actual processing of the input begins. *Note Split Program::, and
-*note Tee Program::, for examples of each way of removing elements from
-`ARGV'.
-
- To actually get options into an `awk' program, end the `awk' options
-with `--' and then supply the `awk' program's options, in the following
+string ('""') into 'ARGV' in place of the file's name. As a special
+feature, 'awk' ignores file names that have been replaced with the null
+string. Another option is to use the 'delete' statement to remove
+elements from 'ARGV' (*note Delete::).
+
+ All of these actions are typically done in the 'BEGIN' rule, before
+actual processing of the input begins. *Note Split Program::, and *note
+Tee Program::, for examples of each way of removing elements from
+'ARGV'.
+
+ To actually get options into an 'awk' program, end the 'awk' options
+with '--' and then supply the 'awk' program's options, in the following
manner:
awk -f myprog.awk -- -v -q file1 file2 ...
- The following fragment processes `ARGV' in order to examine, and
-then remove, the previously mentioned command-line options:
+ The following fragment processes 'ARGV' in order to examine, and then
+remove, the previously mentioned command-line options:
BEGIN {
for (i = 1; i < ARGC; i++) {
@@ -10700,23 +10649,23 @@ then remove, the previously mentioned command-line
options:
}
}
- Ending the `awk' options with `--' isn't necessary in `gawk'. Unless
-`--posix' has been specified, `gawk' silently puts any unrecognized
-options into `ARGV' for the `awk' program to deal with. As soon as it
-sees an unknown option, `gawk' stops looking for other options that it
-might otherwise recognize. The previous command line with `gawk' would
+ Ending the 'awk' options with '--' isn't necessary in 'gawk'. Unless
+'--posix' has been specified, 'gawk' silently puts any unrecognized
+options into 'ARGV' for the 'awk' program to deal with. As soon as it
+sees an unknown option, 'gawk' stops looking for other options that it
+might otherwise recognize. The previous command line with 'gawk' would
be:
gawk -f myprog.awk -q -v file1 file2 ...
-Because `-q' is not a valid `gawk' option, it and the following `-v'
-are passed on to the `awk' program. (*Note Getopt Function::, for an
-`awk' library function that parses command-line options.)
+Because '-q' is not a valid 'gawk' option, it and the following '-v' are
+passed on to the 'awk' program. (*Note Getopt Function::, for an 'awk'
+library function that parses command-line options.)
When designing your program, you should choose options that don't
-conflict with `gawk''s, because it will process any options that it
+conflict with 'gawk''s, because it will process any options that it
accepts before passing the rest of the command line on to your program.
-Using `#!' with the `-E' option may help (*note Executable Scripts::,
+Using '#!' with the '-E' option may help (*note Executable Scripts::,
and *note Options::,).
@@ -10725,82 +10674,80 @@ File: gawk.info, Node: Pattern Action Summary,
Prev: Built-in Variables, Up:
7.6 Summary
===========
- * Pattern-action pairs make up the basic elements of an `awk'
+ * Pattern-action pairs make up the basic elements of an 'awk'
program. Patterns are either normal expressions, range
expressions, or regexp constants; one of the special keywords
- `BEGIN', `END', `BEGINFILE', or `ENDFILE'; or empty. The action
+ 'BEGIN', 'END', 'BEGINFILE', or 'ENDFILE'; or empty. The action
executes if the current record matches the pattern. Empty
(missing) patterns match all records.
- * I/O from `BEGIN' and `END' rules has certain constraints. This is
- also true, only more so, for `BEGINFILE' and `ENDFILE' rules. The
- latter two give you "hooks" into `gawk''s file processing,
- allowing you to recover from a file that otherwise would cause a
- fatal error (such as a file that cannot be opened).
+ * I/O from 'BEGIN' and 'END' rules has certain constraints. This is
+ also true, only more so, for 'BEGINFILE' and 'ENDFILE' rules. The
+ latter two give you "hooks" into 'gawk''s file processing, allowing
+ you to recover from a file that otherwise would cause a fatal error
+ (such as a file that cannot be opened).
- * Shell variables can be used in `awk' programs by careful use of
- shell quoting. It is easier to pass a shell variable into `awk'
- by using the `-v' option and an `awk' variable.
+ * Shell variables can be used in 'awk' programs by careful use of
+ shell quoting. It is easier to pass a shell variable into 'awk' by
+ using the '-v' option and an 'awk' variable.
- * Actions consist of statements enclosed in curly braces. Statements
+ * Actions consist of statements enclosed in curly braces. Statements
are built up from expressions, control statements, compound
statements, input and output statements, and deletion statements.
- * The control statements in `awk' are `if'-`else', `while', `for',
- and `do'-`while'. `gawk' adds the `switch' statement. There are
- two flavors of `for' statement: one for performing general
- looping, and the other for iterating through an array.
+ * The control statements in 'awk' are 'if'-'else', 'while', 'for',
+ and 'do'-'while'. 'gawk' adds the 'switch' statement. There are
+ two flavors of 'for' statement: one for performing general looping,
+ and the other for iterating through an array.
- * `break' and `continue' let you exit early or start the next
- iteration of a loop (or get out of a `switch').
+ * 'break' and 'continue' let you exit early or start the next
+ iteration of a loop (or get out of a 'switch').
- * `next' and `nextfile' let you read the next record and start over
- at the top of your program or skip to the next input file and
- start over, respectively.
+ * 'next' and 'nextfile' let you read the next record and start over
+ at the top of your program or skip to the next input file and start
+ over, respectively.
- * The `exit' statement terminates your program. When executed from
- an action (or function body), it transfers control to the `END'
- statements. From an `END' statement body, it exits immediately.
- You may pass an optional numeric value to be used as `awk''s exit
+ * The 'exit' statement terminates your program. When executed from
+ an action (or function body), it transfers control to the 'END'
+ statements. From an 'END' statement body, it exits immediately.
+ You may pass an optional numeric value to be used as 'awk''s exit
status.
- * Some predefined variables provide control over `awk', mainly for
- I/O. Other variables convey information from `awk' to your
- program.
-
- * `ARGC' and `ARGV' make the command-line arguments available to
- your program. Manipulating them from a `BEGIN' rule lets you
- control how `awk' will process the provided data files.
+ * Some predefined variables provide control over 'awk', mainly for
+ I/O. Other variables convey information from 'awk' to your program.
+ * 'ARGC' and 'ARGV' make the command-line arguments available to your
+ program. Manipulating them from a 'BEGIN' rule lets you control
+ how 'awk' will process the provided data files.
File: gawk.info, Node: Arrays, Next: Functions, Prev: Patterns and Actions,
Up: Top
-8 Arrays in `awk'
+8 Arrays in 'awk'
*****************
An "array" is a table of values called "elements". The elements of an
array are distinguished by their "indices". Indices may be either
numbers or strings.
- This major node describes how arrays work in `awk', how to use array
+ This major node describes how arrays work in 'awk', how to use array
elements, how to scan through every element in an array, and how to
-remove array elements. It also describes how `awk' simulates
+remove array elements. It also describes how 'awk' simulates
multidimensional arrays, as well as some of the less obvious points
-about array usage. The major node moves on to discuss `gawk''s facility
-for sorting arrays, and ends with a brief description of `gawk''s
+about array usage. The major node moves on to discuss 'gawk''s facility
+for sorting arrays, and ends with a brief description of 'gawk''s
ability to support true arrays of arrays.
* Menu:
* Array Basics:: The basics of arrays.
* Numeric Array Subscripts:: How to use numbers as subscripts in
- `awk'.
+ 'awk'.
* Uninitialized Subscripts:: Using Uninitialized variables as subscripts.
-* Delete:: The `delete' statement removes an element
+* Delete:: The 'delete' statement removes an element
from an array.
* Multidimensional:: Emulating multidimensional arrays in
- `awk'.
+ 'awk'.
* Arrays of Arrays:: True multidimensional arrays.
* Arrays Summary:: Summary of arrays.
@@ -10810,8 +10757,8 @@ File: gawk.info, Node: Array Basics, Next: Numeric
Array Subscripts, Up: Arra
8.1 The Basics of Arrays
========================
-This minor node presents the basics: working with elements in arrays
-one at a time, and traversing all of the elements in an array.
+This minor node presents the basics: working with elements in arrays one
+at a time, and traversing all of the elements in an array.
* Menu:
@@ -10819,7 +10766,7 @@ one at a time, and traversing all of the elements in an
array.
* Reference to Elements:: How to examine one element of an array.
* Assigning Elements:: How to change an element of an array.
* Array Example:: Basic Example of an Array
-* Scanning an Array:: A variation of the `for' statement. It
+* Scanning an Array:: A variation of the 'for' statement. It
loops through the indices of an array's
existing elements.
* Controlling Scanning:: Controlling the order in which arrays are
@@ -10831,18 +10778,18 @@ File: gawk.info, Node: Array Intro, Next: Reference
to Elements, Up: Array Ba
8.1.1 Introduction to Arrays
----------------------------
- Doing linear scans over an associative array is like trying to
- club someone to death with a loaded Uzi. -- Larry Wall
+ Doing linear scans over an associative array is like trying to club
+ someone to death with a loaded Uzi.
+ -- _Larry Wall_
- The `awk' language provides one-dimensional arrays for storing
-groups of related strings or numbers. Every `awk' array must have a
-name. Array names have the same syntax as variable names; any valid
-variable name would also be a valid array name. But one name cannot be
-used in both ways (as an array and as a variable) in the same `awk'
-program.
+ The 'awk' language provides one-dimensional arrays for storing groups
+of related strings or numbers. Every 'awk' array must have a name.
+Array names have the same syntax as variable names; any valid variable
+name would also be a valid array name. But one name cannot be used in
+both ways (as an array and as a variable) in the same 'awk' program.
- Arrays in `awk' superficially resemble arrays in other programming
-languages, but there are fundamental differences. In `awk', it isn't
+ Arrays in 'awk' superficially resemble arrays in other programming
+languages, but there are fundamental differences. In 'awk', it isn't
necessary to specify the size of an array before starting to use it.
Additionally, any number or string, not just consecutive integers, may
be used as an array index.
@@ -10854,52 +10801,54 @@ of memory to be allocated for that many elements.
Usually, an index in
the array must be a nonnegative integer. For example, the index zero
specifies the first element in the array, which is actually stored at
the beginning of the block of memory. Index one specifies the second
-element, which is stored in memory right after the first element, and
-so on. It is impossible to add more elements to the array, because it
-has room only for as many elements as given in the declaration. (Some
-languages allow arbitrary starting and ending indices--e.g., `15 ..
+element, which is stored in memory right after the first element, and so
+on. It is impossible to add more elements to the array, because it has
+room only for as many elements as given in the declaration. (Some
+languages allow arbitrary starting and ending indices--e.g., '15 ..
27'--but the size of the array is still fixed when the array is
declared.)
- A contiguous array of four elements might look like *note
-figure-array-elements::, conceptually, if the element values are eight,
-`"foo"', `""', and 30.
+ A contiguous array of four elements might look like *note Figure 8.1:
+figure-array-elements, conceptually, if the element values are eight,
+'"foo"', '""', and 30.
+ [image src="array-elements.txt" alt="A Contiguous Array"
text="+---------+---------+--------+---------+
+| 8 | \"foo\" | \"\" | 30 | @r{Value}
+---------+---------+--------+---------+
-| 8 | "foo" | "" | 30 | @r{Value}
-+---------+---------+--------+---------+
- 0 1 2 3 @r{Index}
+ 0 1 2 3 @r{Index}" ]
+
Figure 8.1: A contiguous array
Only the values are stored; the indices are implicit from the order of
-the values. Here, eight is the value at index zero, because eight
+the values. Here, eight is the value at index zero, because eight
appears in the position with zero elements before it.
- Arrays in `awk' are different--they are "associative". This means
+ Arrays in 'awk' are different--they are "associative". This means
that each array is a collection of pairs--an index and its corresponding
array element value:
Index Value
-------------------------
- `3' `30'
- `1' `"foo"'
- `0' `8'
- `2' `""'
+------------------------
+ '3' '30'
+ '1' '"foo"'
+ '0' '8'
+ '2' '""'
The pairs are shown in jumbled order because their order is
irrelevant.(1)
- One advantage of associative arrays is that new pairs can be added
-at any time. For example, suppose a tenth element is added to the array
-whose value is `"number ten"'. The result is:
+ One advantage of associative arrays is that new pairs can be added at
+any time. For example, suppose a tenth element is added to the array
+whose value is '"number ten"'. The result is:
Index Value
--------------------------------
- `10' `"number ten"'
- `3' `30'
- `1' `"foo"'
- `0' `8'
- `2' `""'
+-------------------------------
+ '10' '"number
+ ten"'
+ '3' '30'
+ '1' '"foo"'
+ '0' '8'
+ '2' '""'
Now the array is "sparse", which just means some indices are missing.
It has elements 0-3 and 10, but doesn't have elements 4, 5, 6, 7, 8, or
@@ -10911,32 +10860,32 @@ an index. For example, the following is an array
that translates words
from English to French:
Index Value
-------------------------
- `"dog"' `"chien"'
- `"cat"' `"chat"'
- `"one"' `"un"'
- `1' `"un"'
+------------------------
+ '"dog"' '"chien"'
+ '"cat"' '"chat"'
+ '"one"' '"un"'
+ '1' '"un"'
Here we decided to translate the number one in both spelled-out and
numeric form--thus illustrating that a single array can have both
numbers and strings as indices. (In fact, array subscripts are always
strings. There are some subtleties to how numbers work when used as
array subscripts; this is discussed in more detail in *note Numeric
-Array Subscripts::.) Here, the number `1' isn't double-quoted, because
-`awk' automatically converts it to a string.
+Array Subscripts::.) Here, the number '1' isn't double-quoted, because
+'awk' automatically converts it to a string.
- The value of `IGNORECASE' has no effect upon array subscripting.
-The identical string value used to store an array element must be used
-to retrieve it. When `awk' creates an array (e.g., with the `split()'
+ The value of 'IGNORECASE' has no effect upon array subscripting. The
+identical string value used to store an array element must be used to
+retrieve it. When 'awk' creates an array (e.g., with the 'split()'
built-in function), that array's indices are consecutive integers
starting at one. (*Note String Functions::.)
- `awk''s arrays are efficient--the time to access an element is
+ 'awk''s arrays are efficient--the time to access an element is
independent of the number of elements in the array.
---------- Footnotes ----------
- (1) The ordering will vary among `awk' implementations, which
+ (1) The ordering will vary among 'awk' implementations, which
typically use hash tables to store array elements and values.
@@ -10954,27 +10903,27 @@ Here, ARRAY is the name of an array. The expression
INDEX-EXPRESSION is
the index of the desired element of the array.
The value of the array reference is the current value of that array
-element. For example, `foo[4.3]' is an expression referencing the
-element of array `foo' at index `4.3'.
+element. For example, 'foo[4.3]' is an expression referencing the
+element of array 'foo' at index '4.3'.
A reference to an array element that has no recorded value yields a
-value of `""', the null string. This includes elements that have not
+value of '""', the null string. This includes elements that have not
been assigned any value as well as elements that have been deleted
(*note Delete::).
- NOTE: A reference to an element that does not exist
- _automatically_ creates that array element, with the null string
- as its value. (In some cases, this is unfortunate, because it
- might waste memory inside `awk'.)
+ NOTE: A reference to an element that does not exist _automatically_
+ creates that array element, with the null string as its value. (In
+ some cases, this is unfortunate, because it might waste memory
+ inside 'awk'.)
- Novice `awk' programmers often make the mistake of checking if an
+ Novice 'awk' programmers often make the mistake of checking if an
element exists by checking if the value is empty:
# Check if "foo" exists in a: Incorrect!
if (a["foo"] != "") ...
- This is incorrect for two reasons. First, it _creates_ `a["foo"]'
- if it didn't exist before! Second, it is valid (if a bit unusual)
+ This is incorrect for two reasons. First, it _creates_ 'a["foo"]'
+ if it didn't exist before! Second, it is valid (if a bit unusual)
to set an array element equal to the empty string.
To determine whether an element exists in an array at a certain
@@ -10984,18 +10933,18 @@ index, use the following expression:
This expression tests whether the particular index INDX exists, without
the side effect of creating that element if it is not present. The
-expression has the value one (true) if `ARRAY[INDX]' exists and zero
-(false) if it does not exist. (We use INDX here, because `index' is
-the name of a built-in function.) For example, this statement tests
-whether the array `frequencies' contains the index `2':
+expression has the value one (true) if 'ARRAY[INDX]' exists and zero
+(false) if it does not exist. (We use INDX here, because 'index' is the
+name of a built-in function.) For example, this statement tests whether
+the array 'frequencies' contains the index '2':
if (2 in frequencies)
print "Subscript 2 is present."
- Note that this is _not_ a test of whether the array `frequencies'
+ Note that this is _not_ a test of whether the array 'frequencies'
contains an element whose _value_ is two. There is no way to do that
except to scan all the elements. Also, this _does not_ create
-`frequencies[2]', while the following (incorrect) alternative does:
+'frequencies[2]', while the following (incorrect) alternative does:
if (frequencies[2] != "")
print "Subscript 2 is present."
@@ -11006,7 +10955,7 @@ File: gawk.info, Node: Assigning Elements, Next:
Array Example, Prev: Referen
8.1.3 Assigning Array Elements
------------------------------
-Array elements can be assigned values just like `awk' variables:
+Array elements can be assigned values just like 'awk' variables:
ARRAY[INDEX-EXPRESSION] = VALUE
@@ -11024,8 +10973,8 @@ The following program takes a list of lines, each
beginning with a line
number, and prints them out in order of line number. The line numbers
are not in order when they are first read--instead, they are scrambled.
This program sorts the lines by making an array using the line numbers
-as subscripts. The program then prints out the lines in sorted order
-of their numbers. It is a very simple program and gets confused upon
+as subscripts. The program then prints out the lines in sorted order of
+their numbers. It is a very simple program and gets confused upon
encountering repeated numbers, gaps, or lines that don't begin with a
number:
@@ -11040,11 +10989,11 @@ number:
print arr[x]
}
- The first rule keeps track of the largest line number seen so far;
-it also stores each line into the array `arr', at an index that is the
+ The first rule keeps track of the largest line number seen so far; it
+also stores each line into the array 'arr', at an index that is the
line's number. The second rule runs after all the input has been read,
-to print out all the lines. When this program is run with the
-following input:
+to print out all the lines. When this program is run with the following
+input:
5 I am the Five man
2 Who are you? The new number two!
@@ -11062,7 +11011,7 @@ Its output is:
If a line number is repeated, the last line with a given number
overrides the others. Gaps in the line numbers can be handled with an
-easy improvement to the program's `END' rule, as follows:
+easy improvement to the program's 'END' rule, as follows:
END {
for (x = 1; x <= max; x++)
@@ -11081,8 +11030,8 @@ executes once for each element of an array. In other
languages, where
arrays are contiguous and indices are limited to nonnegative integers,
this is easy: all the valid indices can be found by counting from the
lowest index up to the highest. This technique won't do the job in
-`awk', because any number or string can be an array index. So `awk'
-has a special kind of `for' statement for scanning an array:
+'awk', because any number or string can be an array index. So 'awk' has
+a special kind of 'for' statement for scanning an array:
for (VAR in ARRAY)
BODY
@@ -11090,14 +11039,14 @@ has a special kind of `for' statement for scanning an
array:
This loop executes BODY once for each index in ARRAY that the program
has previously used, with the variable VAR set to that index.
- The following program uses this form of the `for' statement. The
+ The following program uses this form of the 'for' statement. The
first rule scans the input records and notes which words appear (at
-least once) in the input, by storing a one into the array `used' with
-the word as the index. The second rule scans the elements of `used' to
+least once) in the input, by storing a one into the array 'used' with
+the word as the index. The second rule scans the elements of 'used' to
find all the distinct words that appear in the input. It prints each
word that is more than 10 characters long and also prints the number of
such words. *Note String Functions::, for more information on the
-built-in function `length()'.
+built-in function 'length()'.
# Record a 1 for each word that is used at least once
{
@@ -11120,15 +11069,15 @@ built-in function `length()'.
The order in which elements of the array are accessed by this
statement is determined by the internal arrangement of the array
-elements within `awk' and in standard `awk' cannot be controlled or
+elements within 'awk' and in standard 'awk' cannot be controlled or
changed. This can lead to problems if new elements are added to ARRAY
-by statements in the loop body; it is not predictable whether the `for'
+by statements in the loop body; it is not predictable whether the 'for'
loop will reach them. Similarly, changing VAR inside the loop may
produce strange results. It is best to avoid such things.
- As a point of information, `gawk' sets up the list of elements to be
+ As a point of information, 'gawk' sets up the list of elements to be
iterated over before the loop starts, and does not change it. But not
-all `awk' versions do so. Consider this program, named `loopcheck.awk':
+all 'awk' versions do so. Consider this program, named 'loopcheck.awk':
BEGIN {
a["here"] = "here"
@@ -11142,7 +11091,7 @@ all `awk' versions do so. Consider this program, named
`loopcheck.awk':
}
}
- Here is what happens when run with `gawk' (and `mawk'):
+ Here is what happens when run with 'gawk' (and 'mawk'):
$ gawk -f loopcheck.awk
-| here
@@ -11150,7 +11099,7 @@ all `awk' versions do so. Consider this program, named
`loopcheck.awk':
-| a
-| is
- Contrast this to BWK `awk':
+ Contrast this to BWK 'awk':
$ nawk -f loopcheck.awk
-| loop
@@ -11162,91 +11111,91 @@ all `awk' versions do so. Consider this program,
named `loopcheck.awk':
File: gawk.info, Node: Controlling Scanning, Prev: Scanning an Array, Up:
Array Basics
-8.1.6 Using Predefined Array Scanning Orders with `gawk'
+8.1.6 Using Predefined Array Scanning Orders with 'gawk'
--------------------------------------------------------
-This node describes a feature that is specific to `gawk'.
+This node describes a feature that is specific to 'gawk'.
- By default, when a `for' loop traverses an array, the order is
-undefined, meaning that the `awk' implementation determines the order
-in which the array is traversed. This order is usually based on the
+ By default, when a 'for' loop traverses an array, the order is
+undefined, meaning that the 'awk' implementation determines the order in
+which the array is traversed. This order is usually based on the
internal implementation of arrays and will vary from one version of
-`awk' to the next.
+'awk' to the next.
- Often, though, you may wish to do something simple, such as
-"traverse the array by comparing the indices in ascending order," or
-"traverse the array by comparing the values in descending order."
-`gawk' provides two mechanisms that give you this control:
+ Often, though, you may wish to do something simple, such as "traverse
+the array by comparing the indices in ascending order," or "traverse the
+array by comparing the values in descending order." 'gawk' provides two
+mechanisms that give you this control:
- * Set `PROCINFO["sorted_in"]' to one of a set of predefined values.
+ * Set 'PROCINFO["sorted_in"]' to one of a set of predefined values.
We describe this now.
- * Set `PROCINFO["sorted_in"]' to the name of a user-defined function
- to use for comparison of array elements. This advanced feature is
+ * Set 'PROCINFO["sorted_in"]' to the name of a user-defined function
+ to use for comparison of array elements. This advanced feature is
described later in *note Array Sorting::.
- The following special values for `PROCINFO["sorted_in"]' are
+ The following special values for 'PROCINFO["sorted_in"]' are
available:
-`"@unsorted"'
+'"@unsorted"'
Array elements are processed in arbitrary order, which is the
- default `awk' behavior.
+ default 'awk' behavior.
-`"@ind_str_asc"'
+'"@ind_str_asc"'
Order by indices in ascending order compared as strings; this is
the most basic sort. (Internally, array indices are always
- strings, so with `a[2*5] = 1' the index is `"10"' rather than
+ strings, so with 'a[2*5] = 1' the index is '"10"' rather than
numeric 10.)
-`"@ind_num_asc"'
- Order by indices in ascending order but force them to be treated
- as numbers in the process. Any index with a non-numeric value
- will end up positioned as if it were zero.
+'"@ind_num_asc"'
+ Order by indices in ascending order but force them to be treated as
+ numbers in the process. Any index with a non-numeric value will
+ end up positioned as if it were zero.
-`"@val_type_asc"'
+'"@val_type_asc"'
Order by element values in ascending order (rather than by
indices). Ordering is by the type assigned to the element (*note
Typing and Comparison::). All numeric values come before all
- string values, which in turn come before all subarrays.
- (Subarrays have not been described yet; *note Arrays of Arrays::.)
+ string values, which in turn come before all subarrays. (Subarrays
+ have not been described yet; *note Arrays of Arrays::.)
-`"@val_str_asc"'
+'"@val_str_asc"'
Order by element values in ascending order (rather than by
indices). Scalar values are compared as strings. Subarrays, if
present, come out last.
-`"@val_num_asc"'
+'"@val_num_asc"'
Order by element values in ascending order (rather than by
indices). Scalar values are compared as numbers. Subarrays, if
present, come out last. When numeric values are equal, the string
values are used to provide an ordering: this guarantees consistent
- results across different versions of the C `qsort()' function,(1)
- which `gawk' uses internally to perform the sorting.
+ results across different versions of the C 'qsort()' function,(1)
+ which 'gawk' uses internally to perform the sorting.
-`"@ind_str_desc"'
- Like `"@ind_str_asc"', but the string indices are ordered from
- high to low.
+'"@ind_str_desc"'
+ Like '"@ind_str_asc"', but the string indices are ordered from high
+ to low.
-`"@ind_num_desc"'
- Like `"@ind_num_asc"', but the numeric indices are ordered from
+'"@ind_num_desc"'
+ Like '"@ind_num_asc"', but the numeric indices are ordered from
high to low.
-`"@val_type_desc"'
- Like `"@val_type_asc"', but the element values, based on type, are
+'"@val_type_desc"'
+ Like '"@val_type_asc"', but the element values, based on type, are
ordered from high to low. Subarrays, if present, come out first.
-`"@val_str_desc"'
- Like `"@val_str_asc"', but the element values, treated as strings,
+'"@val_str_desc"'
+ Like '"@val_str_asc"', but the element values, treated as strings,
are ordered from high to low. Subarrays, if present, come out
first.
-`"@val_num_desc"'
- Like `"@val_num_asc"', but the element values, treated as numbers,
+'"@val_num_desc"'
+ Like '"@val_num_asc"', but the element values, treated as numbers,
are ordered from high to low. Subarrays, if present, come out
first.
- The array traversal order is determined before the `for' loop starts
-to run. Changing `PROCINFO["sorted_in"]' in the loop body does not
+ The array traversal order is determined before the 'for' loop starts
+to run. Changing 'PROCINFO["sorted_in"]' in the loop body does not
affect the loop. For example:
$ gawk '
@@ -11278,10 +11227,10 @@ relative to each other is determined by their index
strings.
Here are some additional things to bear in mind about sorted array
traversal:
- * The value of `PROCINFO["sorted_in"]' is global. That is, it affects
- all array traversal `for' loops. If you need to change it within
- your own code, you should see if it's defined and save and restore
- the value:
+ * The value of 'PROCINFO["sorted_in"]' is global. That is, it
+ affects all array traversal 'for' loops. If you need to change it
+ within your own code, you should see if it's defined and save and
+ restore the value:
...
if ("sorted_in" in PROCINFO) {
@@ -11293,22 +11242,22 @@ traversal:
PROCINFO["sorted_in"] = save_sorted
* As already mentioned, the default array traversal order is
- represented by `"@unsorted"'. You can also get the default
- behavior by assigning the null string to `PROCINFO["sorted_in"]'
- or by just deleting the `"sorted_in"' element from the `PROCINFO'
- array with the `delete' statement. (The `delete' statement hasn't
+ represented by '"@unsorted"'. You can also get the default
+ behavior by assigning the null string to 'PROCINFO["sorted_in"]' or
+ by just deleting the '"sorted_in"' element from the 'PROCINFO'
+ array with the 'delete' statement. (The 'delete' statement hasn't
been described yet; *note Delete::.)
- In addition, `gawk' provides built-in functions for sorting arrays;
+ In addition, 'gawk' provides built-in functions for sorting arrays;
see *note Array Sorting Functions::.
---------- Footnotes ----------
- (1) When two elements compare as equal, the C `qsort()' function
-does not guarantee that they will maintain their original relative
-order after sorting. Using the string value to provide a unique
-ordering when the numeric values are equal ensures that `gawk' behaves
-consistently across different environments.
+ (1) When two elements compare as equal, the C 'qsort()' function does
+not guarantee that they will maintain their original relative order
+after sorting. Using the string value to provide a unique ordering when
+the numeric values are equal ensures that 'gawk' behaves consistently
+across different environments.
File: gawk.info, Node: Numeric Array Subscripts, Next: Uninitialized
Subscripts, Prev: Array Basics, Up: Arrays
@@ -11317,11 +11266,11 @@ File: gawk.info, Node: Numeric Array Subscripts,
Next: Uninitialized Subscript
=====================================
An important aspect to remember about arrays is that _array subscripts
-are always strings_. When a numeric value is used as a subscript, it
-is converted to a string value before being used for subscripting
-(*note Conversion::). This means that the value of the predefined
-variable `CONVFMT' can affect how your program accesses elements of an
-array. For example:
+are always strings_. When a numeric value is used as a subscript, it is
+converted to a string value before being used for subscripting (*note
+Conversion::). This means that the value of the predefined variable
+'CONVFMT' can affect how your program accesses elements of an array.
+For example:
xyz = 12.153
data[xyz] = 1
@@ -11331,19 +11280,19 @@ array. For example:
else
printf "%s is not in data\n", xyz
-This prints `12.15 is not in data'. The first statement gives `xyz' a
-numeric value. Assigning to `data[xyz]' subscripts `data' with the
-string value `"12.153"' (using the default conversion value of
-`CONVFMT', `"%.6g"'). Thus, the array element `data["12.153"]' is
+This prints '12.15 is not in data'. The first statement gives 'xyz' a
+numeric value. Assigning to 'data[xyz]' subscripts 'data' with the
+string value '"12.153"' (using the default conversion value of
+'CONVFMT', '"%.6g"'). Thus, the array element 'data["12.153"]' is
assigned the value one. The program then changes the value of
-`CONVFMT'. The test `(xyz in data)' generates a new string value from
-`xyz'--this time `"12.15"'--because the value of `CONVFMT' only allows
-two significant digits. This test fails, because `"12.15"' is
-different from `"12.153"'.
+'CONVFMT'. The test '(xyz in data)' generates a new string value from
+'xyz'--this time '"12.15"'--because the value of 'CONVFMT' only allows
+two significant digits. This test fails, because '"12.15"' is different
+from '"12.153"'.
According to the rules for conversions (*note Conversion::), integer
values always convert to strings as integers, no matter what the value
-of `CONVFMT' may happen to be. So the usual case of the following
+of 'CONVFMT' may happen to be. So the usual case of the following
works:
for (i = 1; i <= maxsub; i++)
@@ -11352,14 +11301,14 @@ works:
The "integer values always convert to strings as integers" rule has
an additional consequence for array indexing. Octal and hexadecimal
constants (*note Nondecimal-numbers::) are converted internally into
-numbers, and their original form is forgotten. This means, for
-example, that `array[17]', `array[021]', and `array[0x11]' all refer to
-the same element!
+numbers, and their original form is forgotten. This means, for example,
+that 'array[17]', 'array[021]', and 'array[0x11]' all refer to the same
+element!
- As with many things in `awk', the majority of the time things work
-as you would expect them to. But it is useful to have a precise
-knowledge of the actual rules, as they can sometimes have a subtle
-effect on your programs.
+ As with many things in 'awk', the majority of the time things work as
+you would expect them to. But it is useful to have a precise knowledge
+of the actual rules, as they can sometimes have a subtle effect on your
+programs.
File: gawk.info, Node: Uninitialized Subscripts, Next: Delete, Prev:
Numeric Array Subscripts, Up: Arrays
@@ -11385,13 +11334,13 @@ might look like this:
the output!
Upon first glance, we would think that this program should have
-worked. The variable `lines' is uninitialized, and uninitialized
-variables have the numeric value zero. So, `awk' should have printed
-the value of `l[0]'.
+worked. The variable 'lines' is uninitialized, and uninitialized
+variables have the numeric value zero. So, 'awk' should have printed
+the value of 'l[0]'.
- The issue here is that subscripts for `awk' arrays are _always_
-strings. Uninitialized variables, when used as strings, have the value
-`""', not zero. Thus, `line 1' ends up stored in `l[""]'. The
+ The issue here is that subscripts for 'awk' arrays are _always_
+strings. Uninitialized variables, when used as strings, have the value
+'""', not zero. Thus, 'line 1' ends up stored in 'l[""]'. The
following version of the program works correctly:
{ l[lines++] = $0 }
@@ -11400,69 +11349,69 @@ following version of the program works correctly:
print l[i]
}
- Here, the `++' forces `lines' to be numeric, thus making the "old
-value" numeric zero. This is then converted to `"0"' as the array
+ Here, the '++' forces 'lines' to be numeric, thus making the "old
+value" numeric zero. This is then converted to '"0"' as the array
subscript.
- Even though it is somewhat unusual, the null string (`""') is a
-valid array subscript. (d.c.) `gawk' warns about the use of the null
-string as a subscript if `--lint' is provided on the command line
-(*note Options::).
+ Even though it is somewhat unusual, the null string ('""') is a valid
+array subscript. (d.c.) 'gawk' warns about the use of the null string
+as a subscript if '--lint' is provided on the command line (*note
+Options::).
File: gawk.info, Node: Delete, Next: Multidimensional, Prev: Uninitialized
Subscripts, Up: Arrays
-8.4 The `delete' Statement
+8.4 The 'delete' Statement
==========================
-To remove an individual element of an array, use the `delete' statement:
+To remove an individual element of an array, use the 'delete' statement:
delete ARRAY[INDEX-EXPRESSION]
Once an array element has been deleted, any value the element once
-had is no longer available. It is as if the element had never been
+had is no longer available. It is as if the element had never been
referred to or been given a value. The following is an example of
deleting elements in an array:
for (i in frequencies)
delete frequencies[i]
-This example removes all the elements from the array `frequencies'.
-Once an element is deleted, a subsequent `for' statement to scan the
-array does not report that element and using the `in' operator to check
+This example removes all the elements from the array 'frequencies'.
+Once an element is deleted, a subsequent 'for' statement to scan the
+array does not report that element and using the 'in' operator to check
for the presence of that element returns zero (i.e., false):
delete foo[4]
if (4 in foo)
print "This will never be printed"
- It is important to note that deleting an element is _not_ the same
-as assigning it a null value (the empty string, `""'). For example:
+ It is important to note that deleting an element is _not_ the same as
+assigning it a null value (the empty string, '""'). For example:
foo[4] = ""
if (4 in foo)
print "This is printed, even though foo[4] is empty"
It is not an error to delete an element that does not exist.
-However, if `--lint' is provided on the command line (*note Options::),
-`gawk' issues a warning message when an element that is not in the
-array is deleted.
+However, if '--lint' is provided on the command line (*note Options::),
+'gawk' issues a warning message when an element that is not in the array
+is deleted.
All the elements of an array may be deleted with a single statement
-by leaving off the subscript in the `delete' statement, as follows:
+by leaving off the subscript in the 'delete' statement, as follows:
delete ARRAY
- Using this version of the `delete' statement is about three times
-more efficient than the equivalent loop that deletes each element one
-at a time.
+ Using this version of the 'delete' statement is about three times
+more efficient than the equivalent loop that deletes each element one at
+a time.
- This form of the `delete' statement is also supported by BWK `awk'
-and `mawk', as well as by a number of other implementations.
+ This form of the 'delete' statement is also supported by BWK 'awk'
+and 'mawk', as well as by a number of other implementations.
- NOTE: For many years, using `delete' without a subscript was a
- common extension. In September 2012, it was accepted for
- inclusion into the POSIX standard. See the Austin Group website
+ NOTE: For many years, using 'delete' without a subscript was a
+ common extension. In September 2012, it was accepted for inclusion
+ into the POSIX standard. See the Austin Group website
(http://austingroupbugs.net/view.php?id=544).
The following statement provides a portable but nonobvious way to
@@ -11470,14 +11419,14 @@ clear out an array:(1)
split("", array)
- The `split()' function (*note String Functions::) clears out the
-target array first. This call asks it to split apart the null string.
+ The 'split()' function (*note String Functions::) clears out the
+target array first. This call asks it to split apart the null string.
Because there is no data to split out, the function simply clears the
array and then returns.
CAUTION: Deleting all the elements from an array does not change
its type; you cannot clear an array and then use the array's name
- as a scalar (i.e., a regular variable). For example, the following
+ as a scalar (i.e., a regular variable). For example, the following
does not work:
a[1] = 3
@@ -11498,41 +11447,39 @@ File: gawk.info, Node: Multidimensional, Next:
Arrays of Arrays, Prev: Delete
* Multiscanning:: Scanning multidimensional arrays.
- A "multidimensional array" is an array in which an element is
-identified by a sequence of indices instead of a single index. For
-example, a two-dimensional array requires two indices. The usual way
-(in many languages, including `awk') to refer to an element of a
-two-dimensional array named `grid' is with `grid[X,Y]'.
+A "multidimensional array" is an array in which an element is identified
+by a sequence of indices instead of a single index. For example, a
+two-dimensional array requires two indices. The usual way (in many
+languages, including 'awk') to refer to an element of a two-dimensional
+array named 'grid' is with 'grid[X,Y]'.
- Multidimensional arrays are supported in `awk' through concatenation
-of indices into one string. `awk' converts the indices into strings
+ Multidimensional arrays are supported in 'awk' through concatenation
+of indices into one string. 'awk' converts the indices into strings
(*note Conversion::) and concatenates them together, with a separator
-between them. This creates a single string that describes the values
-of the separate indices. The combined string is used as a single index
+between them. This creates a single string that describes the values of
+the separate indices. The combined string is used as a single index
into an ordinary, one-dimensional array. The separator used is the
-value of the built-in variable `SUBSEP'.
-
- For example, suppose we evaluate the expression `foo[5,12] = "value"'
-when the value of `SUBSEP' is `"@"'. The numbers 5 and 12 are
-converted to strings and concatenated with an `@' between them,
-yielding `"address@hidden"'; thus, the array element `foo["address@hidden"]'
is set to
-`"value"'.
-
- Once the element's value is stored, `awk' has no record of whether
-it was stored with a single index or a sequence of indices. The two
-expressions `foo[5,12]' and `foo[5 SUBSEP 12]' are always equivalent.
-
- The default value of `SUBSEP' is the string `"\034"', which contains
-a nonprinting character that is unlikely to appear in an `awk' program
-or in most input data. The usefulness of choosing an unlikely
-character comes from the fact that index values that contain a string
-matching `SUBSEP' can lead to combined strings that are ambiguous.
-Suppose that `SUBSEP' is `"@"'; then `foo["address@hidden", "c"]' and
-`foo["a", "address@hidden"]' are indistinguishable because both are actually
-stored as `foo["address@hidden@c"]'.
+value of the built-in variable 'SUBSEP'.
+
+ For example, suppose we evaluate the expression 'foo[5,12] = "value"'
+when the value of 'SUBSEP' is '"@"'. The numbers 5 and 12 are converted
+to strings and concatenated with an '@' between them, yielding
'"address@hidden"';
+thus, the array element 'foo["address@hidden"]' is set to '"value"'.
+
+ Once the element's value is stored, 'awk' has no record of whether it
+was stored with a single index or a sequence of indices. The two
+expressions 'foo[5,12]' and 'foo[5 SUBSEP 12]' are always equivalent.
+
+ The default value of 'SUBSEP' is the string '"\034"', which contains
+a nonprinting character that is unlikely to appear in an 'awk' program
+or in most input data. The usefulness of choosing an unlikely character
+comes from the fact that index values that contain a string matching
+'SUBSEP' can lead to combined strings that are ambiguous. Suppose that
+'SUBSEP' is '"@"'; then 'foo["address@hidden", "c"]' and 'foo["a",
"address@hidden"]' are
+indistinguishable because both are actually stored as
'foo["address@hidden@c"]'.
To test whether a particular index sequence exists in a
-multidimensional array, use the same operator (`in') that is used for
+multidimensional array, use the same operator ('in') that is used for
single-dimensional arrays. Write the whole sequence of indices in
parentheses, separated by commas, as the left operand:
@@ -11581,38 +11528,38 @@ File: gawk.info, Node: Multiscanning, Up:
Multidimensional
8.5.1 Scanning Multidimensional Arrays
--------------------------------------
-There is no special `for' statement for scanning a "multidimensional"
-array. There cannot be one, because, in truth, `awk' does not have
+There is no special 'for' statement for scanning a "multidimensional"
+array. There cannot be one, because, in truth, 'awk' does not have
multidimensional arrays or elements--there is only a multidimensional
_way of accessing_ an array.
However, if your program has an array that is always accessed as
-multidimensional, you can get the effect of scanning it by combining
-the scanning `for' statement (*note Scanning an Array::) with the
-built-in `split()' function (*note String Functions::). It works in
-the following manner:
+multidimensional, you can get the effect of scanning it by combining the
+scanning 'for' statement (*note Scanning an Array::) with the built-in
+'split()' function (*note String Functions::). It works in the
+following manner:
for (combined in array) {
split(combined, separate, SUBSEP)
...
}
-This sets the variable `combined' to each concatenated combined index
-in the array, and splits it into the individual indices by breaking it
-apart where the value of `SUBSEP' appears. The individual indices then
-become the elements of the array `separate'.
+This sets the variable 'combined' to each concatenated combined index in
+the array, and splits it into the individual indices by breaking it
+apart where the value of 'SUBSEP' appears. The individual indices then
+become the elements of the array 'separate'.
- Thus, if a value is previously stored in `array[1, "foo"]', then an
-element with index `"1\034foo"' exists in `array'. (Recall that the
-default value of `SUBSEP' is the character with code 034.) Sooner or
-later, the `for' statement finds that index and does an iteration with
-the variable `combined' set to `"1\034foo"'. Then the `split()'
+ Thus, if a value is previously stored in 'array[1, "foo"]', then an
+element with index '"1\034foo"' exists in 'array'. (Recall that the
+default value of 'SUBSEP' is the character with code 034.) Sooner or
+later, the 'for' statement finds that index and does an iteration with
+the variable 'combined' set to '"1\034foo"'. Then the 'split()'
function is called as follows:
split("1\034foo", separate, "\034")
-The result is to set `separate[1]' to `"1"' and `separate[2]' to
-`"foo"'. Presto! The original sequence of separate indices is
+The result is to set 'separate[1]' to '"1"' and 'separate[2]' to
+'"foo"'. Presto! The original sequence of separate indices is
recovered.
@@ -11621,29 +11568,29 @@ File: gawk.info, Node: Arrays of Arrays, Next:
Arrays Summary, Prev: Multidim
8.6 Arrays of Arrays
====================
-`gawk' goes beyond standard `awk''s multidimensional array access and
-provides true arrays of arrays. Elements of a subarray are referred to
-by their own indices enclosed in square brackets, just like the
-elements of the main array. For example, the following creates a
-two-element subarray at index `1' of the main array `a':
+'gawk' goes beyond standard 'awk''s multidimensional array access and
+provides true arrays of arrays. Elements of a subarray are referred to
+by their own indices enclosed in square brackets, just like the elements
+of the main array. For example, the following creates a two-element
+subarray at index '1' of the main array 'a':
a[1][1] = 1
a[1][2] = 2
- This simulates a true two-dimensional array. Each subarray element
+ This simulates a true two-dimensional array. Each subarray element
can contain another subarray as a value, which in turn can hold other
-arrays as well. In this way, you can create arrays of three or more
-dimensions. The indices can be any `awk' expressions, including scalars
-separated by commas (i.e., a regular `awk' simulated multidimensional
-subscript). So the following is valid in `gawk':
+arrays as well. In this way, you can create arrays of three or more
+dimensions. The indices can be any 'awk' expressions, including scalars
+separated by commas (i.e., a regular 'awk' simulated multidimensional
+subscript). So the following is valid in 'gawk':
a[1][3][1, "name"] = "barney"
- Each subarray and the main array can be of different length. In
+ Each subarray and the main array can be of different length. In
fact, the elements of an array or its subarray do not all have to have
-the same type. This means that the main array and any of its subarrays
-can be nonrectangular, or jagged in structure. You can assign a scalar
-value to the index `4' of the main array `a', even though `a[1]' is
+the same type. This means that the main array and any of its subarrays
+can be nonrectangular, or jagged in structure. You can assign a scalar
+value to the index '4' of the main array 'a', even though 'a[1]' is
itself an array and not a scalar:
a[4] = "An element in a jagged array"
@@ -11651,43 +11598,43 @@ itself an array and not a scalar:
The terms "dimension", "row", and "column" are meaningless when
applied to such an array, but we will use "dimension" henceforth to
imply the maximum number of indices needed to refer to an existing
-element. The type of any element that has already been assigned cannot
-be changed by assigning a value of a different type. You have to first
-delete the current element, which effectively makes `gawk' forget about
+element. The type of any element that has already been assigned cannot
+be changed by assigning a value of a different type. You have to first
+delete the current element, which effectively makes 'gawk' forget about
the element at that index:
delete a[4]
a[4][5][6][7] = "An element in a four-dimensional array"
-This removes the scalar value from index `4' and then inserts a
-three-level nested subarray containing a scalar. You can also delete an
+This removes the scalar value from index '4' and then inserts a
+three-level nested subarray containing a scalar. You can also delete an
entire subarray or subarray of subarrays:
delete a[4][5]
a[4][5] = "An element in subarray a[4]"
- But recall that you can not delete the main array `a' and then use it
+ But recall that you can not delete the main array 'a' and then use it
as a scalar.
The built-in functions that take array arguments can also be used
-with subarrays. For example, the following code fragment uses `length()'
-(*note String Functions::) to determine the number of elements in the
-main array `a' and its subarrays:
+with subarrays. For example, the following code fragment uses
+'length()' (*note String Functions::) to determine the number of
+elements in the main array 'a' and its subarrays:
print length(a), length(a[1]), length(a[1][3])
-This results in the following output for our main array `a':
+This results in the following output for our main array 'a':
2, 3, 1
-The `SUBSCRIPT in ARRAY' expression (*note Reference to Elements::)
-works similarly for both regular `awk'-style arrays and arrays of
-arrays. For example, the tests `1 in a', `3 in a[1]', and `(1, "name")
-in a[1][3]' all evaluate to one (true) for our array `a'.
+The 'SUBSCRIPT in ARRAY' expression (*note Reference to Elements::)
+works similarly for both regular 'awk'-style arrays and arrays of
+arrays. For example, the tests '1 in a', '3 in a[1]', and '(1, "name")
+in a[1][3]' all evaluate to one (true) for our array 'a'.
- The `for (item in array)' statement (*note Scanning an Array::) can
+ The 'for (item in array)' statement (*note Scanning an Array::) can
be nested to scan all the elements of an array of arrays if it is
-rectangular in structure. In order to print the contents (scalar
+rectangular in structure. In order to print the contents (scalar
values) of a two-dimensional array of arrays (i.e., in which each
first-level element is itself an array, not necessarily of the same
length), you could use the following code:
@@ -11696,8 +11643,8 @@ length), you could use the following code:
for (j in array[i])
print array[i][j]
- The `isarray()' function (*note Type Functions::) lets you test if
-an array element is itself an array:
+ The 'isarray()' function (*note Type Functions::) lets you test if an
+array element is itself an array:
for (i in array) {
if (isarray(array[i]) {
@@ -11709,9 +11656,9 @@ an array element is itself an array:
print array[i]
}
- If the structure of a jagged array of arrays is known in advance,
-you can often devise workarounds using control statements. For example,
-the following code prints the elements of our main array `a':
+ If the structure of a jagged array of arrays is known in advance, you
+can often devise workarounds using control statements. For example, the
+following code prints the elements of our main array 'a':
for (i in a) {
for (j in a[i]) {
@@ -11727,14 +11674,14 @@ the following code prints the elements of our main
array `a':
arbitrarily dimensioned array of arrays.
Recall that a reference to an uninitialized array element yields a
-value of `""', the null string. This has one important implication when
+value of '""', the null string. This has one important implication when
you intend to use a subarray as an argument to a function, as
illustrated by the following example:
$ gawk 'BEGIN { split("a b c d", b[1]); print b[1][1] }'
- error--> gawk: cmd. line:1: fatal: split: second argument is not an array
+ error-> gawk: cmd. line:1: fatal: split: second argument is not an array
- The way to work around this is to first force `b[1]' to be an array
+ The way to work around this is to first force 'b[1]' to be an array
by creating an arbitrary index:
$ gawk 'BEGIN { b[1][1] = ""; split("a b c d", b[1]); print b[1][1] }'
@@ -11746,64 +11693,63 @@ File: gawk.info, Node: Arrays Summary, Prev: Arrays
of Arrays, Up: Arrays
8.7 Summary
===========
- * Standard `awk' provides one-dimensional associative arrays (arrays
+ * Standard 'awk' provides one-dimensional associative arrays (arrays
indexed by string values). All arrays are associative; numeric
indices are converted automatically to strings.
- * Array elements are referenced as `ARRAY[INDX]'. Referencing an
+ * Array elements are referenced as 'ARRAY[INDX]'. Referencing an
element creates it if it did not exist previously.
* The proper way to see if an array has an element with a given index
- is to use the `in' operator: `INDX in ARRAY'.
+ is to use the 'in' operator: 'INDX in ARRAY'.
- * Use `for (INDX in ARRAY) ...' to scan through all the individual
- elements of an array. In the body of the loop, INDX takes on the
+ * Use 'for (INDX in ARRAY) ...' to scan through all the individual
+ elements of an array. In the body of the loop, INDX takes on the
value of each element's index in turn.
- * The order in which a `for (INDX in ARRAY)' loop traverses an array
- is undefined in POSIX `awk' and varies among implementations.
- `gawk' lets you control the order by assigning special predefined
- values to `PROCINFO["sorted_in"]'.
+ * The order in which a 'for (INDX in ARRAY)' loop traverses an array
+ is undefined in POSIX 'awk' and varies among implementations.
+ 'gawk' lets you control the order by assigning special predefined
+ values to 'PROCINFO["sorted_in"]'.
- * Use `delete ARRAY[INDX]' to delete an individual element. To
- delete all of the elements in an array, use `delete ARRAY'. This
+ * Use 'delete ARRAY[INDX]' to delete an individual element. To
+ delete all of the elements in an array, use 'delete ARRAY'. This
latter feature has been a common extension for many years and is
now standard, but may not be supported by all commercial versions
- of `awk'.
+ of 'awk'.
- * Standard `awk' simulates multidimensional arrays by separating
+ * Standard 'awk' simulates multidimensional arrays by separating
subscript values with commas. The values are concatenated into a
- single string, separated by the value of `SUBSEP'. The fact that
+ single string, separated by the value of 'SUBSEP'. The fact that
such a subscript was created in this way is not retained; thus,
- changing `SUBSEP' may have unexpected consequences. You can use
- `(SUB1, SUB2, ...) in ARRAY' to see if such a multidimensional
+ changing 'SUBSEP' may have unexpected consequences. You can use
+ '(SUB1, SUB2, ...) in ARRAY' to see if such a multidimensional
subscript exists in ARRAY.
- * `gawk' provides true arrays of arrays. You use a separate set of
+ * 'gawk' provides true arrays of arrays. You use a separate set of
square brackets for each dimension in such an array:
- `data[row][col]', for example. Array elements may thus be either
+ 'data[row][col]', for example. Array elements may thus be either
scalar values (number or string) or other arrays.
- * Use the `isarray()' built-in function to determine if an array
+ * Use the 'isarray()' built-in function to determine if an array
element is itself a subarray.
-
File: gawk.info, Node: Functions, Next: Library Functions, Prev: Arrays,
Up: Top
9 Functions
***********
-This major node describes `awk''s built-in functions, which fall into
-three categories: numeric, string, and I/O. `gawk' provides additional
+This major node describes 'awk''s built-in functions, which fall into
+three categories: numeric, string, and I/O. 'gawk' provides additional
groups of functions to work with values that represent time, do bit
manipulation, sort arrays, provide type information, and
internationalize and localize programs.
- Besides the built-in functions, `awk' has provisions for writing new
+ Besides the built-in functions, 'awk' has provisions for writing new
functions that the rest of a program can use. The second half of this
major node describes these "user-defined" functions. Finally, we
-explore indirect function calls, a `gawk'-specific extension that lets
+explore indirect function calls, a 'gawk'-specific extension that lets
you determine at runtime what function is to be called.
* Menu:
@@ -11819,19 +11765,19 @@ File: gawk.info, Node: Built-in, Next:
User-defined, Up: Functions
9.1 Built-in Functions
======================
-"Built-in" functions are always available for your `awk' program to
-call. This minor node defines all the built-in functions in `awk';
-some of these are mentioned in other sections but are summarized here
-for your convenience.
+"Built-in" functions are always available for your 'awk' program to
+call. This minor node defines all the built-in functions in 'awk'; some
+of these are mentioned in other sections but are summarized here for
+your convenience.
* Menu:
* Calling Built-in:: How to call built-in functions.
* Numeric Functions:: Functions that work with numbers, including
- `int()', `sin()' and `rand()'.
+ 'int()', 'sin()' and 'rand()'.
* String Functions:: Functions for string manipulation, such as
- `split()', `match()' and
- `sprintf()'.
+ 'split()', 'match()' and
+ 'sprintf()'.
* I/O Functions:: Functions for files and shell commands.
* Time Functions:: Functions for dealing with timestamps.
* Bitwise Functions:: Functions for bitwise operations.
@@ -11844,9 +11790,9 @@ File: gawk.info, Node: Calling Built-in, Next:
Numeric Functions, Up: Built-i
9.1.1 Calling Built-in Functions
--------------------------------
-To call one of `awk''s built-in functions, write the name of the
-function followed by arguments in parentheses. For example, `atan2(y +
-z, 1)' is a call to the function `atan2()' and has two arguments.
+To call one of 'awk''s built-in functions, write the name of the
+function followed by arguments in parentheses. For example, 'atan2(y +
+z, 1)' is a call to the function 'atan2()' and has two arguments.
Whitespace is ignored between the built-in function name and the
opening parenthesis, but nonetheless it is good practice to avoid using
@@ -11855,10 +11801,10 @@ this way, and it is easier to avoid mistakes by
following a simple
convention that always works--no whitespace after a function name.
Each built-in function accepts a certain number of arguments. In
-some cases, arguments can be omitted. The defaults for omitted
+some cases, arguments can be omitted. The defaults for omitted
arguments vary from function to function and are described under the
-individual functions. In some `awk' implementations, extra arguments
-given to built-in functions are ignored. However, in `gawk', it is a
+individual functions. In some 'awk' implementations, extra arguments
+given to built-in functions are ignored. However, in 'gawk', it is a
fatal error to give extra arguments to a built-in function.
When a function is called, expressions that create the function's
@@ -11868,20 +11814,19 @@ For example, in the following code fragment:
i = 4
j = sqrt(i++)
-the variable `i' is incremented to the value five before `sqrt()' is
+the variable 'i' is incremented to the value five before 'sqrt()' is
called with a value of four for its actual parameter. The order of
evaluation of the expressions used for the function's parameters is
-undefined. Thus, avoid writing programs that assume that parameters
-are evaluated from left to right or from right to left. For example:
+undefined. Thus, avoid writing programs that assume that parameters are
+evaluated from left to right or from right to left. For example:
i = 5
j = atan2(++i, i *= 2)
- If the order of evaluation is left to right, then `i' first becomes
-six, and then 12, and `atan2()' is called with the two arguments six
-and 12. But if the order of evaluation is right to left, `i' first
-becomes 10, then 11, and `atan2()' is called with the two arguments 11
-and 10.
+ If the order of evaluation is left to right, then 'i' first becomes
+six, and then 12, and 'atan2()' is called with the two arguments six and
+12. But if the order of evaluation is right to left, 'i' first becomes
+10, then 11, and 'atan2()' is called with the two arguments 11 and 10.
File: gawk.info, Node: Numeric Functions, Next: String Functions, Prev:
Calling Built-in, Up: Built-in
@@ -11890,33 +11835,32 @@ File: gawk.info, Node: Numeric Functions, Next:
String Functions, Prev: Calli
-----------------------
The following list describes all of the built-in functions that work
-with numbers. Optional parameters are enclosed in square
-brackets ([ ]):
+with numbers. Optional parameters are enclosed in square brackets ([ ]):
-`atan2(Y, X)'
- Return the arctangent of `Y / X' in radians. You can use `pi =
+'atan2(Y, X)'
+ Return the arctangent of 'Y / X' in radians. You can use 'pi =
atan2(0, -1)' to retrieve the value of pi.
-`cos(X)'
+'cos(X)'
Return the cosine of X, with X in radians.
-`exp(X)'
- Return the exponential of X (`e ^ X') or report an error if X is
+'exp(X)'
+ Return the exponential of X ('e ^ X') or report an error if X is
out of range. The range of values X can have depends on your
machine's floating-point representation.
-`int(X)'
+'int(X)'
Return the nearest integer to X, located between X and zero and
- truncated toward zero. For example, `int(3)' is 3, `int(3.9)' is
- 3, `int(-3.9)' is -3, and `int(-3)' is -3 as well.
+ truncated toward zero. For example, 'int(3)' is 3, 'int(3.9)' is
+ 3, 'int(-3.9)' is -3, and 'int(-3)' is -3 as well.
-`log(X)'
+'log(X)'
Return the natural logarithm of X, if X is positive; otherwise,
- return `NaN' ("not a number") on IEEE 754 systems. Additionally,
- `gawk' prints a warning message when `x' is negative.
+ return 'NaN' ("not a number") on IEEE 754 systems. Additionally,
+ 'gawk' prints a warning message when 'x' is negative.
-`rand()'
- Return a random number. The values of `rand()' are uniformly
+'rand()'
+ Return a random number. The values of 'rand()' are uniformly
distributed between zero and one. The value could be zero but is
never one.(1)
@@ -11930,8 +11874,8 @@ brackets ([ ]):
}
The multiplication produces a random number greater than or equal
- to zero and less than `n'. Using `int()', this result is made into
- an integer between zero and `n' - 1, inclusive.
+ to zero and less than 'n'. Using 'int()', this result is made into
+ an integer between zero and 'n' - 1, inclusive.
The following example uses a similar function to produce random
integers between one and N. This program prints a new random
@@ -11946,57 +11890,57 @@ brackets ([ ]):
printf("%d points\n", roll(6) + roll(6) + roll(6))
}
- CAUTION: In most `awk' implementations, including `gawk',
- `rand()' starts generating numbers from the same starting
- number, or "seed", each time you run `awk'.(2) Thus, a
+ CAUTION: In most 'awk' implementations, including 'gawk',
+ 'rand()' starts generating numbers from the same starting
+ number, or "seed", each time you run 'awk'.(2) Thus, a
program generates the same results each time you run it. The
- numbers are random within one `awk' run but predictable from
+ numbers are random within one 'awk' run but predictable from
run to run. This is convenient for debugging, but if you want
a program to do different things each time it is used, you
- must change the seed to a value that is different in each
- run. To do this, use `srand()'.
+ must change the seed to a value that is different in each run.
+ To do this, use 'srand()'.
-`sin(X)'
+'sin(X)'
Return the sine of X, with X in radians.
-`sqrt(X)'
- Return the positive square root of X. `gawk' prints a warning
- message if X is negative. Thus, `sqrt(4)' is 2.
+'sqrt(X)'
+ Return the positive square root of X. 'gawk' prints a warning
+ message if X is negative. Thus, 'sqrt(4)' is 2.
-`srand('[X]`)'
+'srand('[X]')'
Set the starting point, or seed, for generating random numbers to
the value X.
Each seed value leads to a particular sequence of random
- numbers.(3) Thus, if the seed is set to the same value a second
+ numbers.(3) Thus, if the seed is set to the same value a second
time, the same sequence of random numbers is produced again.
- CAUTION: Different `awk' implementations use different
+ CAUTION: Different 'awk' implementations use different
random-number generators internally. Don't expect the same
- `awk' program to produce the same series of random numbers
- when executed by different versions of `awk'.
+ 'awk' program to produce the same series of random numbers
+ when executed by different versions of 'awk'.
- If the argument X is omitted, as in `srand()', then the current
+ If the argument X is omitted, as in 'srand()', then the current
date and time of day are used for a seed. This is the way to get
random numbers that are truly unpredictable.
- The return value of `srand()' is the previous seed. This makes it
+ The return value of 'srand()' is the previous seed. This makes it
easy to keep track of the seeds in case you need to consistently
reproduce sequences of random numbers.
- POSIX does not specify the initial seed; it differs among `awk'
+ POSIX does not specify the initial seed; it differs among 'awk'
implementations.
---------- Footnotes ----------
- (1) The C version of `rand()' on many Unix systems is known to
+ (1) The C version of 'rand()' on many Unix systems is known to
produce fairly poor sequences of random numbers. However, nothing
-requires that an `awk' implementation use the C `rand()' to implement
-the `awk' version of `rand()'. In fact, `gawk' uses the BSD `random()'
-function, which is considerably better than `rand()', to produce random
+requires that an 'awk' implementation use the C 'rand()' to implement
+the 'awk' version of 'rand()'. In fact, 'gawk' uses the BSD 'random()'
+function, which is considerably better than 'rand()', to produce random
numbers.
- (2) `mawk' uses a different seed each time.
+ (2) 'mawk' uses a different seed each time.
(3) Computer-generated random numbers really are not truly random.
They are technically known as "pseudorandom". This means that although
@@ -12012,39 +11956,38 @@ File: gawk.info, Node: String Functions, Next: I/O
Functions, Prev: Numeric F
The functions in this minor node look at or change the text of one or
more strings.
- `gawk' understands locales (*note Locales::) and does all string
+ 'gawk' understands locales (*note Locales::) and does all string
processing in terms of _characters_, not _bytes_. This distinction is
-particularly important to understand for locales where one character
-may be represented by multiple bytes. Thus, for example, `length()'
-returns the number of characters in a string, and not the number of
-bytes used to represent those characters. Similarly, `index()' works
-with character indices, and not byte indices.
-
- CAUTION: A number of functions deal with indices into strings.
- For these functions, the first character of a string is at
- position (index) one. This is different from C and the languages
- descended from it, where the first character is at position zero.
- You need to remember this when doing index calculations,
- particularly if you are used to C.
+particularly important to understand for locales where one character may
+be represented by multiple bytes. Thus, for example, 'length()' returns
+the number of characters in a string, and not the number of bytes used
+to represent those characters. Similarly, 'index()' works with
+character indices, and not byte indices.
+
+ CAUTION: A number of functions deal with indices into strings. For
+ these functions, the first character of a string is at position
+ (index) one. This is different from C and the languages descended
+ from it, where the first character is at position zero. You need
+ to remember this when doing index calculations, particularly if you
+ are used to C.
In the following list, optional parameters are enclosed in square
-brackets ([ ]). Several functions perform string substitution; the
-full discussion is provided in the description of the `sub()' function,
-which comes toward the end, because the list is presented
-alphabetically.
+brackets ([ ]). Several functions perform string substitution; the full
+discussion is provided in the description of the 'sub()' function, which
+comes toward the end, because the list is presented alphabetically.
- Those functions that are specific to `gawk' are marked with a pound
-sign (`#'). They are not available in compatibility mode (*note
+ Those functions that are specific to 'gawk' are marked with a pound
+sign ('#'). They are not available in compatibility mode (*note
Options::):
* Menu:
-* Gory Details:: More than you want to know about `\' and
- `&' with `sub()', `gsub()', and
- `gensub()'.
+* Gory Details:: More than you want to know about '\' and
+ '&' with 'sub()', 'gsub()', and
+ 'gensub()'.
-`asort('SOURCE [`,' DEST [`,' HOW ] ]`) #'
-`asorti('SOURCE [`,' DEST [`,' HOW ] ]`) #'
+'asort('SOURCE [',' DEST [',' HOW ] ]') #'
+'asorti('SOURCE [',' DEST [',' HOW ] ]') #'
These two functions are similar in behavior, so they are described
together.
@@ -12055,60 +11998,59 @@ Options::):
*note Array Sorting Functions::, for the full story.)
Both functions return the number of elements in the array SOURCE.
- For `asort()', `gawk' sorts the values of SOURCE and replaces the
+ For 'asort()', 'gawk' sorts the values of SOURCE and replaces the
indices of the sorted values of SOURCE with sequential integers
starting with one. If the optional array DEST is specified, then
SOURCE is duplicated into DEST. DEST is then sorted, leaving the
indices of SOURCE unchanged.
- When comparing strings, `IGNORECASE' affects the sorting (*note
- Array Sorting Functions::). If the SOURCE array contains
- subarrays as values (*note Arrays of Arrays::), they will come
- last, after all scalar values. Subarrays are _not_ recursively
- sorted.
+ When comparing strings, 'IGNORECASE' affects the sorting (*note
+ Array Sorting Functions::). If the SOURCE array contains subarrays
+ as values (*note Arrays of Arrays::), they will come last, after
+ all scalar values. Subarrays are _not_ recursively sorted.
- For example, if the contents of `a' are as follows:
+ For example, if the contents of 'a' are as follows:
a["last"] = "de"
a["first"] = "sac"
a["middle"] = "cul"
- A call to `asort()':
+ A call to 'asort()':
asort(a)
- results in the following contents of `a':
+ results in the following contents of 'a':
a[1] = "cul"
a[2] = "de"
a[3] = "sac"
- The `asorti()' function works similarly to `asort()'; however, the
- _indices_ are sorted, instead of the values. Thus, in the previous
+ The 'asorti()' function works similarly to 'asort()'; however, the
+ _indices_ are sorted, instead of the values. Thus, in the previous
example, starting with the same initial set of indices and values
- in `a', calling `asorti(a)' would yield:
+ in 'a', calling 'asorti(a)' would yield:
a[1] = "first"
a[2] = "last"
a[3] = "middle"
-`gensub(REGEXP, REPLACEMENT, HOW' [`, TARGET']`) #'
+'gensub(REGEXP, REPLACEMENT, HOW' [', TARGET']') #'
Search the target string TARGET for matches of the regular
- expression REGEXP. If HOW is a string beginning with `g' or `G'
+ expression REGEXP. If HOW is a string beginning with 'g' or 'G'
(short for "global"), then replace all matches of REGEXP with
REPLACEMENT. Otherwise, HOW is treated as a number indicating
- which match of REGEXP to replace. If no TARGET is supplied, use
- `$0'. It returns the modified string as the result of the
- function and the original target string is _not_ changed.
+ which match of REGEXP to replace. If no TARGET is supplied, use
+ '$0'. It returns the modified string as the result of the function
+ and the original target string is _not_ changed.
- `gensub()' is a general substitution function. Its purpose is to
- provide more features than the standard `sub()' and `gsub()'
+ 'gensub()' is a general substitution function. Its purpose is to
+ provide more features than the standard 'sub()' and 'gsub()'
functions.
- `gensub()' provides an additional feature that is not available in
- `sub()' or `gsub()': the ability to specify components of a regexp
+ 'gensub()' provides an additional feature that is not available in
+ 'sub()' or 'gsub()': the ability to specify components of a regexp
in the replacement text. This is done by using parentheses in the
- regexp to mark the components and then specifying `\N' in the
+ regexp to mark the components and then specifying '\N' in the
replacement text, where N is a digit from 1 to 9. For example:
$ gawk '
@@ -12119,9 +12061,9 @@ Options::):
> }'
-| def abc
- As with `sub()', you must type two backslashes in order to get one
- into the string. In the replacement text, the sequence `\0'
- represents the entire matched text, as does the character `&'.
+ As with 'sub()', you must type two backslashes in order to get one
+ into the string. In the replacement text, the sequence '\0'
+ represents the entire matched text, as does the character '&'.
The following example shows how you can use the third argument to
control which match of the regexp should be changed:
@@ -12130,35 +12072,35 @@ Options::):
> gawk '{ print gensub(/a/, "AA", 2) }'
-| a b c AA b c
- In this case, `$0' is the default target string. `gensub()'
+ In this case, '$0' is the default target string. 'gensub()'
returns the new string as its result, which is passed directly to
- `print' for printing.
+ 'print' for printing.
- If the HOW argument is a string that does not begin with `g' or
- `G', or if it is a number that is less than or equal to zero, only
- one substitution is performed. If HOW is zero, `gawk' issues a
+ If the HOW argument is a string that does not begin with 'g' or
+ 'G', or if it is a number that is less than or equal to zero, only
+ one substitution is performed. If HOW is zero, 'gawk' issues a
warning message.
- If REGEXP does not match TARGET, `gensub()''s return value is the
+ If REGEXP does not match TARGET, 'gensub()''s return value is the
original unchanged value of TARGET.
-`gsub(REGEXP, REPLACEMENT' [`, TARGET']`)'
+'gsub(REGEXP, REPLACEMENT' [', TARGET']')'
Search TARGET for _all_ of the longest, leftmost, _nonoverlapping_
matching substrings it can find and replace them with REPLACEMENT.
- The `g' in `gsub()' stands for "global," which means replace
+ The 'g' in 'gsub()' stands for "global," which means replace
everywhere. For example:
{ gsub(/Britain/, "United Kingdom"); print }
- replaces all occurrences of the string `Britain' with `United
+ replaces all occurrences of the string 'Britain' with 'United
Kingdom' for all input records.
- The `gsub()' function returns the number of substitutions made. If
+ The 'gsub()' function returns the number of substitutions made. If
the variable to search and alter (TARGET) is omitted, then the
- entire input record (`$0') is used. As in `sub()', the characters
- `&' and `\' are special, and the third argument must be assignable.
+ entire input record ('$0') is used. As in 'sub()', the characters
+ '&' and '\' are special, and the third argument must be assignable.
-`index(IN, FIND)'
+'index(IN, FIND)'
Search the string IN for the first occurrence of the string FIND,
and return the position in characters where that occurrence begins
in the string IN. Consider the following example:
@@ -12166,75 +12108,75 @@ Options::):
$ awk 'BEGIN { print index("peanut", "an") }'
-| 3
- If FIND is not found, `index()' returns zero.
+ If FIND is not found, 'index()' returns zero.
- With BWK `awk' and `gawk', it is a fatal error to use a regexp
- constant for FIND. Other implementations allow it, simply
- treating the regexp constant as an expression meaning `$0 ~
- /regexp/'. (d.c.)
+ With BWK 'awk' and 'gawk', it is a fatal error to use a regexp
+ constant for FIND. Other implementations allow it, simply treating
+ the regexp constant as an expression meaning '$0 ~ /regexp/'.
+ (d.c.)
-`length('[STRING]`)'
+'length('[STRING]')'
Return the number of characters in STRING. If STRING is a number,
the length of the digit string representing that number is
- returned. For example, `length("abcde")' is five. By contrast,
- `length(15 * 35)' works out to three. In this example, 15 * 35 =
- 525, and 525 is then converted to the string `"525"', which has
+ returned. For example, 'length("abcde")' is five. By contrast,
+ 'length(15 * 35)' works out to three. In this example, 15 * 35 =
+ 525, and 525 is then converted to the string '"525"', which has
three characters.
- If no argument is supplied, `length()' returns the length of `$0'.
+ If no argument is supplied, 'length()' returns the length of '$0'.
- NOTE: In older versions of `awk', the `length()' function
+ NOTE: In older versions of 'awk', the 'length()' function
could be called without any parentheses. Doing so is
considered poor practice, although the 2008 POSIX standard
explicitly allows it, to support historical practice. For
programs to be maximally portable, always supply the
parentheses.
- If `length()' is called with a variable that has not been used,
- `gawk' forces the variable to be a scalar. Other implementations
- of `awk' leave the variable without a type. (d.c.) Consider:
+ If 'length()' is called with a variable that has not been used,
+ 'gawk' forces the variable to be a scalar. Other implementations
+ of 'awk' leave the variable without a type. (d.c.) Consider:
$ gawk 'BEGIN { print length(x) ; x[1] = 1 }'
-| 0
- error--> gawk: fatal: attempt to use scalar `x' as array
+ error-> gawk: fatal: attempt to use scalar `x' as array
$ nawk 'BEGIN { print length(x) ; x[1] = 1 }'
-| 0
- If `--lint' has been specified on the command line, `gawk' issues a
+ If '--lint' has been specified on the command line, 'gawk' issues a
warning about this.
- With `gawk' and several other `awk' implementations, when given an
- array argument, the `length()' function returns the number of
- elements in the array. (c.e.) This is less useful than it might
+ With 'gawk' and several other 'awk' implementations, when given an
+ array argument, the 'length()' function returns the number of
+ elements in the array. (c.e.) This is less useful than it might
seem at first, as the array is not guaranteed to be indexed from
- one to the number of elements in it. If `--lint' is provided on
- the command line (*note Options::), `gawk' warns that passing an
- array argument is not portable. If `--posix' is supplied, using
- an array argument is a fatal error (*note Arrays::).
+ one to the number of elements in it. If '--lint' is provided on
+ the command line (*note Options::), 'gawk' warns that passing an
+ array argument is not portable. If '--posix' is supplied, using an
+ array argument is a fatal error (*note Arrays::).
-`match(STRING, REGEXP' [`, ARRAY']`)'
+'match(STRING, REGEXP' [', ARRAY']')'
Search STRING for the longest, leftmost substring matched by the
regular expression REGEXP and return the character position (index)
at which that substring begins (one, if it starts at the beginning
of STRING). If no match is found, return zero.
- The REGEXP argument may be either a regexp constant (`/'...`/') or
- a string constant (`"'...`"'). In the latter case, the string is
+ The REGEXP argument may be either a regexp constant ('/'...'/') or
+ a string constant ('"'...'"'). In the latter case, the string is
treated as a regexp to be matched. *Note Computed Regexps::, for a
discussion of the difference between the two forms, and the
implications for writing your program correctly.
The order of the first two arguments is the opposite of most other
string functions that work with regular expressions, such as
- `sub()' and `gsub()'. It might help to remember that for
- `match()', the order is the same as for the `~' operator: `STRING
- ~ REGEXP'.
+ 'sub()' and 'gsub()'. It might help to remember that for
+ 'match()', the order is the same as for the '~' operator: 'STRING ~
+ REGEXP'.
- The `match()' function sets the predefined variable `RSTART' to
- the index. It also sets the predefined variable `RLENGTH' to the
+ The 'match()' function sets the predefined variable 'RSTART' to the
+ index. It also sets the predefined variable 'RLENGTH' to the
length in characters of the matched substring. If no match is
- found, `RSTART' is set to zero, and `RLENGTH' to -1.
+ found, 'RSTART' is set to zero, and 'RLENGTH' to -1.
For example:
@@ -12249,9 +12191,9 @@ Options::):
}
This program looks for lines that match the regular expression
- stored in the variable `regex'. This regular expression can be
- changed. If the first word on a line is `FIND', `regex' is
- changed to be the second word on that line. Therefore, if given:
+ stored in the variable 'regex'. This regular expression can be
+ changed. If the first word on a line is 'FIND', 'regex' is changed
+ to be the second word on that line. Therefore, if given:
FIND ru+n
My program runs
@@ -12261,16 +12203,16 @@ Options::):
This line is property of Reality Engineering Co.
Melvin was here.
- `awk' prints:
+ 'awk' prints:
Match of ru+n found at 12 in My program runs
Match of Melvin found at 1 in Melvin was here.
If ARRAY is present, it is cleared, and then the zeroth element of
- ARRAY is set to the entire portion of STRING matched by REGEXP.
- If REGEXP contains parentheses, the integer-indexed elements of
- ARRAY are set to contain the portion of STRING matching the
- corresponding parenthesized subexpression. For example:
+ ARRAY is set to the entire portion of STRING matched by REGEXP. If
+ REGEXP contains parentheses, the integer-indexed elements of ARRAY
+ are set to contain the portion of STRING matching the corresponding
+ parenthesized subexpression. For example:
$ echo foooobazbarrrrr |
> gawk '{ match($0, /(fo+).+(bar*)/, arr)
@@ -12292,158 +12234,158 @@ Options::):
There may not be subscripts for the start and index for every
parenthesized subexpression, because they may not all have matched
- text; thus, they should be tested for with the `in' operator
- (*note Reference to Elements::).
+ text; thus, they should be tested for with the 'in' operator (*note
+ Reference to Elements::).
- The ARRAY argument to `match()' is a `gawk' extension. In
+ The ARRAY argument to 'match()' is a 'gawk' extension. In
compatibility mode (*note Options::), using a third argument is a
fatal error.
-`patsplit(STRING, ARRAY' [`, FIELDPAT' [`, SEPS' ] ]`) #'
+'patsplit(STRING, ARRAY' [', FIELDPAT' [', SEPS' ] ]') #'
Divide STRING into pieces defined by FIELDPAT and store the pieces
in ARRAY and the separator strings in the SEPS array. The first
- piece is stored in `ARRAY[1]', the second piece in `ARRAY[2]', and
- so forth. The third argument, FIELDPAT, is a regexp describing
- the fields in STRING (just as `FPAT' is a regexp describing the
- fields in input records). It may be either a regexp constant or a
- string. If FIELDPAT is omitted, the value of `FPAT' is used.
- `patsplit()' returns the number of elements created. `SEPS[I]' is
- the separator string between `ARRAY[I]' and `ARRAY[I+1]'. Any
- leading separator will be in `SEPS[0]'.
-
- The `patsplit()' function splits strings into pieces in a manner
- similar to the way input lines are split into fields using `FPAT'
+ piece is stored in 'ARRAY[1]', the second piece in 'ARRAY[2]', and
+ so forth. The third argument, FIELDPAT, is a regexp describing the
+ fields in STRING (just as 'FPAT' is a regexp describing the fields
+ in input records). It may be either a regexp constant or a string.
+ If FIELDPAT is omitted, the value of 'FPAT' is used. 'patsplit()'
+ returns the number of elements created. 'SEPS[I]' is the separator
+ string between 'ARRAY[I]' and 'ARRAY[I+1]'. Any leading separator
+ will be in 'SEPS[0]'.
+
+ The 'patsplit()' function splits strings into pieces in a manner
+ similar to the way input lines are split into fields using 'FPAT'
(*note Splitting By Content::).
- Before splitting the string, `patsplit()' deletes any previously
+ Before splitting the string, 'patsplit()' deletes any previously
existing elements in the arrays ARRAY and SEPS.
-`split(STRING, ARRAY' [`, FIELDSEP' [`, SEPS' ] ]`)'
+'split(STRING, ARRAY' [', FIELDSEP' [', SEPS' ] ]')'
Divide STRING into pieces separated by FIELDSEP and store the
pieces in ARRAY and the separator strings in the SEPS array. The
- first piece is stored in `ARRAY[1]', the second piece in
- `ARRAY[2]', and so forth. The string value of the third argument,
+ first piece is stored in 'ARRAY[1]', the second piece in
+ 'ARRAY[2]', and so forth. The string value of the third argument,
FIELDSEP, is a regexp describing where to split STRING (much as
- `FS' can be a regexp describing where to split input records). If
- FIELDSEP is omitted, the value of `FS' is used. `split()' returns
- the number of elements created. SEPS is a `gawk' extension, with
- `SEPS[I]' being the separator string between `ARRAY[I]' and
- `ARRAY[I+1]'. If FIELDSEP is a single space, then any leading
- whitespace goes into `SEPS[0]' and any trailing whitespace goes
- into `SEPS[N]', where N is the return value of `split()' (i.e.,
- the number of elements in ARRAY).
-
- The `split()' function splits strings into pieces in a manner
+ 'FS' can be a regexp describing where to split input records). If
+ FIELDSEP is omitted, the value of 'FS' is used. 'split()' returns
+ the number of elements created. SEPS is a 'gawk' extension, with
+ 'SEPS[I]' being the separator string between 'ARRAY[I]' and
+ 'ARRAY[I+1]'. If FIELDSEP is a single space, then any leading
+ whitespace goes into 'SEPS[0]' and any trailing whitespace goes
+ into 'SEPS[N]', where N is the return value of 'split()' (i.e., the
+ number of elements in ARRAY).
+
+ The 'split()' function splits strings into pieces in a manner
similar to the way input lines are split into fields. For example:
split("cul-de-sac", a, "-", seps)
- splits the string `"cul-de-sac"' into three fields using `-' as the
- separator. It sets the contents of the array `a' as follows:
+ splits the string '"cul-de-sac"' into three fields using '-' as the
+ separator. It sets the contents of the array 'a' as follows:
a[1] = "cul"
a[2] = "de"
a[3] = "sac"
- and sets the contents of the array `seps' as follows:
+ and sets the contents of the array 'seps' as follows:
seps[1] = "-"
seps[2] = "-"
- The value returned by this call to `split()' is three.
+ The value returned by this call to 'split()' is three.
- As with input field-splitting, when the value of FIELDSEP is
- `" "', leading and trailing whitespace is ignored in values
- assigned to the elements of ARRAY but not in SEPS, and the elements
- are separated by runs of whitespace. Also, as with input field
+ As with input field-splitting, when the value of FIELDSEP is '" "',
+ leading and trailing whitespace is ignored in values assigned to
+ the elements of ARRAY but not in SEPS, and the elements are
+ separated by runs of whitespace. Also, as with input field
splitting, if FIELDSEP is the null string, each individual
character in the string is split into its own array element.
(c.e.)
- Note, however, that `RS' has no effect on the way `split()' works.
- Even though `RS = ""' causes the newline character to also be an
- input field separator, this does not affect how `split()' splits
+ Note, however, that 'RS' has no effect on the way 'split()' works.
+ Even though 'RS = ""' causes the newline character to also be an
+ input field separator, this does not affect how 'split()' splits
strings.
- Modern implementations of `awk', including `gawk', allow the third
- argument to be a regexp constant (`/'...`/') as well as a string.
+ Modern implementations of 'awk', including 'gawk', allow the third
+ argument to be a regexp constant ('/'...'/') as well as a string.
(d.c.) The POSIX standard allows this as well. *Note Computed
Regexps::, for a discussion of the difference between using a
string constant or a regexp constant, and the implications for
writing your program correctly.
- Before splitting the string, `split()' deletes any previously
+ Before splitting the string, 'split()' deletes any previously
existing elements in the arrays ARRAY and SEPS.
- If STRING is null, the array has no elements. (So this is a
+ If STRING is null, the array has no elements. (So this is a
portable way to delete an entire array with one statement. *Note
Delete::.)
If STRING does not match FIELDSEP at all (but is not null), ARRAY
- has one element only. The value of that element is the original
+ has one element only. The value of that element is the original
STRING.
In POSIX mode (*note Options::), the fourth argument is not
allowed.
-`sprintf(FORMAT, EXPRESSION1, ...)'
- Return (without printing) the string that `printf' would have
+'sprintf(FORMAT, EXPRESSION1, ...)'
+ Return (without printing) the string that 'printf' would have
printed out with the same arguments (*note Printf::). For example:
pival = sprintf("pi = %.2f (approx.)", 22/7)
- assigns the string `pi = 3.14 (approx.)' to the variable `pival'.
+ assigns the string 'pi = 3.14 (approx.)' to the variable 'pival'.
-`strtonum(STR) #'
+'strtonum(STR) #'
Examine STR and return its numeric value. If STR begins with a
- leading `0', `strtonum()' assumes that STR is an octal number. If
- STR begins with a leading `0x' or `0X', `strtonum()' assumes that
+ leading '0', 'strtonum()' assumes that STR is an octal number. If
+ STR begins with a leading '0x' or '0X', 'strtonum()' assumes that
STR is a hexadecimal number. For example:
$ echo 0x11 |
> gawk '{ printf "%d\n", strtonum($1) }'
-| 17
- Using the `strtonum()' function is _not_ the same as adding zero
- to a string value; the automatic coercion of strings to numbers
- works only for decimal data, not for octal or hexadecimal.(1)
+ Using the 'strtonum()' function is _not_ the same as adding zero to
+ a string value; the automatic coercion of strings to numbers works
+ only for decimal data, not for octal or hexadecimal.(1)
- Note also that `strtonum()' uses the current locale's decimal point
+ Note also that 'strtonum()' uses the current locale's decimal point
for recognizing numbers (*note Locales::).
-`sub(REGEXP, REPLACEMENT' [`, TARGET']`)'
+'sub(REGEXP, REPLACEMENT' [', TARGET']')'
Search TARGET, which is treated as a string, for the leftmost,
- longest substring matched by the regular expression REGEXP.
- Modify the entire string by replacing the matched text with
- REPLACEMENT. The modified string becomes the new value of TARGET.
- Return the number of substitutions made (zero or one).
+ longest substring matched by the regular expression REGEXP. Modify
+ the entire string by replacing the matched text with REPLACEMENT.
+ The modified string becomes the new value of TARGET. Return the
+ number of substitutions made (zero or one).
- The REGEXP argument may be either a regexp constant (`/'...`/') or
- a string constant (`"'...`"'). In the latter case, the string is
+ The REGEXP argument may be either a regexp constant ('/'...'/') or
+ a string constant ('"'...'"'). In the latter case, the string is
treated as a regexp to be matched. *Note Computed Regexps::, for a
discussion of the difference between the two forms, and the
implications for writing your program correctly.
This function is peculiar because TARGET is not simply used to
compute a value, and not just any expression will do--it must be a
- variable, field, or array element so that `sub()' can store a
+ variable, field, or array element so that 'sub()' can store a
modified value there. If this argument is omitted, then the
- default is to use and alter `$0'.(2) For example:
+ default is to use and alter '$0'.(2) For example:
str = "water, water, everywhere"
sub(/at/, "ith", str)
- sets `str' to `wither, water, everywhere', by replacing the
- leftmost longest occurrence of `at' with `ith'.
+ sets 'str' to 'wither, water, everywhere', by replacing the
+ leftmost longest occurrence of 'at' with 'ith'.
- If the special character `&' appears in REPLACEMENT, it stands for
+ If the special character '&' appears in REPLACEMENT, it stands for
the precise substring that was matched by REGEXP. (If the regexp
can match more than one string, then this precise substring may
vary.) For example:
{ sub(/candidate/, "& and his wife"); print }
- changes the first occurrence of `candidate' to `candidate and his
+ changes the first occurrence of 'candidate' to 'candidate and his
wife' on each input line. Here is another example:
$ awk 'BEGIN {
@@ -12453,30 +12395,30 @@ Options::):
> }'
-| dCaaCbaaa
- This shows how `&' can represent a nonconstant string and also
+ This shows how '&' can represent a nonconstant string and also
illustrates the "leftmost, longest" rule in regexp matching (*note
Leftmost Longest::).
- The effect of this special character (`&') can be turned off by
+ The effect of this special character ('&') can be turned off by
putting a backslash before it in the string. As usual, to insert
one backslash in the string, you must write two backslashes.
- Therefore, write `\\&' in a string constant to include a literal
- `&' in the replacement. For example, the following shows how to
- replace the first `|' on each line with an `&':
+ Therefore, write '\\&' in a string constant to include a literal
+ '&' in the replacement. For example, the following shows how to
+ replace the first '|' on each line with an '&':
{ sub(/\|/, "\\&"); print }
- As mentioned, the third argument to `sub()' must be a variable,
- field, or array element. Some versions of `awk' allow the third
+ As mentioned, the third argument to 'sub()' must be a variable,
+ field, or array element. Some versions of 'awk' allow the third
argument to be an expression that is not an lvalue. In such a
- case, `sub()' still searches for the pattern and returns zero or
+ case, 'sub()' still searches for the pattern and returns zero or
one, but the result of the substitution (if any) is thrown away
- because there is no place to put it. Such versions of `awk'
- accept expressions like the following:
+ because there is no place to put it. Such versions of 'awk' accept
+ expressions like the following:
sub(/USA/, "United States", "the USA and Canada")
- For historical compatibility, `gawk' accepts such erroneous code.
+ For historical compatibility, 'gawk' accepts such erroneous code.
However, using any other nonchangeable object as the third
parameter causes a fatal error and your program will not run.
@@ -12484,26 +12426,26 @@ Options::):
into a string, and then the value of that string is treated as the
regexp to match.
-`substr(STRING, START' [`, LENGTH' ]`)'
+'substr(STRING, START' [', LENGTH' ]')'
Return a LENGTH-character-long substring of STRING, starting at
character number START. The first character of a string is
- character number one.(3) For example, `substr("washington", 5, 3)'
- returns `"ing"'.
+ character number one.(3) For example, 'substr("washington", 5, 3)'
+ returns '"ing"'.
- If LENGTH is not present, `substr()' returns the whole suffix of
+ If LENGTH is not present, 'substr()' returns the whole suffix of
STRING that begins at character number START. For example,
- `substr("washington", 5)' returns `"ington"'. The whole suffix is
+ 'substr("washington", 5)' returns '"ington"'. The whole suffix is
also returned if LENGTH is greater than the number of characters
remaining in the string, counting from character START.
- If START is less than one, `substr()' treats it as if it was one.
- (POSIX doesn't specify what to do in this case: BWK `awk' acts
- this way, and therefore `gawk' does too.) If START is greater
- than the number of characters in the string, `substr()' returns
- the null string. Similarly, if LENGTH is present but less than or
- equal to zero, the null string is returned.
+ If START is less than one, 'substr()' treats it as if it was one.
+ (POSIX doesn't specify what to do in this case: BWK 'awk' acts this
+ way, and therefore 'gawk' does too.) If START is greater than the
+ number of characters in the string, 'substr()' returns the null
+ string. Similarly, if LENGTH is present but less than or equal to
+ zero, the null string is returned.
- The string returned by `substr()' _cannot_ be assigned. Thus, it
+ The string returned by 'substr()' _cannot_ be assigned. Thus, it
is a mistake to attempt to change a portion of a string, as shown
in the following example:
@@ -12511,37 +12453,37 @@ Options::):
# try to get "abCDEf", won't work
substr(string, 3, 3) = "CDE"
- It is also a mistake to use `substr()' as the third argument of
- `sub()' or `gsub()':
+ It is also a mistake to use 'substr()' as the third argument of
+ 'sub()' or 'gsub()':
gsub(/xyz/, "pdq", substr($0, 5, 20)) # WRONG
- (Some commercial versions of `awk' treat `substr()' as assignable,
+ (Some commercial versions of 'awk' treat 'substr()' as assignable,
but doing so is not portable.)
If you need to replace bits and pieces of a string, combine
- `substr()' with string concatenation, in the following manner:
+ 'substr()' with string concatenation, in the following manner:
string = "abcdef"
...
string = substr(string, 1, 2) "CDE" substr(string, 6)
-`tolower(STRING)'
+'tolower(STRING)'
Return a copy of STRING, with each uppercase character in the
string replaced with its corresponding lowercase character.
Nonalphabetic characters are left unchanged. For example,
- `tolower("MiXeD cAsE 123")' returns `"mixed case 123"'.
+ 'tolower("MiXeD cAsE 123")' returns '"mixed case 123"'.
-`toupper(STRING)'
+'toupper(STRING)'
Return a copy of STRING, with each lowercase character in the
string replaced with its corresponding uppercase character.
Nonalphabetic characters are left unchanged. For example,
- `toupper("MiXeD cAsE 123")' returns `"MIXED CASE 123"'.
+ 'toupper("MiXeD cAsE 123")' returns '"MIXED CASE 123"'.
Matching the Null String
- In `awk', the `*' operator can match the null string. This is
-particularly important for the `sub()', `gsub()', and `gensub()'
+ In 'awk', the '*' operator can match the null string. This is
+particularly important for the 'sub()', 'gsub()', and 'gensub()'
functions. For example:
$ echo abc | awk '{ gsub(/m*/, "X"); print }'
@@ -12551,156 +12493,156 @@ Although this makes a certain amount of sense, it
can be surprising.
---------- Footnotes ----------
- (1) Unless you use the `--non-decimal-data' option, which isn't
+ (1) Unless you use the '--non-decimal-data' option, which isn't
recommended. *Note Nondecimal Data::, for more information.
(2) Note that this means that the record will first be regenerated
-using the value of `OFS' if any fields have been changed, and that the
+using the value of 'OFS' if any fields have been changed, and that the
fields will be updated after the substitution, even if the operation is
-a "no-op" such as `sub(/^/, "")'.
+a "no-op" such as 'sub(/^/, "")'.
- (3) This is different from C and C++, in which the first character
-is number zero.
+ (3) This is different from C and C++, in which the first character is
+number zero.
File: gawk.info, Node: Gory Details, Up: String Functions
-9.1.3.1 More about `\' and `&' with `sub()', `gsub()', and `gensub()'
+9.1.3.1 More about '\' and '&' with 'sub()', 'gsub()', and 'gensub()'
.....................................................................
CAUTION: This subsubsection has been reported to cause headaches.
You might want to skip it upon first reading.
- When using `sub()', `gsub()', or `gensub()', and trying to get
+ When using 'sub()', 'gsub()', or 'gensub()', and trying to get
literal backslashes and ampersands into the replacement text, you need
to remember that there are several levels of "escape processing" going
on.
- First, there is the "lexical" level, which is when `awk' reads your
-program and builds an internal copy of it to execute. Then there is
-the runtime level, which is when `awk' actually scans the replacement
-string to determine what to generate.
+ First, there is the "lexical" level, which is when 'awk' reads your
+program and builds an internal copy of it to execute. Then there is the
+runtime level, which is when 'awk' actually scans the replacement string
+to determine what to generate.
- At both levels, `awk' looks for a defined set of characters that can
+ At both levels, 'awk' looks for a defined set of characters that can
come after a backslash. At the lexical level, it looks for the escape
-sequences listed in *note Escape Sequences::. Thus, for every `\' that
-`awk' processes at the runtime level, you must type two backslashes at
+sequences listed in *note Escape Sequences::. Thus, for every '\' that
+'awk' processes at the runtime level, you must type two backslashes at
the lexical level. When a character that is not valid for an escape
-sequence follows the `\', BWK `awk' and `gawk' both simply remove the
-initial `\' and put the next character into the string. Thus, for
-example, `"a\qb"' is treated as `"aqb"'.
-
- At the runtime level, the various functions handle sequences of `\'
-and `&' differently. The situation is (sadly) somewhat complex.
-Historically, the `sub()' and `gsub()' functions treated the
-two-character sequence `\&' specially; this sequence was replaced in
-the generated text with a single `&'. Any other `\' within the
-REPLACEMENT string that did not precede an `&' was passed through
-unchanged. This is illustrated in *note table-sub-escapes::.
-
- You type `sub()' sees `sub()' generates
- ------- --------- --------------
- `\&' `&' The matched text
- `\\&' `\&' A literal `&'
- `\\\&' `\&' A literal `&'
- `\\\\&' `\\&' A literal `\&'
- `\\\\\&' `\\&' A literal `\&'
- `\\\\\\&' `\\\&' A literal `\\&'
- `\\q' `\q' A literal `\q'
-
-Table 9.1: Historical escape sequence processing for `sub()' and
-`gsub()'
+sequence follows the '\', BWK 'awk' and 'gawk' both simply remove the
+initial '\' and put the next character into the string. Thus, for
+example, '"a\qb"' is treated as '"aqb"'.
+
+ At the runtime level, the various functions handle sequences of '\'
+and '&' differently. The situation is (sadly) somewhat complex.
+Historically, the 'sub()' and 'gsub()' functions treated the
+two-character sequence '\&' specially; this sequence was replaced in the
+generated text with a single '&'. Any other '\' within the REPLACEMENT
+string that did not precede an '&' was passed through unchanged. This
+is illustrated in *note Table 9.1: table-sub-escapes.
+
+ You type 'sub()' sees 'sub()' generates
+ ----- ------- ----------
+ '\&' '&' The matched text
+ '\\&' '\&' A literal '&'
+ '\\\&' '\&' A literal '&'
+ '\\\\&' '\\&' A literal '\&'
+ '\\\\\&' '\\&' A literal '\&'
+ '\\\\\\&' '\\\&' A literal '\\&'
+ '\\q' '\q' A literal '\q'
+
+Table 9.1: Historical escape sequence processing for 'sub()' and
+'gsub()'
This table shows the lexical-level processing, where an odd number of
backslashes becomes an even number at the runtime level, as well as the
-runtime processing done by `sub()'. (For the sake of simplicity, the
+runtime processing done by 'sub()'. (For the sake of simplicity, the
rest of the following tables only show the case of even numbers of
backslashes entered at the lexical level.)
The problem with the historical approach is that there is no way to
-get a literal `\' followed by the matched text.
+get a literal '\' followed by the matched text.
Several editions of the POSIX standard attempted to fix this problem
-but weren't successful. The details are irrelevant at this point in
+but weren't successful. The details are irrelevant at this point in
time.
- At one point, the `gawk' maintainer submitted proposed text for a
+ At one point, the 'gawk' maintainer submitted proposed text for a
revised standard that reverts to rules that correspond more closely to
-the original existing practice. The proposed rules have special cases
-that make it possible to produce a `\' preceding the matched text.
-This is shown in *note table-sub-proposed::.
+the original existing practice. The proposed rules have special cases
+that make it possible to produce a '\' preceding the matched text. This
+is shown in *note Table 9.2: table-sub-proposed.
- You type `sub()' sees `sub()' generates
- ------- --------- --------------
- `\\\\\\&' `\\\&' A literal `\&'
- `\\\\&' `\\&' A literal `\', followed by the
matched text
- `\\&' `\&' A literal `&'
- `\\q' `\q' A literal `\q'
- `\\\\' `\\' `\\'
+ You type 'sub()' sees 'sub()' generates
+ ----- ------- ----------
+ '\\\\\\&' '\\\&' A literal '\&'
+ '\\\\&' '\\&' A literal '\', followed by the
matched text
+ '\\&' '\&' A literal '&'
+ '\\q' '\q' A literal '\q'
+ '\\\\' '\\' '\\'
-Table 9.2: `gawk' rules for `sub()' and backslash
+Table 9.2: 'gawk' rules for 'sub()' and backslash
In a nutshell, at the runtime level, there are now three special
-sequences of characters (`\\\&', `\\&', and `\&') whereas historically
-there was only one. However, as in the historical case, any `\' that
-is not part of one of these three sequences is not special and appears
-in the output literally.
+sequences of characters ('\\\&', '\\&', and '\&') whereas historically
+there was only one. However, as in the historical case, any '\' that is
+not part of one of these three sequences is not special and appears in
+the output literally.
- `gawk' 3.0 and 3.1 follow these rules for `sub()' and `gsub()'. The
+ 'gawk' 3.0 and 3.1 follow these rules for 'sub()' and 'gsub()'. The
POSIX standard took much longer to be revised than was expected. In
-addition, the `gawk' maintainer's proposal was lost during the
+addition, the 'gawk' maintainer's proposal was lost during the
standardization process. The final rules are somewhat simpler. The
results are similar except for one case.
- The POSIX rules state that `\&' in the replacement string produces a
-literal `&', `\\' produces a literal `\', and `\' followed by anything
-else is not special; the `\' is placed straight into the output. These
-rules are presented in *note table-posix-sub::.
+ The POSIX rules state that '\&' in the replacement string produces a
+literal '&', '\\' produces a literal '\', and '\' followed by anything
+else is not special; the '\' is placed straight into the output. These
+rules are presented in *note Table 9.3: table-posix-sub.
- You type `sub()' sees `sub()' generates
- ------- --------- --------------
- `\\\\\\&' `\\\&' A literal `\&'
- `\\\\&' `\\&' A literal `\', followed by the
matched text
- `\\&' `\&' A literal `&'
- `\\q' `\q' A literal `\q'
- `\\\\' `\\' `\'
+ You type 'sub()' sees 'sub()' generates
+ ----- ------- ----------
+ '\\\\\\&' '\\\&' A literal '\&'
+ '\\\\&' '\\&' A literal '\', followed by the
matched text
+ '\\&' '\&' A literal '&'
+ '\\q' '\q' A literal '\q'
+ '\\\\' '\\' '\'
-Table 9.3: POSIX rules for `sub()' and `gsub()'
+Table 9.3: POSIX rules for 'sub()' and 'gsub()'
The only case where the difference is noticeable is the last one:
-`\\\\' is seen as `\\' and produces `\' instead of `\\'.
+'\\\\' is seen as '\\' and produces '\' instead of '\\'.
- Starting with version 3.1.4, `gawk' followed the POSIX rules when
-`--posix' was specified (*note Options::). Otherwise, it continued to
+ Starting with version 3.1.4, 'gawk' followed the POSIX rules when
+'--posix' was specified (*note Options::). Otherwise, it continued to
follow the proposed rules, as that had been its behavior for many years.
- When version 4.0.0 was released, the `gawk' maintainer made the
-POSIX rules the default, breaking well over a decade's worth of
-backward compatibility.(1) Needless to say, this was a bad idea, and as
-of version 4.0.1, `gawk' resumed its historical behavior, and only
-follows the POSIX rules when `--posix' is given.
+ When version 4.0.0 was released, the 'gawk' maintainer made the POSIX
+rules the default, breaking well over a decade's worth of backward
+compatibility.(1) Needless to say, this was a bad idea, and as of
+version 4.0.1, 'gawk' resumed its historical behavior, and only follows
+the POSIX rules when '--posix' is given.
- The rules for `gensub()' are considerably simpler. At the runtime
-level, whenever `gawk' sees a `\', if the following character is a
+ The rules for 'gensub()' are considerably simpler. At the runtime
+level, whenever 'gawk' sees a '\', if the following character is a
digit, then the text that matched the corresponding parenthesized
subexpression is placed in the generated output. Otherwise, no matter
-what character follows the `\', it appears in the generated text and
-the `\' does not, as shown in *note table-gensub-escapes::.
+what character follows the '\', it appears in the generated text and the
+'\' does not, as shown in *note Table 9.4: table-gensub-escapes.
- You type `gensub()' sees `gensub()' generates
- ------- ------------ -----------------
- `&' `&' The matched text
- `\\&' `\&' A literal `&'
- `\\\\' `\\' A literal `\'
- `\\\\&' `\\&' A literal `\', then the
matched text
- `\\\\\\&' `\\\&' A literal `\&'
- `\\q' `\q' A literal `q'
+ You type 'gensub()' sees 'gensub()' generates
+ ----- --------- ------------
+ '&' '&' The matched text
+ '\\&' '\&' A literal '&'
+ '\\\\' '\\' A literal '\'
+ '\\\\&' '\\&' A literal '\', then the
matched text
+ '\\\\\\&' '\\\&' A literal '\&'
+ '\\q' '\q' A literal 'q'
-Table 9.4: Escape sequence processing for `gensub()'
+Table 9.4: Escape sequence processing for 'gensub()'
Because of the complexity of the lexical- and runtime-level
-processing and the special cases for `sub()' and `gsub()', we recommend
-the use of `gawk' and `gensub()' when you have to do substitutions.
+processing and the special cases for 'sub()' and 'gsub()', we recommend
+the use of 'gawk' and 'gensub()' when you have to do substitutions.
---------- Footnotes ----------
@@ -12714,75 +12656,74 @@ File: gawk.info, Node: I/O Functions, Next: Time
Functions, Prev: String Func
9.1.4 Input/Output Functions
----------------------------
-The following functions relate to input/output (I/O). Optional
+The following functions relate to input/output (I/O). Optional
parameters are enclosed in square brackets ([ ]):
-`close('FILENAME [`,' HOW]`)'
- Close the file FILENAME for input or output. Alternatively, the
+'close('FILENAME [',' HOW]')'
+ Close the file FILENAME for input or output. Alternatively, the
argument may be a shell command that was used for creating a
- coprocess, or for redirecting to or from a pipe; then the
- coprocess or pipe is closed. *Note Close Files And Pipes::, for
- more information.
+ coprocess, or for redirecting to or from a pipe; then the coprocess
+ or pipe is closed. *Note Close Files And Pipes::, for more
+ information.
When closing a coprocess, it is occasionally useful to first close
one end of the two-way pipe and then to close the other. This is
- done by providing a second argument to `close()'. This second
- argument (HOW) should be one of the two string values `"to"' or
- `"from"', indicating which end of the pipe to close. Case in the
+ done by providing a second argument to 'close()'. This second
+ argument (HOW) should be one of the two string values '"to"' or
+ '"from"', indicating which end of the pipe to close. Case in the
string does not matter. *Note Two-way I/O::, which discusses this
feature in more detail and gives an example.
- Note that the second argument to `close()' is a `gawk' extension;
+ Note that the second argument to 'close()' is a 'gawk' extension;
it is not available in compatibility mode (*note Options::).
-`fflush('[FILENAME]`)'
- Flush any buffered output associated with FILENAME, which is
- either a file opened for writing or a shell command for
- redirecting output to a pipe or coprocess.
+'fflush('[FILENAME]')'
+ Flush any buffered output associated with FILENAME, which is either
+ a file opened for writing or a shell command for redirecting output
+ to a pipe or coprocess.
Many utility programs "buffer" their output (i.e., they save
information to write to a disk file or the screen in memory until
there is enough for it to be worthwhile to send the data to the
output device). This is often more efficient than writing every
little bit of information as soon as it is ready. However,
- sometimes it is necessary to force a program to "flush" its
- buffers (i.e., write the information to its destination, even if a
- buffer is not full). This is the purpose of the `fflush()'
- function--`gawk' also buffers its output, and the `fflush()'
- function forces `gawk' to flush its buffers.
+ sometimes it is necessary to force a program to "flush" its buffers
+ (i.e., write the information to its destination, even if a buffer
+ is not full). This is the purpose of the 'fflush()'
+ function--'gawk' also buffers its output, and the 'fflush()'
+ function forces 'gawk' to flush its buffers.
- Brian Kernighan added `fflush()' to his `awk' in April 1992. For
+ Brian Kernighan added 'fflush()' to his 'awk' in April 1992. For
two decades, it was a common extension. In December 2012, it was
accepted for inclusion into the POSIX standard. See the Austin
Group website (http://austingroupbugs.net/view.php?id=634).
- POSIX standardizes `fflush()' as follows: if there is no argument,
- or if the argument is the null string (`""'), then `awk' flushes
+ POSIX standardizes 'fflush()' as follows: if there is no argument,
+ or if the argument is the null string ('""'), then 'awk' flushes
the buffers for _all_ open output files and pipes.
- NOTE: Prior to version 4.0.2, `gawk' would flush only the
- standard output if there was no argument, and flush all
- output files and pipes if the argument was the null string.
- This was changed in order to be compatible with Brian
- Kernighan's `awk', in the hope that standardizing this
- feature in POSIX would then be easier (which indeed proved to
- be the case).
+ NOTE: Prior to version 4.0.2, 'gawk' would flush only the
+ standard output if there was no argument, and flush all output
+ files and pipes if the argument was the null string. This was
+ changed in order to be compatible with Brian Kernighan's
+ 'awk', in the hope that standardizing this feature in POSIX
+ would then be easier (which indeed proved to be the case).
- With `gawk', you can use `fflush("/dev/stdout")' if you wish
+ With 'gawk', you can use 'fflush("/dev/stdout")' if you wish
to flush only the standard output.
- `fflush()' returns zero if the buffer is successfully flushed;
- otherwise, it returns a nonzero value. (`gawk' returns -1.) In
+ 'fflush()' returns zero if the buffer is successfully flushed;
+ otherwise, it returns a nonzero value. ('gawk' returns -1.) In
the case where all buffers are flushed, the return value is zero
only if all buffers were flushed successfully. Otherwise, it is
- -1, and `gawk' warns about the problem FILENAME.
+ -1, and 'gawk' warns about the problem FILENAME.
- `gawk' also issues a warning message if you attempt to flush a
- file or pipe that was opened for reading (such as with `getline'),
- or if FILENAME is not an open file, pipe, or coprocess. In such a
- case, `fflush()' returns -1, as well.
+ 'gawk' also issues a warning message if you attempt to flush a file
+ or pipe that was opened for reading (such as with 'getline'), or if
+ FILENAME is not an open file, pipe, or coprocess. In such a case,
+ 'fflush()' returns -1, as well.
- Interactive Versus Noninteractive Buffering
+ Interactive Versus Noninteractive Buffering
As a side point, buffering issues can be even more confusing if
your program is "interactive" (i.e., communicating with a user
@@ -12800,7 +12741,7 @@ parameters are enclosed in square brackets ([ ]):
-| 5
Ctrl-d
- Each line of output is printed immediately. Compare that behavior
+ Each line of output is printed immediately. Compare that behavior
with this example:
$ awk '{ print $1 + $2 }' | cat
@@ -12810,25 +12751,25 @@ parameters are enclosed in square brackets ([ ]):
-| 2
-| 5
- Here, no output is printed until after the `Ctrl-d' is typed,
- because it is all buffered and sent down the pipe to `cat' in one
+ Here, no output is printed until after the 'Ctrl-d' is typed,
+ because it is all buffered and sent down the pipe to 'cat' in one
shot.
-`system(COMMAND)'
- Execute the operating system command COMMAND and then return to
- the `awk' program. Return COMMAND's exit status.
+'system(COMMAND)'
+ Execute the operating system command COMMAND and then return to the
+ 'awk' program. Return COMMAND's exit status.
- For example, if the following fragment of code is put in your `awk'
+ For example, if the following fragment of code is put in your 'awk'
program:
END {
system("date | mail -s 'awk run done' root")
}
- the system administrator is sent mail when the `awk' program
+ the system administrator is sent mail when the 'awk' program
finishes processing input and begins its end-of-input processing.
- Note that redirecting `print' or `printf' into a pipe is often
+ Note that redirecting 'print' or 'printf' into a pipe is often
enough to accomplish your task. If you need to run many commands,
it is more efficient to simply print them down a pipeline to the
shell:
@@ -12837,37 +12778,35 @@ parameters are enclosed in square brackets ([ ]):
print COMMAND | "/bin/sh"
close("/bin/sh")
- However, if your `awk' program is interactive, `system()' is
- useful for running large self-contained programs, such as a shell
- or an editor. Some operating systems cannot implement the
- `system()' function. `system()' causes a fatal error if it is not
- supported.
+ However, if your 'awk' program is interactive, 'system()' is useful
+ for running large self-contained programs, such as a shell or an
+ editor. Some operating systems cannot implement the 'system()'
+ function. 'system()' causes a fatal error if it is not supported.
- NOTE: When `--sandbox' is specified, the `system()' function
+ NOTE: When '--sandbox' is specified, the 'system()' function
is disabled (*note Options::).
+ Controlling Output Buffering with 'system()'
- Controlling Output Buffering with `system()'
-
- The `fflush()' function provides explicit control over output
+ The 'fflush()' function provides explicit control over output
buffering for individual files and pipes. However, its use is not
-portable to many older `awk' implementations. An alternative method to
-flush output buffers is to call `system()' with a null string as its
+portable to many older 'awk' implementations. An alternative method to
+flush output buffers is to call 'system()' with a null string as its
argument:
system("") # flush output
-`gawk' treats this use of the `system()' function as a special case and
+'gawk' treats this use of the 'system()' function as a special case and
is smart enough not to run a shell (or other command interpreter) with
-the empty command. Therefore, with `gawk', this idiom is not only
+the empty command. Therefore, with 'gawk', this idiom is not only
useful, it is also efficient. Although this method should work with
-other `awk' implementations, it does not necessarily avoid starting an
+other 'awk' implementations, it does not necessarily avoid starting an
unnecessary shell. (Other implementations may only flush the buffer
associated with the standard output and not necessarily all buffered
output.)
If you think about what a programmer expects, it makes sense that
-`system()' should flush any pending output. The following program:
+'system()' should flush any pending output. The following program:
BEGIN {
print "first print"
@@ -12887,13 +12826,13 @@ and not:
first print
second print
- If `awk' did not flush its buffers before calling `system()', you
+ If 'awk' did not flush its buffers before calling 'system()', you
would see the latter (undesirable) output.
---------- Footnotes ----------
- (1) A program is interactive if the standard output is connected to
-a terminal device. On modern systems, this means your keyboard and
+ (1) A program is interactive if the standard output is connected to a
+terminal device. On modern systems, this means your keyboard and
screen.
@@ -12902,266 +12841,264 @@ File: gawk.info, Node: Time Functions, Next:
Bitwise Functions, Prev: I/O Fun
9.1.5 Time Functions
--------------------
-`awk' programs are commonly used to process log files containing
+'awk' programs are commonly used to process log files containing
timestamp information, indicating when a particular log record was
-written. Many programs log their timestamps in the form returned by
-the `time()' system call, which is the number of seconds since a
-particular epoch. On POSIX-compliant systems, it is the number of
-seconds since 1970-01-01 00:00:00 UTC, not counting leap seconds.(1)
-All known POSIX-compliant systems support timestamps from 0 through
-2^31 - 1, which is sufficient to represent times through 2038-01-19
-03:14:07 UTC. Many systems support a wider range of timestamps,
-including negative timestamps that represent times before the epoch.
+written. Many programs log their timestamps in the form returned by the
+'time()' system call, which is the number of seconds since a particular
+epoch. On POSIX-compliant systems, it is the number of seconds since
+1970-01-01 00:00:00 UTC, not counting leap seconds.(1) All known
+POSIX-compliant systems support timestamps from 0 through 2^31 - 1,
+which is sufficient to represent times through 2038-01-19 03:14:07 UTC.
+Many systems support a wider range of timestamps, including negative
+timestamps that represent times before the epoch.
In order to make it easier to process such log files and to produce
-useful reports, `gawk' provides the following functions for working
-with timestamps. They are `gawk' extensions; they are not specified in
-the POSIX standard.(2) However, recent versions of `mawk' (*note Other
+useful reports, 'gawk' provides the following functions for working with
+timestamps. They are 'gawk' extensions; they are not specified in the
+POSIX standard.(2) However, recent versions of 'mawk' (*note Other
Versions::) also support these functions. Optional parameters are
enclosed in square brackets ([ ]):
-`mktime(DATESPEC)'
+'mktime(DATESPEC)'
Turn DATESPEC into a timestamp in the same form as is returned by
- `systime()'. It is similar to the function of the same name in
- ISO C. The argument, DATESPEC, is a string of the form
- `"YYYY MM DD HH MM SS [DST]"'. The string consists of six or
- seven numbers representing, respectively, the full year including
- century, the month from 1 to 12, the day of the month from 1 to
- 31, the hour of the day from 0 to 23, the minute from 0 to 59, the
+ 'systime()'. It is similar to the function of the same name in ISO
+ C. The argument, DATESPEC, is a string of the form
+ '"YYYY MM DD HH MM SS [DST]"'. The string consists of six or seven
+ numbers representing, respectively, the full year including
+ century, the month from 1 to 12, the day of the month from 1 to 31,
+ the hour of the day from 0 to 23, the minute from 0 to 59, the
second from 0 to 60,(3) and an optional daylight-savings flag.
The values of these numbers need not be within the ranges
specified; for example, an hour of -1 means 1 hour before midnight.
The origin-zero Gregorian calendar is assumed, with year 0
- preceding year 1 and year -1 preceding year 0. The time is
- assumed to be in the local time zone. If the daylight-savings
- flag is positive, the time is assumed to be daylight savings time;
- if zero, the time is assumed to be standard time; and if negative
- (the default), `mktime()' attempts to determine whether daylight
- savings time is in effect for the specified time.
+ preceding year 1 and year -1 preceding year 0. The time is assumed
+ to be in the local time zone. If the daylight-savings flag is
+ positive, the time is assumed to be daylight savings time; if zero,
+ the time is assumed to be standard time; and if negative (the
+ default), 'mktime()' attempts to determine whether daylight savings
+ time is in effect for the specified time.
If DATESPEC does not contain enough elements or if the resulting
- time is out of range, `mktime()' returns -1.
-
-`strftime('[FORMAT [`,' TIMESTAMP [`,' UTC-FLAG] ] ]`)'
- Format the time specified by TIMESTAMP based on the contents of
- the FORMAT string and return the result. It is similar to the
- function of the same name in ISO C. If UTC-FLAG is present and is
- either nonzero or non-null, the value is formatted as UTC
- (Coordinated Universal Time, formerly GMT or Greenwich Mean Time).
- Otherwise, the value is formatted for the local time zone. The
- TIMESTAMP is in the same format as the value returned by the
- `systime()' function. If no TIMESTAMP argument is supplied,
- `gawk' uses the current time of day as the timestamp. Without a
- FORMAT argument, `strftime()' uses the value of
- `PROCINFO["strftime"]' as the format string (*note Built-in
- Variables::). The default string value is
- `"%a %b %e %H:%M:%S %Z %Y"'. This format string produces output
- that is equivalent to that of the `date' utility. You can assign
- a new value to `PROCINFO["strftime"]' to change the default
- format; see the following list for the various format directives.
-
-`systime()'
+ time is out of range, 'mktime()' returns -1.
+
+'strftime('[FORMAT [',' TIMESTAMP [',' UTC-FLAG] ] ]')'
+ Format the time specified by TIMESTAMP based on the contents of the
+ FORMAT string and return the result. It is similar to the function
+ of the same name in ISO C. If UTC-FLAG is present and is either
+ nonzero or non-null, the value is formatted as UTC (Coordinated
+ Universal Time, formerly GMT or Greenwich Mean Time). Otherwise,
+ the value is formatted for the local time zone. The TIMESTAMP is
+ in the same format as the value returned by the 'systime()'
+ function. If no TIMESTAMP argument is supplied, 'gawk' uses the
+ current time of day as the timestamp. Without a FORMAT argument,
+ 'strftime()' uses the value of 'PROCINFO["strftime"]' as the format
+ string (*note Built-in Variables::). The default string value is
+ '"%a %b %e %H:%M:%S %Z %Y"'. This format string produces output
+ that is equivalent to that of the 'date' utility. You can assign a
+ new value to 'PROCINFO["strftime"]' to change the default format;
+ see the following list for the various format directives.
+
+'systime()'
Return the current time as the number of seconds since the system
epoch. On POSIX systems, this is the number of seconds since
1970-01-01 00:00:00 UTC, not counting leap seconds. It may be a
different number on other systems.
- The `systime()' function allows you to compare a timestamp from a
-log file with the current time of day. In particular, it is easy to
+ The 'systime()' function allows you to compare a timestamp from a log
+file with the current time of day. In particular, it is easy to
determine how long ago a particular record was logged. It also allows
you to produce log records using the "seconds since the epoch" format.
- The `mktime()' function allows you to convert a textual
-representation of a date and time into a timestamp. This makes it
-easy to do before/after comparisons of dates and times, particularly
-when dealing with date and time data coming from an external source,
-such as a log file.
+ The 'mktime()' function allows you to convert a textual
+representation of a date and time into a timestamp. This makes it easy
+to do before/after comparisons of dates and times, particularly when
+dealing with date and time data coming from an external source, such as
+a log file.
- The `strftime()' function allows you to easily turn a timestamp into
-human-readable information. It is similar in nature to the `sprintf()'
+ The 'strftime()' function allows you to easily turn a timestamp into
+human-readable information. It is similar in nature to the 'sprintf()'
function (*note String Functions::), in that it copies nonformat
specification characters verbatim to the returned string, while
substituting date and time values for format specifications in the
FORMAT string.
- `strftime()' is guaranteed by the 1999 ISO C standard(4) to support
+ 'strftime()' is guaranteed by the 1999 ISO C standard(4) to support
the following date format specifications:
-`%a'
+'%a'
The locale's abbreviated weekday name.
-`%A'
+'%A'
The locale's full weekday name.
-`%b'
+'%b'
The locale's abbreviated month name.
-`%B'
+'%B'
The locale's full month name.
-`%c'
+'%c'
The locale's "appropriate" date and time representation. (This is
- `%A %B %d %T %Y' in the `"C"' locale.)
+ '%A %B %d %T %Y' in the '"C"' locale.)
-`%C'
+'%C'
The century part of the current year. This is the year divided by
100 and truncated to the next lower integer.
-`%d'
+'%d'
The day of the month as a decimal number (01-31).
-`%D'
- Equivalent to specifying `%m/%d/%y'.
+'%D'
+ Equivalent to specifying '%m/%d/%y'.
-`%e'
+'%e'
The day of the month, padded with a space if it is only one digit.
-`%F'
- Equivalent to specifying `%Y-%m-%d'. This is the ISO 8601 date
+'%F'
+ Equivalent to specifying '%Y-%m-%d'. This is the ISO 8601 date
format.
-`%g'
+'%g'
The year modulo 100 of the ISO 8601 week number, as a decimal
number (00-99). For example, January 1, 2012, is in week 53 of
- 2011. Thus, the year of its ISO 8601 week number is 2011, even
+ 2011. Thus, the year of its ISO 8601 week number is 2011, even
though its year is 2012. Similarly, December 31, 2012, is in week
- 1 of 2013. Thus, the year of its ISO week number is 2013, even
+ 1 of 2013. Thus, the year of its ISO week number is 2013, even
though its year is 2012.
-`%G'
+'%G'
The full year of the ISO week number, as a decimal number.
-`%h'
- Equivalent to `%b'.
+'%h'
+ Equivalent to '%b'.
-`%H'
+'%H'
The hour (24-hour clock) as a decimal number (00-23).
-`%I'
+'%I'
The hour (12-hour clock) as a decimal number (01-12).
-`%j'
+'%j'
The day of the year as a decimal number (001-366).
-`%m'
+'%m'
The month as a decimal number (01-12).
-`%M'
+'%M'
The minute as a decimal number (00-59).
-`%n'
+'%n'
A newline character (ASCII LF).
-`%p'
- The locale's equivalent of the AM/PM designations associated with
- a 12-hour clock.
+'%p'
+ The locale's equivalent of the AM/PM designations associated with a
+ 12-hour clock.
-`%r'
- The locale's 12-hour clock time. (This is `%I:%M:%S %p' in the
- `"C"' locale.)
+'%r'
+ The locale's 12-hour clock time. (This is '%I:%M:%S %p' in the
+ '"C"' locale.)
-`%R'
- Equivalent to specifying `%H:%M'.
+'%R'
+ Equivalent to specifying '%H:%M'.
-`%S'
+'%S'
The second as a decimal number (00-60).
-`%t'
+'%t'
A TAB character.
-`%T'
- Equivalent to specifying `%H:%M:%S'.
+'%T'
+ Equivalent to specifying '%H:%M:%S'.
-`%u'
+'%u'
The weekday as a decimal number (1-7). Monday is day one.
-`%U'
- The week number of the year (with the first Sunday as the first
- day of week one) as a decimal number (00-53).
+'%U'
+ The week number of the year (with the first Sunday as the first day
+ of week one) as a decimal number (00-53).
-`%V'
- The week number of the year (with the first Monday as the first
- day of week one) as a decimal number (01-53). The method for
+'%V'
+ The week number of the year (with the first Monday as the first day
+ of week one) as a decimal number (01-53). The method for
determining the week number is as specified by ISO 8601. (To wit:
if the week containing January 1 has four or more days in the new
year, then it is week one; otherwise it is week 53 of the previous
year and the next week is week one.)
-`%w'
+'%w'
The weekday as a decimal number (0-6). Sunday is day zero.
-`%W'
- The week number of the year (with the first Monday as the first
- day of week one) as a decimal number (00-53).
+'%W'
+ The week number of the year (with the first Monday as the first day
+ of week one) as a decimal number (00-53).
-`%x'
- The locale's "appropriate" date representation. (This is `%A %B
- %d %Y' in the `"C"' locale.)
+'%x'
+ The locale's "appropriate" date representation. (This is '%A %B %d
+ %Y' in the '"C"' locale.)
-`%X'
- The locale's "appropriate" time representation. (This is `%T' in
- the `"C"' locale.)
+'%X'
+ The locale's "appropriate" time representation. (This is '%T' in
+ the '"C"' locale.)
-`%y'
+'%y'
The year modulo 100 as a decimal number (00-99).
-`%Y'
+'%Y'
The full year as a decimal number (e.g., 2015).
-`%z'
- The time zone offset in a `+HHMM' format (e.g., the format
+'%z'
+ The time zone offset in a '+HHMM' format (e.g., the format
necessary to produce RFC 822/RFC 1036 date headers).
-`%Z'
+'%Z'
The time zone name or abbreviation; no characters if no time zone
is determinable.
-`%Ec %EC %Ex %EX %Ey %EY %Od %Oe %OH'
-`%OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy'
+'%Ec %EC %Ex %EX %Ey %EY %Od %Oe %OH'
+'%OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy'
"Alternative representations" for the specifications that use only
- the second letter (`%c', `%C', and so on).(5) (These facilitate
- compliance with the POSIX `date' utility.)
+ the second letter ('%c', '%C', and so on).(5) (These facilitate
+ compliance with the POSIX 'date' utility.)
-`%%'
- A literal `%'.
+'%%'
+ A literal '%'.
If a conversion specifier is not one of those just listed, the
behavior is undefined.(6)
- For systems that are not yet fully standards-compliant, `gawk'
-supplies a copy of `strftime()' from the GNU C Library. It supports
-all of the just-listed format specifications. If that version is used
-to compile `gawk' (*note Installation::), then the following additional
+ For systems that are not yet fully standards-compliant, 'gawk'
+supplies a copy of 'strftime()' from the GNU C Library. It supports all
+of the just-listed format specifications. If that version is used to
+compile 'gawk' (*note Installation::), then the following additional
format specifications are available:
-`%k'
+'%k'
The hour (24-hour clock) as a decimal number (0-23). Single-digit
numbers are padded with a space.
-`%l'
+'%l'
The hour (12-hour clock) as a decimal number (1-12). Single-digit
numbers are padded with a space.
-`%s'
+'%s'
The time as a decimal timestamp in seconds since the epoch.
-
Additionally, the alternative representations are recognized but
their normal representations are used.
- The following example is an `awk' implementation of the POSIX `date'
-utility. Normally, the `date' utility prints the current date and time
+ The following example is an 'awk' implementation of the POSIX 'date'
+utility. Normally, the 'date' utility prints the current date and time
of day in a well-known format. However, if you provide an argument to
-it that begins with a `+', `date' copies nonformat specifier characters
+it that begins with a '+', 'date' copies nonformat specifier characters
to the standard output and interprets the current time according to the
format specifiers in the string. For example:
$ date '+Today is %A, %B %d, %Y.'
-| Today is Monday, September 22, 2014.
- Here is the `gawk' version of the `date' utility. It has a shell
-"wrapper" to handle the `-u' option, which requires that `date' run as
+ Here is the 'gawk' version of the 'date' utility. It has a shell
+"wrapper" to handle the '-u' option, which requires that 'date' run as
if the time zone is set to UTC:
#! /bin/sh
@@ -13193,14 +13130,14 @@ if the time zone is set to UTC:
(1) *Note Glossary::, especially the entries "Epoch" and "UTC."
- (2) The GNU `date' utility can also do many of the things described
+ (2) The GNU 'date' utility can also do many of the things described
here. Its use may be preferable for simple time-related operations in
shell scripts.
(3) Occasionally there are minutes in a year with a leap second,
which is why the seconds can go up to 60.
- (4) Unfortunately, not every system's `strftime()' necessarily
+ (4) Unfortunately, not every system's 'strftime()' necessarily
supports all of the conversions listed here.
(5) If you don't understand any of this, don't worry about it; these
@@ -13209,8 +13146,8 @@ Other internationalization features are described in
*note
Internationalization::.
(6) This is because ISO C leaves the behavior of the C version of
-`strftime()' undefined and `gawk' uses the system's version of
-`strftime()' if it's there. Typically, the conversion specifier either
+'strftime()' undefined and 'gawk' uses the system's version of
+'strftime()' if it's there. Typically, the conversion specifier either
does not appear in the returned string or appears literally.
@@ -13219,20 +13156,20 @@ File: gawk.info, Node: Bitwise Functions, Next:
Type Functions, Prev: Time Fu
9.1.6 Bit-Manipulation Functions
--------------------------------
- I can explain it for you, but I can't understand it for you. --
- Anonymous
+ I can explain it for you, but I can't understand it for you.
+ -- _Anonymous_
- Many languages provide the ability to perform "bitwise" operations
-on two integer numbers. In other words, the operation is performed on
-each successive pair of bits in the operands. Three common operations
-are bitwise AND, OR, and XOR. The operations are described in *note
-table-bitwise-ops::.
+ Many languages provide the ability to perform "bitwise" operations on
+two integer numbers. In other words, the operation is performed on each
+successive pair of bits in the operands. Three common operations are
+bitwise AND, OR, and XOR. The operations are described in *note Table
+9.5: table-bitwise-ops.
Bit operator
| AND | OR | XOR
|--+--+--+--+--+--
Operands | 0 | 1 | 0 | 1 | 0 | 1
- ---------+--+--+--+--+--+--
+ -------+--+--+--+--+--+--
0 | 0 0 | 0 1 | 0 1
1 | 0 1 | 1 1 | 1 0
@@ -13241,45 +13178,46 @@ Table 9.5: Bitwise operations
As you can see, the result of an AND operation is 1 only when _both_
bits are 1. The result of an OR operation is 1 if _either_ bit is 1.
The result of an XOR operation is 1 if either bit is 1, but not both.
-The next operation is the "complement"; the complement of 1 is 0 and
-the complement of 0 is 1. Thus, this operation "flips" all the bits of
-a given value.
+The next operation is the "complement"; the complement of 1 is 0 and the
+complement of 0 is 1. Thus, this operation "flips" all the bits of a
+given value.
Finally, two other common operations are to shift the bits left or
-right. For example, if you have a bit string `10111001' and you shift
-it right by three bits, you end up with `00010111'.(1) If you start
-over again with `10111001' and shift it left by three bits, you end up
-with `11001000'. The following list describes `gawk''s built-in
+right. For example, if you have a bit string '10111001' and you shift
+it right by three bits, you end up with '00010111'.(1) If you start
+over again with '10111001' and shift it left by three bits, you end up
+with '11001000'. The following list describes 'gawk''s built-in
functions that implement the bitwise operations. Optional parameters
are enclosed in square brackets ([ ]):
-``and('V1`,' V2 [`,' ...]`)''
- Return the bitwise AND of the arguments. There must be at least
+'and(V1, V2 [, ...])'
+ Return the bitwise AND of the arguments. There must be at least
two.
-``compl(VAL)''
+'compl(VAL)'
Return the bitwise complement of VAL.
-``lshift(VAL, COUNT)''
+'lshift(VAL, COUNT)'
Return the value of VAL, shifted left by COUNT bits.
-``or('V1`,' V2 [`,' ...]`)''
- Return the bitwise OR of the arguments. There must be at least two.
+'or(V1, V2 [, ...])'
+ Return the bitwise OR of the arguments. There must be at least
+ two.
-``rshift(VAL, COUNT)''
+'rshift(VAL, COUNT)'
Return the value of VAL, shifted right by COUNT bits.
-``xor('V1`,' V2 [`,' ...]`)''
- Return the bitwise XOR of the arguments. There must be at least
+'xor(V1, V2 [, ...])'
+ Return the bitwise XOR of the arguments. There must be at least
two.
- For all of these functions, first the double-precision
-floating-point value is converted to the widest C unsigned integer
-type, then the bitwise operation is performed. If the result cannot be
-represented exactly as a C `double', leading nonzero bits are removed
-one by one until it can be represented exactly. The result is then
-converted back into a C `double'. (If you don't understand this
-paragraph, don't worry about it.)
+ For all of these functions, first the double-precision floating-point
+value is converted to the widest C unsigned integer type, then the
+bitwise operation is performed. If the result cannot be represented
+exactly as a C 'double', leading nonzero bits are removed one by one
+until it can be represented exactly. The result is then converted back
+into a C 'double'. (If you don't understand this paragraph, don't worry
+about it.)
Here is a user-defined function (*note User-defined::) that
illustrates the use of these functions:
@@ -13323,28 +13261,28 @@ This program produces the following output when run:
-| lshift(0x99, 2) = 0x264 = 0000001001100100
-| rshift(0x99, 2) = 0x26 = 00100110
- The `bits2str()' function turns a binary number into a string.
-Initializing `mask' to one creates a binary value where the rightmost
+ The 'bits2str()' function turns a binary number into a string.
+Initializing 'mask' to one creates a binary value where the rightmost
bit is set to one. Using this mask, the function repeatedly checks the
rightmost bit. ANDing the mask with the value indicates whether the
-rightmost bit is one or not. If so, a `"1"' is concatenated onto the
-front of the string. Otherwise, a `"0"' is added. The value is then
+rightmost bit is one or not. If so, a '"1"' is concatenated onto the
+front of the string. Otherwise, a '"0"' is added. The value is then
shifted right by one bit and the loop continues until there are no more
one bits.
- If the initial value is zero, it returns a simple `"0"'. Otherwise,
-at the end, it pads the value with zeros to represent multiples of
-8-bit quantities. This is typical in modern computers.
+ If the initial value is zero, it returns a simple '"0"'. Otherwise,
+at the end, it pads the value with zeros to represent multiples of 8-bit
+quantities. This is typical in modern computers.
- The main code in the `BEGIN' rule shows the difference between the
+ The main code in the 'BEGIN' rule shows the difference between the
decimal and octal values for the same numbers (*note
Nondecimal-numbers::), and then demonstrates the results of the
-`compl()', `lshift()', and `rshift()' functions.
+'compl()', 'lshift()', and 'rshift()' functions.
---------- Footnotes ----------
- (1) This example shows that zeros come in on the left side. For
-`gawk', this is always true, but in some languages, it's possible to
+ (1) This example shows that zeros come in on the left side. For
+'gawk', this is always true, but in some languages, it's possible to
have the left side fill with ones.
@@ -13353,26 +13291,26 @@ File: gawk.info, Node: Type Functions, Next: I18N
Functions, Prev: Bitwise Fu
9.1.7 Getting Type Information
------------------------------
-`gawk' provides a single function that lets you distinguish an array
+'gawk' provides a single function that lets you distinguish an array
from a scalar variable. This is necessary for writing code that
traverses every element of an array of arrays (*note Arrays of
Arrays::).
-`isarray(X)'
- Return a true value if X is an array. Otherwise, return false.
+'isarray(X)'
+ Return a true value if X is an array. Otherwise, return false.
- `isarray()' is meant for use in two circumstances. The first is when
+ 'isarray()' is meant for use in two circumstances. The first is when
traversing a multidimensional array: you can test if an element is
-itself an array or not. The second is inside the body of a
-user-defined function (not discussed yet; *note User-defined::), to
-test if a parameter is an array or not.
+itself an array or not. The second is inside the body of a user-defined
+function (not discussed yet; *note User-defined::), to test if a
+parameter is an array or not.
- NOTE: Using `isarray()' at the global level to test variables
- makes no sense. Because you are the one writing the program, you
- are supposed to know if your variables are arrays or not. And in
- fact, due to the way `gawk' works, if you pass the name of a
- variable that has not been previously used to `isarray()', `gawk'
- ends up turning it into a scalar.
+ NOTE: Using 'isarray()' at the global level to test variables makes
+ no sense. Because you are the one writing the program, you are
+ supposed to know if your variables are arrays or not. And in fact,
+ due to the way 'gawk' works, if you pass the name of a variable
+ that has not been previously used to 'isarray()', 'gawk' ends up
+ turning it into a scalar.
File: gawk.info, Node: I18N Functions, Prev: Type Functions, Up: Built-in
@@ -13380,35 +13318,34 @@ File: gawk.info, Node: I18N Functions, Prev: Type
Functions, Up: Built-in
9.1.8 String-Translation Functions
----------------------------------
-`gawk' provides facilities for internationalizing `awk' programs.
-These include the functions described in the following list. The
-descriptions here are purposely brief. *Note Internationalization::,
-for the full story. Optional parameters are enclosed in square
-brackets ([ ]):
+'gawk' provides facilities for internationalizing 'awk' programs. These
+include the functions described in the following list. The descriptions
+here are purposely brief. *Note Internationalization::, for the full
+story. Optional parameters are enclosed in square brackets ([ ]):
-`bindtextdomain(DIRECTORY' [`,' DOMAIN]`)'
- Set the directory in which `gawk' will look for message
- translation files, in case they will not or cannot be placed in
- the "standard" locations (e.g., during testing). It returns the
- directory in which DOMAIN is "bound."
+'bindtextdomain(DIRECTORY' [',' DOMAIN]')'
+ Set the directory in which 'gawk' will look for message translation
+ files, in case they will not or cannot be placed in the "standard"
+ locations (e.g., during testing). It returns the directory in
+ which DOMAIN is "bound."
- The default DOMAIN is the value of `TEXTDOMAIN'. If DIRECTORY is
- the null string (`""'), then `bindtextdomain()' returns the
- current binding for the given DOMAIN.
+ The default DOMAIN is the value of 'TEXTDOMAIN'. If DIRECTORY is
+ the null string ('""'), then 'bindtextdomain()' returns the current
+ binding for the given DOMAIN.
-`dcgettext(STRING' [`,' DOMAIN [`,' CATEGORY] ]`)'
+'dcgettext(STRING' [',' DOMAIN [',' CATEGORY] ]')'
Return the translation of STRING in text domain DOMAIN for locale
category CATEGORY. The default value for DOMAIN is the current
- value of `TEXTDOMAIN'. The default value for CATEGORY is
- `"LC_MESSAGES"'.
+ value of 'TEXTDOMAIN'. The default value for CATEGORY is
+ '"LC_MESSAGES"'.
-`dcngettext(STRING1, STRING2, NUMBER' [`,' DOMAIN [`,' CATEGORY] ]`)'
+'dcngettext(STRING1, STRING2, NUMBER' [',' DOMAIN [',' CATEGORY] ]')'
Return the plural form used for NUMBER of the translation of
STRING1 and STRING2 in text domain DOMAIN for locale category
- CATEGORY. STRING1 is the English singular variant of a message,
- and STRING2 is the English plural variant of the same message.
- The default value for DOMAIN is the current value of `TEXTDOMAIN'.
- The default value for CATEGORY is `"LC_MESSAGES"'.
+ CATEGORY. STRING1 is the English singular variant of a message,
+ and STRING2 is the English plural variant of the same message. The
+ default value for DOMAIN is the current value of 'TEXTDOMAIN'. The
+ default value for CATEGORY is '"LC_MESSAGES"'.
File: gawk.info, Node: User-defined, Next: Indirect Calls, Prev: Built-in,
Up: Functions
@@ -13416,10 +13353,10 @@ File: gawk.info, Node: User-defined, Next: Indirect
Calls, Prev: Built-in, U
9.2 User-Defined Functions
==========================
-Complicated `awk' programs can often be simplified by defining your own
-functions. User-defined functions can be called just like built-in
-ones (*note Function Calls::), but it is up to you to define them
-(i.e., to tell `awk' what they should do).
+Complicated 'awk' programs can often be simplified by defining your own
+functions. User-defined functions can be called just like built-in ones
+(*note Function Calls::), but it is up to you to define them (i.e., to
+tell 'awk' what they should do).
* Menu:
@@ -13437,28 +13374,29 @@ File: gawk.info, Node: Definition Syntax, Next:
Function Example, Up: User-de
--------------------------------
It's entirely fair to say that the awk syntax for local variable
- definitions is appallingly awful. -- Brian Kernighan
+ definitions is appallingly awful.
+ -- _Brian Kernighan_
Definitions of functions can appear anywhere between the rules of an
-`awk' program. Thus, the general form of an `awk' program is extended
+'awk' program. Thus, the general form of an 'awk' program is extended
to include sequences of rules _and_ user-defined function definitions.
There is no need to put the definition of a function before all uses of
-the function. This is because `awk' reads the entire program before
+the function. This is because 'awk' reads the entire program before
starting to execute any of it.
The definition of a function named NAME looks like this:
- `function' NAME`('[PARAMETER-LIST]`)'
- `{'
+ 'function' NAME'('[PARAMETER-LIST]')'
+ '{'
BODY-OF-FUNCTION
- `}'
+ '}'
-Here, NAME is the name of the function to define. A valid function
-name is like a valid variable name: a sequence of letters, digits, and
+Here, NAME is the name of the function to define. A valid function name
+is like a valid variable name: a sequence of letters, digits, and
underscores that doesn't start with a digit. Here too, only the 52
upper- and lowercase English letters may be used in a function name.
-Within a single `awk' program, any particular name can only be used as
-a variable, array, or function.
+Within a single 'awk' program, any particular name can only be used as a
+variable, array, or function.
PARAMETER-LIST is an optional list of the function's arguments and
local variable names, separated by commas. When the function is called,
@@ -13473,24 +13411,24 @@ have a parameter with the same name as the function
itself.
variables (*note Built-in Variables::), nor may a function
parameter have the same name as another function.
- Not all versions of `awk' enforce these restrictions. `gawk'
- always enforces the first restriction. With `--posix' (*note
+ Not all versions of 'awk' enforce these restrictions. 'gawk'
+ always enforces the first restriction. With '--posix' (*note
Options::), it also enforces the second restriction.
Local variables act like the empty string if referenced where a
string value is required, and like zero if referenced where a numeric
-value is required. This is the same as the behavior of regular
+value is required. This is the same as the behavior of regular
variables that have never been assigned a value. (There is more to
understand about local variables; *note Dynamic Typing::.)
- The BODY-OF-FUNCTION consists of `awk' statements. It is the most
+ The BODY-OF-FUNCTION consists of 'awk' statements. It is the most
important part of the definition, because it says what the function
should actually _do_. The argument names exist to give the body a way
to talk about the arguments; local variables exist to give the body
places to keep temporary values.
Argument names are not distinguished syntactically from local
-variable names. Instead, the number of arguments supplied when the
+variable names. Instead, the number of arguments supplied when the
function is called determines how many argument variables there are.
Thus, if three argument values are given, the first three names in
PARAMETER-LIST are arguments and the rest are local variables.
@@ -13500,18 +13438,18 @@ calls to the function, some of the names in
PARAMETER-LIST may be
arguments on some occasions and local variables on others. Another way
to think of this is that omitted arguments default to the null string.
- Usually when you write a function, you know how many names you
-intend to use for arguments and how many you intend to use as local
-variables. It is conventional to place some extra space between the
-arguments and the local variables, in order to document how your
-function is supposed to be used.
+ Usually when you write a function, you know how many names you intend
+to use for arguments and how many you intend to use as local variables.
+It is conventional to place some extra space between the arguments and
+the local variables, in order to document how your function is supposed
+to be used.
During execution of the function body, the arguments and local
variable values hide, or "shadow", any variables of the same names used
in the rest of the program. The shadowed variables are not accessible
in the function definition, because there is no way to name them while
their names have been taken away for the arguments and local variables.
-All other variables used in the `awk' program can be referenced or set
+All other variables used in the 'awk' program can be referenced or set
normally in the function's body.
The arguments and local variables last only as long as the function
@@ -13524,32 +13462,31 @@ function. When this happens, we say the function is
"recursive". The
act of a function calling itself is called "recursion".
All the built-in functions return a value to their caller.
-User-defined functions can do so also, using the `return' statement,
+User-defined functions can do so also, using the 'return' statement,
which is described in detail in *note Return Statement::. Many of the
-subsequent examples in this minor node use the `return' statement.
+subsequent examples in this minor node use the 'return' statement.
- In many `awk' implementations, including `gawk', the keyword
-`function' may be abbreviated `func'. (c.e.) However, POSIX only
-specifies the use of the keyword `function'. This actually has some
-practical implications. If `gawk' is in POSIX-compatibility mode
-(*note Options::), then the following statement does _not_ define a
-function:
+ In many 'awk' implementations, including 'gawk', the keyword
+'function' may be abbreviated 'func'. (c.e.) However, POSIX only
+specifies the use of the keyword 'function'. This actually has some
+practical implications. If 'gawk' is in POSIX-compatibility mode (*note
+Options::), then the following statement does _not_ define a function:
func foo() { a = sqrt($1) ; print a }
Instead, it defines a rule that, for each record, concatenates the value
-of the variable `func' with the return value of the function `foo'. If
+of the variable 'func' with the return value of the function 'foo'. If
the resulting string is non-null, the action is executed. This is
-probably not what is desired. (`awk' accepts this input as
+probably not what is desired. ('awk' accepts this input as
syntactically valid, because functions may be used before they are
-defined in `awk' programs.(1))
+defined in 'awk' programs.(1))
- To ensure that your `awk' programs are portable, always use the
-keyword `function' when defining a function.
+ To ensure that your 'awk' programs are portable, always use the
+keyword 'function' when defining a function.
---------- Footnotes ----------
- (1) This program won't actually run, because `foo()' is undefined.
+ (1) This program won't actually run, because 'foo()' is undefined.
File: gawk.info, Node: Function Example, Next: Function Caveats, Prev:
Definition Syntax, Up: User-defined
@@ -13557,7 +13494,7 @@ File: gawk.info, Node: Function Example, Next:
Function Caveats, Prev: Defini
9.2.2 Function Definition Examples
----------------------------------
-Here is an example of a user-defined function, called `myprint()', that
+Here is an example of a user-defined function, called 'myprint()', that
takes a number and prints it in a specific format:
function myprint(num)
@@ -13565,7 +13502,7 @@ takes a number and prints it in a specific format:
printf "%6.3g\n", num
}
-To illustrate, here is an `awk' rule that uses our `myprint()' function:
+To illustrate, here is an 'awk' rule that uses our 'myprint()' function:
$3 > 0 { myprint($3) }
@@ -13594,8 +13531,8 @@ extra whitespace signifies the start of the local
variable list):
When working with arrays, it is often necessary to delete all the
elements in an array and start over with a new list of elements (*note
Delete::). Instead of having to repeat this loop everywhere that you
-need to clear out an array, your program can just call `delarray()'.
-(This guarantees portability. The use of `delete ARRAY' to delete the
+need to clear out an array, your program can just call 'delarray()'.
+(This guarantees portability. The use of 'delete ARRAY' to delete the
contents of an entire array is a relatively recent(1) addition to the
POSIX standard.)
@@ -13613,17 +13550,17 @@ empty:
return (rev(substr(str, 2)) substr(str, 1, 1))
}
- If this function is in a file named `rev.awk', it can be tested this
+ If this function is in a file named 'rev.awk', it can be tested this
way:
$ echo "Don't Panic!" |
> gawk -e '{ print rev($0) }' -f rev.awk
-| !cinaP t'noD
- The C `ctime()' function takes a timestamp and returns it as a
+ The C 'ctime()' function takes a timestamp and returns it as a
string, formatted in a well-known fashion. The following example uses
-the built-in `strftime()' function (*note Time Functions::) to create
-an `awk' version of `ctime()':
+the built-in 'strftime()' function (*note Time Functions::) to create an
+'awk' version of 'ctime()':
# ctime.awk
#
@@ -13638,10 +13575,10 @@ an `awk' version of `ctime()':
return strftime(format, ts)
}
- You might think that `ctime()' could use `PROCINFO["strftime"]' for
-its format string. That would be a mistake, because `ctime()' is
+ You might think that 'ctime()' could use 'PROCINFO["strftime"]' for
+its format string. That would be a mistake, because 'ctime()' is
supposed to return the time formatted in a standard fashion, and
-user-level code could have changed `PROCINFO["strftime"]'.
+user-level code could have changed 'PROCINFO["strftime"]'.
---------- Footnotes ----------
@@ -13670,20 +13607,20 @@ File: gawk.info, Node: Calling A Function, Next:
Variable Scope, Up: Function
...............................
A function call consists of the function name followed by the arguments
-in parentheses. `awk' expressions are what you write in the call for
+in parentheses. 'awk' expressions are what you write in the call for
the arguments. Each time the call is executed, these expressions are
evaluated, and the values become the actual arguments. For example,
-here is a call to `foo()' with three arguments (the first being a
-string concatenation):
+here is a call to 'foo()' with three arguments (the first being a string
+concatenation):
foo(x y, "lose", 4 * z)
CAUTION: Whitespace characters (spaces and TABs) are not allowed
between the function name and the opening parenthesis of the
- argument list. If you write whitespace by mistake, `awk' might
- think that you mean to concatenate a variable with an expression
- in parentheses. However, it notices that you used a function name
- and not a variable name, and reports an error.
+ argument list. If you write whitespace by mistake, 'awk' might
+ think that you mean to concatenate a variable with an expression in
+ parentheses. However, it notices that you used a function name and
+ not a variable name, and reports an error.
File: gawk.info, Node: Variable Scope, Next: Pass By Value/Reference, Prev:
Calling A Function, Up: Function Caveats
@@ -13692,14 +13629,14 @@ File: gawk.info, Node: Variable Scope, Next: Pass
By Value/Reference, Prev: C
..................................
Unlike in many languages, there is no way to make a variable local to a
-`{' ... `}' block in `awk', but you can make a variable local to a
-function. It is good practice to do so whenever a variable is needed
+'{' ... '}' block in 'awk', but you can make a variable local to a
+function. It is good practice to do so whenever a variable is needed
only in that function.
To make a variable local to a function, simply declare the variable
as an argument after the actual function arguments (*note Definition
-Syntax::). Look at the following example, where variable `i' is a
-global variable used by both functions `foo()' and `bar()':
+Syntax::). Look at the following example, where variable 'i' is a
+global variable used by both functions 'foo()' and 'bar()':
function bar()
{
@@ -13722,8 +13659,8 @@ global variable used by both functions `foo()' and
`bar()':
print "top's i=" i
}
- Running this script produces the following, because the `i' in
-functions `foo()' and `bar()' and at the top level refer to the same
+ Running this script produces the following, because the 'i' in
+functions 'foo()' and 'bar()' and at the top level refer to the same
variable instance:
top's i=10
@@ -13734,9 +13671,9 @@ variable instance:
foo's i=3
top's i=3
- If you want `i' to be local to both `foo()' and `bar()', do as
-follows (the extra space before `i' is a coding convention to indicate
-that `i' is a local variable, not an argument):
+ If you want 'i' to be local to both 'foo()' and 'bar()', do as
+follows (the extra space before 'i' is a coding convention to indicate
+that 'i' is a local variable, not an argument):
function bar( i)
{
@@ -13770,7 +13707,7 @@ that `i' is a local variable, not an argument):
top's i=10
Besides scalar values (strings and numbers), you may also have local
-arrays. By using a parameter name as an array, `awk' treats it as an
+arrays. By using a parameter name as an array, 'awk' treats it as an
array, and it is local to the function. In addition, recursive calls
create new arrays. Consider this example:
@@ -13811,7 +13748,7 @@ File: gawk.info, Node: Pass By Value/Reference, Prev:
Variable Scope, Up: Fun
9.2.3.3 Passing Function Arguments by Value Or by Reference
...........................................................
-In `awk', when you declare a function, there is no way to declare
+In 'awk', when you declare a function, there is no way to declare
explicitly whether the arguments are passed "by value" or "by
reference".
@@ -13829,11 +13766,11 @@ example, if you write the following code:
foo = "bar"
z = myfunc(foo)
-then you should not think of the argument to `myfunc()' as being "the
-variable `foo'." Instead, think of the argument as the string value
-`"bar"'. If the function `myfunc()' alters the values of its local
+then you should not think of the argument to 'myfunc()' as being "the
+variable 'foo'." Instead, think of the argument as the string value
+'"bar"'. If the function 'myfunc()' alters the values of its local
variables, this has no effect on any other variables. Thus, if
-`myfunc()' does this:
+'myfunc()' does this:
function myfunc(str)
{
@@ -13842,11 +13779,11 @@ variables, this has no effect on any other variables.
Thus, if
print str
}
-to change its first argument variable `str', it does _not_ change the
-value of `foo' in the caller. The role of `foo' in calling `myfunc()'
-ended when its value (`"bar"') was computed. If `str' also exists
-outside of `myfunc()', the function body cannot alter this outer value,
-because it is shadowed during the execution of `myfunc()' and cannot be
+to change its first argument variable 'str', it does _not_ change the
+value of 'foo' in the caller. The role of 'foo' in calling 'myfunc()'
+ended when its value ('"bar"') was computed. If 'str' also exists
+outside of 'myfunc()', the function body cannot alter this outer value,
+because it is shadowed during the execution of 'myfunc()' and cannot be
seen or changed from there.
However, when arrays are the parameters to functions, they are _not_
@@ -13870,12 +13807,12 @@ function _are_ visible outside that function.
a[1], a[2], a[3]
}
- prints `a[1] = 1, a[2] = two, a[3] = 3', because `changeit()'
- stores `"two"' in the second element of `a'.
+ prints 'a[1] = 1, a[2] = two, a[3] = 3', because 'changeit()'
+ stores '"two"' in the second element of 'a'.
- Some `awk' implementations allow you to call a function that has not
-been defined. They only report a problem at runtime, when the program
-actually tries to call the function. For example:
+ Some 'awk' implementations allow you to call a function that has not
+been defined. They only report a problem at runtime, when the program
+actually tries to call the function. For example:
BEGIN {
if (0)
@@ -13886,53 +13823,52 @@ actually tries to call the function. For example:
function bar() { ... }
# note that `foo' is not defined
-Because the `if' statement will never be true, it is not really a
-problem that `foo()' has not been defined. Usually, though, it is a
+Because the 'if' statement will never be true, it is not really a
+problem that 'foo()' has not been defined. Usually, though, it is a
problem if a program calls an undefined function.
- If `--lint' is specified (*note Options::), `gawk' reports calls to
+ If '--lint' is specified (*note Options::), 'gawk' reports calls to
undefined functions.
- Some `awk' implementations generate a runtime error if you use
-either the `next' statement or the `nextfile' statement (*note Next
+ Some 'awk' implementations generate a runtime error if you use either
+the 'next' statement or the 'nextfile' statement (*note Next
Statement::, and *note Nextfile Statement::) inside a user-defined
-function. `gawk' does not have this limitation.
+function. 'gawk' does not have this limitation.
File: gawk.info, Node: Return Statement, Next: Dynamic Typing, Prev:
Function Caveats, Up: User-defined
-9.2.4 The `return' Statement
+9.2.4 The 'return' Statement
----------------------------
-As seen in several earlier examples, the body of a user-defined
-function can contain a `return' statement. This statement returns
-control to the calling part of the `awk' program. It can also be used
-to return a value for use in the rest of the `awk' program. It looks
-like this:
+As seen in several earlier examples, the body of a user-defined function
+can contain a 'return' statement. This statement returns control to the
+calling part of the 'awk' program. It can also be used to return a
+value for use in the rest of the 'awk' program. It looks like this:
- `return' [EXPRESSION]
+ 'return' [EXPRESSION]
The EXPRESSION part is optional. Due most likely to an oversight,
POSIX does not define what the return value is if you omit the
EXPRESSION. Technically speaking, this makes the returned value
undefined, and therefore, unpredictable. In practice, though, all
-versions of `awk' simply return the null string, which acts like zero
-if used in a numeric context.
+versions of 'awk' simply return the null string, which acts like zero if
+used in a numeric context.
- A `return' statement without an EXPRESSION is assumed at the end of
+ A 'return' statement without an EXPRESSION is assumed at the end of
every function definition. So, if control reaches the end of the
function body, then technically the function returns an unpredictable
-value. In practice, it returns the empty string. `awk' does _not_
-warn you if you use the return value of such a function.
+value. In practice, it returns the empty string. 'awk' does _not_ warn
+you if you use the return value of such a function.
Sometimes, you want to write a function for what it does, not for
-what it returns. Such a function corresponds to a `void' function in
-C, C++, or Java, or to a `procedure' in Ada. Thus, it may be
-appropriate to not return any value; simply bear in mind that you
-should not be using the return value of such a function.
+what it returns. Such a function corresponds to a 'void' function in C,
+C++, or Java, or to a 'procedure' in Ada. Thus, it may be appropriate
+to not return any value; simply bear in mind that you should not be
+using the return value of such a function.
- The following is an example of a user-defined function that returns
-a value for the largest number among the elements of an array:
+ The following is an example of a user-defined function that returns a
+value for the largest number among the elements of an array:
function maxelt(vec, i, ret)
{
@@ -13943,16 +13879,15 @@ a value for the largest number among the elements of
an array:
return ret
}
-You call `maxelt()' with one argument, which is an array name. The
-local variables `i' and `ret' are not intended to be arguments; there
-is nothing to stop you from passing more than one argument to
-`maxelt()' but the results would be strange. The extra space before
-`i' in the function parameter list indicates that `i' and `ret' are
-local variables. You should follow this convention when defining
-functions.
+You call 'maxelt()' with one argument, which is an array name. The
+local variables 'i' and 'ret' are not intended to be arguments; there is
+nothing to stop you from passing more than one argument to 'maxelt()'
+but the results would be strange. The extra space before 'i' in the
+function parameter list indicates that 'i' and 'ret' are local
+variables. You should follow this convention when defining functions.
- The following program uses the `maxelt()' function. It loads an
-array, calls `maxelt()', and then reports the maximum number in that
+ The following program uses the 'maxelt()' function. It loads an
+array, calls 'maxelt()', and then reports the maximum number in that
array:
function maxelt(vec, i, ret)
@@ -13991,8 +13926,8 @@ File: gawk.info, Node: Dynamic Typing, Prev: Return
Statement, Up: User-defin
9.2.5 Functions and Their Effects on Variable Typing
----------------------------------------------------
-`awk' is a very fluid language. It is possible that `awk' can't tell
-if an identifier represents a scalar variable or an array until runtime.
+'awk' is a very fluid language. It is possible that 'awk' can't tell if
+an identifier represents a scalar variable or an array until runtime.
Here is an annotated sample program:
function foo(a)
@@ -14008,9 +13943,9 @@ Here is an annotated sample program:
x = 1 # now not allowed, runtime error
}
- In this example, the first call to `foo()' generates a fatal error,
-so `awk' will not report the second error. If you comment out that
-call, though, then `awk' does report the second error.
+ In this example, the first call to 'foo()' generates a fatal error,
+so 'awk' will not report the second error. If you comment out that
+call, though, then 'awk' does report the second error.
Usually, such things aren't a big issue, but it's worth being aware
of them.
@@ -14021,23 +13956,23 @@ File: gawk.info, Node: Indirect Calls, Next:
Functions Summary, Prev: User-de
9.3 Indirect Function Calls
===========================
-This section describes an advanced, `gawk'-specific extension.
+This section describes an advanced, 'gawk'-specific extension.
Often, you may wish to defer the choice of function to call until
runtime. For example, you may have different kinds of records, each of
which should be processed differently.
- Normally, you would have to use a series of `if'-`else' statements
-to decide which function to call. By using "indirect" function calls,
-you can specify the name of the function to call as a string variable,
-and then call the function. Let's look at an example.
+ Normally, you would have to use a series of 'if'-'else' statements to
+decide which function to call. By using "indirect" function calls, you
+can specify the name of the function to call as a string variable, and
+then call the function. Let's look at an example.
- Suppose you have a file with your test scores for the classes you
-are taking, and you wish to get the sum and the average of your test
-scores. The first field is the class name. The following fields are
-the functions to call to process the data, up to a "marker" field
-`data:'. Following the marker, to the end of the record, are the
-various numeric test scores.
+ Suppose you have a file with your test scores for the classes you are
+taking, and you wish to get the sum and the average of your test scores.
+The first field is the class name. The following fields are the
+functions to call to process the data, up to a "marker" field 'data:'.
+Following the marker, to the end of the record, are the various numeric
+test scores.
Here is the initial file:
@@ -14059,13 +13994,13 @@ various numeric test scores.
}
This style of programming works, but can be awkward. With "indirect"
-function calls, you tell `gawk' to use the _value_ of a variable as the
+function calls, you tell 'gawk' to use the _value_ of a variable as the
_name_ of the function to call.
The syntax is similar to that of a regular function call: an
identifier immediately followed by an opening parenthesis, any
arguments, and then a closing parenthesis, with the addition of a
-leading `@' character:
+leading '@' character:
the_func = "sum"
result = @the_func() # calls the sum() function
@@ -14098,7 +14033,7 @@ using indirect function calls:
}
These two functions expect to work on fields; thus, the parameters
-`first' and `last' indicate where in the fields to start and end.
+'first' and 'last' indicate where in the fields to start and end.
Otherwise, they perform the expected computations and are not unusual:
# For each record, print the class name and the requested statistics
@@ -14122,14 +14057,14 @@ Otherwise, they perform the expected computations and
are not unusual:
print ""
}
- This is the main processing for each record. It prints the class
-name (with underscores replaced with spaces). It then finds the start
-of the actual data, saving it in `start'. The last part of the code
-loops through each function name (from `$2' up to the marker, `data:'),
-calling the function named by the field. The indirect function call
-itself occurs as a parameter in the call to `printf'. (The `printf'
-format string uses `%s' as the format specifier so that we can use
-functions that return strings, as well as numbers. Note that the result
+ This is the main processing for each record. It prints the class
+name (with underscores replaced with spaces). It then finds the start
+of the actual data, saving it in 'start'. The last part of the code
+loops through each function name (from '$2' up to the marker, 'data:'),
+calling the function named by the field. The indirect function call
+itself occurs as a parameter in the call to 'printf'. (The 'printf'
+format string uses '%s' as the format specifier so that we can use
+functions that return strings, as well as numbers. Note that the result
from the indirect call is concatenated with the empty string, in order
to force it to be a string value.)
@@ -14152,13 +14087,13 @@ to force it to be a string value.)
may think at first. The C and C++ languages provide "function
pointers," which are a mechanism for calling a function chosen at
runtime. One of the most well-known uses of this ability is the C
-`qsort()' function, which sorts an array using the famous "quicksort"
+'qsort()' function, which sorts an array using the famous "quicksort"
algorithm (see the Wikipedia article
(http://en.wikipedia.org/wiki/Quicksort) for more information). To use
this function, you supply a pointer to a comparison function. This
mechanism allows you to sort arbitrary data in an arbitrary fashion.
- We can do something similar using `gawk', like this:
+ We can do something similar using 'gawk', like this:
# quicksort.awk --- Quicksort algorithm, with user-supplied
# comparison function
@@ -14190,13 +14125,13 @@ mechanism allows you to sort arbitrary data in an
arbitrary fashion.
data[j] = temp
}
- The `quicksort()' function receives the `data' array, the starting
-and ending indices to sort (`left' and `right'), and the name of a
-function that performs a "less than" comparison. It then implements
-the quicksort algorithm.
+ The 'quicksort()' function receives the 'data' array, the starting
+and ending indices to sort ('left' and 'right'), and the name of a
+function that performs a "less than" comparison. It then implements the
+quicksort algorithm.
To make use of the sorting function, we return to our previous
-example. The first thing to do is write some comparison functions:
+example. The first thing to do is write some comparison functions:
# num_lt --- do a numeric less than comparison
@@ -14212,15 +14147,15 @@ example. The first thing to do is write some
comparison functions:
return ((left + 0) >= (right + 0))
}
- The `num_ge()' function is needed to perform a descending sort; when
+ The 'num_ge()' function is needed to perform a descending sort; when
used to perform a "less than" test, it actually does the opposite
(greater than or equal to), which yields data sorted in descending
order.
- Next comes a sorting function. It is parameterized with the
-starting and ending field numbers and the comparison function. It
-builds an array with the data and calls `quicksort()' appropriately,
-and then formats the results as a single string:
+ Next comes a sorting function. It is parameterized with the starting
+and ending field numbers and the comparison function. It builds an
+array with the data and calls 'quicksort()' appropriately, and then
+formats the results as a single string:
# do_sort --- sort the data according to `compare'
# and return it as a string
@@ -14242,7 +14177,7 @@ and then formats the results as a single string:
return retval
}
- Finally, the two sorting functions call `do_sort()', passing in the
+ Finally, the two sorting functions call 'do_sort()', passing in the
names of the two comparison functions:
# sort --- sort the data in ascending order and return it as a string
@@ -14287,37 +14222,38 @@ names of the two comparison functions:
-| rsort: <100.0 95.6 93.4 87.1>
Another example where indirect functions calls are useful can be
-found in processing arrays. This is described in *note Walking Arrays::.
+found in processing arrays. This is described in *note Walking
+Arrays::.
- Remember that you must supply a leading `@' in front of an indirect
+ Remember that you must supply a leading '@' in front of an indirect
function call.
- Starting with version 4.1.2 of `gawk', indirect function calls may
-also be used with built-in functions and with extension functions
-(*note Dynamic Extensions::). There are some limitations when calling
-built-in functions indirectly, as follows.
+ Starting with version 4.1.2 of 'gawk', indirect function calls may
+also be used with built-in functions and with extension functions (*note
+Dynamic Extensions::). There are some limitations when calling built-in
+functions indirectly, as follows.
* You cannot pass a regular expression constant to a built-in
- function through an indirect function call.(1) This applies to the
- `sub()', `gsub()', `gensub()', `match()', `split()' and
- `patsplit()' functions.
+ function through an indirect function call.(1) This applies to the
+ 'sub()', 'gsub()', 'gensub()', 'match()', 'split()' and
+ 'patsplit()' functions.
- * If calling `sub()' or `gsub()', you may only pass two arguments,
+ * If calling 'sub()' or 'gsub()', you may only pass two arguments,
since those functions are unusual in that they update their third
- argument. This means that `$0' will be updated.
+ argument. This means that '$0' will be updated.
- `gawk' does its best to make indirect function calls efficient. For
+ 'gawk' does its best to make indirect function calls efficient. For
example, in the following case:
for (i = 1; i <= n; i++)
@the_func()
-`gawk' looks up the actual function to call only once.
+'gawk' looks up the actual function to call only once.
---------- Footnotes ----------
(1) This may change in a future version; recheck the documentation
-that comes with your version of `gawk' to see if it has.
+that comes with your version of 'gawk' to see if it has.
File: gawk.info, Node: Functions Summary, Prev: Indirect Calls, Up:
Functions
@@ -14325,28 +14261,28 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
9.4 Summary
===========
- * `awk' provides built-in functions and lets you define your own
+ * 'awk' provides built-in functions and lets you define your own
functions.
- * POSIX `awk' provides three kinds of built-in functions: numeric,
- string, and I/O. `gawk' provides functions that sort arrays, work
+ * POSIX 'awk' provides three kinds of built-in functions: numeric,
+ string, and I/O. 'gawk' provides functions that sort arrays, work
with values representing time, do bit manipulation, determine
variable type (array versus scalar), and internationalize and
- localize programs. `gawk' also provides several extensions to
- some of standard functions, typically in the form of additional
+ localize programs. 'gawk' also provides several extensions to some
+ of standard functions, typically in the form of additional
arguments.
* Functions accept zero or more arguments and return a value. The
expressions that provide the argument values are completely
- evaluated before the function is called. Order of evaluation is
+ evaluated before the function is called. Order of evaluation is
not defined. The return value can be ignored.
- * The handling of backslash in `sub()' and `gsub()' is not simple.
- It is more straightforward in `gawk''s `gensub()' function, but
+ * The handling of backslash in 'sub()' and 'gsub()' is not simple.
+ It is more straightforward in 'gawk''s 'gensub()' function, but
that function still requires care in its use.
* User-defined functions provide important capabilities but come with
- some syntactic inelegancies. In a function call, there cannot be
+ some syntactic inelegancies. In a function call, there cannot be
any space between the function name and the opening left
parenthesis of the argument list. Also, there is no provision for
local variables, so the convention is to add extra parameters, and
@@ -14354,17 +14290,17 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
whitespace.
* User-defined functions may call other user-defined (and built-in)
- functions and may call themselves recursively. Function parameters
+ functions and may call themselves recursively. Function parameters
"hide" any global variables of the same names. You cannot use the
- name of a reserved variable (such as `ARGC') as the name of a
+ name of a reserved variable (such as 'ARGC') as the name of a
parameter in user-defined functions.
- * Scalar values are passed to user-defined functions by value. Array
+ * Scalar values are passed to user-defined functions by value. Array
parameters are passed by reference; any changes made by the
function to array parameters are thus visible after the function
has returned.
- * Use the `return' statement to return from a user-defined function.
+ * Use the 'return' statement to return from a user-defined function.
An optional expression becomes the function's return value. Only
scalar values may be returned by a function.
@@ -14372,25 +14308,24 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
function, how that function treats the variable can set its nature:
either scalar or array.
- * `gawk' provides indirect function calls using a special syntax.
- By setting a variable to the name of a function, you can determine
- at runtime what function will be called at that point in the
- program. This is equivalent to function pointers in C and C++.
-
+ * 'gawk' provides indirect function calls using a special syntax. By
+ setting a variable to the name of a function, you can determine at
+ runtime what function will be called at that point in the program.
+ This is equivalent to function pointers in C and C++.
File: gawk.info, Node: Library Functions, Next: Sample Programs, Prev:
Functions, Up: Top
-10 A Library of `awk' Functions
+10 A Library of 'awk' Functions
*******************************
-*note User-defined::, describes how to write your own `awk' functions.
+*note User-defined::, describes how to write your own 'awk' functions.
Writing functions is important, because it allows you to encapsulate
algorithms and program tasks in a single place. It simplifies
programming, making program development more manageable and making
programs more readable.
- In their seminal 1976 book, `Software Tools',(1) Brian Kernighan and
+ In their seminal 1976 book, 'Software Tools',(1) Brian Kernighan and
P.J. Plauger wrote:
Good Programming is not learned from generalities, but by seeing
@@ -14402,38 +14337,38 @@ P.J. Plauger wrote:
In fact, they felt this idea was so important that they placed this
statement on the cover of their book. Because we believe strongly that
-their statement is correct, this major node and *note Sample
-Programs::, provide a good-sized body of code for you to read and, we
-hope, to learn from.
+their statement is correct, this major node and *note Sample Programs::,
+provide a good-sized body of code for you to read and, we hope, to learn
+from.
- This major node presents a library of useful `awk' functions. Many
+ This major node presents a library of useful 'awk' functions. Many
of the sample programs presented later in this Info file use these
functions. The functions are presented here in a progression from
simple to complex.
*note Extract Program::, presents a program that you can use to
-extract the source code for these example library functions and
-programs from the Texinfo source for this Info file. (This has already
-been done as part of the `gawk' distribution.)
+extract the source code for these example library functions and programs
+from the Texinfo source for this Info file. (This has already been done
+as part of the 'gawk' distribution.)
- If you have written one or more useful, general-purpose `awk'
-functions and would like to contribute them to the `awk' user
-community, see *note How To Contribute::, for more information.
+ If you have written one or more useful, general-purpose 'awk'
+functions and would like to contribute them to the 'awk' user community,
+see *note How To Contribute::, for more information.
The programs in this major node and in *note Sample Programs::,
-freely use `gawk'-specific features. Rewriting these programs for
-different implementations of `awk' is pretty straightforward:
+freely use 'gawk'-specific features. Rewriting these programs for
+different implementations of 'awk' is pretty straightforward:
- * Diagnostic error messages are sent to `/dev/stderr'. Use `| "cat
- 1>&2"' instead of `> "/dev/stderr"' if your system does not have a
- `/dev/stderr', or if you cannot use `gawk'.
+ * Diagnostic error messages are sent to '/dev/stderr'. Use '| "cat
+ 1>&2"' instead of '> "/dev/stderr"' if your system does not have a
+ '/dev/stderr', or if you cannot use 'gawk'.
- * A number of programs use `nextfile' (*note Nextfile Statement::)
- to skip any remaining input in the input file.
+ * A number of programs use 'nextfile' (*note Nextfile Statement::) to
+ skip any remaining input in the input file.
* Finally, some of the programs choose to ignore upper- and lowercase
- distinctions in their input. They do so by assigning one to
- `IGNORECASE'. You can achieve almost the same effect(2) by adding
+ distinctions in their input. They do so by assigning one to
+ 'IGNORECASE'. You can achieve almost the same effect(2) by adding
the following rule to the beginning of the program:
# ignore case
@@ -14463,7 +14398,7 @@ different implementations of `awk' is pretty
straightforward:
book have yet to be learned by a vast number of practicing programmers.
(2) The effects are not identical. Output of the transformed record
-will be in all lowercase, while `IGNORECASE' preserves the original
+will be in all lowercase, while 'IGNORECASE' preserves the original
contents of the input record.
@@ -14472,47 +14407,47 @@ File: gawk.info, Node: Library Names, Next: General
Functions, Up: Library Fu
10.1 Naming Library Function Global Variables
=============================================
-Due to the way the `awk' language evolved, variables are either
-"global" (usable by the entire program) or "local" (usable just by a
-specific function). There is no intermediate state analogous to
-`static' variables in C.
+Due to the way the 'awk' language evolved, variables are either "global"
+(usable by the entire program) or "local" (usable just by a specific
+function). There is no intermediate state analogous to 'static'
+variables in C.
Library functions often need to have global variables that they can
use to preserve state information between calls to the function--for
-example, `getopt()''s variable `_opti' (*note Getopt Function::). Such
+example, 'getopt()''s variable '_opti' (*note Getopt Function::). Such
variables are called "private", as the only functions that need to use
them are the ones in the library.
When writing a library function, you should try to choose names for
your private variables that will not conflict with any variables used by
either another library function or a user's main program. For example,
-a name like `i' or `j' is not a good choice, because user programs
-often use variable names like these for their own purposes.
+a name like 'i' or 'j' is not a good choice, because user programs often
+use variable names like these for their own purposes.
The example programs shown in this major node all start the names of
-their private variables with an underscore (`_'). Users generally
-don't use leading underscores in their variable names, so this
-convention immediately decreases the chances that the variable names
-will be accidentally shared with the user's program.
+their private variables with an underscore ('_'). Users generally don't
+use leading underscores in their variable names, so this convention
+immediately decreases the chances that the variable names will be
+accidentally shared with the user's program.
In addition, several of the library functions use a prefix that helps
indicate what function or set of functions use the variables--for
-example, `_pw_byname()' in the user database routines (*note Passwd
+example, '_pw_byname()' in the user database routines (*note Passwd
Functions::). This convention is recommended, as it even further
-decreases the chance of inadvertent conflict among variable names.
-Note that this convention is used equally well for variable names and
-for private function names.(1)
+decreases the chance of inadvertent conflict among variable names. Note
+that this convention is used equally well for variable names and for
+private function names.(1)
As a final note on variable naming, if a function makes global
variables available for use by a main program, it is a good convention
to start those variables' names with a capital letter--for example,
-`getopt()''s `Opterr' and `Optind' variables (*note Getopt Function::).
+'getopt()''s 'Opterr' and 'Optind' variables (*note Getopt Function::).
The leading capital letter indicates that it is global, while the fact
that the variable name is not all capital letters indicates that the
-variable is not one of `awk''s predefined variables, such as `FS'.
+variable is not one of 'awk''s predefined variables, such as 'FS'.
It is also important that _all_ variables in library functions that
-do not need to save state are, in fact, declared local.(2) If this is
+do not need to save state are, in fact, declared local.(2) If this is
not done, the variables could accidentally be used in the user's
program, leading to bugs that are very difficult to track down:
@@ -14529,22 +14464,22 @@ single associative array to hold the values needed by
the library
function(s), or "package." This significantly decreases the number of
actual global names in use. For example, the functions described in
*note Passwd Functions::, might have used array elements
-`PW_data["inited"]', `PW_data["total"]', `PW_data["count"]', and
-`PW_data["awklib"]', instead of `_pw_inited', `_pw_awklib', `_pw_total',
-and `_pw_count'.
+'PW_data["inited"]', 'PW_data["total"]', 'PW_data["count"]', and
+'PW_data["awklib"]', instead of '_pw_inited', '_pw_awklib', '_pw_total',
+and '_pw_count'.
The conventions presented in this minor node are exactly that:
-conventions. You are not required to write your programs this way--we
+conventions. You are not required to write your programs this way--we
merely recommend that you do so.
---------- Footnotes ----------
(1) Although all the library routines could have been rewritten to
use this convention, this was not done, in order to show how our own
-`awk' programming style has evolved and to provide some basis for this
+'awk' programming style has evolved and to provide some basis for this
discussion.
- (2) `gawk''s `--dump-variables' command-line option is useful for
+ (2) 'gawk''s '--dump-variables' command-line option is useful for
verifying this.
@@ -14559,10 +14494,10 @@ programming use.
* Menu:
* Strtonum Function:: A replacement for the built-in
- `strtonum()' function.
-* Assert Function:: A function for assertions in `awk'
+ 'strtonum()' function.
+* Assert Function:: A function for assertions in 'awk'
programs.
-* Round Function:: A function for rounding if `sprintf()'
+* Round Function:: A function for rounding if 'sprintf()'
does not do it correctly.
* Cliff Random Function:: The Cliff Random Number Generator.
* Ordinal Functions:: Functions for using characters as numbers and
@@ -14578,9 +14513,9 @@ File: gawk.info, Node: Strtonum Function, Next:
Assert Function, Up: General
10.2.1 Converting Strings to Numbers
------------------------------------
-The `strtonum()' function (*note String Functions::) is a `gawk'
+The 'strtonum()' function (*note String Functions::) is a 'gawk'
extension. The following function provides an implementation for other
-versions of `awk':
+versions of 'awk':
# mystrtonum --- convert string to number
@@ -14637,26 +14572,26 @@ versions of `awk':
# }
The function first looks for C-style octal numbers (base 8). If the
-input string matches a regular expression describing octal numbers,
-then `mystrtonum()' loops through each character in the string. It
-sets `k' to the index in `"1234567"' of the current octal digit. The
-return value will either be the same number as the digit, or zero if
-the character is not there, which will be true for a `0'. This is
-safe, because the regexp test in the `if' ensures that only octal
-values are converted.
+input string matches a regular expression describing octal numbers, then
+'mystrtonum()' loops through each character in the string. It sets 'k'
+to the index in '"1234567"' of the current octal digit. The return
+value will either be the same number as the digit, or zero if the
+character is not there, which will be true for a '0'. This is safe,
+because the regexp test in the 'if' ensures that only octal values are
+converted.
Similar logic applies to the code that checks for and converts a
-hexadecimal value, which starts with `0x' or `0X'. The use of
-`tolower()' simplifies the computation for finding the correct numeric
+hexadecimal value, which starts with '0x' or '0X'. The use of
+'tolower()' simplifies the computation for finding the correct numeric
value for each hexadecimal digit.
Finally, if the string matches the (rather complicated) regexp for a
-regular decimal integer or floating-point number, the computation `ret
-= str + 0' lets `awk' convert the value to a number.
+regular decimal integer or floating-point number, the computation 'ret =
+str + 0' lets 'awk' convert the value to a number.
- A commented-out test program is included, so that the function can
-be tested with `gawk' and the results compared to the built-in
-`strtonum()' function.
+ A commented-out test program is included, so that the function can be
+tested with 'gawk' and the results compared to the built-in 'strtonum()'
+function.
File: gawk.info, Node: Assert Function, Next: Round Function, Prev:
Strtonum Function, Up: General Functions
@@ -14664,15 +14599,15 @@ File: gawk.info, Node: Assert Function, Next: Round
Function, Prev: Strtonum
10.2.2 Assertions
-----------------
-When writing large programs, it is often useful to know that a
-condition or set of conditions is true. Before proceeding with a
-particular computation, you make a statement about what you believe to
-be the case. Such a statement is known as an "assertion". The C
-language provides an `<assert.h>' header file and corresponding
-`assert()' macro that a programmer can use to make assertions. If an
-assertion fails, the `assert()' macro arranges to print a diagnostic
-message describing the condition that should have been true but was
-not, and then it kills the program. In C, using `assert()' looks this:
+When writing large programs, it is often useful to know that a condition
+or set of conditions is true. Before proceeding with a particular
+computation, you make a statement about what you believe to be the case.
+Such a statement is known as an "assertion". The C language provides an
+'<assert.h>' header file and corresponding 'assert()' macro that a
+programmer can use to make assertions. If an assertion fails, the
+'assert()' macro arranges to print a diagnostic message describing the
+condition that should have been true but was not, and then it kills the
+program. In C, using 'assert()' looks this:
#include <assert.h>
@@ -14688,8 +14623,8 @@ not, and then it kills the program. In C, using
`assert()' looks this:
The C language makes it possible to turn the condition into a string
for use in printing the diagnostic message. This is not possible in
-`awk', so this `assert()' function also requires a string version of
-the condition that is being tested. Following is the function:
+'awk', so this 'assert()' function also requires a string version of the
+condition that is being tested. Following is the function:
# assert --- assert that a condition is true. Otherwise, exit.
@@ -14708,20 +14643,20 @@ the condition that is being tested. Following is the
function:
exit 1
}
- The `assert()' function tests the `condition' parameter. If it is
-false, it prints a message to standard error, using the `string'
+ The 'assert()' function tests the 'condition' parameter. If it is
+false, it prints a message to standard error, using the 'string'
parameter to describe the failed condition. It then sets the variable
-`_assert_exit' to one and executes the `exit' statement. The `exit'
-statement jumps to the `END' rule. If the `END' rule finds
-`_assert_exit' to be true, it exits immediately.
+'_assert_exit' to one and executes the 'exit' statement. The 'exit'
+statement jumps to the 'END' rule. If the 'END' rule finds
+'_assert_exit' to be true, it exits immediately.
- The purpose of the test in the `END' rule is to keep any other `END'
+ The purpose of the test in the 'END' rule is to keep any other 'END'
rules from running. When an assertion fails, the program should exit
-immediately. If no assertions fail, then `_assert_exit' is still false
-when the `END' rule is run normally, and the rest of the program's
-`END' rules execute. For all of this to work correctly, `assert.awk'
-must be the first source file read by `awk'. The function can be used
-in a program in the following way:
+immediately. If no assertions fail, then '_assert_exit' is still false
+when the 'END' rule is run normally, and the rest of the program's 'END'
+rules execute. For all of this to work correctly, 'assert.awk' must be
+the first source file read by 'awk'. The function can be used in a
+program in the following way:
function myfunc(a, b)
{
@@ -14733,16 +14668,16 @@ If the assertion fails, you see a message similar to
the following:
mydata:1357: assertion failed: a <= 5 && b >= 17.1
- There is a small problem with this version of `assert()'. An `END'
-rule is automatically added to the program calling `assert()'.
-Normally, if a program consists of just a `BEGIN' rule, the input files
-and/or standard input are not read. However, now that the program has
-an `END' rule, `awk' attempts to read the input data files or standard
-input (*note Using BEGIN/END::), most likely causing the program to
-hang as it waits for input.
+ There is a small problem with this version of 'assert()'. An 'END'
+rule is automatically added to the program calling 'assert()'.
+Normally, if a program consists of just a 'BEGIN' rule, the input files
+and/or standard input are not read. However, now that the program has
+an 'END' rule, 'awk' attempts to read the input data files or standard
+input (*note Using BEGIN/END::), most likely causing the program to hang
+as it waits for input.
- There is a simple workaround to this: make sure that such a `BEGIN'
-rule always ends with an `exit' statement.
+ There is a simple workaround to this: make sure that such a 'BEGIN'
+rule always ends with an 'exit' statement.
File: gawk.info, Node: Round Function, Next: Cliff Random Function, Prev:
Assert Function, Up: General Functions
@@ -14750,15 +14685,15 @@ File: gawk.info, Node: Round Function, Next: Cliff
Random Function, Prev: Ass
10.2.3 Rounding Numbers
-----------------------
-The way `printf' and `sprintf()' (*note Printf::) perform rounding
-often depends upon the system's C `sprintf()' subroutine. On many
-machines, `sprintf()' rounding is "unbiased", which means it doesn't
-always round a trailing .5 up, contrary to naive expectations. In
-unbiased rounding, .5 rounds to even, rather than always up, so 1.5
-rounds to 2 but 4.5 rounds to 4. This means that if you are using a
-format that does rounding (e.g., `"%.0f"'), you should check what your
-system does. The following function does traditional rounding; it
-might be useful if your `awk''s `printf' does unbiased rounding:
+The way 'printf' and 'sprintf()' (*note Printf::) perform rounding often
+depends upon the system's C 'sprintf()' subroutine. On many machines,
+'sprintf()' rounding is "unbiased", which means it doesn't always round
+a trailing .5 up, contrary to naive expectations. In unbiased rounding,
+.5 rounds to even, rather than always up, so 1.5 rounds to 2 but 4.5
+rounds to 4. This means that if you are using a format that does
+rounding (e.g., '"%.0f"'), you should check what your system does. The
+following function does traditional rounding; it might be useful if your
+'awk''s 'printf' does unbiased rounding:
# round.awk --- do normal rounding
@@ -14797,10 +14732,10 @@ File: gawk.info, Node: Cliff Random Function, Next:
Ordinal Functions, Prev:
----------------------------------------
The Cliff random number generator
-(http://mathworld.wolfram.com/CliffRandomNumberGenerator.html) is a
-very simple random number generator that "passes the noise sphere test
-for randomness by showing no structure." It is easily programmed, in
-less than 10 lines of `awk' code:
+(http://mathworld.wolfram.com/CliffRandomNumberGenerator.html) is a very
+simple random number generator that "passes the noise sphere test for
+randomness by showing no structure." It is easily programmed, in less
+than 10 lines of 'awk' code:
# cliff_rand.awk --- generate Cliff random numbers
@@ -14816,7 +14751,7 @@ less than 10 lines of `awk' code:
This algorithm requires an initial "seed" of 0.1. Each new value
uses the current seed as input for the calculation. If the built-in
-`rand()' function (*note Numeric Functions::) isn't random enough, you
+'rand()' function (*note Numeric Functions::) isn't random enough, you
might try using this function instead.
@@ -14825,15 +14760,15 @@ File: gawk.info, Node: Ordinal Functions, Next:
Join Function, Prev: Cliff Ra
10.2.5 Translating Between Characters and Numbers
-------------------------------------------------
-One commercial implementation of `awk' supplies a built-in function,
-`ord()', which takes a character and returns the numeric value for that
+One commercial implementation of 'awk' supplies a built-in function,
+'ord()', which takes a character and returns the numeric value for that
character in the machine's character set. If the string passed to
-`ord()' has more than one character, only the first one is used.
+'ord()' has more than one character, only the first one is used.
- The inverse of this function is `chr()' (from the function of the
-same name in Pascal), which takes a number and returns the
-corresponding character. Both functions are written very nicely in
-`awk'; there is no real reason to build them into the `awk' interpreter:
+ The inverse of this function is 'chr()' (from the function of the
+same name in Pascal), which takes a number and returns the corresponding
+character. Both functions are written very nicely in 'awk'; there is no
+real reason to build them into the 'awk' interpreter:
# ord.awk --- do ord and chr
@@ -14864,17 +14799,16 @@ corresponding character. Both functions are written
very nicely in
}
}
- Some explanation of the numbers used by `_ord_init()' is worthwhile.
+ Some explanation of the numbers used by '_ord_init()' is worthwhile.
The most prominent character set in use today is ASCII.(1) Although an
8-bit byte can hold 256 distinct values (from 0 to 255), ASCII only
-defines characters that use the values from 0 to 127.(2) In the now
+defines characters that use the values from 0 to 127.(2) In the now
distant past, at least one minicomputer manufacturer used ASCII, but
-with mark parity, meaning that the leftmost bit in the byte is always
-1. This means that on those systems, characters have numeric values
-from 128 to 255. Finally, large mainframe systems use the EBCDIC
-character set, which uses all 256 values. There are other character
-sets in use on some older systems, but they are not really worth
-worrying about:
+with mark parity, meaning that the leftmost bit in the byte is always 1.
+This means that on those systems, characters have numeric values from
+128 to 255. Finally, large mainframe systems use the EBCDIC character
+set, which uses all 256 values. There are other character sets in use
+on some older systems, but they are not really worth worrying about:
function ord(str, c)
{
@@ -14900,9 +14834,9 @@ worrying about:
# }
An obvious improvement to these functions is to move the code for the
-`_ord_init' function into the body of the `BEGIN' rule. It was written
+'_ord_init' function into the body of the 'BEGIN' rule. It was written
this way initially for ease of development. There is a "test program"
-in a `BEGIN' rule, to test the function. It is commented out for
+in a 'BEGIN' rule, to test the function. It is commented out for
production use.
---------- Footnotes ----------
@@ -14913,8 +14847,8 @@ Unicode support, a character can occupy up to 32 bits,
making simple
tests such as used here prohibitively expensive.
(2) ASCII has been extended in many countries to use the values from
-128 to 255 for country-specific characters. If your system uses these
-extensions, you can simplify `_ord_init()' to loop from 0 to 255.
+128 to 255 for country-specific characters. If your system uses these
+extensions, you can simplify '_ord_init()' to loop from 0 to 255.
File: gawk.info, Node: Join Function, Next: Getlocaltime Function, Prev:
Ordinal Functions, Up: General Functions
@@ -14924,15 +14858,15 @@ File: gawk.info, Node: Join Function, Next:
Getlocaltime Function, Prev: Ordi
When doing string processing, it is often useful to be able to join all
the strings in an array into one long string. The following function,
-`join()', accomplishes this task. It is used later in several of the
+'join()', accomplishes this task. It is used later in several of the
application programs (*note Sample Programs::).
- Good function design is important; this function needs to be
-general, but it should also have a reasonable default behavior. It is
-called with an array as well as the beginning and ending indices of the
-elements in the array to be merged. This assumes that the array
-indices are numeric--a reasonable assumption, as the array was likely
-created with `split()' (*note String Functions::):
+ Good function design is important; this function needs to be general,
+but it should also have a reasonable default behavior. It is called
+with an array as well as the beginning and ending indices of the
+elements in the array to be merged. This assumes that the array indices
+are numeric--a reasonable assumption, as the array was likely created
+with 'split()' (*note String Functions::):
# join.awk --- join an array into a string
@@ -14950,18 +14884,18 @@ created with `split()' (*note String Functions::):
An optional additional argument is the separator to use when joining
the strings back together. If the caller supplies a nonempty value,
-`join()' uses it; if it is not supplied, it has a null value. In this
-case, `join()' uses a single space as a default separator for the
-strings. If the value is equal to `SUBSEP', then `join()' joins the
-strings with no separator between them. `SUBSEP' serves as a "magic"
+'join()' uses it; if it is not supplied, it has a null value. In this
+case, 'join()' uses a single space as a default separator for the
+strings. If the value is equal to 'SUBSEP', then 'join()' joins the
+strings with no separator between them. 'SUBSEP' serves as a "magic"
value to indicate that there should be no separation between the
component strings.(1)
---------- Footnotes ----------
- (1) It would be nice if `awk' had an assignment operator for
-concatenation. The lack of an explicit operator for concatenation
-makes string operations more difficult than they really need to be.
+ (1) It would be nice if 'awk' had an assignment operator for
+concatenation. The lack of an explicit operator for concatenation makes
+string operations more difficult than they really need to be.
File: gawk.info, Node: Getlocaltime Function, Next: Readfile Function,
Prev: Join Function, Up: General Functions
@@ -14969,15 +14903,15 @@ File: gawk.info, Node: Getlocaltime Function, Next:
Readfile Function, Prev:
10.2.7 Managing the Time of Day
-------------------------------
-The `systime()' and `strftime()' functions described in *note Time
+The 'systime()' and 'strftime()' functions described in *note Time
Functions::, provide the minimum functionality necessary for dealing
-with the time of day in human-readable form. Although `strftime()' is
+with the time of day in human-readable form. Although 'strftime()' is
extensive, the control formats are not necessarily easy to remember or
intuitively obvious when reading a program.
- The following function, `getlocaltime()', populates a user-supplied
+ The following function, 'getlocaltime()', populates a user-supplied
array with preformatted time information. It returns a string with the
-current time formatted in the same way as the `date' utility:
+current time formatted in the same way as the 'date' utility:
# getlocaltime.awk --- get the time of day in a usable format
@@ -15040,9 +14974,9 @@ current time formatted in the same way as the `date'
utility:
}
The string indices are easier to use and read than the various
-formats required by `strftime()'. The `alarm' program presented in
+formats required by 'strftime()'. The 'alarm' program presented in
*note Alarm Program::, uses this function. A more general design for
-the `getlocaltime()' function would have allowed the user to supply an
+the 'getlocaltime()' function would have allowed the user to supply an
optional timestamp value to use instead of the current time.
@@ -15052,7 +14986,7 @@ File: gawk.info, Node: Readfile Function, Next: Shell
Quoting, Prev: Getlocal
-----------------------------------
Often, it is convenient to have the entire contents of a file available
-in memory as a single string. A straightforward but naive way to do
+in memory as a single string. A straightforward but naive way to do
that might be as follows:
function readfile(file, tmp, contents)
@@ -15068,9 +15002,9 @@ that might be as follows:
return contents
}
- This function reads from `file' one record at a time, building up
-the full contents of the file in the local variable `contents'. It
-works, but is not necessarily efficient.
+ This function reads from 'file' one record at a time, building up the
+full contents of the file in the local variable 'contents'. It works,
+but is not necessarily efficient.
The following function, based on a suggestion by Denis Shirokov,
reads the entire contents of the named file in one shot:
@@ -15088,22 +15022,21 @@ reads the entire contents of the named file in one
shot:
return tmp
}
- It works by setting `RS' to `^$', a regular expression that will
-never match if the file has contents. `gawk' reads data from the file
-into `tmp', attempting to match `RS'. The match fails after each read,
-but fails quickly, such that `gawk' fills `tmp' with the entire
-contents of the file. (*Note Records::, for information on `RT' and
-`RS'.)
+ It works by setting 'RS' to '^$', a regular expression that will
+never match if the file has contents. 'gawk' reads data from the file
+into 'tmp', attempting to match 'RS'. The match fails after each read,
+but fails quickly, such that 'gawk' fills 'tmp' with the entire contents
+of the file. (*Note Records::, for information on 'RT' and 'RS'.)
- In the case that `file' is empty, the return value is the null
+ In the case that 'file' is empty, the return value is the null
string. Thus, calling code may use something like:
contents = readfile("/some/path")
if (length(contents) == 0)
# file was empty ...
- This tests the result to see if it is empty or not. An equivalent
-test would be `contents == ""'.
+ This tests the result to see if it is empty or not. An equivalent
+test would be 'contents == ""'.
*Note Extension Sample Readfile::, for an extension function that
also reads an entire file into memory.
@@ -15125,21 +15058,21 @@ frequently:
INPUT_PROGRAM | awk "$awkp" | /bin/sh
- For example, a program of his named `flac-edit' has this form:
+ For example, a program of his named 'flac-edit' has this form:
$ flac-edit -song="Whoope! That's Great" file.flac
It generates the following output, which is to be piped to the shell
-(`/bin/sh'):
+('/bin/sh'):
chmod +w file.flac
metaflac --remove-tag=TITLE file.flac
LANG=en_US.88591 metaflac --set-tag=TITLE='Whoope! That'"'"'s Great'
file.flac
chmod -w file.flac
- Note the need for shell quoting. The function `shell_quote()' does
-it. `SINGLE' is the one-character string `"'"' and `QSINGLE' is the
-three-character string `"\"'\""':
+ Note the need for shell quoting. The function 'shell_quote()' does
+it. 'SINGLE' is the one-character string '"'"' and 'QSINGLE' is the
+three-character string '"\"'\""':
# shell_quote --- quote an argument for passing to the shell
@@ -15183,24 +15116,24 @@ File: gawk.info, Node: Filetrans Function, Next:
Rewind Function, Up: Data Fi
10.3.1 Noting Data file Boundaries
----------------------------------
-The `BEGIN' and `END' rules are each executed exactly once, at the
-beginning and end of your `awk' program, respectively (*note
-BEGIN/END::). We (the `gawk' authors) once had a user who mistakenly
-thought that the `BEGIN' rules were executed at the beginning of each
-data file and the `END' rules were executed at the end of each data
+The 'BEGIN' and 'END' rules are each executed exactly once, at the
+beginning and end of your 'awk' program, respectively (*note
+BEGIN/END::). We (the 'gawk' authors) once had a user who mistakenly
+thought that the 'BEGIN' rules were executed at the beginning of each
+data file and the 'END' rules were executed at the end of each data
file.
When informed that this was not the case, the user requested that we
-add new special patterns to `gawk', named `BEGIN_FILE' and `END_FILE',
+add new special patterns to 'gawk', named 'BEGIN_FILE' and 'END_FILE',
that would have the desired behavior. He even supplied us the code to
do so.
- Adding these special patterns to `gawk' wasn't necessary; the job
-can be done cleanly in `awk' itself, as illustrated by the following
-library program. It arranges to call two user-supplied functions,
-`beginfile()' and `endfile()', at the beginning and end of each data
-file. Besides solving the problem in only nine(!) lines of code, it
-does so _portably_; this works with any implementation of `awk':
+ Adding these special patterns to 'gawk' wasn't necessary; the job can
+be done cleanly in 'awk' itself, as illustrated by the following library
+program. It arranges to call two user-supplied functions, 'beginfile()'
+and 'endfile()', at the beginning and end of each data file. Besides
+solving the problem in only nine(!) lines of code, it does so
+_portably_; this works with any implementation of 'awk':
# transfile.awk
#
@@ -15222,25 +15155,25 @@ does so _portably_; this works with any
implementation of `awk':
This file must be loaded before the user's "main" program, so that
the rule it supplies is executed first.
- This rule relies on `awk''s `FILENAME' variable, which automatically
+ This rule relies on 'awk''s 'FILENAME' variable, which automatically
changes for each new data file. The current file name is saved in a
-private variable, `_oldfilename'. If `FILENAME' does not equal
-`_oldfilename', then a new data file is being processed and it is
-necessary to call `endfile()' for the old file. Because `endfile()'
+private variable, '_oldfilename'. If 'FILENAME' does not equal
+'_oldfilename', then a new data file is being processed and it is
+necessary to call 'endfile()' for the old file. Because 'endfile()'
should only be called if a file has been processed, the program first
-checks to make sure that `_oldfilename' is not the null string. The
-program then assigns the current file name to `_oldfilename' and calls
-`beginfile()' for the file. Because, like all `awk' variables,
-`_oldfilename' is initialized to the null string, this rule executes
+checks to make sure that '_oldfilename' is not the null string. The
+program then assigns the current file name to '_oldfilename' and calls
+'beginfile()' for the file. Because, like all 'awk' variables,
+'_oldfilename' is initialized to the null string, this rule executes
correctly even for the first data file.
- The program also supplies an `END' rule to do the final processing
-for the last file. Because this `END' rule comes before any `END' rules
-supplied in the "main" program, `endfile()' is called first. Once
-again, the value of multiple `BEGIN' and `END' rules should be clear.
+ The program also supplies an 'END' rule to do the final processing
+for the last file. Because this 'END' rule comes before any 'END' rules
+supplied in the "main" program, 'endfile()' is called first. Once
+again, the value of multiple 'BEGIN' and 'END' rules should be clear.
If the same data file occurs twice in a row on the command line, then
-`endfile()' and `beginfile()' are not executed at the end of the first
+'endfile()' and 'beginfile()' are not executed at the end of the first
pass and at the beginning of the second pass. The following version
solves the problem:
@@ -15260,19 +15193,19 @@ solves the problem:
*note Wc Program::, shows how this library function can be used and
how it simplifies writing the main program.
- So Why Does `gawk' Have `BEGINFILE' and `ENDFILE'?
+ So Why Does 'gawk' Have 'BEGINFILE' and 'ENDFILE'?
- You are probably wondering, if `beginfile()' and `endfile()'
-functions can do the job, why does `gawk' have `BEGINFILE' and
-`ENDFILE' patterns?
+ You are probably wondering, if 'beginfile()' and 'endfile()'
+functions can do the job, why does 'gawk' have 'BEGINFILE' and 'ENDFILE'
+patterns?
- Good question. Normally, if `awk' cannot open a file, this causes
-an immediate fatal error. In this case, there is no way for a
-user-defined function to deal with the problem, as the mechanism for
-calling it relies on the file being open and at the first record. Thus,
-the main reason for `BEGINFILE' is to give you a "hook" to catch files
-that cannot be processed. `ENDFILE' exists for symmetry, and because
-it provides an easy way to do per-file cleanup processing. For more
+ Good question. Normally, if 'awk' cannot open a file, this causes an
+immediate fatal error. In this case, there is no way for a user-defined
+function to deal with the problem, as the mechanism for calling it
+relies on the file being open and at the first record. Thus, the main
+reason for 'BEGINFILE' is to give you a "hook" to catch files that
+cannot be processed. 'ENDFILE' exists for symmetry, and because it
+provides an easy way to do per-file cleanup processing. For more
information, refer to *note BEGINFILE/ENDFILE::.
@@ -15283,12 +15216,12 @@ File: gawk.info, Node: Rewind Function, Next: File
Checking, Prev: Filetrans
Another request for a new built-in function was for a function that
would make it possible to reread the current file. The requesting user
-didn't want to have to use `getline' (*note Getline::) inside a loop.
+didn't want to have to use 'getline' (*note Getline::) inside a loop.
- However, as long as you are not in the `END' rule, it is quite easy
+ However, as long as you are not in the 'END' rule, it is quite easy
to arrange to immediately close the current input file and then start
over with it from the top. For lack of a better name, we'll call the
-function `rewind()':
+function 'rewind()':
# rewind.awk --- rewind the current file and start over
@@ -15308,11 +15241,11 @@ function `rewind()':
nextfile
}
- The `rewind()' function relies on the `ARGIND' variable (*note
-Auto-set::), which is specific to `gawk'. It also relies on the
-`nextfile' keyword (*note Nextfile Statement::). Because of this, you
-should not call it from an `ENDFILE' rule. (This isn't necessary
-anyway, because `gawk' goes to the next file as soon as an `ENDFILE'
+ The 'rewind()' function relies on the 'ARGIND' variable (*note
+Auto-set::), which is specific to 'gawk'. It also relies on the
+'nextfile' keyword (*note Nextfile Statement::). Because of this, you
+should not call it from an 'ENDFILE' rule. (This isn't necessary
+anyway, because 'gawk' goes to the next file as soon as an 'ENDFILE'
rule finishes!)
@@ -15321,10 +15254,10 @@ File: gawk.info, Node: File Checking, Next: Empty
Files, Prev: Rewind Functio
10.3.3 Checking for Readable Data files
---------------------------------------
-Normally, if you give `awk' a data file that isn't readable, it stops
+Normally, if you give 'awk' a data file that isn't readable, it stops
with a fatal error. There are times when you might want to just ignore
-such files and keep going.(1) You can do this by prepending the
-following program to your `awk' program:
+such files and keep going.(1) You can do this by prepending the
+following program to your 'awk' program:
# readable.awk --- library file to skip over unreadable files
@@ -15340,17 +15273,17 @@ following program to your `awk' program:
}
}
- This works, because the `getline' won't be fatal. Removing the
-element from `ARGV' with `delete' skips the file (because it's no
-longer in the list). See also *note ARGC and ARGV::.
+ This works, because the 'getline' won't be fatal. Removing the
+element from 'ARGV' with 'delete' skips the file (because it's no longer
+in the list). See also *note ARGC and ARGV::.
- Because `awk' variable names only allow the English letters, the
+ Because 'awk' variable names only allow the English letters, the
regular expression check purposely does not use character classes such
-as `[:alpha:]' and `[:alnum:]' (*note Bracket Expressions::).
+as '[:alpha:]' and '[:alnum:]' (*note Bracket Expressions::).
---------- Footnotes ----------
- (1) The `BEGINFILE' special pattern (*note BEGINFILE/ENDFILE::)
+ (1) The 'BEGINFILE' special pattern (*note BEGINFILE/ENDFILE::)
provides an alternative mechanism for dealing with files that can't be
opened. However, the code here provides a portable solution.
@@ -15360,20 +15293,19 @@ File: gawk.info, Node: Empty Files, Next: Ignoring
Assigns, Prev: File Checki
10.3.4 Checking for Zero-Length Files
-------------------------------------
-All known `awk' implementations silently skip over zero-length files.
-This is a by-product of `awk''s implicit
-read-a-record-and-match-against-the-rules loop: when `awk' tries to
-read a record from an empty file, it immediately receives an
-end-of-file indication, closes the file, and proceeds on to the next
-command-line data file, _without_ executing any user-level `awk'
-program code.
-
- Using `gawk''s `ARGIND' variable (*note Built-in Variables::), it is
-possible to detect when an empty data file has been skipped. Similar
-to the library file presented in *note Filetrans Function::, the
-following library file calls a function named `zerofile()' that the
-user must provide. The arguments passed are the file name and the
-position in `ARGV' where it was found:
+All known 'awk' implementations silently skip over zero-length files.
+This is a by-product of 'awk''s implicit
+read-a-record-and-match-against-the-rules loop: when 'awk' tries to read
+a record from an empty file, it immediately receives an end-of-file
+indication, closes the file, and proceeds on to the next command-line
+data file, _without_ executing any user-level 'awk' program code.
+
+ Using 'gawk''s 'ARGIND' variable (*note Built-in Variables::), it is
+possible to detect when an empty data file has been skipped. Similar to
+the library file presented in *note Filetrans Function::, the following
+library file calls a function named 'zerofile()' that the user must
+provide. The arguments passed are the file name and the position in
+'ARGV' where it was found:
# zerofile.awk --- library file to process empty input files
@@ -15392,18 +15324,18 @@ position in `ARGV' where it was found:
zerofile(ARGV[Argind], Argind)
}
- The user-level variable `Argind' allows the `awk' program to track
-its progress through `ARGV'. Whenever the program detects that
-`ARGIND' is greater than `Argind + 1', it means that one or more empty
-files were skipped. The action then calls `zerofile()' for each such
-file, incrementing `Argind' along the way.
+ The user-level variable 'Argind' allows the 'awk' program to track
+its progress through 'ARGV'. Whenever the program detects that 'ARGIND'
+is greater than 'Argind + 1', it means that one or more empty files were
+skipped. The action then calls 'zerofile()' for each such file,
+incrementing 'Argind' along the way.
- The `Argind != ARGIND' rule simply keeps `Argind' up to date in the
+ The 'Argind != ARGIND' rule simply keeps 'Argind' up to date in the
normal case.
- Finally, the `END' rule catches the case of any empty files at the
+ Finally, the 'END' rule catches the case of any empty files at the
end of the command-line arguments. Note that the test in the condition
-of the `for' loop uses the `<=' operator, not `<'.
+of the 'for' loop uses the '<=' operator, not '<'.
File: gawk.info, Node: Ignoring Assigns, Prev: Empty Files, Up: Data File
Management
@@ -15411,13 +15343,13 @@ File: gawk.info, Node: Ignoring Assigns, Prev:
Empty Files, Up: Data File Man
10.3.5 Treating Assignments as File names
-----------------------------------------
-Occasionally, you might not want `awk' to process command-line variable
+Occasionally, you might not want 'awk' to process command-line variable
assignments (*note Assignment Options::). In particular, if you have a
-file name that contains an `=' character, `awk' treats the file name as
+file name that contains an '=' character, 'awk' treats the file name as
an assignment and does not process it.
Some users have suggested an additional command-line option for
-`gawk' to disable command-line assignments. However, some simple
+'gawk' to disable command-line assignments. However, some simple
programming with a library file does the trick:
# noassign.awk --- library file to avoid the need for a
@@ -15440,10 +15372,10 @@ programming with a library file does the trick:
awk -v No_command_assign=1 -f noassign.awk -f yourprog.awk *
The function works by looping through the arguments. It prepends
-`./' to any argument that matches the form of a variable assignment,
+'./' to any argument that matches the form of a variable assignment,
turning that argument into a file name.
- The use of `No_command_assign' allows you to disable command-line
+ The use of 'No_command_assign' allows you to disable command-line
assignments at invocation time, by giving the variable a true value.
When not set, it is initially zero (i.e., false), so the command-line
arguments are left alone.
@@ -15455,32 +15387,32 @@ File: gawk.info, Node: Getopt Function, Next:
Passwd Functions, Prev: Data Fi
====================================
Most utilities on POSIX-compatible systems take options on the command
-line that can be used to change the way a program behaves. `awk' is an
+line that can be used to change the way a program behaves. 'awk' is an
example of such a program (*note Options::). Often, options take
"arguments" (i.e., data that the program needs to correctly obey the
-command-line option). For example, `awk''s `-F' option requires a
+command-line option). For example, 'awk''s '-F' option requires a
string to use as the field separator. The first occurrence on the
-command line of either `--' or a string that does not begin with `-'
+command line of either '--' or a string that does not begin with '-'
ends the options.
- Modern Unix systems provide a C function named `getopt()' for
+ Modern Unix systems provide a C function named 'getopt()' for
processing command-line arguments. The programmer provides a string
-describing the one-letter options. If an option requires an argument,
-it is followed in the string with a colon. `getopt()' is also passed
+describing the one-letter options. If an option requires an argument,
+it is followed in the string with a colon. 'getopt()' is also passed
the count and values of the command-line arguments and is called in a
-loop. `getopt()' processes the command-line arguments for option
+loop. 'getopt()' processes the command-line arguments for option
letters. Each time around the loop, it returns a single character
-representing the next option letter that it finds, or `?' if it finds
-an invalid option. When it returns -1, there are no options left on
-the command line.
+representing the next option letter that it finds, or '?' if it finds an
+invalid option. When it returns -1, there are no options left on the
+command line.
- When using `getopt()', options that do not take arguments can be
-grouped together. Furthermore, options that take arguments require
-that the argument be present. The argument can immediately follow the
-option letter, or it can be a separate command-line argument.
+ When using 'getopt()', options that do not take arguments can be
+grouped together. Furthermore, options that take arguments require that
+the argument be present. The argument can immediately follow the option
+letter, or it can be a separate command-line argument.
Given a hypothetical program that takes three command-line options,
-`-a', `-b', and `-c', where `-b' requires an argument, all of the
+'-a', '-b', and '-c', where '-b' requires an argument, all of the
following are valid ways of invoking the program:
prog -a -b foo -c data1 data2 data3
@@ -15489,30 +15421,30 @@ following are valid ways of invoking the program:
Notice that when the argument is grouped with its option, the rest of
the argument is considered to be the option's argument. In this
-example, `-acbfoo' indicates that all of the `-a', `-b', and `-c'
-options were supplied, and that `foo' is the argument to the `-b'
+example, '-acbfoo' indicates that all of the '-a', '-b', and '-c'
+options were supplied, and that 'foo' is the argument to the '-b'
option.
- `getopt()' provides four external variables that the programmer can
+ 'getopt()' provides four external variables that the programmer can
use:
-`optind'
- The index in the argument value array (`argv') where the first
+'optind'
+ The index in the argument value array ('argv') where the first
nonoption command-line argument can be found.
-`optarg'
+'optarg'
The string value of the argument to an option.
-`opterr'
- Usually `getopt()' prints an error message when it finds an invalid
- option. Setting `opterr' to zero disables this feature. (An
+'opterr'
+ Usually 'getopt()' prints an error message when it finds an invalid
+ option. Setting 'opterr' to zero disables this feature. (An
application might want to print its own error message.)
-`optopt'
+'optopt'
The letter representing the command-line option.
- The following C fragment shows how `getopt()' might process
-command-line arguments for `awk':
+ The following C fragment shows how 'getopt()' might process
+command-line arguments for 'awk':
int
main(int argc, char *argv[])
@@ -15543,15 +15475,15 @@ command-line arguments for `awk':
...
}
- As a side point, `gawk' actually uses the GNU `getopt_long()'
+ As a side point, 'gawk' actually uses the GNU 'getopt_long()'
function to process both normal and GNU-style long options (*note
Options::).
- The abstraction provided by `getopt()' is very useful and is quite
-handy in `awk' programs as well. Following is an `awk' version of
-`getopt()'. This function highlights one of the greatest weaknesses in
-`awk', which is that it is very poor at manipulating single characters.
-Repeated calls to `substr()' are necessary for accessing individual
+ The abstraction provided by 'getopt()' is very useful and is quite
+handy in 'awk' programs as well. Following is an 'awk' version of
+'getopt()'. This function highlights one of the greatest weaknesses in
+'awk', which is that it is very poor at manipulating single characters.
+Repeated calls to 'substr()' are necessary for accessing individual
characters (*note String Functions::).(1)
The discussion that follows walks through the code a bit at a time:
@@ -15572,15 +15504,15 @@ characters (*note String Functions::).(1)
# Private Data:
# _opti -- index in multiflag option, e.g., -abc
- The function starts out with comments presenting a list of the
-global variables it uses, what the return values are, what they mean,
-and any global variables that are "private" to this library function.
-Such documentation is essential for any program, and particularly for
-library functions.
+ The function starts out with comments presenting a list of the global
+variables it uses, what the return values are, what they mean, and any
+global variables that are "private" to this library function. Such
+documentation is essential for any program, and particularly for library
+functions.
- The `getopt()' function first checks that it was indeed called with
-a string of options (the `options' parameter). If `options' has a zero
-length, `getopt()' immediately returns -1:
+ The 'getopt()' function first checks that it was indeed called with a
+string of options (the 'options' parameter). If 'options' has a zero
+length, 'getopt()' immediately returns -1:
function getopt(argc, argv, options, thisopt, i)
{
@@ -15596,16 +15528,16 @@ length, `getopt()' immediately returns -1:
return -1
}
- The next thing to check for is the end of the options. A `--' ends
+ The next thing to check for is the end of the options. A '--' ends
the command-line options, as does any command-line argument that does
-not begin with a `-'. `Optind' is used to step through the array of
-command-line arguments; it retains its value across calls to
-`getopt()', because it is a global variable.
+not begin with a '-'. 'Optind' is used to step through the array of
+command-line arguments; it retains its value across calls to 'getopt()',
+because it is a global variable.
- The regular expression that is used, `/^-[^:[:space:]/', checks for
-a `-' followed by anything that is not whitespace and not a colon. If
-the current command-line argument does not match this pattern, it is
-not an option, and it ends option processing. Continuing on:
+ The regular expression that is used, '/^-[^:[:space:]/', checks for a
+'-' followed by anything that is not whitespace and not a colon. If the
+current command-line argument does not match this pattern, it is not an
+option, and it ends option processing. Continuing on:
if (_opti == 0)
_opti = 2
@@ -15623,31 +15555,31 @@ not an option, and it ends option processing.
Continuing on:
return "?"
}
- The `_opti' variable tracks the position in the current command-line
-argument (`argv[Optind]'). If multiple options are grouped together
-with one `-' (e.g., `-abx'), it is necessary to return them to the user
+ The '_opti' variable tracks the position in the current command-line
+argument ('argv[Optind]'). If multiple options are grouped together
+with one '-' (e.g., '-abx'), it is necessary to return them to the user
one at a time.
- If `_opti' is equal to zero, it is set to two, which is the index in
-the string of the next character to look at (we skip the `-', which is
-at position one). The variable `thisopt' holds the character, obtained
-with `substr()'. It is saved in `Optopt' for the main program to use.
+ If '_opti' is equal to zero, it is set to two, which is the index in
+the string of the next character to look at (we skip the '-', which is
+at position one). The variable 'thisopt' holds the character, obtained
+with 'substr()'. It is saved in 'Optopt' for the main program to use.
- If `thisopt' is not in the `options' string, then it is an invalid
-option. If `Opterr' is nonzero, `getopt()' prints an error message on
+ If 'thisopt' is not in the 'options' string, then it is an invalid
+option. If 'Opterr' is nonzero, 'getopt()' prints an error message on
the standard error that is similar to the message from the C version of
-`getopt()'.
+'getopt()'.
- Because the option is invalid, it is necessary to skip it and move
-on to the next option character. If `_opti' is greater than or equal
-to the length of the current command-line argument, it is necessary to
-move on to the next argument, so `Optind' is incremented and `_opti' is
-reset to zero. Otherwise, `Optind' is left alone and `_opti' is merely
+ Because the option is invalid, it is necessary to skip it and move on
+to the next option character. If '_opti' is greater than or equal to
+the length of the current command-line argument, it is necessary to move
+on to the next argument, so 'Optind' is incremented and '_opti' is reset
+to zero. Otherwise, 'Optind' is left alone and '_opti' is merely
incremented.
- In any case, because the option is invalid, `getopt()' returns `"?"'.
-The main program can examine `Optopt' if it needs to know what the
-invalid option letter actually is. Continuing on:
+ In any case, because the option is invalid, 'getopt()' returns '"?"'.
+The main program can examine 'Optopt' if it needs to know what the
+invalid option letter actually is. Continuing on:
if (substr(options, i + 1, 1) == ":") {
# get option argument
@@ -15660,12 +15592,12 @@ invalid option letter actually is. Continuing on:
Optarg = ""
If the option requires an argument, the option letter is followed by
-a colon in the `options' string. If there are remaining characters in
-the current command-line argument (`argv[Optind]'), then the rest of
-that string is assigned to `Optarg'. Otherwise, the next command-line
-argument is used (`-xFOO' versus `-x FOO'). In either case, `_opti' is
+a colon in the 'options' string. If there are remaining characters in
+the current command-line argument ('argv[Optind]'), then the rest of
+that string is assigned to 'Optarg'. Otherwise, the next command-line
+argument is used ('-xFOO' versus '-x FOO'). In either case, '_opti' is
reset to zero, because there are no more characters left to examine in
-the current command-line argument. Continuing:
+the current command-line argument. Continuing:
if (_opti == 0 || _opti >= length(argv[Optind])) {
Optind++
@@ -15675,18 +15607,18 @@ the current command-line argument. Continuing:
return thisopt
}
- Finally, if `_opti' is either zero or greater than the length of the
-current command-line argument, it means this element in `argv' is
-through being processed, so `Optind' is incremented to point to the
-next element in `argv'. If neither condition is true, then only
-`_opti' is incremented, so that the next option letter can be processed
-on the next call to `getopt()'.
+ Finally, if '_opti' is either zero or greater than the length of the
+current command-line argument, it means this element in 'argv' is
+through being processed, so 'Optind' is incremented to point to the next
+element in 'argv'. If neither condition is true, then only '_opti' is
+incremented, so that the next option letter can be processed on the next
+call to 'getopt()'.
- The `BEGIN' rule initializes both `Opterr' and `Optind' to one.
-`Opterr' is set to one, because the default behavior is for `getopt()'
-to print a diagnostic message upon seeing an invalid option. `Optind'
+ The 'BEGIN' rule initializes both 'Opterr' and 'Optind' to one.
+'Opterr' is set to one, because the default behavior is for 'getopt()'
+to print a diagnostic message upon seeing an invalid option. 'Optind'
is set to one, because there's no reason to look at the program name,
-which is in `ARGV[0]':
+which is in 'ARGV[0]':
BEGIN {
Opterr = 1 # default is to diagnose
@@ -15704,7 +15636,7 @@ which is in `ARGV[0]':
}
}
- The rest of the `BEGIN' rule is a simple test program. Here are the
+ The rest of the 'BEGIN' rule is a simple test program. Here are the
results of two sample runs of the test program:
$ awk -f getopt.awk -v _getopt_test=1 -- -a -cbARG bax -x
@@ -15717,32 +15649,32 @@ results of two sample runs of the test program:
$ awk -f getopt.awk -v _getopt_test=1 -- -a -x -- xyz abc
-| c = <a>, Optarg = <>
- error--> x -- invalid option
+ error-> x -- invalid option
-| c = <?>, Optarg = <>
-| non-option arguments:
-| ARGV[4] = <xyz>
-| ARGV[5] = <abc>
- In both runs, the first `--' terminates the arguments to `awk', so
-that it does not try to interpret the `-a', etc., as its own options.
+ In both runs, the first '--' terminates the arguments to 'awk', so
+that it does not try to interpret the '-a', etc., as its own options.
- NOTE: After `getopt()' is through, user-level code must clear out
- all the elements of `ARGV' from 1 to `Optind', so that `awk' does
+ NOTE: After 'getopt()' is through, user-level code must clear out
+ all the elements of 'ARGV' from 1 to 'Optind', so that 'awk' does
not try to process the command-line options as file names.
- Using `#!' with the `-E' option may help avoid conflicts between
-your program's options and `gawk''s options, as `-E' causes `gawk' to
-abandon processing of further options (*note Executable Scripts::, and
-*note Options::).
+ Using '#!' with the '-E' option may help avoid conflicts between your
+program's options and 'gawk''s options, as '-E' causes 'gawk' to abandon
+processing of further options (*note Executable Scripts::, and *note
+Options::).
Several of the sample programs presented in *note Sample Programs::,
-use `getopt()' to process their arguments.
+use 'getopt()' to process their arguments.
---------- Footnotes ----------
- (1) This function was written before `gawk' acquired the ability to
-split strings into single characters using `""' as the separator. We
-have left it alone, as using `substr()' is more portable.
+ (1) This function was written before 'gawk' acquired the ability to
+split strings into single characters using '""' as the separator. We
+have left it alone, as using 'substr()' is more portable.
File: gawk.info, Node: Passwd Functions, Next: Group Functions, Prev:
Getopt Function, Up: Library Functions
@@ -15750,33 +15682,33 @@ File: gawk.info, Node: Passwd Functions, Next:
Group Functions, Prev: Getopt
10.5 Reading the User Database
==============================
-The `PROCINFO' array (*note Built-in Variables::) provides access to
-the current user's real and effective user and group ID numbers, and,
-if available, the user's supplementary group set. However, because
-these are numbers, they do not provide very useful information to the
-average user. There needs to be some way to find the user information
-associated with the user and group ID numbers. This minor node
-presents a suite of functions for retrieving information from the user
-database. *Note Group Functions::, for a similar suite that retrieves
-information from the group database.
+The 'PROCINFO' array (*note Built-in Variables::) provides access to the
+current user's real and effective user and group ID numbers, and, if
+available, the user's supplementary group set. However, because these
+are numbers, they do not provide very useful information to the average
+user. There needs to be some way to find the user information
+associated with the user and group ID numbers. This minor node presents
+a suite of functions for retrieving information from the user database.
+*Note Group Functions::, for a similar suite that retrieves information
+from the group database.
The POSIX standard does not define the file where user information is
-kept. Instead, it provides the `<pwd.h>' header file and several C
+kept. Instead, it provides the '<pwd.h>' header file and several C
language subroutines for obtaining user information. The primary
-function is `getpwent()', for "get password entry." The "password"
-comes from the original user database file, `/etc/passwd', which stores
+function is 'getpwent()', for "get password entry." The "password"
+comes from the original user database file, '/etc/passwd', which stores
user information along with the encrypted passwords (hence the name).
- Although an `awk' program could simply read `/etc/passwd' directly,
-this file may not contain complete information about the system's set
-of users.(1) To be sure you are able to produce a readable and complete
-version of the user database, it is necessary to write a small C
-program that calls `getpwent()'. `getpwent()' is defined as returning
-a pointer to a `struct passwd'. Each time it is called, it returns the
-next entry in the database. When there are no more entries, it returns
-`NULL', the null pointer. When this happens, the C program should call
-`endpwent()' to close the database. Following is `pwcat', a C program
-that "cats" the password database:
+ Although an 'awk' program could simply read '/etc/passwd' directly,
+this file may not contain complete information about the system's set of
+users.(1) To be sure you are able to produce a readable and complete
+version of the user database, it is necessary to write a small C program
+that calls 'getpwent()'. 'getpwent()' is defined as returning a pointer
+to a 'struct passwd'. Each time it is called, it returns the next entry
+in the database. When there are no more entries, it returns 'NULL', the
+null pointer. When this happens, the C program should call 'endpwent()'
+to close the database. Following is 'pwcat', a C program that "cats"
+the password database:
/*
* pwcat.c
@@ -15801,8 +15733,8 @@ that "cats" the password database:
}
If you don't understand C, don't worry about it. The output from
-`pwcat' is the user database, in the traditional `/etc/passwd' format
-of colon-separated fields. The fields are:
+'pwcat' is the user database, in the traditional '/etc/passwd' format of
+colon-separated fields. The fields are:
Login name
The user's login name.
@@ -15813,26 +15745,26 @@ Encrypted password
User-ID
The user's numeric user ID number. (On some systems, it's a C
- `long', and not an `int'. Thus, we cast it to `long' for all
+ 'long', and not an 'int'. Thus, we cast it to 'long' for all
cases.)
Group-ID
- The user's numeric group ID number. (Similar comments about
- `long' versus `int' apply here.)
+ The user's numeric group ID number. (Similar comments about 'long'
+ versus 'int' apply here.)
Full name
- The user's full name, and perhaps other information associated
- with the user.
+ The user's full name, and perhaps other information associated with
+ the user.
Home directory
The user's login (or "home") directory (familiar to shell
- programmers as `$HOME').
+ programmers as '$HOME').
Login shell
The program that is run when the user logs in. This is usually a
shell, such as Bash.
- A few lines representative of `pwcat''s output are as follows:
+ A few lines representative of 'pwcat''s output are as follows:
$ pwcat
-| root:x:0:1:Operator:/:/bin/sh
@@ -15845,9 +15777,9 @@ Login shell
-| andy:abcca2:113:10:Andy Jacobs:/home/andy:/bin/sh
...
- With that introduction, following is a group of functions for
-getting user information. There are several functions here,
-corresponding to the C functions of the same names:
+ With that introduction, following is a group of functions for getting
+user information. There are several functions here, corresponding to
+the C functions of the same names:
# passwd.awk --- access password file information
@@ -15887,38 +15819,38 @@ corresponding to the C functions of the same names:
$0 = olddol0
}
- The `BEGIN' rule sets a private variable to the directory where
-`pwcat' is stored. Because it is used to help out an `awk' library
-routine, we have chosen to put it in `/usr/local/libexec/awk'; however,
+ The 'BEGIN' rule sets a private variable to the directory where
+'pwcat' is stored. Because it is used to help out an 'awk' library
+routine, we have chosen to put it in '/usr/local/libexec/awk'; however,
you might want it to be in a different directory on your system.
- The function `_pw_init()' fills three copies of the user information
+ The function '_pw_init()' fills three copies of the user information
into three associative arrays. The arrays are indexed by username
-(`_pw_byname'), by user ID number (`_pw_byuid'), and by order of
-occurrence (`_pw_bycount'). The variable `_pw_inited' is used for
-efficiency, as `_pw_init()' needs to be called only once.
-
- Because this function uses `getline' to read information from
-`pwcat', it first saves the values of `FS', `RS', and `$0'. It notes
-in the variable `using_fw' whether field splitting with `FIELDWIDTHS'
-is in effect or not. Doing so is necessary, as these functions could
-be called from anywhere within a user's program, and the user may have
-his or her own way of splitting records and fields. This makes it
-possible to restore the correct field-splitting mechanism later. The
-test can only be true for `gawk'. It is false if using `FS' or `FPAT',
-or on some other `awk' implementation.
-
- The code that checks for using `FPAT', using `using_fpat' and
-`PROCINFO["FS"]', is similar.
+('_pw_byname'), by user ID number ('_pw_byuid'), and by order of
+occurrence ('_pw_bycount'). The variable '_pw_inited' is used for
+efficiency, as '_pw_init()' needs to be called only once.
+
+ Because this function uses 'getline' to read information from
+'pwcat', it first saves the values of 'FS', 'RS', and '$0'. It notes in
+the variable 'using_fw' whether field splitting with 'FIELDWIDTHS' is in
+effect or not. Doing so is necessary, as these functions could be
+called from anywhere within a user's program, and the user may have his
+or her own way of splitting records and fields. This makes it possible
+to restore the correct field-splitting mechanism later. The test can
+only be true for 'gawk'. It is false if using 'FS' or 'FPAT', or on
+some other 'awk' implementation.
+
+ The code that checks for using 'FPAT', using 'using_fpat' and
+'PROCINFO["FS"]', is similar.
The main part of the function uses a loop to read database lines,
-split the lines into fields, and then store the lines into each array
-as necessary. When the loop is done, `_pw_init()' cleans up by closing
-the pipeline, setting `_pw_inited' to one, and restoring `FS' (and
-`FIELDWIDTHS' or `FPAT' if necessary), `RS', and `$0'. The use of
-`_pw_count' is explained shortly.
+split the lines into fields, and then store the lines into each array as
+necessary. When the loop is done, '_pw_init()' cleans up by closing the
+pipeline, setting '_pw_inited' to one, and restoring 'FS' (and
+'FIELDWIDTHS' or 'FPAT' if necessary), 'RS', and '$0'. The use of
+'_pw_count' is explained shortly.
- The `getpwnam()' function takes a username as a string argument. If
+ The 'getpwnam()' function takes a username as a string argument. If
that user is in the database, it returns the appropriate line.
Otherwise, it relies on the array reference to a nonexistent element to
create the element with the null string as its value:
@@ -15929,9 +15861,9 @@ create the element with the null string as its value:
return _pw_byname[name]
}
- Similarly, the `getpwuid()' function takes a user ID number
-argument. If that user number is in the database, it returns the
-appropriate line. Otherwise, it returns the null string:
+ Similarly, the 'getpwuid()' function takes a user ID number argument.
+If that user number is in the database, it returns the appropriate line.
+Otherwise, it returns the null string:
function getpwuid(uid)
{
@@ -15939,9 +15871,9 @@ appropriate line. Otherwise, it returns the null string:
return _pw_byuid[uid]
}
- The `getpwent()' function simply steps through the database, one
-entry at a time. It uses `_pw_count' to track its current position in
-the `_pw_bycount' array:
+ The 'getpwent()' function simply steps through the database, one
+entry at a time. It uses '_pw_count' to track its current position in
+the '_pw_bycount' array:
function getpwent()
{
@@ -15951,8 +15883,8 @@ the `_pw_bycount' array:
return ""
}
- The `endpwent()' function resets `_pw_count' to zero, so that
-subsequent calls to `getpwent()' start over again:
+ The 'endpwent()' function resets '_pw_count' to zero, so that
+subsequent calls to 'getpwent()' start over again:
function endpwent()
{
@@ -15960,24 +15892,24 @@ subsequent calls to `getpwent()' start over again:
}
A conscious design decision in this suite is that each subroutine
-calls `_pw_init()' to initialize the database arrays. The overhead of
-running a separate process to generate the user database, and the I/O
-to scan it, are only incurred if the user's main program actually calls
-one of these functions. If this library file is loaded along with a
-user's program, but none of the routines are ever called, then there is
-no extra runtime overhead. (The alternative is move the body of
-`_pw_init()' into a `BEGIN' rule, which always runs `pwcat'. This
+calls '_pw_init()' to initialize the database arrays. The overhead of
+running a separate process to generate the user database, and the I/O to
+scan it, are only incurred if the user's main program actually calls one
+of these functions. If this library file is loaded along with a user's
+program, but none of the routines are ever called, then there is no
+extra runtime overhead. (The alternative is move the body of
+'_pw_init()' into a 'BEGIN' rule, which always runs 'pwcat'. This
simplifies the code but runs an extra process that may never be needed.)
- In turn, calling `_pw_init()' is not too expensive, because the
-`_pw_inited' variable keeps the program from reading the data more than
+ In turn, calling '_pw_init()' is not too expensive, because the
+'_pw_inited' variable keeps the program from reading the data more than
once. If you are worried about squeezing every last cycle out of your
-`awk' program, the check of `_pw_inited' could be moved out of
-`_pw_init()' and duplicated in all the other functions. In practice,
-this is not necessary, as most `awk' programs are I/O-bound, and such a
+'awk' program, the check of '_pw_inited' could be moved out of
+'_pw_init()' and duplicated in all the other functions. In practice,
+this is not necessary, as most 'awk' programs are I/O-bound, and such a
change would clutter up the code.
- The `id' program in *note Id Program::, uses these functions.
+ The 'id' program in *note Id Program::, uses these functions.
---------- Footnotes ----------
@@ -15990,14 +15922,14 @@ File: gawk.info, Node: Group Functions, Next:
Walking Arrays, Prev: Passwd Fu
10.6 Reading the Group Database
===============================
-Much of the discussion presented in *note Passwd Functions::, applies
-to the group database as well. Although there has traditionally been a
-well-known file (`/etc/group') in a well-known format, the POSIX
-standard only provides a set of C library routines (`<grp.h>' and
-`getgrent()') for accessing the information. Even though this file may
+Much of the discussion presented in *note Passwd Functions::, applies to
+the group database as well. Although there has traditionally been a
+well-known file ('/etc/group') in a well-known format, the POSIX
+standard only provides a set of C library routines ('<grp.h>' and
+'getgrent()') for accessing the information. Even though this file may
exist, it may not have complete information. Therefore, as with the
user database, it is necessary to have a small C program that generates
-the group database as its output. `grcat', a C program that "cats" the
+the group database as its output. 'grcat', a C program that "cats" the
group database, is as follows:
/*
@@ -16035,24 +15967,24 @@ Group Name
The group's name.
Group Password
- The group's encrypted password. In practice, this field is never
- used; it is usually empty or set to `*'.
+ The group's encrypted password. In practice, this field is never
+ used; it is usually empty or set to '*'.
Group ID Number
The group's numeric group ID number; the association of name to
number must be unique within the file. (On some systems it's a C
- `long', and not an `int'. Thus, we cast it to `long' for all
+ 'long', and not an 'int'. Thus, we cast it to 'long' for all
cases.)
Group Member List
A comma-separated list of usernames. These users are members of
the group. Modern Unix systems allow users to be members of
- several groups simultaneously. If your system does, then there
- are elements `"group1"' through `"groupN"' in `PROCINFO' for those
- group ID numbers. (Note that `PROCINFO' is a `gawk' extension;
+ several groups simultaneously. If your system does, then there are
+ elements '"group1"' through '"groupN"' in 'PROCINFO' for those
+ group ID numbers. (Note that 'PROCINFO' is a 'gawk' extension;
*note Built-in Variables::.)
- Here is what running `grcat' might produce:
+ Here is what running 'grcat' might produce:
$ grcat
-| wheel:*:0:arnold
@@ -16120,23 +16052,23 @@ the same names:
$0 = olddol0
}
- The `BEGIN' rule sets a private variable to the directory where
-`grcat' is stored. Because it is used to help out an `awk' library
-routine, we have chosen to put it in `/usr/local/libexec/awk'. You
+ The 'BEGIN' rule sets a private variable to the directory where
+'grcat' is stored. Because it is used to help out an 'awk' library
+routine, we have chosen to put it in '/usr/local/libexec/awk'. You
might want it to be in a different directory on your system.
These routines follow the same general outline as the user database
-routines (*note Passwd Functions::). The `_gr_inited' variable is used
+routines (*note Passwd Functions::). The '_gr_inited' variable is used
to ensure that the database is scanned no more than once. The
-`_gr_init()' function first saves `FS', `RS', and `$0', and then sets
-`FS' and `RS' to the correct values for scanning the group information.
-It also takes care to note whether `FIELDWIDTHS' or `FPAT' is being
+'_gr_init()' function first saves 'FS', 'RS', and '$0', and then sets
+'FS' and 'RS' to the correct values for scanning the group information.
+It also takes care to note whether 'FIELDWIDTHS' or 'FPAT' is being
used, and to restore the appropriate field-splitting mechanism.
The group information is stored in several associative arrays. The
-arrays are indexed by group name (`_gr_byname'), by group ID number
-(`_gr_bygid'), and by position in the database (`_gr_bycount'). There
-is an additional array indexed by username (`_gr_groupsbyuser'), which
+arrays are indexed by group name ('_gr_byname'), by group ID number
+('_gr_bygid'), and by position in the database ('_gr_bycount'). There
+is an additional array indexed by username ('_gr_groupsbyuser'), which
is a space-separated list of groups to which each user belongs.
Unlike in the user database, it is possible to have multiple records
@@ -16147,16 +16079,15 @@ following:
tvpeople:*:101:johnny,jay,arsenio
tvpeople:*:101:david,conan,tom,joan
- For this reason, `_gr_init()' looks to see if a group name or group
-ID number is already seen. If so, the usernames are simply
-concatenated onto the previous list of users.(1)
+ For this reason, '_gr_init()' looks to see if a group name or group
+ID number is already seen. If so, the usernames are simply concatenated
+onto the previous list of users.(1)
- Finally, `_gr_init()' closes the pipeline to `grcat', restores `FS'
-(and `FIELDWIDTHS' or `FPAT', if necessary), `RS', and `$0',
-initializes `_gr_count' to zero (it is used later), and makes
-`_gr_inited' nonzero.
+ Finally, '_gr_init()' closes the pipeline to 'grcat', restores 'FS'
+(and 'FIELDWIDTHS' or 'FPAT', if necessary), 'RS', and '$0', initializes
+'_gr_count' to zero (it is used later), and makes '_gr_inited' nonzero.
- The `getgrnam()' function takes a group name as its argument, and if
+ The 'getgrnam()' function takes a group name as its argument, and if
that group exists, it is returned. Otherwise, it relies on the array
reference to a nonexistent element to create the element with the null
string as its value:
@@ -16167,7 +16098,7 @@ string as its value:
return _gr_byname[group]
}
- The `getgrgid()' function is similar; it takes a numeric group ID and
+ The 'getgrgid()' function is similar; it takes a numeric group ID and
looks up the information associated with that group ID:
function getgrgid(gid)
@@ -16176,7 +16107,7 @@ looks up the information associated with that group ID:
return _gr_bygid[gid]
}
- The `getgruser()' function does not have a C counterpart. It takes a
+ The 'getgruser()' function does not have a C counterpart. It takes a
username and returns the list of groups that have the user as a member:
function getgruser(user)
@@ -16185,8 +16116,8 @@ username and returns the list of groups that have the
user as a member:
return _gr_groupsbyuser[user]
}
- The `getgrent()' function steps through the database one entry at a
-time. It uses `_gr_count' to track its position in the list:
+ The 'getgrent()' function steps through the database one entry at a
+time. It uses '_gr_count' to track its position in the list:
function getgrent()
{
@@ -16196,30 +16127,30 @@ time. It uses `_gr_count' to track its position in
the list:
return ""
}
- The `endgrent()' function resets `_gr_count' to zero so that
-`getgrent()' can start over again:
+ The 'endgrent()' function resets '_gr_count' to zero so that
+'getgrent()' can start over again:
function endgrent()
{
_gr_count = 0
}
- As with the user database routines, each function calls `_gr_init()'
+ As with the user database routines, each function calls '_gr_init()'
to initialize the arrays. Doing so only incurs the extra overhead of
-running `grcat' if these functions are used (as opposed to moving the
-body of `_gr_init()' into a `BEGIN' rule).
+running 'grcat' if these functions are used (as opposed to moving the
+body of '_gr_init()' into a 'BEGIN' rule).
Most of the work is in scanning the database and building the various
associative arrays. The functions that the user calls are themselves
-very simple, relying on `awk''s associative arrays to do work.
+very simple, relying on 'awk''s associative arrays to do work.
- The `id' program in *note Id Program::, uses these functions.
+ The 'id' program in *note Id Program::, uses these functions.
---------- Footnotes ----------
(1) There is a subtle problem with the code just presented. Suppose
-that the first time there were no names. This code adds the names with
-a leading comma. It also doesn't check that there is a `$4'.
+that the first time there were no names. This code adds the names with
+a leading comma. It also doesn't check that there is a '$4'.
File: gawk.info, Node: Walking Arrays, Next: Library Functions Summary,
Prev: Group Functions, Up: Library Functions
@@ -16227,11 +16158,11 @@ File: gawk.info, Node: Walking Arrays, Next:
Library Functions Summary, Prev:
10.7 Traversing Arrays of Arrays
================================
-*note Arrays of Arrays::, described how `gawk' provides arrays of
+*note Arrays of Arrays::, described how 'gawk' provides arrays of
arrays. In particular, any element of an array may be either a scalar
-or another array. The `isarray()' function (*note Type Functions::)
+or another array. The 'isarray()' function (*note Type Functions::)
lets you distinguish an array from a scalar. The following function,
-`walk_array()', recursively traverses an array, printing the element
+'walk_array()', recursively traverses an array, printing the element
indices and values. You call it with the array and a string
representing the name of the array:
@@ -16245,7 +16176,7 @@ representing the name of the array:
}
}
-It works by looping over each element of the array. If any given
+It works by looping over each element of the array. If any given
element is itself an array, the function calls itself recursively,
passing the subarray and a new string representing the current index.
Otherwise, the function simply prints the element's name, index, and
@@ -16273,8 +16204,8 @@ value. Here is a main program to demonstrate:
-| a[4][2] = 42
The function just presented simply prints the name and value of each
-scalar array element. However, it is easy to generalize it, by passing
-in the name of a function to call when walking an array. The modified
+scalar array element. However, it is easy to generalize it, by passing
+in the name of a function to call when walking an array. The modified
function looks like this:
function process_array(arr, name, process, do_arrays, i, new_name)
@@ -16292,16 +16223,16 @@ function looks like this:
The arguments are as follows:
-`arr'
+'arr'
The array.
-`name'
+'name'
The name of the array (a string).
-`process'
+'process'
The name of the function to call.
-`do_arrays'
+'do_arrays'
If this is true, the function can handle elements that are
subarrays.
@@ -16309,7 +16240,7 @@ function looks like this:
further.
When run with the following scaffolding, the function produces the
-same results as does the earlier version of `walk_array()':
+same results as does the earlier version of 'walk_array()':
BEGIN {
a[1] = 1
@@ -16343,67 +16274,65 @@ File: gawk.info, Node: Library Functions Summary,
Next: Library Exercises, Pr
* The functions presented here fit into the following categories:
- General problems
+ General problems
Number-to-string conversion, testing assertions, rounding,
random number generation, converting characters to numbers,
joining strings, getting easily usable time-of-day
information, and reading a whole file in one shot
- Managing data files
+ Managing data files
Noting data file boundaries, rereading the current file,
checking for readable files, checking for zero-length files,
and treating assignments as file names
- Processing command-line options
- An `awk' version of the standard C `getopt()' function
+ Processing command-line options
+ An 'awk' version of the standard C 'getopt()' function
- Reading the user and group databases
+ Reading the user and group databases
Two sets of routines that parallel the C library versions
- Traversing arrays of arrays
+ Traversing arrays of arrays
Two functions that traverse an array of arrays to any depth
-
File: gawk.info, Node: Library Exercises, Prev: Library Functions Summary,
Up: Library Functions
10.9 Exercises
==============
- 1. In *note Empty Files::, we presented the `zerofile.awk' program,
- which made use of `gawk''s `ARGIND' variable. Can this problem be
- solved without relying on `ARGIND'? If so, how?
+ 1. In *note Empty Files::, we presented the 'zerofile.awk' program,
+ which made use of 'gawk''s 'ARGIND' variable. Can this problem be
+ solved without relying on 'ARGIND'? If so, how?
2. As a related challenge, revise that code to handle the case where
- an intervening value in `ARGV' is a variable assignment.
+ an intervening value in 'ARGV' is a variable assignment.
3. *note Walking Arrays::, presented a function that walked a
multidimensional array to print it out. However, walking an array
and processing each element is a general-purpose operation.
- Generalize the `walk_array()' function by adding an additional
- parameter named `process'.
+ Generalize the 'walk_array()' function by adding an additional
+ parameter named 'process'.
Then, inside the loop, instead of printing the array element's
index and value, use the indirect function call syntax (*note
- Indirect Calls::) on `process', passing it the index and the value.
+ Indirect Calls::) on 'process', passing it the index and the value.
- When calling `walk_array()', you would pass the name of a
+ When calling 'walk_array()', you would pass the name of a
user-defined function that expects to receive an index and a value,
and then processes the element.
Test your new version by printing the array; you should end up with
output identical to that of the original version.
-
File: gawk.info, Node: Sample Programs, Next: Advanced Features, Prev:
Library Functions, Up: Top
-11 Practical `awk' Programs
+11 Practical 'awk' Programs
***************************
*note Library Functions::, presents the idea that reading programs in a
language contributes to learning that language. This major node
-continues that theme, presenting a potpourri of `awk' programs for your
+continues that theme, presenting a potpourri of 'awk' programs for your
reading enjoyment.
Many of these programs use library functions presented in *note
@@ -16413,7 +16342,7 @@ Library Functions::.
* Running Examples:: How to run these examples.
* Clones:: Clones of common utilities.
-* Miscellaneous Programs:: Some interesting `awk' programs.
+* Miscellaneous Programs:: Some interesting 'awk' programs.
* Programs Summary:: Summary of programs.
* Programs Exercises:: Exercises.
@@ -16427,16 +16356,16 @@ To run a given program, you would typically do
something like this:
awk -f PROGRAM -- OPTIONS FILES
-Here, PROGRAM is the name of the `awk' program (such as `cut.awk'),
+Here, PROGRAM is the name of the 'awk' program (such as 'cut.awk'),
OPTIONS are any command-line options for the program that start with a
-`-', and FILES are the actual data files.
+'-', and FILES are the actual data files.
- If your system supports the `#!' executable interpreter mechanism
+ If your system supports the '#!' executable interpreter mechanism
(*note Executable Scripts::), you can instead run your program directly:
cut.awk -c1-8 myfiles > results
- If your `awk' is not `gawk', you may instead need to use this:
+ If your 'awk' is not 'gawk', you may instead need to use this:
cut.awk -- -c1-8 myfiles > results
@@ -16447,28 +16376,28 @@ File: gawk.info, Node: Clones, Next: Miscellaneous
Programs, Prev: Running Ex
==========================================
This minor node presents a number of POSIX utilities implemented in
-`awk'. Reinventing these programs in `awk' is often enjoyable, because
+'awk'. Reinventing these programs in 'awk' is often enjoyable, because
the algorithms can be very clearly expressed, and the code is usually
-very concise and simple. This is true because `awk' does so much for
+very concise and simple. This is true because 'awk' does so much for
you.
It should be noted that these programs are not necessarily intended
to replace the installed versions on your system. Nor may all of these
programs be fully compliant with the most recent POSIX standard. This
-is not a problem; their purpose is to illustrate `awk' language
+is not a problem; their purpose is to illustrate 'awk' language
programming for "real-world" tasks.
The programs are presented in alphabetical order.
* Menu:
-* Cut Program:: The `cut' utility.
-* Egrep Program:: The `egrep' utility.
-* Id Program:: The `id' utility.
-* Split Program:: The `split' utility.
-* Tee Program:: The `tee' utility.
-* Uniq Program:: The `uniq' utility.
-* Wc Program:: The `wc' utility.
+* Cut Program:: The 'cut' utility.
+* Egrep Program:: The 'egrep' utility.
+* Id Program:: The 'id' utility.
+* Split Program:: The 'split' utility.
+* Tee Program:: The 'tee' utility.
+* Uniq Program:: The 'uniq' utility.
+* Wc Program:: The 'wc' utility.
File: gawk.info, Node: Cut Program, Next: Egrep Program, Up: Clones
@@ -16476,43 +16405,43 @@ File: gawk.info, Node: Cut Program, Next: Egrep
Program, Up: Clones
11.2.1 Cutting Out Fields and Columns
-------------------------------------
-The `cut' utility selects, or "cuts," characters or fields from its
+The 'cut' utility selects, or "cuts," characters or fields from its
standard input and sends them to its standard output. Fields are
separated by TABs by default, but you may supply a command-line option
to change the field "delimiter" (i.e., the field-separator character).
-`cut''s definition of fields is less general than `awk''s.
+'cut''s definition of fields is less general than 'awk''s.
- A common use of `cut' might be to pull out just the login names of
-logged-on users from the output of `who'. For example, the following
+ A common use of 'cut' might be to pull out just the login names of
+logged-on users from the output of 'who'. For example, the following
pipeline generates a sorted, unique list of the logged-on users:
who | cut -c1-8 | sort | uniq
- The options for `cut' are:
+ The options for 'cut' are:
-`-c LIST'
+'-c LIST'
Use LIST as the list of characters to cut out. Items within the
list may be separated by commas, and ranges of characters can be
- separated with dashes. The list `1-8,15,22-35' specifies
+ separated with dashes. The list '1-8,15,22-35' specifies
characters 1 through 8, 15, and 22 through 35.
-`-f LIST'
+'-f LIST'
Use LIST as the list of fields to cut out.
-`-d DELIM'
+'-d DELIM'
Use DELIM as the field-separator character instead of the TAB
character.
-`-s'
+'-s'
Suppress printing of lines that do not contain the field delimiter.
- The `awk' implementation of `cut' uses the `getopt()' library
-function (*note Getopt Function::) and the `join()' library function
+ The 'awk' implementation of 'cut' uses the 'getopt()' library
+function (*note Getopt Function::) and the 'join()' library function
(*note Join Function::).
The program begins with a comment describing the options, the library
-functions needed, and a `usage()' function that prints out a usage
-message and exits. `usage()' is called if invalid arguments are
+functions needed, and a 'usage()' function that prints out a usage
+message and exits. 'usage()' is called if invalid arguments are
supplied:
# cut.awk --- implement cut in awk
@@ -16533,12 +16462,12 @@ supplied:
exit 1
}
- Next comes a `BEGIN' rule that parses the command-line options. It
-sets `FS' to a single TAB character, because that is `cut''s default
-field separator. The rule then sets the output field separator to be the
-same as the input field separator. A loop using `getopt()' steps
+ Next comes a 'BEGIN' rule that parses the command-line options. It
+sets 'FS' to a single TAB character, because that is 'cut''s default
+field separator. The rule then sets the output field separator to be
+the same as the input field separator. A loop using 'getopt()' steps
through the command-line options. Exactly one of the variables
-`by_fields' or `by_chars' is set to true, to indicate that processing
+'by_fields' or 'by_chars' is set to true, to indicate that processing
should be done by fields or by characters, respectively. When cutting
by characters, the output field separator is set to the null string:
@@ -16574,18 +16503,18 @@ by characters, the output field separator is set to
the null string:
ARGV[i] = ""
The code must take special care when the field delimiter is a space.
-Using a single space (`" "') for the value of `FS' is incorrect--`awk'
-would separate fields with runs of spaces, TABs, and/or newlines, and
-we want them to be separated with individual spaces. Also remember
-that after `getopt()' is through (as described in *note Getopt
-Function::), we have to clear out all the elements of `ARGV' from 1 to
-`Optind', so that `awk' does not try to process the command-line options
-as file names.
+Using a single space ('" "') for the value of 'FS' is incorrect--'awk'
+would separate fields with runs of spaces, TABs, and/or newlines, and we
+want them to be separated with individual spaces. Also remember that
+after 'getopt()' is through (as described in *note Getopt Function::),
+we have to clear out all the elements of 'ARGV' from 1 to 'Optind', so
+that 'awk' does not try to process the command-line options as file
+names.
After dealing with the command-line options, the program verifies
-that the options make sense. Only one or the other of `-c' and `-f'
+that the options make sense. Only one or the other of '-c' and '-f'
should be used, and both require a field list. Then the program calls
-either `set_fieldlist()' or `set_charlist()' to pull apart the list of
+either 'set_fieldlist()' or 'set_charlist()' to pull apart the list of
fields or characters:
if (by_fields && by_chars)
@@ -16605,13 +16534,13 @@ fields or characters:
set_charlist()
}
- `set_fieldlist()' splits the field list apart at the commas into an
+ 'set_fieldlist()' splits the field list apart at the commas into an
array. Then, for each element of the array, it looks to see if the
element is actually a range, and if so, splits it apart. The function
checks the range to make sure that the first number is smaller than the
-second. Each number in the list is added to the `flist' array, which
-simply lists the fields that will be printed. Normal field splitting
-is used. The program lets `awk' handle the job of doing the field
+second. Each number in the list is added to the 'flist' array, which
+simply lists the fields that will be printed. Normal field splitting is
+used. The program lets 'awk' handle the job of doing the field
splitting:
function set_fieldlist( n, m, i, j, k, f, g)
@@ -16634,20 +16563,20 @@ splitting:
nfields = j - 1
}
- The `set_charlist()' function is more complicated than
-`set_fieldlist()'. The idea here is to use `gawk''s `FIELDWIDTHS'
+ The 'set_charlist()' function is more complicated than
+'set_fieldlist()'. The idea here is to use 'gawk''s 'FIELDWIDTHS'
variable (*note Constant Size::), which describes constant-width input.
When using a character list, that is exactly what we have.
- Setting up `FIELDWIDTHS' is more complicated than simply listing the
+ Setting up 'FIELDWIDTHS' is more complicated than simply listing the
fields that need to be printed. We have to keep track of the fields to
print and also the intervening characters that have to be skipped. For
example, suppose you wanted characters 1 through 8, 15, and 22 through
-35. You would use `-c 1-8,15,22-35'. The necessary value for
-`FIELDWIDTHS' is `"8 6 1 6 14"'. This yields five fields, and the
-fields to print are `$1', `$3', and `$5'. The intermediate fields are
-"filler", which is stuff in between the desired data. `flist' lists
-the fields to print, and `t' tracks the complete field list, including
+35. You would use '-c 1-8,15,22-35'. The necessary value for
+'FIELDWIDTHS' is '"8 6 1 6 14"'. This yields five fields, and the
+fields to print are '$1', '$3', and '$5'. The intermediate fields are
+"filler", which is stuff in between the desired data. 'flist' lists the
+fields to print, and 't' tracks the complete field list, including
filler fields:
function set_charlist( field, i, j, f, g, n, m, t,
@@ -16690,15 +16619,15 @@ filler fields:
nfields = j - 1
}
- Next is the rule that processes the data. If the `-s' option is
-given, then `suppress' is true. The first `if' statement makes sure
-that the input record does have the field separator. If `cut' is
-processing fields, `suppress' is true, and the field separator
-character is not in the record, then the record is skipped.
+ Next is the rule that processes the data. If the '-s' option is
+given, then 'suppress' is true. The first 'if' statement makes sure
+that the input record does have the field separator. If 'cut' is
+processing fields, 'suppress' is true, and the field separator character
+is not in the record, then the record is skipped.
- If the record is valid, then `gawk' has split the data into fields,
-either using the character in `FS' or using fixed-length fields and
-`FIELDWIDTHS'. The loop goes through the list of fields that should be
+ If the record is valid, then 'gawk' has split the data into fields,
+either using the character in 'FS' or using fixed-length fields and
+'FIELDWIDTHS'. The loop goes through the list of fields that should be
printed. The corresponding field is printed if it contains data. If
the next field also has data, then the separator character is written
out between the fields:
@@ -16717,10 +16646,10 @@ out between the fields:
print ""
}
- This version of `cut' relies on `gawk''s `FIELDWIDTHS' variable to
-do the character-based cutting. It is possible in other `awk'
-implementations to use `substr()' (*note String Functions::), but it is
-also extremely painful. The `FIELDWIDTHS' variable supplies an elegant
+ This version of 'cut' relies on 'gawk''s 'FIELDWIDTHS' variable to do
+the character-based cutting. It is possible in other 'awk'
+implementations to use 'substr()' (*note String Functions::), but it is
+also extremely painful. The 'FIELDWIDTHS' variable supplies an elegant
solution to the problem of picking the input line apart by characters.
@@ -16729,53 +16658,52 @@ File: gawk.info, Node: Egrep Program, Next: Id
Program, Prev: Cut Program, U
11.2.2 Searching for Regular Expressions in Files
-------------------------------------------------
-The `egrep' utility searches files for patterns. It uses regular
-expressions that are almost identical to those available in `awk'
-(*note Regexp::). You invoke it as follows:
+The 'egrep' utility searches files for patterns. It uses regular
+expressions that are almost identical to those available in 'awk' (*note
+Regexp::). You invoke it as follows:
- `egrep' [OPTIONS] `'PATTERN'' FILES ...
+ 'egrep' [OPTIONS] ''PATTERN'' FILES ...
The PATTERN is a regular expression. In typical usage, the regular
expression is quoted to prevent the shell from expanding any of the
-special characters as file name wildcards. Normally, `egrep' prints
-the lines that matched. If multiple file names are provided on the
-command line, each output line is preceded by the name of the file and
-a colon.
+special characters as file name wildcards. Normally, 'egrep' prints the
+lines that matched. If multiple file names are provided on the command
+line, each output line is preceded by the name of the file and a colon.
- The options to `egrep' are as follows:
+ The options to 'egrep' are as follows:
-`-c'
- Print out a count of the lines that matched the pattern, instead
- of the lines themselves.
+'-c'
+ Print out a count of the lines that matched the pattern, instead of
+ the lines themselves.
-`-s'
+'-s'
Be silent. No output is produced and the exit value indicates
whether the pattern was matched.
-`-v'
- Invert the sense of the test. `egrep' prints the lines that do
+'-v'
+ Invert the sense of the test. 'egrep' prints the lines that do
_not_ match the pattern and exits successfully if the pattern is
not matched.
-`-i'
+'-i'
Ignore case distinctions in both the pattern and the input data.
-`-l'
+'-l'
Only print (list) the names of the files that matched, not the
lines that matched.
-`-e PATTERN'
- Use PATTERN as the regexp to match. The purpose of the `-e'
- option is to allow patterns that start with a `-'.
+'-e PATTERN'
+ Use PATTERN as the regexp to match. The purpose of the '-e' option
+ is to allow patterns that start with a '-'.
- This version uses the `getopt()' library function (*note Getopt
+ This version uses the 'getopt()' library function (*note Getopt
Function::) and the file transition library program (*note Filetrans
Function::).
- The program begins with a descriptive comment and then a `BEGIN' rule
-that processes the command-line arguments with `getopt()'. The `-i'
-(ignore case) option is particularly easy with `gawk'; we just use the
-`IGNORECASE' predefined variable (*note Built-in Variables::):
+ The program begins with a descriptive comment and then a 'BEGIN' rule
+that processes the command-line arguments with 'getopt()'. The '-i'
+(ignore case) option is particularly easy with 'gawk'; we just use the
+'IGNORECASE' predefined variable (*note Built-in Variables::):
# egrep.awk --- simulate egrep in awk
#
@@ -16807,10 +16735,10 @@ that processes the command-line arguments with
`getopt()'. The `-i'
usage()
}
- Next comes the code that handles the `egrep'-specific behavior. If no
-pattern is supplied with `-e', the first nonoption on the command line
-is used. The `awk' command-line arguments up to `ARGV[Optind]' are
-cleared, so that `awk' won't try to process them as files. If no files
+ Next comes the code that handles the 'egrep'-specific behavior. If
+no pattern is supplied with '-e', the first nonoption on the command
+line is used. The 'awk' command-line arguments up to 'ARGV[Optind]' are
+cleared, so that 'awk' won't try to process them as files. If no files
are specified, the standard input is used, and if multiple files are
specified, we make sure to note this so that the file names can precede
the matched lines in the output:
@@ -16831,24 +16759,24 @@ the matched lines in the output:
}
The last two lines are commented out, as they are not needed in
-`gawk'. They should be uncommented if you have to use another version
-of `awk'.
+'gawk'. They should be uncommented if you have to use another version
+of 'awk'.
The next set of lines should be uncommented if you are not using
-`gawk'. This rule translates all the characters in the input line into
-lowercase if the `-i' option is specified.(1) The rule is commented out
-as it is not necessary with `gawk':
+'gawk'. This rule translates all the characters in the input line into
+lowercase if the '-i' option is specified.(1) The rule is commented out
+as it is not necessary with 'gawk':
#{
# if (IGNORECASE)
# $0 = tolower($0)
#}
- The `beginfile()' function is called by the rule in `ftrans.awk'
-when each new file is processed. In this case, it is very simple; all
-it does is initialize a variable `fcount' to zero. `fcount' tracks how
+ The 'beginfile()' function is called by the rule in 'ftrans.awk' when
+each new file is processed. In this case, it is very simple; all it
+does is initialize a variable 'fcount' to zero. 'fcount' tracks how
many lines in the current file matched the pattern. Naming the
-parameter `junk' shows we know that `beginfile()' is called with a
+parameter 'junk' shows we know that 'beginfile()' is called with a
parameter, but that we're not interested in its value:
function beginfile(junk)
@@ -16856,13 +16784,13 @@ parameter, but that we're not interested in its value:
fcount = 0
}
- The `endfile()' function is called after each file has been
+ The 'endfile()' function is called after each file has been
processed. It affects the output only when the user wants a count of
-the number of lines that matched. `no_print' is true only if the exit
-status is desired. `count_only' is true if line counts are desired.
-`egrep' therefore only prints line counts if printing and counting are
+the number of lines that matched. 'no_print' is true only if the exit
+status is desired. 'count_only' is true if line counts are desired.
+'egrep' therefore only prints line counts if printing and counting are
enabled. The output format must be adjusted depending upon the number
-of files to process. Finally, `fcount' is added to `total', so that we
+of files to process. Finally, 'fcount' is added to 'total', so that we
know the total number of lines that matched the pattern:
function endfile(file)
@@ -16877,25 +16805,25 @@ know the total number of lines that matched the
pattern:
total += fcount
}
- The `BEGINFILE' and `ENDFILE' special patterns (*note
+ The 'BEGINFILE' and 'ENDFILE' special patterns (*note
BEGINFILE/ENDFILE::) could be used, but then the program would be
-`gawk'-specific. Additionally, this example was written before `gawk'
-acquired `BEGINFILE' and `ENDFILE'.
+'gawk'-specific. Additionally, this example was written before 'gawk'
+acquired 'BEGINFILE' and 'ENDFILE'.
- The following rule does most of the work of matching lines. The
-variable `matches' is true if the line matched the pattern. If the user
-wants lines that did not match, the sense of `matches' is inverted
-using the `!' operator. `fcount' is incremented with the value of
-`matches', which is either one or zero, depending upon a successful or
-unsuccessful match. If the line does not match, the `next' statement
-just moves on to the next record.
+ The following rule does most of the work of matching lines. The
+variable 'matches' is true if the line matched the pattern. If the user
+wants lines that did not match, the sense of 'matches' is inverted using
+the '!' operator. 'fcount' is incremented with the value of 'matches',
+which is either one or zero, depending upon a successful or unsuccessful
+match. If the line does not match, the 'next' statement just moves on
+to the next record.
A number of additional tests are made, but they are only done if we
are not counting lines. First, if the user only wants the exit status
-(`no_print' is true), then it is enough to know that _one_ line in this
-file matched, and we can skip on to the next file with `nextfile'.
+('no_print' is true), then it is enough to know that _one_ line in this
+file matched, and we can skip on to the next file with 'nextfile'.
Similarly, if we are only printing file names, we can print the file
-name, and then skip to the next file with `nextfile'. Finally, each
+name, and then skip to the next file with 'nextfile'. Finally, each
line is printed, with a leading file name and colon if necessary:
{
@@ -16924,14 +16852,14 @@ line is printed, with a leading file name and colon
if necessary:
}
}
- The `END' rule takes care of producing the correct exit status. If
+ The 'END' rule takes care of producing the correct exit status. If
there are no matches, the exit status is one; otherwise, it is zero:
END {
exit (total == 0)
}
- The `usage()' function prints a usage message in case of invalid
+ The 'usage()' function prints a usage message in case of invalid
options, and then exits:
function usage()
@@ -16952,30 +16880,30 @@ File: gawk.info, Node: Id Program, Next: Split
Program, Prev: Egrep Program,
11.2.3 Printing Out User Information
------------------------------------
-The `id' utility lists a user's real and effective user ID numbers,
-real and effective group ID numbers, and the user's group set, if any.
-`id' only prints the effective user ID and group ID if they are
-different from the real ones. If possible, `id' also supplies the
-corresponding user and group names. The output might look like this:
+The 'id' utility lists a user's real and effective user ID numbers, real
+and effective group ID numbers, and the user's group set, if any. 'id'
+only prints the effective user ID and group ID if they are different
+from the real ones. If possible, 'id' also supplies the corresponding
+user and group names. The output might look like this:
$ id
-| uid=1000(arnold) gid=1000(arnold)
groups=1000(arnold),4(adm),7(lp),27(sudo)
- This information is part of what is provided by `gawk''s `PROCINFO'
-array (*note Built-in Variables::). However, the `id' utility provides
+ This information is part of what is provided by 'gawk''s 'PROCINFO'
+array (*note Built-in Variables::). However, the 'id' utility provides
a more palatable output than just individual numbers.
- Here is a simple version of `id' written in `awk'. It uses the user
+ Here is a simple version of 'id' written in 'awk'. It uses the user
database library functions (*note Passwd Functions::) and the group
database library functions (*note Group Functions::) from *note Library
Functions::.
The program is fairly straightforward. All the work is done in the
-`BEGIN' rule. The user and group ID numbers are obtained from
-`PROCINFO'. The code is repetitive. The entry in the user database
-for the real user ID number is split into parts at the `:'. The name is
-the first field. Similar code is used for the effective user ID number
-and the group numbers:
+'BEGIN' rule. The user and group ID numbers are obtained from
+'PROCINFO'. The code is repetitive. The entry in the user database for
+the real user ID number is split into parts at the ':'. The name is the
+first field. Similar code is used for the effective user ID number and
+the group numbers:
# id.awk --- implement id in awk
#
@@ -17032,22 +16960,22 @@ and the group numbers:
}
}
- The test in the `for' loop is worth noting. Any supplementary
-groups in the `PROCINFO' array have the indices `"group1"' through
-`"groupN"' for some N (i.e., the total number of supplementary groups).
-However, we don't know in advance how many of these groups there are.
+ The test in the 'for' loop is worth noting. Any supplementary groups
+in the 'PROCINFO' array have the indices '"group1"' through '"groupN"'
+for some N (i.e., the total number of supplementary groups). However,
+we don't know in advance how many of these groups there are.
This loop works by starting at one, concatenating the value with
-`"group"', and then using `in' to see if that value is in the array
-(*note Reference to Elements::). Eventually, `i' is incremented past
+'"group"', and then using 'in' to see if that value is in the array
+(*note Reference to Elements::). Eventually, 'i' is incremented past
the last group in the array and the loop exits.
- The loop is also correct if there are _no_ supplementary groups;
-then the condition is false the first time it's tested, and the loop
-body never executes.
+ The loop is also correct if there are _no_ supplementary groups; then
+the condition is false the first time it's tested, and the loop body
+never executes.
- The `pr_first_field()' function simply isolates out some code that
-is used repeatedly, making the whole program shorter and cleaner. In
+ The 'pr_first_field()' function simply isolates out some code that is
+used repeatedly, making the whole program shorter and cleaner. In
particular, moving the check for the empty string into this function
saves several lines of code.
@@ -17057,29 +16985,29 @@ File: gawk.info, Node: Split Program, Next: Tee
Program, Prev: Id Program, U
11.2.4 Splitting a Large File into Pieces
-----------------------------------------
-The `split' program splits large text files into smaller pieces. Usage
+The 'split' program splits large text files into smaller pieces. Usage
is as follows:(1)
- `split' [`-COUNT'] [FILE] [PREFIX]
+ 'split' ['-COUNT'] [FILE] [PREFIX]
- By default, the output files are named `xaa', `xab', and so on. Each
+ By default, the output files are named 'xaa', 'xab', and so on. Each
file has 1,000 lines in it, with the likely exception of the last file.
To change the number of lines in each file, supply a number on the
-command line preceded with a minus sign (e.g., `-500' for files with
-500 lines in them instead of 1,000). To change the names of the output
-files to something like `myfileaa', `myfileab', and so on, supply an
+command line preceded with a minus sign (e.g., '-500' for files with 500
+lines in them instead of 1,000). To change the names of the output
+files to something like 'myfileaa', 'myfileab', and so on, supply an
additional argument that specifies the file name prefix.
- Here is a version of `split' in `awk'. It uses the `ord()' and
-`chr()' functions presented in *note Ordinal Functions::.
+ Here is a version of 'split' in 'awk'. It uses the 'ord()' and
+'chr()' functions presented in *note Ordinal Functions::.
The program first sets its defaults, and then tests to make sure
there are not too many arguments. It then looks at each argument in
turn. The first argument could be a minus sign followed by a number.
If it is, this happens to look like a negative number, so it is made
-positive, and that is the count of lines. The data file name is
-skipped over and the final argument is used as the prefix for the
-output file names:
+positive, and that is the count of lines. The data file name is skipped
+over and the final argument is used as the prefix for the output file
+names:
# split.awk --- do split in awk
#
@@ -17110,13 +17038,13 @@ output file names:
out = (outfile s1 s2)
}
- The next rule does most of the work. `tcount' (temporary count)
-tracks how many lines have been printed to the output file so far. If
-it is greater than `count', it is time to close the current file and
-start a new one. `s1' and `s2' track the current suffixes for the file
-name. If they are both `z', the file is just too big. Otherwise, `s1'
-moves to the next letter in the alphabet and `s2' starts over again at
-`a':
+ The next rule does most of the work. 'tcount' (temporary count)
+tracks how many lines have been printed to the output file so far. If
+it is greater than 'count', it is time to close the current file and
+start a new one. 's1' and 's2' track the current suffixes for the file
+name. If they are both 'z', the file is just too big. Otherwise, 's1'
+moves to the next letter in the alphabet and 's2' starts over again at
+'a':
{
if (++tcount > count) {
@@ -17138,7 +17066,7 @@ moves to the next letter in the alphabet and `s2'
starts over again at
print > out
}
-The `usage()' function simply prints an error message and exits:
+The 'usage()' function simply prints an error message and exits:
function usage()
{
@@ -17146,14 +17074,14 @@ The `usage()' function simply prints an error message
and exits:
exit 1
}
- This program is a bit sloppy; it relies on `awk' to automatically
-close the last file instead of doing it in an `END' rule. It also
+ This program is a bit sloppy; it relies on 'awk' to automatically
+close the last file instead of doing it in an 'END' rule. It also
assumes that letters are contiguous in the character set, which isn't
true for EBCDIC systems.
---------- Footnotes ----------
- (1) This is the traditional usage. The POSIX usage is different, but
+ (1) This is the traditional usage. The POSIX usage is different, but
not relevant for what the program aims to demonstrate.
@@ -17162,25 +17090,25 @@ File: gawk.info, Node: Tee Program, Next: Uniq
Program, Prev: Split Program,
11.2.5 Duplicating Output into Multiple Files
---------------------------------------------
-The `tee' program is known as a "pipe fitting." `tee' copies its
+The 'tee' program is known as a "pipe fitting." 'tee' copies its
standard input to its standard output and also duplicates it to the
files named on the command line. Its usage is as follows:
- `tee' [`-a'] FILE ...
+ 'tee' ['-a'] FILE ...
- The `-a' option tells `tee' to append to the named files, instead of
+ The '-a' option tells 'tee' to append to the named files, instead of
truncating them and starting over.
- The `BEGIN' rule first makes a copy of all the command-line arguments
-into an array named `copy'. `ARGV[0]' is not needed, so it is not
-copied. `tee' cannot use `ARGV' directly, because `awk' attempts to
-process each file name in `ARGV' as input data.
+ The 'BEGIN' rule first makes a copy of all the command-line arguments
+into an array named 'copy'. 'ARGV[0]' is not needed, so it is not
+copied. 'tee' cannot use 'ARGV' directly, because 'awk' attempts to
+process each file name in 'ARGV' as input data.
- If the first argument is `-a', then the flag variable `append' is
-set to true, and both `ARGV[1]' and `copy[1]' are deleted. If `ARGC' is
-less than two, then no file names were supplied and `tee' prints a
-usage message and exits. Finally, `awk' is forced to read the standard
-input by setting `ARGV[1]' to `"-"' and `ARGC' to two:
+ If the first argument is '-a', then the flag variable 'append' is set
+to true, and both 'ARGV[1]' and 'copy[1]' are deleted. If 'ARGC' is
+less than two, then no file names were supplied and 'tee' prints a usage
+message and exits. Finally, 'awk' is forced to read the standard input
+by setting 'ARGV[1]' to '"-"' and 'ARGC' to two:
# tee.awk --- tee in awk
#
@@ -17229,14 +17157,13 @@ It is also possible to write the loop this way:
else
print > copy[i]
-This is more concise, but it is also less efficient. The `if' is
-tested for each record and for each output file. By duplicating the
-loop body, the `if' is only tested once for each input record. If
-there are N input records and M output files, the first method only
-executes N `if' statements, while the second executes N`*'M `if'
-statements.
+This is more concise, but it is also less efficient. The 'if' is tested
+for each record and for each output file. By duplicating the loop body,
+the 'if' is only tested once for each input record. If there are N
+input records and M output files, the first method only executes N 'if'
+statements, while the second executes N'*'M 'if' statements.
- Finally, the `END' rule cleans up by closing all the output files:
+ Finally, the 'END' rule cleans up by closing all the output files:
END {
for (i in copy)
@@ -17249,64 +17176,64 @@ File: gawk.info, Node: Uniq Program, Next: Wc
Program, Prev: Tee Program, Up
11.2.6 Printing Nonduplicated Lines of Text
-------------------------------------------
-The `uniq' utility reads sorted lines of data on its standard input,
-and by default removes duplicate lines. In other words, it only prints
-unique lines--hence the name. `uniq' has a number of options. The
+The 'uniq' utility reads sorted lines of data on its standard input, and
+by default removes duplicate lines. In other words, it only prints
+unique lines--hence the name. 'uniq' has a number of options. The
usage is as follows:
- `uniq' [`-udc' [`-N']] [`+N'] [INPUTFILE [OUTPUTFILE]]
+ 'uniq' ['-udc' ['-N']] ['+N'] [INPUTFILE [OUTPUTFILE]]
- The options for `uniq' are:
+ The options for 'uniq' are:
-`-d'
+'-d'
Print only repeated (duplicated) lines.
-`-u'
+'-u'
Print only nonrepeated (unique) lines.
-`-c'
- Count lines. This option overrides `-d' and `-u'. Both repeated
+'-c'
+ Count lines. This option overrides '-d' and '-u'. Both repeated
and nonrepeated lines are counted.
-`-N'
+'-N'
Skip N fields before comparing lines. The definition of fields is
- similar to `awk''s default: nonwhitespace characters separated by
+ similar to 'awk''s default: nonwhitespace characters separated by
runs of spaces and/or TABs.
-`+N'
+'+N'
Skip N characters before comparing lines. Any fields specified
- with `-N' are skipped first.
+ with '-N' are skipped first.
-`INPUTFILE'
- Data is read from the input file named on the command line,
- instead of from the standard input.
+'INPUTFILE'
+ Data is read from the input file named on the command line, instead
+ of from the standard input.
-`OUTPUTFILE'
+'OUTPUTFILE'
The generated output is sent to the named output file, instead of
to the standard output.
- Normally `uniq' behaves as if both the `-d' and `-u' options are
+ Normally 'uniq' behaves as if both the '-d' and '-u' options are
provided.
- `uniq' uses the `getopt()' library function (*note Getopt Function::)
-and the `join()' library function (*note Join Function::).
+ 'uniq' uses the 'getopt()' library function (*note Getopt Function::)
+and the 'join()' library function (*note Join Function::).
- The program begins with a `usage()' function and then a brief
-outline of the options and their meanings in comments. The `BEGIN'
-rule deals with the command-line arguments and options. It uses a trick
-to get `getopt()' to handle options of the form `-25', treating such an
-option as the option letter `2' with an argument of `5'. If indeed two
-or more digits are supplied (`Optarg' looks like a number), `Optarg' is
+ The program begins with a 'usage()' function and then a brief outline
+of the options and their meanings in comments. The 'BEGIN' rule deals
+with the command-line arguments and options. It uses a trick to get
+'getopt()' to handle options of the form '-25', treating such an option
+as the option letter '2' with an argument of '5'. If indeed two or more
+digits are supplied ('Optarg' looks like a number), 'Optarg' is
concatenated with the option digit and then the result is added to zero
to make it into a number. If there is only one digit in the option,
-then `Optarg' is not needed. In this case, `Optind' must be decremented
-so that `getopt()' processes it next time. This code is admittedly a
+then 'Optarg' is not needed. In this case, 'Optind' must be decremented
+so that 'getopt()' processes it next time. This code is admittedly a
bit tricky.
If no options are supplied, then the default is taken, to print both
repeated and nonrepeated lines. The output file, if provided, is
-assigned to `outputfile'. Early on, `outputfile' is initialized to the
-standard output, `/dev/stdout':
+assigned to 'outputfile'. Early on, 'outputfile' is initialized to the
+standard output, '/dev/stdout':
# uniq.awk --- do uniq in awk
#
@@ -17365,21 +17292,20 @@ standard output, `/dev/stdout':
}
}
- The following function, `are_equal()', compares the current line,
-`$0', to the previous line, `last'. It handles skipping fields and
+ The following function, 'are_equal()', compares the current line,
+'$0', to the previous line, 'last'. It handles skipping fields and
characters. If no field count and no character count are specified,
-`are_equal()' returns one or zero depending upon the result of a simple
-string comparison of `last' and `$0'.
+'are_equal()' returns one or zero depending upon the result of a simple
+string comparison of 'last' and '$0'.
Otherwise, things get more complicated. If fields have to be
-skipped, each line is broken into an array using `split()' (*note
-String Functions::); the desired fields are then joined back into a line
-using `join()'. The joined lines are stored in `clast' and `cline'.
-If no fields are skipped, `clast' and `cline' are set to `last' and
-`$0', respectively. Finally, if characters are skipped, `substr()' is
-used to strip off the leading `charcount' characters in `clast' and
-`cline'. The two strings are then compared and `are_equal()' returns
-the result:
+skipped, each line is broken into an array using 'split()' (*note String
+Functions::); the desired fields are then joined back into a line using
+'join()'. The joined lines are stored in 'clast' and 'cline'. If no
+fields are skipped, 'clast' and 'cline' are set to 'last' and '$0',
+respectively. Finally, if characters are skipped, 'substr()' is used to
+strip off the leading 'charcount' characters in 'clast' and 'cline'.
+The two strings are then compared and 'are_equal()' returns the result:
function are_equal( n, m, clast, cline, alast, aline)
{
@@ -17404,23 +17330,23 @@ the result:
}
The following two rules are the body of the program. The first one
-is executed only for the very first line of data. It sets `last' equal
-to `$0', so that subsequent lines of text have something to be compared
+is executed only for the very first line of data. It sets 'last' equal
+to '$0', so that subsequent lines of text have something to be compared
to.
- The second rule does the work. The variable `equal' is one or zero,
-depending upon the results of `are_equal()''s comparison. If `uniq' is
-counting repeated lines, and the lines are equal, then it increments
-the `count' variable. Otherwise, it prints the line and resets `count',
+ The second rule does the work. The variable 'equal' is one or zero,
+depending upon the results of 'are_equal()''s comparison. If 'uniq' is
+counting repeated lines, and the lines are equal, then it increments the
+'count' variable. Otherwise, it prints the line and resets 'count',
because the two lines are not equal.
- If `uniq' is not counting, and if the lines are equal, `count' is
+ If 'uniq' is not counting, and if the lines are equal, 'count' is
incremented. Nothing is printed, as the point is to remove duplicates.
-Otherwise, if `uniq' is counting repeated lines and more than one line
-is seen, or if `uniq' is counting nonrepeated lines and only one line
-is seen, then the line is printed, and `count' is reset.
+Otherwise, if 'uniq' is counting repeated lines and more than one line
+is seen, or if 'uniq' is counting nonrepeated lines and only one line is
+seen, then the line is printed, and 'count' is reset.
- Finally, similar logic is used in the `END' rule to print the final
+ Finally, similar logic is used in the 'END' rule to print the final
line of input data:
NR == 1 {
@@ -17468,44 +17394,44 @@ File: gawk.info, Node: Wc Program, Prev: Uniq
Program, Up: Clones
11.2.7 Counting Things
----------------------
-The `wc' (word count) utility counts lines, words, and characters in
-one or more input files. Its usage is as follows:
+The 'wc' (word count) utility counts lines, words, and characters in one
+or more input files. Its usage is as follows:
- `wc' [`-lwc'] [FILES ...]
+ 'wc' ['-lwc'] [FILES ...]
- If no files are specified on the command line, `wc' reads its
-standard input. If there are multiple files, it also prints total
+ If no files are specified on the command line, 'wc' reads its
+standard input. If there are multiple files, it also prints total
counts for all the files. The options and their meanings are as
follows:
-`-l'
+'-l'
Count only lines.
-`-w'
+'-w'
Count only words. A "word" is a contiguous sequence of
nonwhitespace characters, separated by spaces and/or TABs.
- Luckily, this is the normal way `awk' separates fields in its
- input data.
+ Luckily, this is the normal way 'awk' separates fields in its input
+ data.
-`-c'
+'-c'
Count only characters.
- Implementing `wc' in `awk' is particularly elegant, because `awk'
-does a lot of the work for us; it splits lines into words (i.e.,
-fields) and counts them, it counts lines (i.e., records), and it can
-easily tell us how long a line is.
+ Implementing 'wc' in 'awk' is particularly elegant, because 'awk'
+does a lot of the work for us; it splits lines into words (i.e., fields)
+and counts them, it counts lines (i.e., records), and it can easily tell
+us how long a line is.
- This program uses the `getopt()' library function (*note Getopt
+ This program uses the 'getopt()' library function (*note Getopt
Function::) and the file-transition functions (*note Filetrans
Function::).
This version has one notable difference from traditional versions of
-`wc': it always prints the counts in the order lines, words, and
-characters. Traditional versions note the order of the `-l', `-w', and
-`-c' options on the command line, and print the counts in that order.
+'wc': it always prints the counts in the order lines, words, and
+characters. Traditional versions note the order of the '-l', '-w', and
+'-c' options on the command line, and print the counts in that order.
- The `BEGIN' rule does the argument processing. The variable
-`print_total' is true if more than one file is named on the command
+ The 'BEGIN' rule does the argument processing. The variable
+'print_total' is true if more than one file is named on the command
line:
# wc.awk --- count lines, words, characters
@@ -17540,9 +17466,9 @@ line:
print_total = (ARGC - i > 2)
}
- The `beginfile()' function is simple; it just resets the counts of
+ The 'beginfile()' function is simple; it just resets the counts of
lines, words, and characters to zero, and saves the current file name in
-`fname':
+'fname':
function beginfile(file)
{
@@ -17550,10 +17476,10 @@ lines, words, and characters to zero, and saves the
current file name in
fname = FILENAME
}
- The `endfile()' function adds the current file's numbers to the
+ The 'endfile()' function adds the current file's numbers to the
running totals of lines, words, and characters. It then prints out
-those numbers for the file that was just read. It relies on
-`beginfile()' to reset the numbers for the following data file:
+those numbers for the file that was just read. It relies on
+'beginfile()' to reset the numbers for the following data file:
function endfile(file)
{
@@ -17569,12 +17495,12 @@ those numbers for the file that was just read. It
relies on
printf "\t%s\n", fname
}
- There is one rule that is executed for each line. It adds the length
-of the record, plus one, to `chars'.(1) Adding one plus the record
+ There is one rule that is executed for each line. It adds the length
+of the record, plus one, to 'chars'.(1) Adding one plus the record
length is needed because the newline character separating records (the
-value of `RS') is not part of the record itself, and thus not included
-in its length. Next, `lines' is incremented for each line read, and
-`words' is incremented by the value of `NF', which is the number of
+value of 'RS') is not part of the record itself, and thus not included
+in its length. Next, 'lines' is incremented for each line read, and
+'words' is incremented by the value of 'NF', which is the number of
"words" on this line:
# do per line
@@ -17584,7 +17510,7 @@ in its length. Next, `lines' is incremented for each
line read, and
words += NF
}
- Finally, the `END' rule simply prints the totals for all the files:
+ Finally, the 'END' rule simply prints the totals for all the files:
END {
if (print_total) {
@@ -17600,13 +17526,13 @@ in its length. Next, `lines' is incremented for each
line read, and
---------- Footnotes ----------
- (1) Because `gawk' understands multibyte locales, this code counts
+ (1) Because 'gawk' understands multibyte locales, this code counts
characters, not bytes.
File: gawk.info, Node: Miscellaneous Programs, Next: Programs Summary,
Prev: Clones, Up: Sample Programs
-11.3 A Grab Bag of `awk' Programs
+11.3 A Grab Bag of 'awk' Programs
=================================
This minor node is a large "grab bag" of miscellaneous programs. We
@@ -17616,7 +17542,7 @@ hope you find them both interesting and enjoyable.
* Dupword Program:: Finding duplicated words in a document.
* Alarm Program:: An alarm clock.
-* Translate Program:: A program similar to the `tr' utility.
+* Translate Program:: A program similar to the 'tr' utility.
* Labels Program:: Printing mailing labels.
* Word Sorting:: A program to produce a word usage count.
* History Sorting:: Eliminating duplicate entries from a history
@@ -17624,7 +17550,7 @@ hope you find them both interesting and enjoyable.
* Extract Program:: Pulling out programs from Texinfo source
files.
* Simple Sed:: A Simple Stream Editor.
-* Igawk Program:: A wrapper for `awk' that includes
+* Igawk Program:: A wrapper for 'awk' that includes
files.
* Anagram Program:: Finding anagrams from a dictionary.
* Signature Program:: People do amazing things with too much time on
@@ -17638,22 +17564,22 @@ File: gawk.info, Node: Dupword Program, Next: Alarm
Program, Up: Miscellaneou
A common error when writing large amounts of prose is to accidentally
duplicate words. Typically you will see this in text as something like
-"the the program does the following..." When the text is online, often
+"the the program does the following..." When the text is online, often
the duplicated words occur at the end of one line and the beginning of
another, making them very difficult to spot.
- This program, `dupword.awk', scans through a file one line at a time
+ This program, 'dupword.awk', scans through a file one line at a time
and looks for adjacent occurrences of the same word. It also saves the
-last word on a line (in the variable `prev') for comparison with the
+last word on a line (in the variable 'prev') for comparison with the
first word on the next line.
- The first two statements make sure that the line is all lowercase,
-so that, for example, "The" and "the" compare equal to each other. The
+ The first two statements make sure that the line is all lowercase, so
+that, for example, "The" and "the" compare equal to each other. The
next statement replaces nonalphanumeric and nonwhitespace characters
with spaces, so that punctuation does not affect the comparison either.
The characters are replaced with spaces so that formatting controls
-don't create nonsense words (e.g., the Texinfo address@hidden' becomes
-`codeNF' if punctuation is simply deleted). The record is then resplit
+don't create nonsense words (e.g., the Texinfo '@code{NF}' becomes
+'codeNF' if punctuation is simply deleted). The record is then resplit
into fields, yielding just the actual words on the line, and ensuring
that there are no empty fields.
@@ -17684,30 +17610,30 @@ File: gawk.info, Node: Alarm Program, Next:
Translate Program, Prev: Dupword
11.3.2 An Alarm Clock Program
-----------------------------
- Nothing cures insomnia like a ringing alarm clock. -- Arnold
- Robbins
+ Nothing cures insomnia like a ringing alarm clock.
+ -- _Arnold Robbins_
+ Sleep is for web developers.
+ -- _Erik Quanstrom_
- Sleep is for web developers. -- Erik Quanstrom
-
- The following program is a simple "alarm clock" program. You give
-it a time of day and an optional message. At the specified time, it
-prints the message on the standard output. In addition, you can give it
-the number of times to repeat the message as well as a delay between
+ The following program is a simple "alarm clock" program. You give it
+a time of day and an optional message. At the specified time, it prints
+the message on the standard output. In addition, you can give it the
+number of times to repeat the message as well as a delay between
repetitions.
- This program uses the `getlocaltime()' function from *note
+ This program uses the 'getlocaltime()' function from *note
Getlocaltime Function::.
- All the work is done in the `BEGIN' rule. The first part is argument
+ All the work is done in the 'BEGIN' rule. The first part is argument
checking and setting of defaults: the delay, the count, and the message
to print. If the user supplied a message without the ASCII BEL
-character (known as the "alert" character, `"\a"'), then it is added to
+character (known as the "alert" character, '"\a"'), then it is added to
the message. (On many systems, printing the ASCII BEL generates an
-audible alert. Thus, when the alarm goes off, the system calls attention
-to itself in case the user is not looking at the computer.) Just for a
-change, this program uses a `switch' statement (*note Switch
+audible alert. Thus, when the alarm goes off, the system calls
+attention to itself in case the user is not looking at the computer.)
+Just for a change, this program uses a 'switch' statement (*note Switch
Statement::), but the processing could be done with a series of
-`if'-`else' statements instead. Here is the program:
+'if'-'else' statements instead. Here is the program:
# alarm.awk --- set an alarm
#
@@ -17755,10 +17681,9 @@ Statement::), but the processing could be done with a
series of
The next minor node of code turns the alarm time into hours and
minutes, converts it (if necessary) to a 24-hour clock, and then turns
-that time into a count of the seconds since midnight. Next it turns
-the current time into a count of seconds since midnight. The
-difference between the two is how long to wait before setting off the
-alarm:
+that time into a count of the seconds since midnight. Next it turns the
+current time into a count of seconds since midnight. The difference
+between the two is how long to wait before setting off the alarm:
# split up alarm time
split(ARGV[1], atime, ":")
@@ -17788,12 +17713,12 @@ alarm:
exit 1
}
- Finally, the program uses the `system()' function (*note I/O
-Functions::) to call the `sleep' utility. The `sleep' utility simply
+ Finally, the program uses the 'system()' function (*note I/O
+Functions::) to call the 'sleep' utility. The 'sleep' utility simply
pauses for the given number of seconds. If the exit status is not zero,
-the program assumes that `sleep' was interrupted and exits. If `sleep'
+the program assumes that 'sleep' was interrupted and exits. If 'sleep'
exited with an OK status (zero), then the program prints the message in
-a loop, again using `sleep' to delay for however many seconds are
+a loop, again using 'sleep' to delay for however many seconds are
necessary:
# zzzzzz..... go away if interrupted
@@ -17818,14 +17743,14 @@ File: gawk.info, Node: Translate Program, Next:
Labels Program, Prev: Alarm P
11.3.3 Transliterating Characters
---------------------------------
-The system `tr' utility transliterates characters. For example, it is
+The system 'tr' utility transliterates characters. For example, it is
often used to map uppercase letters into lowercase for further
processing:
GENERATE DATA | tr 'A-Z' 'a-z' | PROCESS DATA ...
- `tr' requires two lists of characters.(1) When processing the
-input, the first character in the first list is replaced with the first
+ 'tr' requires two lists of characters.(1) When processing the input,
+the first character in the first list is replaced with the first
character in the second list, the second character in the first list is
replaced with the second character in the second list, and so on. If
there are more characters in the "from" list than in the "to" list, the
@@ -17833,38 +17758,38 @@ last character of the "to" list is used for the
remaining characters in
the "from" list.
Once upon a time, a user proposed adding a transliteration function
-to `gawk'. The following program was written to prove that character
+to 'gawk'. The following program was written to prove that character
transliteration could be done with a user-level function. This program
-is not as complete as the system `tr' utility, but it does most of the
+is not as complete as the system 'tr' utility, but it does most of the
job.
- The `translate' program was written long before `gawk' acquired the
+ The 'translate' program was written long before 'gawk' acquired the
ability to split each character in a string into separate array
-elements. Thus, it makes repeated use of the `substr()', `index()',
-and `gsub()' built-in functions (*note String Functions::). There are
-two functions. The first, `stranslate()', takes three arguments:
+elements. Thus, it makes repeated use of the 'substr()', 'index()', and
+'gsub()' built-in functions (*note String Functions::). There are two
+functions. The first, 'stranslate()', takes three arguments:
-`from'
+'from'
A list of characters from which to translate
-`to'
+'to'
A list of characters to which to translate
-`target'
+'target'
The string on which to do the translation
- Associative arrays make the translation part fairly easy. `t_ar'
+ Associative arrays make the translation part fairly easy. 't_ar'
holds the "to" characters, indexed by the "from" characters. Then a
-simple loop goes through `from', one character at a time. For each
-character in `from', if the character appears in `target', it is
-replaced with the corresponding `to' character.
+simple loop goes through 'from', one character at a time. For each
+character in 'from', if the character appears in 'target', it is
+replaced with the corresponding 'to' character.
- The `translate()' function calls `stranslate()', using `$0' as the
-target. The main program sets two global variables, `FROM' and `TO',
-from the command line, and then changes `ARGV' so that `awk' reads from
+ The 'translate()' function calls 'stranslate()', using '$0' as the
+target. The main program sets two global variables, 'FROM' and 'TO',
+from the command line, and then changes 'ARGV' so that 'awk' reads from
the standard input.
- Finally, the processing rule simply calls `translate()' for each
+ Finally, the processing rule simply calls 'translate()' for each
record:
# translate.awk --- do tr-like stuff
@@ -17915,30 +17840,30 @@ record:
}
It is possible to do character transliteration in a user-level
-function, but it is not necessarily efficient, and we (the `gawk'
+function, but it is not necessarily efficient, and we (the 'gawk'
developers) started to consider adding a built-in function. However,
shortly after writing this program, we learned that Brian Kernighan had
-added the `toupper()' and `tolower()' functions to his `awk' (*note
+added the 'toupper()' and 'tolower()' functions to his 'awk' (*note
String Functions::). These functions handle the vast majority of the
cases where character transliteration is necessary, and so we chose to
-simply add those functions to `gawk' as well and then leave well enough
+simply add those functions to 'gawk' as well and then leave well enough
alone.
- An obvious improvement to this program would be to set up the `t_ar'
-array only once, in a `BEGIN' rule. However, this assumes that the
+ An obvious improvement to this program would be to set up the 't_ar'
+array only once, in a 'BEGIN' rule. However, this assumes that the
"from" and "to" lists will never change throughout the lifetime of the
program.
Another obvious improvement is to enable the use of ranges, such as
-`a-z', as allowed by the `tr' utility. Look at the code for `cut.awk'
+'a-z', as allowed by the 'tr' utility. Look at the code for 'cut.awk'
(*note Cut Program::) for inspiration.
---------- Footnotes ----------
(1) On some older systems, including Solaris, the system version of
-`tr' may require that the lists be written as range expressions
-enclosed in square brackets (`[a-z]') and quoted, to prevent the shell
-from attempting a file name expansion. This is not a feature.
+'tr' may require that the lists be written as range expressions enclosed
+in square brackets ('[a-z]') and quoted, to prevent the shell from
+attempting a file name expansion. This is not a feature.
File: gawk.info, Node: Labels Program, Next: Word Sorting, Prev: Translate
Program, Up: Miscellaneous Programs
@@ -17953,23 +17878,23 @@ be no more than five lines of data. Each address is
separated from the
next by a blank line.
The basic idea is to read 20 labels' worth of data. Each line of
-each label is stored in the `line' array. The single rule takes care
-of filling the `line' array and printing the page when 20 labels have
-been read.
+each label is stored in the 'line' array. The single rule takes care of
+filling the 'line' array and printing the page when 20 labels have been
+read.
- The `BEGIN' rule simply sets `RS' to the empty string, so that `awk'
-splits records at blank lines (*note Records::). It sets `MAXLINES' to
+ The 'BEGIN' rule simply sets 'RS' to the empty string, so that 'awk'
+splits records at blank lines (*note Records::). It sets 'MAXLINES' to
100, because 100 is the maximum number of lines on the page (20 * 5 =
100).
- Most of the work is done in the `printpage()' function. The label
-lines are stored sequentially in the `line' array. But they have to
-print horizontally: `line[1]' next to `line[6]', `line[2]' next to
-`line[7]', and so on. Two loops accomplish this. The outer loop,
-controlled by `i', steps through every 10 lines of data; this is each
-row of labels. The inner loop, controlled by `j', goes through the
-lines within the row. As `j' goes from 0 to 4, `i+j' is the `j'th line
-in the row, and `i+j+5' is the entry next to it. The output ends up
+ Most of the work is done in the 'printpage()' function. The label
+lines are stored sequentially in the 'line' array. But they have to
+print horizontally: 'line[1]' next to 'line[6]', 'line[2]' next to
+'line[7]', and so on. Two loops accomplish this. The outer loop,
+controlled by 'i', steps through every 10 lines of data; this is each
+row of labels. The inner loop, controlled by 'j', goes through the
+lines within the row. As 'j' goes from 0 to 4, 'i+j' is the 'j'th line
+in the row, and 'i+j+5' is the entry next to it. The output ends up
looking something like this:
line 1 line 6
@@ -17979,7 +17904,7 @@ looking something like this:
line 5 line 10
...
-The `printf' format string `%-41s' left-aligns the data and prints it
+The 'printf' format string '%-41s' left-aligns the data and prints it
within a fixed-width field.
As a final note, an extra blank line is printed at lines 21 and 61,
@@ -17988,7 +17913,7 @@ particular brand of labels in use when the program was
written. You
will also note that there are two blank lines at the top and two blank
lines at the bottom.
- The `END' rule arranges to flush the final page of labels; there may
+ The 'END' rule arranges to flush the final page of labels; there may
not have been an even multiple of 20 labels in the data:
# labels.awk --- print mailing labels
@@ -18055,9 +17980,9 @@ File: gawk.info, Node: Word Sorting, Next: History
Sorting, Prev: Labels Prog
When working with large amounts of text, it can be interesting to know
how often different words appear. For example, an author may overuse
certain words, in which case he or she might wish to find synonyms to
-substitute for words that appear too often. This node develops a
-program for counting words and presenting the frequency information in
-a useful format.
+substitute for words that appear too often. This node develops a
+program for counting words and presenting the frequency information in a
+useful format.
At first glance, a program like this would seem to do the job:
@@ -18073,33 +17998,33 @@ a useful format.
printf "%s\t%d\n", word, freq[word]
}
- The program relies on `awk''s default field-splitting mechanism to
+ The program relies on 'awk''s default field-splitting mechanism to
break each line up into "words" and uses an associative array named
-`freq', indexed by each word, to count the number of times the word
-occurs. In the `END' rule, it prints the counts.
+'freq', indexed by each word, to count the number of times the word
+occurs. In the 'END' rule, it prints the counts.
This program has several problems that prevent it from being useful
on real text files:
- * The `awk' language considers upper- and lowercase characters to be
+ * The 'awk' language considers upper- and lowercase characters to be
distinct. Therefore, "bartender" and "Bartender" are not treated
as the same word. This is undesirable, because words are
- capitalized if they begin sentences in normal text, and a
- frequency analyzer should not be sensitive to capitalization.
+ capitalized if they begin sentences in normal text, and a frequency
+ analyzer should not be sensitive to capitalization.
- * Words are detected using the `awk' convention that fields are
+ * Words are detected using the 'awk' convention that fields are
separated just by whitespace. Other characters in the input
- (except newlines) don't have any special meaning to `awk'. This
+ (except newlines) don't have any special meaning to 'awk'. This
means that punctuation characters count as part of words.
* The output does not come out in any useful order. You're more
likely to be interested in which words occur most frequently or in
having an alphabetized table of how frequently each word occurs.
- The first problem can be solved by using `tolower()' to remove case
-distinctions. The second problem can be solved by using `gsub()' to
+ The first problem can be solved by using 'tolower()' to remove case
+distinctions. The second problem can be solved by using 'gsub()' to
remove punctuation characters. Finally, we solve the third problem by
-using the system `sort' utility to process the output of the `awk'
+using the system 'sort' utility to process the output of the 'awk'
script. Here is the new version of the program:
# wordfreq.awk --- print list of word frequencies
@@ -18117,30 +18042,29 @@ script. Here is the new version of the program:
printf "%s\t%d\n", word, freq[word]
}
- The regexp `/[^[:alnum:]_[:blank:]]/' might have been written
-`/[[:punct:]]/', but then underscores would also be removed, and we
-want to keep them.
+ The regexp '/[^[:alnum:]_[:blank:]]/' might have been written
+'/[[:punct:]]/', but then underscores would also be removed, and we want
+to keep them.
- Assuming we have saved this program in a file named `wordfreq.awk',
-and that the data is in `file1', the following pipeline:
+ Assuming we have saved this program in a file named 'wordfreq.awk',
+and that the data is in 'file1', the following pipeline:
awk -f wordfreq.awk file1 | sort -k 2nr
-produces a table of the words appearing in `file1' in order of
+produces a table of the words appearing in 'file1' in order of
decreasing frequency.
- The `awk' program suitably massages the data and produces a word
-frequency table, which is not ordered. The `awk' script's output is
-then sorted by the `sort' utility and printed on the screen.
+ The 'awk' program suitably massages the data and produces a word
+frequency table, which is not ordered. The 'awk' script's output is
+then sorted by the 'sort' utility and printed on the screen.
- The options given to `sort' specify a sort that uses the second
-field of each input line (skipping one field), that the sort keys
-should be treated as numeric quantities (otherwise `15' would come
-before `5'), and that the sorting should be done in descending
-(reverse) order.
+ The options given to 'sort' specify a sort that uses the second field
+of each input line (skipping one field), that the sort keys should be
+treated as numeric quantities (otherwise '15' would come before '5'),
+and that the sorting should be done in descending (reverse) order.
- The `sort' could even be done from within the program, by changing
-the `END' action to:
+ The 'sort' could even be done from within the program, by changing
+the 'END' action to:
END {
sort = "sort -k 2nr"
@@ -18152,7 +18076,7 @@ the `END' action to:
This way of sorting must be used on systems that do not have true
pipes at the command-line (or batch-file) level. See the general
operating system documentation for more information on how to use the
-`sort' program.
+'sort' program.
File: gawk.info, Node: History Sorting, Next: Extract Program, Prev: Word
Sorting, Up: Miscellaneous Programs
@@ -18160,24 +18084,24 @@ File: gawk.info, Node: History Sorting, Next:
Extract Program, Prev: Word Sor
11.3.6 Removing Duplicates from Unsorted Text
---------------------------------------------
-The `uniq' program (*note Uniq Program::) removes duplicate lines from
+The 'uniq' program (*note Uniq Program::) removes duplicate lines from
_sorted_ data.
- Suppose, however, you need to remove duplicate lines from a data
-file but that you want to preserve the order the lines are in. A good
-example of this might be a shell history file. The history file keeps
-a copy of all the commands you have entered, and it is not unusual to
-repeat a command several times in a row. Occasionally you might want
-to compact the history by removing duplicate entries. Yet it is
-desirable to maintain the order of the original commands.
-
- This simple program does the job. It uses two arrays. The `data'
-array is indexed by the text of each line. For each line, `data[$0]'
-is incremented. If a particular line has not been seen before, then
-`data[$0]' is zero. In this case, the text of the line is stored in
-`lines[count]'. Each element of `lines' is a unique command, and the
-indices of `lines' indicate the order in which those lines are
-encountered. The `END' rule simply prints out the lines, in order:
+ Suppose, however, you need to remove duplicate lines from a data file
+but that you want to preserve the order the lines are in. A good
+example of this might be a shell history file. The history file keeps a
+copy of all the commands you have entered, and it is not unusual to
+repeat a command several times in a row. Occasionally you might want to
+compact the history by removing duplicate entries. Yet it is desirable
+to maintain the order of the original commands.
+
+ This simple program does the job. It uses two arrays. The 'data'
+array is indexed by the text of each line. For each line, 'data[$0]' is
+incremented. If a particular line has not been seen before, then
+'data[$0]' is zero. In this case, the text of the line is stored in
+'lines[count]'. Each element of 'lines' is a unique command, and the
+indices of 'lines' indicate the order in which those lines are
+encountered. The 'END' rule simply prints out the lines, in order:
# histsort.awk --- compact a shell history file
# Thanks to Byron Rakitzis for the general idea
@@ -18193,12 +18117,12 @@ encountered. The `END' rule simply prints out the
lines, in order:
}
This program also provides a foundation for generating other useful
-information. For example, using the following `print' statement in the
-`END' rule indicates how often a particular command is used:
+information. For example, using the following 'print' statement in the
+'END' rule indicates how often a particular command is used:
print data[lines[i]], lines[i]
-This works because `data[$0]' is incremented each time a line is seen.
+This works because 'data[$0]' is incremented each time a line is seen.
File: gawk.info, Node: Extract Program, Next: Simple Sed, Prev: History
Sorting, Up: Miscellaneous Programs
@@ -18207,51 +18131,51 @@ File: gawk.info, Node: Extract Program, Next:
Simple Sed, Prev: History Sorti
----------------------------------------------------
The nodes *note Library Functions::, and *note Sample Programs::, are
-the top level nodes for a large number of `awk' programs. If you want
+the top level nodes for a large number of 'awk' programs. If you want
to experiment with these programs, it is tedious to type them in by
hand. Here we present a program that can extract parts of a Texinfo
input file into separate files.
-This Info file is written in Texinfo
+ This Info file is written in Texinfo
(http://www.gnu.org/software/texinfo/), the GNU Project's document
formatting language. A single Texinfo source file can be used to
produce both printed documentation, with TeX, and online documentation.
-(The Texinfo language is described fully, starting with *note
-(Texinfo)Top:: texinfo,Texinfo--The GNU Documentation Format.)
+(The Texinfo language is described fully, starting with *note (Texinfo,
+texinfo,Texinfo---The GNU Documentation Format)Top::.)
For our purposes, it is enough to know three things about Texinfo
input files:
- * The "at" symbol (`@') is special in Texinfo, much as the backslash
- (`\') is in C or `awk'. Literal `@' symbols are represented in
- Texinfo source files as `@@'.
+ * The "at" symbol ('@') is special in Texinfo, much as the backslash
+ ('\') is in C or 'awk'. Literal '@' symbols are represented in
+ Texinfo source files as '@@'.
- * Comments start with either address@hidden' or address@hidden'. The
- file-extraction program works by using special comments that start
- at the beginning of a line.
+ * Comments start with either '@c' or '@comment'. The file-extraction
+ program works by using special comments that start at the beginning
+ of a line.
- * Lines containing address@hidden' and address@hidden group' commands
bracket
- example text that should not be split across a page boundary.
+ * Lines containing '@group' and '@end group' commands bracket example
+ text that should not be split across a page boundary.
(Unfortunately, TeX isn't always smart enough to do things exactly
right, so we have to give it some help.)
- The following program, `extract.awk', reads through a Texinfo source
+ The following program, 'extract.awk', reads through a Texinfo source
file and does two things, based on the special comments. Upon seeing
address@hidden system ...', it runs a command, by extracting the command text
from
-the control line and passing it on to the `system()' function (*note
-I/O Functions::). Upon seeing address@hidden file FILENAME', each subsequent
line
-is sent to the file FILENAME, until address@hidden endfile' is encountered.
The
-rules in `extract.awk' match either address@hidden' or address@hidden' by
letting the
-`omment' part be optional. Lines containing address@hidden' and
address@hidden group'
-are simply removed. `extract.awk' uses the `join()' library function
-(*note Join Function::).
+'@c system ...', it runs a command, by extracting the command text from
+the control line and passing it on to the 'system()' function (*note I/O
+Functions::). Upon seeing '@c file FILENAME', each subsequent line is
+sent to the file FILENAME, until '@c endfile' is encountered. The rules
+in 'extract.awk' match either '@c' or '@comment' by letting the 'omment'
+part be optional. Lines containing '@group' and '@end group' are simply
+removed. 'extract.awk' uses the 'join()' library function (*note Join
+Function::).
- The example programs in the online Texinfo source for `GAWK:
-Effective AWK Programming' (`gawktexi.in') have all been bracketed
-inside `file' and `endfile' lines. The `gawk' distribution uses a copy
-of `extract.awk' to extract the sample programs and install many of
-them in a standard directory where `gawk' can find them. The Texinfo
-file looks something like this:
+ The example programs in the online Texinfo source for 'GAWK:
+Effective AWK Programming' ('gawktexi.in') have all been bracketed
+inside 'file' and 'endfile' lines. The 'gawk' distribution uses a copy
+of 'extract.awk' to extract the sample programs and install many of them
+in a standard directory where 'gawk' can find them. The Texinfo file
+looks something like this:
...
This program has a @code{BEGIN} rule
@@ -18272,11 +18196,11 @@ file looks something like this:
@end example
...
- `extract.awk' begins by setting `IGNORECASE' to one, so that mixed
+ 'extract.awk' begins by setting 'IGNORECASE' to one, so that mixed
upper- and lowercase letters in the directives won't matter.
- The first rule handles calling `system()', checking that a command is
-given (`NF' is at least three) and also checking that the command exits
+ The first rule handles calling 'system()', checking that a command is
+given ('NF' is at least three) and also checking that the command exits
with a zero exit status, signifying OK:
# extract.awk --- extract files and run programs from Texinfo files
@@ -18300,36 +18224,34 @@ with a zero exit status, signifying OK:
}
}
-The variable `e' is used so that the rule fits nicely on the screen.
+The variable 'e' is used so that the rule fits nicely on the screen.
The second rule handles moving data into files. It verifies that a
file name is given in the directive. If the file named is not the
current file, then the current file is closed. Keeping the current file
-open until a new file is encountered allows the use of the `>'
+open until a new file is encountered allows the use of the '>'
redirection for printing the contents, keeping open-file management
simple.
- The `for' loop does the work. It reads lines using `getline' (*note
+ The 'for' loop does the work. It reads lines using 'getline' (*note
Getline::). For an unexpected end-of-file, it calls the
-`unexpected_eof()' function. If the line is an "endfile" line, then it
-breaks out of the loop. If the line is an address@hidden' or address@hidden
group'
+'unexpected_eof()' function. If the line is an "endfile" line, then it
+breaks out of the loop. If the line is an '@group' or '@end group'
line, then it ignores it and goes on to the next line. Similarly,
comments within examples are also ignored.
Most of the work is in the following few lines. If the line has no
-`@' symbols, the program can print it directly. Otherwise, each
-leading `@' must be stripped off. To remove the `@' symbols, the line
-is split into separate elements of the array `a', using the `split()'
-function (*note String Functions::). The `@' symbol is used as the
-separator character. Each element of `a' that is empty indicates two
-successive `@' symbols in the original line. For each two empty
-elements (`@@' in the original file), we have to add a single `@'
-symbol back in.
-
- When the processing of the array is finished, `join()' is called
-with the value of `SUBSEP' (*note Multidimensional::), to rejoin the
-pieces back into a single line. That line is then printed to the
-output file:
+'@' symbols, the program can print it directly. Otherwise, each leading
+'@' must be stripped off. To remove the '@' symbols, the line is split
+into separate elements of the array 'a', using the 'split()' function
+(*note String Functions::). The '@' symbol is used as the separator
+character. Each element of 'a' that is empty indicates two successive
+'@' symbols in the original line. For each two empty elements ('@@' in
+the original file), we have to add a single '@' symbol back in.
+
+ When the processing of the array is finished, 'join()' is called with
+the value of 'SUBSEP' (*note Multidimensional::), to rejoin the pieces
+back into a single line. That line is then printed to the output file:
/address@hidden(omment)?[ \t]+file/ {
if (NF != 3) {
@@ -18370,16 +18292,16 @@ output file:
}
}
- An important thing to note is the use of the `>' redirection.
-Output done with `>' only opens the file once; it stays open and
-subsequent output is appended to the file (*note Redirection::). This
-makes it easy to mix program text and explanatory prose for the same
-sample source file (as has been done here!) without any hassle. The
-file is only closed when a new data file name is encountered or at the
-end of the input file.
+ An important thing to note is the use of the '>' redirection. Output
+done with '>' only opens the file once; it stays open and subsequent
+output is appended to the file (*note Redirection::). This makes it
+easy to mix program text and explanatory prose for the same sample
+source file (as has been done here!) without any hassle. The file is
+only closed when a new data file name is encountered or at the end of
+the input file.
- Finally, the function `unexpected_eof()' prints an appropriate error
-message and then exits. The `END' rule handles the final cleanup,
+ Finally, the function 'unexpected_eof()' prints an appropriate error
+message and then exits. The 'END' rule handles the final cleanup,
closing the open file:
function unexpected_eof()
@@ -18400,24 +18322,24 @@ File: gawk.info, Node: Simple Sed, Next: Igawk
Program, Prev: Extract Program
11.3.8 A Simple Stream Editor
-----------------------------
-The `sed' utility is a "stream editor", a program that reads a stream
-of data, makes changes to it, and passes it on. It is often used to
-make global changes to a large file or to a stream of data generated by
-a pipeline of commands. Although `sed' is a complicated program in its
-own right, its most common use is to perform global substitutions in
-the middle of a pipeline:
+The 'sed' utility is a "stream editor", a program that reads a stream of
+data, makes changes to it, and passes it on. It is often used to make
+global changes to a large file or to a stream of data generated by a
+pipeline of commands. Although 'sed' is a complicated program in its
+own right, its most common use is to perform global substitutions in the
+middle of a pipeline:
COMMAND1 < orig.data | sed 's/old/new/g' | COMMAND2 > result
- Here, `s/old/new/g' tells `sed' to look for the regexp `old' on each
-input line and globally replace it with the text `new' (i.e., all the
-occurrences on a line). This is similar to `awk''s `gsub()' function
+ Here, 's/old/new/g' tells 'sed' to look for the regexp 'old' on each
+input line and globally replace it with the text 'new' (i.e., all the
+occurrences on a line). This is similar to 'awk''s 'gsub()' function
(*note String Functions::).
- The following program, `awksed.awk', accepts at least two
+ The following program, 'awksed.awk', accepts at least two
command-line arguments: the pattern to look for and the text to replace
-it with. Any additional arguments are treated as data file names to
-process. If none are provided, the standard input is used:
+it with. Any additional arguments are treated as data file names to
+process. If none are provided, the standard input is used:
# awksed.awk --- do s/foo/bar/g using just print
# Thanks to Michael Brennan for the idea
@@ -18448,32 +18370,32 @@ process. If none are provided, the standard input is
used:
print
}
- The program relies on `gawk''s ability to have `RS' be a regexp, as
-well as on the setting of `RT' to the actual text that terminates the
+ The program relies on 'gawk''s ability to have 'RS' be a regexp, as
+well as on the setting of 'RT' to the actual text that terminates the
record (*note Records::).
- The idea is to have `RS' be the pattern to look for. `gawk'
-automatically sets `$0' to the text between matches of the pattern.
-This is text that we want to keep, unmodified. Then, by setting `ORS'
-to the replacement text, a simple `print' statement outputs the text we
+ The idea is to have 'RS' be the pattern to look for. 'gawk'
+automatically sets '$0' to the text between matches of the pattern.
+This is text that we want to keep, unmodified. Then, by setting 'ORS'
+to the replacement text, a simple 'print' statement outputs the text we
want to keep, followed by the replacement text.
There is one wrinkle to this scheme, which is what to do if the last
-record doesn't end with text that matches `RS'. Using a `print'
+record doesn't end with text that matches 'RS'. Using a 'print'
statement unconditionally prints the replacement text, which is not
-correct. However, if the file did not end in text that matches `RS',
-`RT' is set to the null string. In this case, we can print `$0' using
-`printf' (*note Printf::).
-
- The `BEGIN' rule handles the setup, checking for the right number of
-arguments and calling `usage()' if there is a problem. Then it sets
-`RS' and `ORS' from the command-line arguments and sets `ARGV[1]' and
-`ARGV[2]' to the null string, so that they are not treated as file names
+correct. However, if the file did not end in text that matches 'RS',
+'RT' is set to the null string. In this case, we can print '$0' using
+'printf' (*note Printf::).
+
+ The 'BEGIN' rule handles the setup, checking for the right number of
+arguments and calling 'usage()' if there is a problem. Then it sets
+'RS' and 'ORS' from the command-line arguments and sets 'ARGV[1]' and
+'ARGV[2]' to the null string, so that they are not treated as file names
(*note ARGC and ARGV::).
- The `usage()' function prints an error message and exits. Finally,
+ The 'usage()' function prints an error message and exits. Finally,
the single rule handles the printing scheme outlined earlier, using
-`print' or `printf' as appropriate, depending upon the value of `RT'.
+'print' or 'printf' as appropriate, depending upon the value of 'RT'.
File: gawk.info, Node: Igawk Program, Next: Anagram Program, Prev: Simple
Sed, Up: Miscellaneous Programs
@@ -18481,18 +18403,18 @@ File: gawk.info, Node: Igawk Program, Next: Anagram
Program, Prev: Simple Sed
11.3.9 An Easy Way to Use Library Functions
-------------------------------------------
-In *note Include Files::, we saw how `gawk' provides a built-in
-file-inclusion capability. However, this is a `gawk' extension. This
+In *note Include Files::, we saw how 'gawk' provides a built-in
+file-inclusion capability. However, this is a 'gawk' extension. This
minor node provides the motivation for making file inclusion available
-for standard `awk', and shows how to do it using a combination of shell
-and `awk' programming.
-
- Using library functions in `awk' can be very beneficial. It
-encourages code reuse and the writing of general functions. Programs are
-smaller and therefore clearer. However, using library functions is
-only easy when writing `awk' programs; it is painful when running them,
-requiring multiple `-f' options. If `gawk' is unavailable, then so too
-is the `AWKPATH' environment variable and the ability to put `awk'
+for standard 'awk', and shows how to do it using a combination of shell
+and 'awk' programming.
+
+ Using library functions in 'awk' can be very beneficial. It
+encourages code reuse and the writing of general functions. Programs
+are smaller and therefore clearer. However, using library functions is
+only easy when writing 'awk' programs; it is painful when running them,
+requiring multiple '-f' options. If 'gawk' is unavailable, then so too
+is the 'AWKPATH' environment variable and the ability to put 'awk'
functions into a library directory (*note Options::). It would be nice
to be able to write programs in the following manner:
@@ -18508,94 +18430,94 @@ to be able to write programs in the following manner:
...
}
- The following program, `igawk.sh', provides this service. It
-simulates `gawk''s searching of the `AWKPATH' variable and also allows
-"nested" includes (i.e., a file that is included with address@hidden' can
-contain further address@hidden' statements). `igawk' makes an effort to
-only include files once, so that nested includes don't accidentally
-include a library function twice.
+ The following program, 'igawk.sh', provides this service. It
+simulates 'gawk''s searching of the 'AWKPATH' variable and also allows
+"nested" includes (i.e., a file that is included with '@include' can
+contain further '@include' statements). 'igawk' makes an effort to only
+include files once, so that nested includes don't accidentally include a
+library function twice.
- `igawk' should behave just like `gawk' externally. This means it
-should accept all of `gawk''s command-line arguments, including the
-ability to have multiple source files specified via `-f' and the
-ability to mix command-line and library source files.
+ 'igawk' should behave just like 'gawk' externally. This means it
+should accept all of 'gawk''s command-line arguments, including the
+ability to have multiple source files specified via '-f' and the ability
+to mix command-line and library source files.
- The program is written using the POSIX Shell (`sh') command
-language.(1) It works as follows:
+ The program is written using the POSIX Shell ('sh') command
+language.(1) It works as follows:
1. Loop through the arguments, saving anything that doesn't represent
- `awk' source code for later, when the expanded program is run.
+ 'awk' source code for later, when the expanded program is run.
- 2. For any arguments that do represent `awk' text, put the arguments
+ 2. For any arguments that do represent 'awk' text, put the arguments
into a shell variable that will be expanded. There are two cases:
- a. Literal text, provided with `-e' or `--source'. This text is
+ a. Literal text, provided with '-e' or '--source'. This text is
just appended directly.
- b. Source file names, provided with `-f'. We use a neat trick
- and append address@hidden FILENAME' to the shell variable's
+ b. Source file names, provided with '-f'. We use a neat trick
+ and append '@include FILENAME' to the shell variable's
contents. Because the file-inclusion program works the way
- `gawk' does, this gets the text of the file included in the
+ 'gawk' does, this gets the text of the file included in the
program at the correct point.
- 3. Run an `awk' program (naturally) over the shell variable's
- contents to expand address@hidden' statements. The expanded program is
- placed in a second shell variable.
+ 3. Run an 'awk' program (naturally) over the shell variable's contents
+ to expand '@include' statements. The expanded program is placed in
+ a second shell variable.
- 4. Run the expanded program with `gawk' and any other original
+ 4. Run the expanded program with 'gawk' and any other original
command-line arguments that the user supplied (such as the data
file names).
This program uses shell variables extensively: for storing
-command-line arguments and the text of the `awk' program that will
+command-line arguments and the text of the 'awk' program that will
expand the user's program, for the user's original program, and for the
expanded program. Doing so removes some potential problems that might
arise were we to use temporary files instead, at the cost of making the
script somewhat more complicated.
The initial part of the program turns on shell tracing if the first
-argument is `debug'.
+argument is 'debug'.
The next part loops through all the command-line arguments. There
are several cases of interest:
-`--'
- This ends the arguments to `igawk'. Anything else should be
- passed on to the user's `awk' program without being evaluated.
+'--'
+ This ends the arguments to 'igawk'. Anything else should be passed
+ on to the user's 'awk' program without being evaluated.
-`-W'
- This indicates that the next option is specific to `gawk'. To make
- argument processing easier, the `-W' is appended to the front of
- the remaining arguments and the loop continues. (This is an `sh'
+'-W'
+ This indicates that the next option is specific to 'gawk'. To make
+ argument processing easier, the '-W' is appended to the front of
+ the remaining arguments and the loop continues. (This is an 'sh'
programming trick. Don't worry about it if you are not familiar
- with `sh'.)
+ with 'sh'.)
-`-v', `-F'
- These are saved and passed on to `gawk'.
+'-v', '-F'
+ These are saved and passed on to 'gawk'.
-`-f', `--file', `--file=', `-Wfile='
- The file name is appended to the shell variable `program' with an
- address@hidden' statement. The `expr' utility is used to remove the
- leading option part of the argument (e.g., `--file='). (Typical
- `sh' usage would be to use the `echo' and `sed' utilities to do
- this work. Unfortunately, some versions of `echo' evaluate escape
+'-f', '--file', '--file=', '-Wfile='
+ The file name is appended to the shell variable 'program' with an
+ '@include' statement. The 'expr' utility is used to remove the
+ leading option part of the argument (e.g., '--file='). (Typical
+ 'sh' usage would be to use the 'echo' and 'sed' utilities to do
+ this work. Unfortunately, some versions of 'echo' evaluate escape
sequences in their arguments, possibly mangling the program text.
- Using `expr' avoids this problem.)
+ Using 'expr' avoids this problem.)
-`--source', `--source=', `-Wsource='
- The source text is appended to `program'.
+'--source', '--source=', '-Wsource='
+ The source text is appended to 'program'.
-`--version', `-Wversion'
- `igawk' prints its version number, runs `gawk --version' to get
- the `gawk' version information, and then exits.
+'--version', '-Wversion'
+ 'igawk' prints its version number, runs 'gawk --version' to get the
+ 'gawk' version information, and then exits.
- If none of the `-f', `--file', `-Wfile', `--source', or `-Wsource'
+ If none of the '-f', '--file', '-Wfile', '--source', or '-Wsource'
arguments are supplied, then the first nonoption argument should be the
-`awk' program. If there are no command-line arguments left, `igawk'
+'awk' program. If there are no command-line arguments left, 'igawk'
prints an error message and exits. Otherwise, the first argument is
-appended to `program'. In any case, after the arguments have been
-processed, the shell variable `program' contains the complete text of
-the original `awk' program.
+appended to 'program'. In any case, after the arguments have been
+processed, the shell variable 'program' contains the complete text of
+the original 'awk' program.
The program is as follows:
@@ -18675,27 +18597,27 @@ the original `awk' program.
# At this point, `program' has the program.
- The `awk' program to process address@hidden' directives is stored in the
-shell variable `expand_prog'. Doing this keeps the shell script
-readable. The `awk' program reads through the user's program, one line
-at a time, using `getline' (*note Getline::). The input file names and
address@hidden' statements are managed using a stack. As each address@hidden'
is
+ The 'awk' program to process '@include' directives is stored in the
+shell variable 'expand_prog'. Doing this keeps the shell script
+readable. The 'awk' program reads through the user's program, one line
+at a time, using 'getline' (*note Getline::). The input file names and
+'@include' statements are managed using a stack. As each '@include' is
encountered, the current file name is "pushed" onto the stack and the
-file named in the address@hidden' directive becomes the current file name.
+file named in the '@include' directive becomes the current file name.
As each file is finished, the stack is "popped," and the previous input
file becomes the current input file again. The process is started by
making the original file the first one on the stack.
- The `pathto()' function does the work of finding the full path to a
-file. It simulates `gawk''s behavior when searching the `AWKPATH'
+ The 'pathto()' function does the work of finding the full path to a
+file. It simulates 'gawk''s behavior when searching the 'AWKPATH'
environment variable (*note AWKPATH Variable::). If a file name has a
-`/' in it, no path search is done. Similarly, if the file name is
-`"-"', then that string is used as-is. Otherwise, the file name is
-concatenated with the name of each directory in the path, and an
-attempt is made to open the generated file name. The only way to test
-if a file can be read in `awk' is to go ahead and try to read it with
-`getline'; this is what `pathto()' does.(2) If the file can be read, it
-is closed and the file name is returned:
+'/' in it, no path search is done. Similarly, if the file name is
+'"-"', then that string is used as-is. Otherwise, the file name is
+concatenated with the name of each directory in the path, and an attempt
+is made to open the generated file name. The only way to test if a file
+can be read in 'awk' is to go ahead and try to read it with 'getline';
+this is what 'pathto()' does.(2) If the file can be read, it is closed
+and the file name is returned:
expand_prog='
@@ -18718,9 +18640,9 @@ is closed and the file name is returned:
return ""
}
- The main program is contained inside one `BEGIN' rule. The first
-thing it does is set up the `pathlist' array that `pathto()' uses.
-After splitting the path on `:', null elements are replaced with `"."',
+ The main program is contained inside one 'BEGIN' rule. The first
+thing it does is set up the 'pathlist' array that 'pathto()' uses.
+After splitting the path on ':', null elements are replaced with '"."',
which represents the current directory:
BEGIN {
@@ -18731,21 +18653,21 @@ which represents the current directory:
pathlist[i] = "."
}
- The stack is initialized with `ARGV[1]', which will be
-`"/dev/stdin"'. The main loop comes next. Input lines are read in
-succession. Lines that do not start with address@hidden' are printed
-verbatim. If the line does start with address@hidden', the file name is in
-`$2'. `pathto()' is called to generate the full path. If it cannot,
+ The stack is initialized with 'ARGV[1]', which will be
+'"/dev/stdin"'. The main loop comes next. Input lines are read in
+succession. Lines that do not start with '@include' are printed
+verbatim. If the line does start with '@include', the file name is in
+'$2'. 'pathto()' is called to generate the full path. If it cannot,
then the program prints an error message and continues.
The next thing to check is if the file is included already. The
-`processed' array is indexed by the full file name of each included
-file and it tracks this information for us. If the file is seen again,
-a warning message is printed. Otherwise, the new file name is pushed
-onto the stack and processing continues.
+'processed' array is indexed by the full file name of each included file
+and it tracks this information for us. If the file is seen again, a
+warning message is printed. Otherwise, the new file name is pushed onto
+the stack and processing continues.
- Finally, when `getline' encounters the end of the input file, the
-file is closed and the stack is popped. When `stackptr' is less than
+ Finally, when 'getline' encounters the end of the input file, the
+file is closed and the stack is popped. When 'stackptr' is less than
zero, the program is done:
stackptr = 0
@@ -18780,80 +18702,79 @@ zero, the program is done:
EOF
)
- The shell construct `COMMAND << MARKER' is called a "here document".
+ The shell construct 'COMMAND << MARKER' is called a "here document".
Everything in the shell script up to the MARKER is fed to COMMAND as
input. The shell processes the contents of the here document for
variable and command substitution (and possibly other things as well,
depending upon the shell).
- The shell construct `$(...)' is called "command substitution". The
+ The shell construct '$(...)' is called "command substitution". The
output of the command inside the parentheses is substituted into the
command line. Because the result is used in a variable assignment, it
is saved as a single string, even if the results contain whitespace.
- The expanded program is saved in the variable `processed_program'.
+ The expanded program is saved in the variable 'processed_program'.
It's done in these steps:
- 1. Run `gawk' with the address@hidden'-processing program (the value of
- the `expand_prog' shell variable) reading standard input.
+ 1. Run 'gawk' with the '@include'-processing program (the value of the
+ 'expand_prog' shell variable) reading standard input.
2. Standard input is the contents of the user's program, from the
- shell variable `program'. Feed its contents to `gawk' via a here
+ shell variable 'program'. Feed its contents to 'gawk' via a here
document.
3. Save the results of this processing in the shell variable
- `processed_program' by using command substitution.
+ 'processed_program' by using command substitution.
- The last step is to call `gawk' with the expanded program, along
-with the original options and command-line arguments that the user
-supplied:
+ The last step is to call 'gawk' with the expanded program, along with
+the original options and command-line arguments that the user supplied:
eval gawk $opts -- '"$processed_program"' '"$@"'
- The `eval' command is a shell construct that reruns the shell's
+ The 'eval' command is a shell construct that reruns the shell's
parsing process. This keeps things properly quoted.
- This version of `igawk' represents the fifth version of this program.
+ This version of 'igawk' represents the fifth version of this program.
There are four key simplifications that make the program work better:
- * Using address@hidden' even for the files named with `-f' makes building
- the initial collected `awk' program much simpler; all the
- address@hidden' processing can be done once.
+ * Using '@include' even for the files named with '-f' makes building
+ the initial collected 'awk' program much simpler; all the
+ '@include' processing can be done once.
- * Not trying to save the line read with `getline' in the `pathto()'
- function when testing for the file's accessibility for use with
- the main program simplifies things considerably.
+ * Not trying to save the line read with 'getline' in the 'pathto()'
+ function when testing for the file's accessibility for use with the
+ main program simplifies things considerably.
- * Using a `getline' loop in the `BEGIN' rule does it all in one
+ * Using a 'getline' loop in the 'BEGIN' rule does it all in one
place. It is not necessary to call out to a separate loop for
- processing nested address@hidden' statements.
+ processing nested '@include' statements.
- * Instead of saving the expanded program in a temporary file,
- putting it in a shell variable avoids some potential security
- problems. This has the disadvantage that the script relies upon
- more features of the `sh' language, making it harder to follow for
- those who aren't familiar with `sh'.
+ * Instead of saving the expanded program in a temporary file, putting
+ it in a shell variable avoids some potential security problems.
+ This has the disadvantage that the script relies upon more features
+ of the 'sh' language, making it harder to follow for those who
+ aren't familiar with 'sh'.
Also, this program illustrates that it is often worthwhile to combine
-`sh' and `awk' programming together. You can usually accomplish quite
-a lot, without having to resort to low-level programming in C or C++,
-and it is frequently easier to do certain kinds of string and argument
-manipulation using the shell than it is in `awk'.
+'sh' and 'awk' programming together. You can usually accomplish quite a
+lot, without having to resort to low-level programming in C or C++, and
+it is frequently easier to do certain kinds of string and argument
+manipulation using the shell than it is in 'awk'.
- Finally, `igawk' shows that it is not always necessary to add new
+ Finally, 'igawk' shows that it is not always necessary to add new
features to a program; they can often be layered on top.(3)
---------- Footnotes ----------
- (1) Fully explaining the `sh' language is beyond the scope of this
-book. We provide some minimal explanations, but see a good shell
+ (1) Fully explaining the 'sh' language is beyond the scope of this
+book. We provide some minimal explanations, but see a good shell
programming book if you wish to understand things in more depth.
- (2) On some very old versions of `awk', the test `getline junk < t'
+ (2) On some very old versions of 'awk', the test 'getline junk < t'
can loop forever if the file exists but is empty.
- (3) `gawk' does address@hidden' processing itself in order to support the
-use of `awk' programs as Web CGI scripts.
+ (3) 'gawk' does '@include' processing itself in order to support the
+use of 'awk' programs as Web CGI scripts.
File: gawk.info, Node: Anagram Program, Next: Signature Program, Prev:
Igawk Program, Up: Miscellaneous Programs
@@ -18862,11 +18783,11 @@ File: gawk.info, Node: Anagram Program, Next:
Signature Program, Prev: Igawk
------------------------------------------
An interesting programming challenge is to search for "anagrams" in a
-word list (such as `/usr/share/dict/words' on many GNU/Linux systems).
+word list (such as '/usr/share/dict/words' on many GNU/Linux systems).
One word is an anagram of another if both words contain the same letters
(e.g., "babbling" and "blabbing").
- Column 2, Problem C, of Jon Bentley's `Programming Pearls', Second
+ Column 2, Problem C, of Jon Bentley's 'Programming Pearls', Second
Edition, presents an elegant algorithm. The idea is to give words that
are anagrams a common signature, sort all the words together by their
signatures, and then print them. Dr. Bentley observes that taking the
@@ -18883,17 +18804,17 @@ order:
/'s$/ { next } # Skip possessives
- The program starts with a header, and then a rule to skip
-possessives in the dictionary file. The next rule builds up the data
-structure. The first dimension of the array is indexed by the
-signature; the second dimension is the word itself:
+ The program starts with a header, and then a rule to skip possessives
+in the dictionary file. The next rule builds up the data structure.
+The first dimension of the array is indexed by the signature; the second
+dimension is the word itself:
{
key = word2key($1) # Build signature
data[key][$1] = $1 # Store word with signature
}
- The `word2key()' function creates the signature. It splits the word
+ The 'word2key()' function creates the signature. It splits the word
apart into individual letters, sorts the letters, and then joins them
back together:
@@ -18910,9 +18831,9 @@ back together:
return result
}
- Finally, the `END' rule traverses the array and prints out the
-anagram lists. It sends the output to the system `sort' command
-because otherwise the anagrams would appear in arbitrary order:
+ Finally, the 'END' rule traverses the array and prints out the
+anagram lists. It sends the output to the system 'sort' command because
+otherwise the anagrams would appear in arbitrary order:
END {
sort = "sort"
@@ -18952,7 +18873,7 @@ File: gawk.info, Node: Signature Program, Prev:
Anagram Program, Up: Miscella
The following program was written by Davide Brini and is published on
his website (http://backreference.org/2011/02/03/obfuscated-awk/). It
-serves as his signature in the Usenet group `comp.lang.awk'. He
+serves as his signature in the Usenet group 'comp.lang.awk'. He
supplies the following copyright terms:
Copyright (C) 2008 Davide Brini
@@ -18979,30 +18900,28 @@ File: gawk.info, Node: Programs Summary, Next:
Programs Exercises, Prev: Misc
11.4 Summary
============
- * The programs provided in this major node continue on the theme
- that reading programs is an excellent way to learn Good
- Programming.
+ * The programs provided in this major node continue on the theme that
+ reading programs is an excellent way to learn Good Programming.
- * Using `#!' to make `awk' programs directly runnable makes them
- easier to use. Otherwise, invoke the program using `awk -f ...'.
+ * Using '#!' to make 'awk' programs directly runnable makes them
+ easier to use. Otherwise, invoke the program using 'awk -f ...'.
- * Reimplementing standard POSIX programs in `awk' is a pleasant
- exercise; `awk''s expressive power lets you write such programs in
+ * Reimplementing standard POSIX programs in 'awk' is a pleasant
+ exercise; 'awk''s expressive power lets you write such programs in
relatively few lines of code, yet they are functionally complete
and usable.
- * One of standard `awk''s weaknesses is working with individual
- characters. The ability to use `split()' with the empty string as
+ * One of standard 'awk''s weaknesses is working with individual
+ characters. The ability to use 'split()' with the empty string as
the separator can considerably simplify such tasks.
* The examples here demonstrate the usefulness of the library
functions from *note Library Functions::, for a number of real (if
small) programs.
- * Besides reinventing POSIX wheels, other programs solved a
- selection of interesting problems, such as finding duplicate words
- in text, printing mailing labels, and finding anagrams.
-
+ * Besides reinventing POSIX wheels, other programs solved a selection
+ of interesting problems, such as finding duplicate words in text,
+ printing mailing labels, and finding anagrams.
File: gawk.info, Node: Programs Exercises, Prev: Programs Summary, Up:
Sample Programs
@@ -19010,51 +18929,51 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
11.5 Exercises
==============
- 1. Rewrite `cut.awk' (*note Cut Program::) using `split()' with `""'
+ 1. Rewrite 'cut.awk' (*note Cut Program::) using 'split()' with '""'
as the separator.
- 2. In *note Egrep Program::, we mentioned that `egrep -i' could be
- simulated in versions of `awk' without `IGNORECASE' by using
- `tolower()' on the line and the pattern. In a footnote there, we
+ 2. In *note Egrep Program::, we mentioned that 'egrep -i' could be
+ simulated in versions of 'awk' without 'IGNORECASE' by using
+ 'tolower()' on the line and the pattern. In a footnote there, we
also mentioned that this solution has a bug: the translated line is
output, and not the original one. Fix this problem.
- 3. The POSIX version of `id' takes options that control which
- information is printed. Modify the `awk' version (*note Id
+ 3. The POSIX version of 'id' takes options that control which
+ information is printed. Modify the 'awk' version (*note Id
Program::) to accept the same arguments and perform in the same
way.
- 4. The `split.awk' program (*note Split Program::) assumes that
+ 4. The 'split.awk' program (*note Split Program::) assumes that
letters are contiguous in the character set, which isn't true for
- EBCDIC systems. Fix this problem. (Hint: Consider a different
- way to work through the alphabet, without relying on `ord()' and
- `chr()'.)
+ EBCDIC systems. Fix this problem. (Hint: Consider a different way
+ to work through the alphabet, without relying on 'ord()' and
+ 'chr()'.)
- 5. In `uniq.awk' (*note Uniq Program::, the logic for choosing which
+ 5. In 'uniq.awk' (*note Uniq Program::, the logic for choosing which
lines to print represents a "state machine", which is "a device
that can be in one of a set number of stable conditions depending
on its previous condition and on the present values of its
- inputs."(1) Brian Kernighan suggests that "an alternative approach
- to state machines is to just read the input into an array, then
- use indexing. It's almost always easier code, and for most inputs
+ inputs."(1) Brian Kernighan suggests that "an alternative approach
+ to state machines is to just read the input into an array, then use
+ indexing. It's almost always easier code, and for most inputs
where you would use this, just as fast." Rewrite the logic to
follow this suggestion.
- 6. Why can't the `wc.awk' program (*note Wc Program::) just use the
- value of `FNR' in `endfile()'? Hint: Examine the code in *note
+ 6. Why can't the 'wc.awk' program (*note Wc Program::) just use the
+ value of 'FNR' in 'endfile()'? Hint: Examine the code in *note
Filetrans Function::.
- 7. Manipulation of individual characters in the `translate' program
- (*note Translate Program::) is painful using standard `awk'
- functions. Given that `gawk' can split strings into individual
- characters using `""' as the separator, how might you use this
+ 7. Manipulation of individual characters in the 'translate' program
+ (*note Translate Program::) is painful using standard 'awk'
+ functions. Given that 'gawk' can split strings into individual
+ characters using '""' as the separator, how might you use this
feature to simplify the program?
- 8. The `extract.awk' program (*note Extract Program::) was written
- before `gawk' had the `gensub()' function. Use it to simplify the
+ 8. The 'extract.awk' program (*note Extract Program::) was written
+ before 'gawk' had the 'gensub()' function. Use it to simplify the
code.
- 9. Compare the performance of the `awksed.awk' program (*note Simple
+ 9. Compare the performance of the 'awksed.awk' program (*note Simple
Sed::) with the more straightforward:
BEGIN {
@@ -19065,82 +18984,80 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
{ gsub(pat, repl); print }
- 10. What are the advantages and disadvantages of `awksed.awk' versus
- the real `sed' utility?
+ 10. What are the advantages and disadvantages of 'awksed.awk' versus
+ the real 'sed' utility?
- 11. In *note Igawk Program::, we mentioned that not trying to save the
- line read with `getline' in the `pathto()' function when testing
+ 11. In *note Igawk Program::, we mentioned that not trying to save the
+ line read with 'getline' in the 'pathto()' function when testing
for the file's accessibility for use with the main program
simplifies things considerably. What problem does this engender
though?
- 12. As an additional example of the idea that it is not always
+ 12. As an additional example of the idea that it is not always
necessary to add new features to a program, consider the idea of
having two files in a directory in the search path:
- `default.awk'
- This file contains a set of default library functions, such
- as `getopt()' and `assert()'.
+ 'default.awk'
+ This file contains a set of default library functions, such as
+ 'getopt()' and 'assert()'.
- `site.awk'
+ 'site.awk'
This file contains library functions that are specific to a
site or installation; i.e., locally developed functions.
- Having a separate file allows `default.awk' to change with
- new `gawk' releases, without requiring the system
- administrator to update it each time by adding the local
- functions.
+ Having a separate file allows 'default.awk' to change with new
+ 'gawk' releases, without requiring the system administrator to
+ update it each time by adding the local functions.
- One user suggested that `gawk' be modified to automatically read
+ One user suggested that 'gawk' be modified to automatically read
these files upon startup. Instead, it would be very simple to
- modify `igawk' to do this. Since `igawk' can process nested
- address@hidden' directives, `default.awk' could simply contain
- address@hidden' statements for the desired library functions. Make
- this change.
-
- 13. Modify `anagram.awk' (*note Anagram Program::), to avoid the use
- of the external `sort' utility.
+ modify 'igawk' to do this. Since 'igawk' can process nested
+ '@include' directives, 'default.awk' could simply contain
+ '@include' statements for the desired library functions. Make this
+ change.
+ 13. Modify 'anagram.awk' (*note Anagram Program::), to avoid the use
+ of the external 'sort' utility.
---------- Footnotes ----------
- (1) This is the definition returned from entering `define: state
+ (1) This is the definition returned from entering 'define: state
machine' into Google.
File: gawk.info, Node: Advanced Features, Next: Internationalization, Prev:
Sample Programs, Up: Top
-12 Advanced Features of `gawk'
+12 Advanced Features of 'gawk'
******************************
Write documentation as if whoever reads it is a violent psychopath
- who knows where you live. -- Steve English, as quoted by Peter
- Langston
-
- This major node discusses advanced features in `gawk'. It's a bit
-of a "grab bag" of items that are otherwise unrelated to each other.
-First, we look at a command-line option that allows `gawk' to recognize
-nondecimal numbers in input data, not just in `awk' programs. Then,
-`gawk''s special features for sorting arrays are presented. Next,
+ who knows where you live.
+ -- _Steve English, as quoted by Peter Langston_
+
+ This major node discusses advanced features in 'gawk'. It's a bit of
+a "grab bag" of items that are otherwise unrelated to each other.
+First, we look at a command-line option that allows 'gawk' to recognize
+nondecimal numbers in input data, not just in 'awk' programs. Then,
+'gawk''s special features for sorting arrays are presented. Next,
two-way I/O, discussed briefly in earlier parts of this Info file, is
described in full detail, along with the basics of TCP/IP networking.
-Finally, we see how `gawk' can "profile" an `awk' program, making it
+Finally, we see how 'gawk' can "profile" an 'awk' program, making it
possible to tune it for performance.
- Additional advanced features are discussed in separate major nodes
-of their own:
+ Additional advanced features are discussed in separate major nodes of
+their own:
* *note Internationalization::, discusses how to internationalize
- your `awk' programs, so that they can speak multiple national
+ your 'awk' programs, so that they can speak multiple national
languages.
- * *note Debugger::, describes `gawk''s built-in command-line
- debugger for debugging `awk' programs.
+ * *note Debugger::, describes 'gawk''s built-in command-line debugger
+ for debugging 'awk' programs.
* *note Arbitrary Precision Arithmetic::, describes how you can use
- `gawk' to perform arbitrary-precision arithmetic.
+ 'gawk' to perform arbitrary-precision arithmetic.
* *note Dynamic Extensions::, discusses the ability to dynamically
- add new built-in functions to `gawk'.
+ add new built-in functions to 'gawk'.
* Menu:
@@ -19148,8 +19065,8 @@ of their own:
* Array Sorting:: Facilities for controlling array traversal and
sorting arrays.
* Two-way I/O:: Two-way communications with another process.
-* TCP/IP Networking:: Using `gawk' for network programming.
-* Profiling:: Profiling your `awk' programs.
+* TCP/IP Networking:: Using 'gawk' for network programming.
+* Profiling:: Profiling your 'awk' programs.
* Advanced Features Summary:: Summary of advanced features.
@@ -19158,23 +19075,23 @@ File: gawk.info, Node: Nondecimal Data, Next: Array
Sorting, Up: Advanced Fea
12.1 Allowing Nondecimal Input Data
===================================
-If you run `gawk' with the `--non-decimal-data' option, you can have
+If you run 'gawk' with the '--non-decimal-data' option, you can have
nondecimal values in your input data:
$ echo 0123 123 0x123 |
> gawk --non-decimal-data '{ printf "%d, %d, %d\n", $1, $2, $3 }'
-| 83, 123, 291
- For this feature to work, write your program so that `gawk' treats
+ For this feature to work, write your program so that 'gawk' treats
your data as numeric:
$ echo 0123 123 0x123 | gawk '{ print $1, $2, $3 }'
-| 0123 123 0x123
-The `print' statement treats its expressions as strings. Although the
+The 'print' statement treats its expressions as strings. Although the
fields can act as numbers when necessary, they are still strings, so
-`print' does not try to treat them numerically. You need to add zero
-to a field to force it to be treated as a number. For example:
+'print' does not try to treat them numerically. You need to add zero to
+a field to force it to be treated as a number. For example:
$ echo 0123 123 0x123 | gawk --non-decimal-data '
> { print $1, $2, $3
@@ -19187,13 +19104,13 @@ because using this facility could lead to surprising
results, the
default is to leave it disabled. If you want it, you must explicitly
request it.
- CAUTION: _Use of this option is not recommended._ It can break old
- programs very badly. Instead, use the `strtonum()' function to
+ CAUTION: _Use of this option is not recommended._ It can break old
+ programs very badly. Instead, use the 'strtonum()' function to
convert your data (*note String Functions::). This makes your
programs easier to write and easier to read, and leads to less
surprising results.
- This option may disappear in a future version of `gawk'.
+ This option may disappear in a future version of 'gawk'.
File: gawk.info, Node: Array Sorting, Next: Two-way I/O, Prev: Nondecimal
Data, Up: Advanced Features
@@ -19201,10 +19118,10 @@ File: gawk.info, Node: Array Sorting, Next: Two-way
I/O, Prev: Nondecimal Dat
12.2 Controlling Array Traversal and Array Sorting
==================================================
-`gawk' lets you control the order in which a `for (INDX in ARRAY)' loop
+'gawk' lets you control the order in which a 'for (INDX in ARRAY)' loop
traverses an array.
- In addition, two built-in functions, `asort()' and `asorti()', let
+ In addition, two built-in functions, 'asort()' and 'asorti()', let
you sort arrays based on the array values and indices, respectively.
These two functions also provide control over the sorting criteria used
to order the elements during sorting.
@@ -19212,7 +19129,7 @@ to order the elements during sorting.
* Menu:
* Controlling Array Traversal:: How to use PROCINFO["sorted_in"].
-* Array Sorting Functions:: How to use `asort()' and `asorti()'.
+* Array Sorting Functions:: How to use 'asort()' and 'asorti()'.
File: gawk.info, Node: Controlling Array Traversal, Next: Array Sorting
Functions, Up: Array Sorting
@@ -19220,20 +19137,20 @@ File: gawk.info, Node: Controlling Array Traversal,
Next: Array Sorting Functi
12.2.1 Controlling Array Traversal
----------------------------------
-By default, the order in which a `for (INDX in ARRAY)' loop scans an
+By default, the order in which a 'for (INDX in ARRAY)' loop scans an
array is not defined; it is generally based upon the internal
-implementation of arrays inside `awk'.
+implementation of arrays inside 'awk'.
Often, though, it is desirable to be able to loop over the elements
-in a particular order that you, the programmer, choose. `gawk' lets
-you do this.
+in a particular order that you, the programmer, choose. 'gawk' lets you
+do this.
*note Controlling Scanning::, describes how you can assign special,
-predefined values to `PROCINFO["sorted_in"]' in order to control the
-order in which `gawk' traverses an array during a `for' loop.
+predefined values to 'PROCINFO["sorted_in"]' in order to control the
+order in which 'gawk' traverses an array during a 'for' loop.
- In addition, the value of `PROCINFO["sorted_in"]' can be a function
-name.(1) This lets you traverse an array based on any custom criterion.
+ In addition, the value of 'PROCINFO["sorted_in"]' can be a function
+name.(1) This lets you traverse an array based on any custom criterion.
The array elements are ordered according to the return value of this
function. The comparison function should be defined with at least four
arguments:
@@ -19244,22 +19161,22 @@ arguments:
RETURN < 0; 0; OR > 0
}
- Here, `i1' and `i2' are the indices, and `v1' and `v2' are the
-corresponding values of the two elements being compared. Either `v1'
-or `v2', or both, can be arrays if the array being traversed contains
+ Here, 'i1' and 'i2' are the indices, and 'v1' and 'v2' are the
+corresponding values of the two elements being compared. Either 'v1' or
+'v2', or both, can be arrays if the array being traversed contains
subarrays as values. (*Note Arrays of Arrays::, for more information
about subarrays.) The three possible return values are interpreted as
follows:
-`comp_func(i1, v1, i2, v2) < 0'
- Index `i1' comes before index `i2' during loop traversal.
+'comp_func(i1, v1, i2, v2) < 0'
+ Index 'i1' comes before index 'i2' during loop traversal.
-`comp_func(i1, v1, i2, v2) == 0'
- Indices `i1' and `i2' come together, but the relative order with
+'comp_func(i1, v1, i2, v2) == 0'
+ Indices 'i1' and 'i2' come together, but the relative order with
respect to each other is undefined.
-`comp_func(i1, v1, i2, v2) > 0'
- Index `i1' comes after index `i2' during loop traversal.
+'comp_func(i1, v1, i2, v2) > 0'
+ Index 'i1' comes after index 'i2' during loop traversal.
Our first comparison function can be used to scan an array in
numerical order of the indices:
@@ -19299,7 +19216,7 @@ traversal:
return (v1 < v2) ? -1 : (v1 != v2)
}
- Here is a main program to demonstrate how `gawk' behaves using each
+ Here is a main program to demonstrate how 'gawk' behaves using each
of the previous functions:
BEGIN {
@@ -19375,9 +19292,9 @@ specific field position and can be used for this
purpose:
}
The first field in each entry of the password file is the user's
-login name, and the fields are separated by colons. Each record
-defines a subarray, with each field as an element in the subarray.
-Running the program produces the following output:
+login name, and the fields are separated by colons. Each record defines
+a subarray, with each field as an element in the subarray. Running the
+program produces the following output:
$ gawk -v POS=1 -F: -f sort.awk /etc/passwd
-| adm:x:3:4:adm:/var/adm:/sbin/nologin
@@ -19403,9 +19320,9 @@ tied elements come out in arbitrary order can be an
issue, especially
when comparing item values. The partial ordering of the equal elements
may change the next time the array is traversed, if other elements are
added to or removed from the array. One way to resolve ties when
-comparing elements with otherwise equal values is to include the
-indices in the comparison rules. Note that doing this may make the
-loop traversal less efficient, so consider it only if necessary. The
+comparing elements with otherwise equal values is to include the indices
+in the comparison rules. Note that doing this may make the loop
+traversal less efficient, so consider it only if necessary. The
following comparison functions force a deterministic order, and are
based on the fact that the (string) indices of two elements are never
equal:
@@ -19430,38 +19347,38 @@ such a function.
When string comparisons are made during a sort, either for element
values where one or both aren't numbers, or for element indices handled
-as strings, the value of `IGNORECASE' (*note Built-in Variables::)
+as strings, the value of 'IGNORECASE' (*note Built-in Variables::)
controls whether the comparisons treat corresponding upper- and
lowercase letters as equivalent or distinct.
Another point to keep in mind is that in the case of subarrays, the
element values can themselves be arrays; a production comparison
-function should use the `isarray()' function (*note Type Functions::)
-to check for this, and choose a defined sorting order for subarrays.
+function should use the 'isarray()' function (*note Type Functions::) to
+check for this, and choose a defined sorting order for subarrays.
- All sorting based on `PROCINFO["sorted_in"]' is disabled in POSIX
-mode, because the `PROCINFO' array is not special in that case.
+ All sorting based on 'PROCINFO["sorted_in"]' is disabled in POSIX
+mode, because the 'PROCINFO' array is not special in that case.
- As a side note, sorting the array indices before traversing the
-array has been reported to add a 15% to 20% overhead to the execution
-time of `awk' programs. For this reason, sorted array traversal is not
-the default.
+ As a side note, sorting the array indices before traversing the array
+has been reported to add a 15% to 20% overhead to the execution time of
+'awk' programs. For this reason, sorted array traversal is not the
+default.
---------- Footnotes ----------
- (1) This is why the predefined sorting orders start with an `@'
+ (1) This is why the predefined sorting orders start with an '@'
character, which cannot be part of an identifier.
File: gawk.info, Node: Array Sorting Functions, Prev: Controlling Array
Traversal, Up: Array Sorting
-12.2.2 Sorting Array Values and Indices with `gawk'
+12.2.2 Sorting Array Values and Indices with 'gawk'
---------------------------------------------------
-In most `awk' implementations, sorting an array requires writing a
-`sort()' function. This can be educational for exploring different
+In most 'awk' implementations, sorting an array requires writing a
+'sort()' function. This can be educational for exploring different
sorting algorithms, but usually that's not the point of the program.
-`gawk' provides the built-in `asort()' and `asorti()' functions (*note
+'gawk' provides the built-in 'asort()' and 'asorti()' functions (*note
String Functions::) for sorting arrays. For example:
POPULATE THE ARRAY data
@@ -19469,30 +19386,30 @@ String Functions::) for sorting arrays. For example:
for (i = 1; i <= n; i++)
DO SOMETHING WITH data[i]
- After the call to `asort()', the array `data' is indexed from 1 to
-some number N, the total number of elements in `data'. (This count is
-`asort()''s return value.) `data[1]' <= `data[2]' <= `data[3]', and so
+ After the call to 'asort()', the array 'data' is indexed from 1 to
+some number N, the total number of elements in 'data'. (This count is
+'asort()''s return value.) 'data[1]' <= 'data[2]' <= 'data[3]', and so
on. The default comparison is based on the type of the elements (*note
Typing and Comparison::). All numeric values come before all string
values, which in turn come before all subarrays.
- An important side effect of calling `asort()' is that _the array's
-original indices are irrevocably lost_. As this isn't always
-desirable, `asort()' accepts a second argument:
+ An important side effect of calling 'asort()' is that _the array's
+original indices are irrevocably lost_. As this isn't always desirable,
+'asort()' accepts a second argument:
POPULATE THE ARRAY source
n = asort(source, dest)
for (i = 1; i <= n; i++)
DO SOMETHING WITH dest[i]
- In this case, `gawk' copies the `source' array into the `dest' array
-and then sorts `dest', destroying its indices. However, the `source'
+ In this case, 'gawk' copies the 'source' array into the 'dest' array
+and then sorts 'dest', destroying its indices. However, the 'source'
array is not affected.
Often, what's needed is to sort on the values of the _indices_
-instead of the values of the elements. To do that, use the `asorti()'
+instead of the values of the elements. To do that, use the 'asorti()'
function. The interface and behavior are identical to that of
-`asort()', except that the index values are used for sorting and become
+'asort()', except that the index values are used for sorting and become
the values of the result array:
{ source[$0] = some_func($0) }
@@ -19508,15 +19425,15 @@ the values of the result array:
}
}
- So far, so good. Now it starts to get interesting. Both `asort()'
-and `asorti()' accept a third string argument to control comparison of
-array elements. When we introduced `asort()' and `asorti()' in *note
+ So far, so good. Now it starts to get interesting. Both 'asort()'
+and 'asorti()' accept a third string argument to control comparison of
+array elements. When we introduced 'asort()' and 'asorti()' in *note
String Functions::, we ignored this third argument; however, now is the
time to describe how this argument affects these two functions.
Basically, the third argument specifies how the array is to be
-sorted. There are two possibilities. As with `PROCINFO["sorted_in"]',
-this argument may be one of the predefined names that `gawk' provides
+sorted. There are two possibilities. As with 'PROCINFO["sorted_in"]',
+this argument may be one of the predefined names that 'gawk' provides
(*note Controlling Scanning::), or it may be the name of a user-defined
function (*note Controlling Array Traversal::).
@@ -19524,27 +19441,27 @@ function (*note Controlling Array Traversal::).
chooses_, taking into account just the indices, just the values, or
both. This is extremely powerful.
- Once the array is sorted, `asort()' takes the _values_ in their
-final order and uses them to fill in the result array, whereas
-`asorti()' takes the _indices_ in their final order and uses them to
-fill in the result array.
+ Once the array is sorted, 'asort()' takes the _values_ in their final
+order and uses them to fill in the result array, whereas 'asorti()'
+takes the _indices_ in their final order and uses them to fill in the
+result array.
NOTE: Copying array indices and elements isn't expensive in terms
- of memory. Internally, `gawk' maintains "reference counts" to
- data. For example, when `asort()' copies the first array to the
+ of memory. Internally, 'gawk' maintains "reference counts" to
+ data. For example, when 'asort()' copies the first array to the
second one, there is only one copy of the original array elements'
data, even though both arrays use the values.
- Because `IGNORECASE' affects string comparisons, the value of
-`IGNORECASE' also affects sorting for both `asort()' and `asorti()'.
+ Because 'IGNORECASE' affects string comparisons, the value of
+'IGNORECASE' also affects sorting for both 'asort()' and 'asorti()'.
Note also that the locale's sorting order does _not_ come into play;
comparisons are based on character values only.(1)
---------- Footnotes ----------
(1) This is true because locale-based comparison occurs only when in
-POSIX-compatibility mode, and because `asort()' and `asorti()' are
-`gawk' extensions, they are not available in that case.
+POSIX-compatibility mode, and because 'asort()' and 'asorti()' are
+'gawk' extensions, they are not available in that case.
File: gawk.info, Node: Two-way I/O, Next: TCP/IP Networking, Prev: Array
Sorting, Up: Advanced Features
@@ -19568,14 +19485,15 @@ temporary files:
close(tempfile)
system("rm " tempfile)
-This works, but not elegantly. Among other things, it requires that
-the program be run in a directory that cannot be shared among users;
-for example, `/tmp' will not do, as another user might happen to be
-using a temporary file with the same name.(1) However, with `gawk', it
-is possible to open a _two-way_ pipe to another process. The second
-process is termed a "coprocess", as it runs in parallel with `gawk'.
-The two-way connection is created using the `|&' operator (borrowed
-from the Korn shell, `ksh'):(2)
+This works, but not elegantly. Among other things, it requires that the
+program be run in a directory that cannot be shared among users; for
+example, '/tmp' will not do, as another user might happen to be using a
+temporary file with the same name.(1)
+
+ However, with 'gawk', it is possible to open a _two-way_ pipe to
+another process. The second process is termed a "coprocess", as it runs
+in parallel with 'gawk'. The two-way connection is created using the
+'|&' operator (borrowed from the Korn shell, 'ksh'):(2)
do {
print DATA |& "subprogram"
@@ -19583,43 +19501,42 @@ from the Korn shell, `ksh'):(2)
} while (DATA LEFT TO PROCESS)
close("subprogram")
- The first time an I/O operation is executed using the `|&' operator,
-`gawk' creates a two-way pipeline to a child process that runs the
-other program. Output created with `print' or `printf' is written to
-the program's standard input, and output from the program's standard
-output can be read by the `gawk' program using `getline'. As is the
-case with processes started by `|', the subprogram can be any program,
-or pipeline of programs, that can be started by the shell.
+ The first time an I/O operation is executed using the '|&' operator,
+'gawk' creates a two-way pipeline to a child process that runs the other
+program. Output created with 'print' or 'printf' is written to the
+program's standard input, and output from the program's standard output
+can be read by the 'gawk' program using 'getline'. As is the case with
+processes started by '|', the subprogram can be any program, or pipeline
+of programs, that can be started by the shell.
There are some cautionary items to be aware of:
- * As the code inside `gawk' currently stands, the coprocess's
- standard error goes to the same place that the parent `gawk''s
- standard error goes. It is not possible to read the child's
+ * As the code inside 'gawk' currently stands, the coprocess's
+ standard error goes to the same place that the parent 'gawk''s
+ standard error goes. It is not possible to read the child's
standard error separately.
- * I/O buffering may be a problem. `gawk' automatically flushes all
+ * I/O buffering may be a problem. 'gawk' automatically flushes all
output down the pipe to the coprocess. However, if the coprocess
- does not flush its output, `gawk' may hang when doing a `getline'
+ does not flush its output, 'gawk' may hang when doing a 'getline'
in order to read the coprocess's results. This could lead to a
situation known as "deadlock", where each process is waiting for
the other one to do something.
It is possible to close just one end of the two-way pipe to a
-coprocess, by supplying a second argument to the `close()' function of
-either `"to"' or `"from"' (*note Close Files And Pipes::). These
-strings tell `gawk' to close the end of the pipe that sends data to the
+coprocess, by supplying a second argument to the 'close()' function of
+either '"to"' or '"from"' (*note Close Files And Pipes::). These
+strings tell 'gawk' to close the end of the pipe that sends data to the
coprocess or the end that reads from it, respectively.
- This is particularly necessary in order to use the system `sort'
-utility as part of a coprocess; `sort' must read _all_ of its input
-data before it can produce any output. The `sort' program does not
-receive an end-of-file indication until `gawk' closes the write end of
-the pipe.
+ This is particularly necessary in order to use the system 'sort'
+utility as part of a coprocess; 'sort' must read _all_ of its input data
+before it can produce any output. The 'sort' program does not receive
+an end-of-file indication until 'gawk' closes the write end of the pipe.
- When you have finished writing data to the `sort' utility, you can
-close the `"to"' end of the pipe, and then start reading sorted data
-via `getline'. For example:
+ When you have finished writing data to the 'sort' utility, you can
+close the '"to"' end of the pipe, and then start reading sorted data via
+'getline'. For example:
BEGIN {
command = "LC_ALL=C sort"
@@ -19635,20 +19552,20 @@ via `getline'. For example:
}
This program writes the letters of the alphabet in reverse order, one
-per line, down the two-way pipe to `sort'. It then closes the write
-end of the pipe, so that `sort' receives an end-of-file indication.
-This causes `sort' to sort the data and write the sorted data back to
-the `gawk' program. Once all of the data has been read, `gawk'
-terminates the coprocess and exits.
-
- As a side note, the assignment `LC_ALL=C' in the `sort' command
-ensures traditional Unix (ASCII) sorting from `sort'. This is not
+per line, down the two-way pipe to 'sort'. It then closes the write end
+of the pipe, so that 'sort' receives an end-of-file indication. This
+causes 'sort' to sort the data and write the sorted data back to the
+'gawk' program. Once all of the data has been read, 'gawk' terminates
+the coprocess and exits.
+
+ As a side note, the assignment 'LC_ALL=C' in the 'sort' command
+ensures traditional Unix (ASCII) sorting from 'sort'. This is not
strictly necessary here, but it's good to know how to do this.
- You may also use pseudo-ttys (ptys) for two-way communication
-instead of pipes, if your system supports them. This is done on a
-per-command basis, by setting a special element in the `PROCINFO' array
-(*note Auto-set::), like so:
+ You may also use pseudo-ttys (ptys) for two-way communication instead
+of pipes, if your system supports them. This is done on a per-command
+basis, by setting a special element in the 'PROCINFO' array (*note
+Auto-set::), like so:
command = "sort -nr" # command, save in convenience variable
PROCINFO[command, "pty"] = 1 # update PROCINFO
@@ -19657,13 +19574,13 @@ per-command basis, by setting a special element in
the `PROCINFO' array
Using ptys usually avoids the buffer deadlock issues described earlier,
at some loss in performance. If your system does not have ptys, or if
-all the system's ptys are in use, `gawk' automatically falls back to
+all the system's ptys are in use, 'gawk' automatically falls back to
using regular pipes.
---------- Footnotes ----------
- (1) Michael Brennan suggests the use of `rand()' to generate unique
-file names. This is a valid point; nevertheless, temporary files remain
+ (1) Michael Brennan suggests the use of 'rand()' to generate unique
+file names. This is a valid point; nevertheless, temporary files remain
more difficult to use than two-way pipes.
(2) This is very different from the same operator in the C shell and
@@ -19672,60 +19589,60 @@ in Bash.
File: gawk.info, Node: TCP/IP Networking, Next: Profiling, Prev: Two-way
I/O, Up: Advanced Features
-12.4 Using `gawk' for Network Programming
+12.4 Using 'gawk' for Network Programming
=========================================
- `EMRED':
- A host is a host from coast to coast,
- and nobody talks to a host that's close,
- unless the host that isn't close
- is busy, hung, or dead. -- Mike O'Brien (aka Mr. Protocol)
+ 'EMRED':
+ A host is a host from coast to coast,
+ and nobody talks to a host that's close,
+ unless the host that isn't close
+ is busy, hung, or dead.
+ -- _Mike O'Brien (aka Mr. Protocol)_
-In addition to being able to open a two-way pipeline to a coprocess on
-the same system (*note Two-way I/O::), it is possible to make a two-way
-connection to another process on another system across an IP network
-connection.
+ In addition to being able to open a two-way pipeline to a coprocess
+on the same system (*note Two-way I/O::), it is possible to make a
+two-way connection to another process on another system across an IP
+network connection.
You can think of this as just a _very long_ two-way pipeline to a
-coprocess. The way `gawk' decides that you want to use TCP/IP
+coprocess. The way 'gawk' decides that you want to use TCP/IP
networking is by recognizing special file names that begin with one of
-`/inet/', `/inet4/', or `/inet6/'.
+'/inet/', '/inet4/', or '/inet6/'.
The full syntax of the special file name is
-`/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT'. The
-components are:
+'/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT'. The components
+are:
NET-TYPE
- Specifies the kind of Internet connection to make. Use `/inet4/'
- to force IPv4, and `/inet6/' to force IPv6. Plain `/inet/' (which
+ Specifies the kind of Internet connection to make. Use '/inet4/'
+ to force IPv4, and '/inet6/' to force IPv6. Plain '/inet/' (which
used to be the only option) uses the system default, most likely
IPv4.
PROTOCOL
- The protocol to use over IP. This must be either `tcp', or `udp',
+ The protocol to use over IP. This must be either 'tcp', or 'udp',
for a TCP or UDP IP connection, respectively. TCP should be used
for most applications.
LOCAL-PORT
- The local TCP or UDP port number to use. Use a port number of `0'
- when you want the system to pick a port. This is what you should do
- when writing a TCP or UDP client. You may also use a well-known
- service name, such as `smtp' or `http', in which case `gawk'
+ The local TCP or UDP port number to use. Use a port number of '0'
+ when you want the system to pick a port. This is what you should
+ do when writing a TCP or UDP client. You may also use a well-known
+ service name, such as 'smtp' or 'http', in which case 'gawk'
attempts to determine the predefined port number using the C
- `getaddrinfo()' function.
+ 'getaddrinfo()' function.
REMOTE-HOST
The IP address or fully qualified domain name of the Internet host
to which you want to connect.
REMOTE-PORT
- The TCP or UDP port number to use on the given REMOTE-HOST.
- Again, use `0' if you don't care, or else a well-known service
- name.
+ The TCP or UDP port number to use on the given REMOTE-HOST. Again,
+ use '0' if you don't care, or else a well-known service name.
- NOTE: Failure in opening a two-way socket will result in a
- nonfatal error being returned to the calling code. The value of
- `ERRNO' indicates the error (*note Auto-set::).
+ NOTE: Failure in opening a two-way socket will result in a nonfatal
+ error being returned to the calling code. The value of 'ERRNO'
+ indicates the error (*note Auto-set::).
Consider the following very simple example:
@@ -19737,38 +19654,37 @@ REMOTE-PORT
}
This program reads the current date and time from the local system's
-TCP `daytime' server. It then prints the results and closes the
+TCP 'daytime' server. It then prints the results and closes the
connection.
- Because this topic is extensive, the use of `gawk' for TCP/IP
-programming is documented separately. See *note (General
-Introduction)Top:: gawkinet, TCP/IP Internetworking with `gawk', for a
-much more complete introduction and discussion, as well as extensive
-examples.
+ Because this topic is extensive, the use of 'gawk' for TCP/IP
+programming is documented separately. See *note (General Introduction,
+gawkinet, TCP/IP Internetworking with 'gawk')Top::, for a much more
+complete introduction and discussion, as well as extensive examples.
File: gawk.info, Node: Profiling, Next: Advanced Features Summary, Prev:
TCP/IP Networking, Up: Advanced Features
-12.5 Profiling Your `awk' Programs
+12.5 Profiling Your 'awk' Programs
==================================
-You may produce execution traces of your `awk' programs. This is done
-by passing the option `--profile' to `gawk'. When `gawk' has finished
+You may produce execution traces of your 'awk' programs. This is done
+by passing the option '--profile' to 'gawk'. When 'gawk' has finished
running, it creates a profile of your program in a file named
-`awkprof.out'. Because it is profiling, it also executes up to 45%
-slower than `gawk' normally does.
+'awkprof.out'. Because it is profiling, it also executes up to 45%
+slower than 'gawk' normally does.
- As shown in the following example, the `--profile' option can be
-used to change the name of the file where `gawk' will write the profile:
+ As shown in the following example, the '--profile' option can be used
+to change the name of the file where 'gawk' will write the profile:
gawk --profile=myprog.prof -f myprog.awk data1 data2
-In the preceding example, `gawk' places the profile in `myprog.prof'
-instead of in `awkprof.out'.
+In the preceding example, 'gawk' places the profile in 'myprog.prof'
+instead of in 'awkprof.out'.
- Here is a sample session showing a simple `awk' program, its input
-data, and the results from running `gawk' with the `--profile' option.
-First, the `awk' program:
+ Here is a sample session showing a simple 'awk' program, its input
+data, and the results from running 'gawk' with the '--profile' option.
+First, the 'awk' program:
BEGIN { print "First BEGIN rule" }
@@ -19804,9 +19720,9 @@ First, the `awk' program:
foo
junk
- Here is the `awkprof.out' that results from running the `gawk'
+ Here is the 'awkprof.out' that results from running the 'gawk'
profiler on this program and data (this example also illustrates that
-`awk' programmers sometimes get up very early in the morning to work):
+'awk' programmers sometimes get up very early in the morning to work):
# gawk profile, created Mon Sep 29 05:16:21 2014
@@ -19858,62 +19774,61 @@ profiler on this program and data (this example also
illustrates that
This example illustrates many of the basic features of profiling
output. They are as follows:
- * The program is printed in the order `BEGIN' rules, `BEGINFILE'
- rules, pattern-action rules, `ENDFILE' rules, `END' rules, and
- functions, listed alphabetically. Multiple `BEGIN' and `END'
- rules retain their separate identities, as do multiple `BEGINFILE'
- and `ENDFILE' rules.
+ * The program is printed in the order 'BEGIN' rules, 'BEGINFILE'
+ rules, pattern-action rules, 'ENDFILE' rules, 'END' rules, and
+ functions, listed alphabetically. Multiple 'BEGIN' and 'END' rules
+ retain their separate identities, as do multiple 'BEGINFILE' and
+ 'ENDFILE' rules.
- * Pattern-action rules have two counts. The first count, to the
- left of the rule, shows how many times the rule's pattern was
- _tested_. The second count, to the right of the rule's opening
- left brace in a comment, shows how many times the rule's action
- was _executed_. The difference between the two indicates how many
- times the rule's pattern evaluated to false.
+ * Pattern-action rules have two counts. The first count, to the left
+ of the rule, shows how many times the rule's pattern was _tested_.
+ The second count, to the right of the rule's opening left brace in
+ a comment, shows how many times the rule's action was _executed_.
+ The difference between the two indicates how many times the rule's
+ pattern evaluated to false.
- * Similarly, the count for an `if'-`else' statement shows how many
+ * Similarly, the count for an 'if'-'else' statement shows how many
times the condition was tested. To the right of the opening left
- brace for the `if''s body is a count showing how many times the
- condition was true. The count for the `else' indicates how many
+ brace for the 'if''s body is a count showing how many times the
+ condition was true. The count for the 'else' indicates how many
times the test failed.
- * The count for a loop header (such as `for' or `while') shows how
- many times the loop test was executed. (Because of this, you
- can't just look at the count on the first statement in a rule to
+ * The count for a loop header (such as 'for' or 'while') shows how
+ many times the loop test was executed. (Because of this, you can't
+ just look at the count on the first statement in a rule to
determine how many times the rule was executed. If the first
statement is a loop, the count is misleading.)
- * For user-defined functions, the count next to the `function'
+ * For user-defined functions, the count next to the 'function'
keyword indicates how many times the function was called. The
- counts next to the statements in the body show how many times
- those statements were executed.
+ counts next to the statements in the body show how many times those
+ statements were executed.
- * The layout uses "K&R" style with TABs. Braces are used
- everywhere, even when the body of an `if', `else', or loop is only
- a single statement.
+ * The layout uses "K&R" style with TABs. Braces are used everywhere,
+ even when the body of an 'if', 'else', or loop is only a single
+ statement.
* Parentheses are used only where needed, as indicated by the
structure of the program and the precedence rules. For example,
- `(3 + 5) * 4' means add three and five, then multiply the total by
- four. However, `3 + 5 * 4' has no parentheses, and means `3 + (5
- * 4)'.
+ '(3 + 5) * 4' means add three and five, then multiply the total by
+ four. However, '3 + 5 * 4' has no parentheses, and means '3 + (5 *
+ 4)'.
- * Parentheses are used around the arguments to `print' and `printf'
- only when the `print' or `printf' statement is followed by a
+ * Parentheses are used around the arguments to 'print' and 'printf'
+ only when the 'print' or 'printf' statement is followed by a
redirection. Similarly, if the target of a redirection isn't a
scalar, it gets parenthesized.
- * `gawk' supplies leading comments in front of the `BEGIN' and `END'
- rules, the `BEGINFILE' and `ENDFILE' rules, the pattern-action
+ * 'gawk' supplies leading comments in front of the 'BEGIN' and 'END'
+ rules, the 'BEGINFILE' and 'ENDFILE' rules, the pattern-action
rules, and the functions.
-
The profiled version of your program may not look exactly like what
-you typed when you wrote it. This is because `gawk' creates the
-profiled version by "pretty-printing" its internal representation of
-the program. The advantage to this is that `gawk' can produce a
-standard representation. The disadvantage is that all source code
-comments are lost. Also, things such as:
+you typed when you wrote it. This is because 'gawk' creates the
+profiled version by "pretty-printing" its internal representation of the
+program. The advantage to this is that 'gawk' can produce a standard
+representation. The disadvantage is that all source code comments are
+lost. Also, things such as:
/foo/
@@ -19925,23 +19840,23 @@ come out as:
which is correct, but possibly unexpected.
- Besides creating profiles when a program has completed, `gawk' can
-produce a profile while it is running. This is useful if your `awk'
+ Besides creating profiles when a program has completed, 'gawk' can
+produce a profile while it is running. This is useful if your 'awk'
program goes into an infinite loop and you want to see what has been
-executed. To use this feature, run `gawk' with the `--profile' option
+executed. To use this feature, run 'gawk' with the '--profile' option
in the background:
$ gawk --profile -f myprog &
[1] 13992
The shell prints a job number and process ID number; in this case,
-13992. Use the `kill' command to send the `USR1' signal to `gawk':
+13992. Use the 'kill' command to send the 'USR1' signal to 'gawk':
$ kill -USR1 13992
As usual, the profiled version of the program is written to
-`awkprof.out', or to a different file if one was specified with the
-`--profile' option.
+'awkprof.out', or to a different file if one was specified with the
+'--profile' option.
Along with the regular profile, as shown earlier, the profile file
includes a trace of any active functions:
@@ -19953,26 +19868,26 @@ includes a trace of any active functions:
# 1. foo
# -- main --
- You may send `gawk' the `USR1' signal as many times as you like.
+ You may send 'gawk' the 'USR1' signal as many times as you like.
Each time, the profile and function call trace are appended to the
output profile file.
- If you use the `HUP' signal instead of the `USR1' signal, `gawk'
+ If you use the 'HUP' signal instead of the 'USR1' signal, 'gawk'
produces the profile and the function call trace and then exits.
- When `gawk' runs on MS-Windows systems, it uses the `INT' and `QUIT'
-signals for producing the profile, and in the case of the `INT' signal,
-`gawk' exits. This is because these systems don't support the `kill'
+ When 'gawk' runs on MS-Windows systems, it uses the 'INT' and 'QUIT'
+signals for producing the profile, and in the case of the 'INT' signal,
+'gawk' exits. This is because these systems don't support the 'kill'
command, so the only signals you can deliver to a program are those
-generated by the keyboard. The `INT' signal is generated by the
-`Ctrl-c' or `Ctrl-BREAK' key, while the `QUIT' signal is generated by
-the `Ctrl-\' key.
+generated by the keyboard. The 'INT' signal is generated by the
+'Ctrl-c' or 'Ctrl-BREAK' key, while the 'QUIT' signal is generated by
+the 'Ctrl-\' key.
- Finally, `gawk' also accepts another option, `--pretty-print'. When
-called this way, `gawk' "pretty-prints" the program into `awkprof.out',
+ Finally, 'gawk' also accepts another option, '--pretty-print'. When
+called this way, 'gawk' "pretty-prints" the program into 'awkprof.out',
without any execution counts.
- NOTE: The `--pretty-print' option still runs your program. This
+ NOTE: The '--pretty-print' option still runs your program. This
will change in the next major release.
@@ -19981,47 +19896,46 @@ File: gawk.info, Node: Advanced Features Summary,
Prev: Profiling, Up: Advanc
12.6 Summary
============
- * The `--non-decimal-data' option causes `gawk' to treat octal- and
+ * The '--non-decimal-data' option causes 'gawk' to treat octal- and
hexadecimal-looking input data as octal and hexadecimal. This
option should be used with caution or not at all; use of
- `strtonum()' is preferable. Note that this option may disappear
- in a future version of `gawk'.
+ 'strtonum()' is preferable. Note that this option may disappear in
+ a future version of 'gawk'.
- * You can take over complete control of sorting in `for (INDX in
- ARRAY)' array traversal by setting `PROCINFO["sorted_in"]' to the
+ * You can take over complete control of sorting in 'for (INDX in
+ ARRAY)' array traversal by setting 'PROCINFO["sorted_in"]' to the
name of a user-defined function that does the comparison of array
elements based on index and value.
* Similarly, you can supply the name of a user-defined comparison
- function as the third argument to either `asort()' or `asorti()'
- to control how those functions sort arrays. Or you may provide one
- of the predefined control strings that work for
- `PROCINFO["sorted_in"]'.
-
- * You can use the `|&' operator to create a two-way pipe to a
- coprocess. You read from the coprocess with `getline' and write
- to it with `print' or `printf'. Use `close()' to close off the
+ function as the third argument to either 'asort()' or 'asorti()' to
+ control how those functions sort arrays. Or you may provide one of
+ the predefined control strings that work for
+ 'PROCINFO["sorted_in"]'.
+
+ * You can use the '|&' operator to create a two-way pipe to a
+ coprocess. You read from the coprocess with 'getline' and write to
+ it with 'print' or 'printf'. Use 'close()' to close off the
coprocess completely, or optionally, close off one side of the
two-way communications.
- * By using special file names with the `|&' operator, you can open a
+ * By using special file names with the '|&' operator, you can open a
TCP/IP (or UDP/IP) connection to remote hosts on the Internet.
- `gawk' supports both IPv4 and IPv6.
+ 'gawk' supports both IPv4 and IPv6.
- * You can generate statement count profiles of your program. This
+ * You can generate statement count profiles of your program. This
can help you determine which parts of your program may be taking
the most time and let you tune them more easily. Sending the
- `USR1' signal while profiling causes `gawk' to dump the profile
- and keep going, including a function call stack.
+ 'USR1' signal while profiling causes 'gawk' to dump the profile and
+ keep going, including a function call stack.
- * You can also just "pretty-print" the program. This currently also
+ * You can also just "pretty-print" the program. This currently also
runs the program, but that will change in the next major release.
-
File: gawk.info, Node: Internationalization, Next: Debugger, Prev: Advanced
Features, Up: Top
-13 Internationalization with `gawk'
+13 Internationalization with 'gawk'
***********************************
Once upon a time, computer makers wrote software that worked only in
@@ -20033,21 +19947,21 @@ became a common practice.
For many years, the ability to provide internationalization was
largely restricted to programs written in C and C++. This major node
-describes the underlying library `gawk' uses for internationalization,
-as well as how `gawk' makes internationalization features available at
-the `awk' program level. Having internationalization available at the
-`awk' level gives software developers additional flexibility--they are
+describes the underlying library 'gawk' uses for internationalization,
+as well as how 'gawk' makes internationalization features available at
+the 'awk' program level. Having internationalization available at the
+'awk' level gives software developers additional flexibility--they are
no longer forced to write in C or C++ when internationalization is a
requirement.
* Menu:
* I18N and L10N:: Internationalization and Localization.
-* Explaining gettext:: How GNU `gettext' works.
+* Explaining gettext:: How GNU 'gettext' works.
* Programmer i18n:: Features for the programmer.
* Translator i18n:: Features for the translator.
* I18N Example:: A simple i18n example.
-* Gawk I18N:: `gawk' is also internationalized.
+* Gawk I18N:: 'gawk' is also internationalized.
* I18N Summary:: Summary of I18N stuff.
@@ -20059,69 +19973,69 @@ File: gawk.info, Node: I18N and L10N, Next:
Explaining gettext, Up: Internati
"Internationalization" means writing (or modifying) a program once, in
such a way that it can use multiple languages without requiring further
source code changes. "Localization" means providing the data necessary
-for an internationalized program to work in a particular language.
-Most typically, these terms refer to features such as the language used
-for printing error messages, the language used to read responses, and
-information related to how numerical and monetary values are printed
-and read.
+for an internationalized program to work in a particular language. Most
+typically, these terms refer to features such as the language used for
+printing error messages, the language used to read responses, and
+information related to how numerical and monetary values are printed and
+read.
File: gawk.info, Node: Explaining gettext, Next: Programmer i18n, Prev:
I18N and L10N, Up: Internationalization
-13.2 GNU `gettext'
+13.2 GNU 'gettext'
==================
-`gawk' uses GNU `gettext' to provide its internationalization features.
-The facilities in GNU `gettext' focus on messages: strings printed by a
-program, either directly or via formatting with `printf' or
-`sprintf()'.(1)
+'gawk' uses GNU 'gettext' to provide its internationalization features.
+The facilities in GNU 'gettext' focus on messages: strings printed by a
+program, either directly or via formatting with 'printf' or
+'sprintf()'.(1)
- When using GNU `gettext', each application has its own "text
-domain". This is a unique name, such as `kpilot' or `gawk', that
-identifies the application. A complete application may have multiple
+ When using GNU 'gettext', each application has its own "text domain".
+This is a unique name, such as 'kpilot' or 'gawk', that identifies the
+application. A complete application may have multiple
components--programs written in C or C++, as well as scripts written in
-`sh' or `awk'. All of the components use the same text domain.
+'sh' or 'awk'. All of the components use the same text domain.
To make the discussion concrete, assume we're writing an application
-named `guide'. Internationalization consists of the following steps,
-in this order:
+named 'guide'. Internationalization consists of the following steps, in
+this order:
- 1. The programmer reviews the source for all of `guide''s components
+ 1. The programmer reviews the source for all of 'guide''s components
and marks each string that is a candidate for translation. For
- example, `"`-F': option required"' is a good candidate for
+ example, '"`-F': option required"' is a good candidate for
translation. A table with strings of option names is not (e.g.,
- `gawk''s `--profile' option should remain the same, no matter what
+ 'gawk''s '--profile' option should remain the same, no matter what
the local language).
- 2. The programmer indicates the application's text domain (`"guide"')
- to the `gettext' library, by calling the `textdomain()' function.
+ 2. The programmer indicates the application's text domain ('"guide"')
+ to the 'gettext' library, by calling the 'textdomain()' function.
3. Messages from the application are extracted from the source code
- and collected into a portable object template file (`guide.pot'),
+ and collected into a portable object template file ('guide.pot'),
which lists the strings and their translations. The translations
- are initially empty. The original (usually English) messages
- serve as the key for lookup of the translations.
+ are initially empty. The original (usually English) messages serve
+ as the key for lookup of the translations.
- 4. For each language with a translator, `guide.pot' is copied to a
- portable object file (`.po') and translations are created and
+ 4. For each language with a translator, 'guide.pot' is copied to a
+ portable object file ('.po') and translations are created and
shipped with the application. For example, there might be a
- `fr.po' for a French translation.
+ 'fr.po' for a French translation.
- 5. Each language's `.po' file is converted into a binary message
- object (`.gmo') file. A message object file contains the original
- messages and their translations in a binary format that allows
- fast lookup of translations at runtime.
+ 5. Each language's '.po' file is converted into a binary message
+ object ('.gmo') file. A message object file contains the original
+ messages and their translations in a binary format that allows fast
+ lookup of translations at runtime.
- 6. When `guide' is built and installed, the binary translation files
+ 6. When 'guide' is built and installed, the binary translation files
are installed in a standard place.
- 7. For testing and development, it is possible to tell `gettext' to
- use `.gmo' files in a different directory than the standard one by
- using the `bindtextdomain()' function.
+ 7. For testing and development, it is possible to tell 'gettext' to
+ use '.gmo' files in a different directory than the standard one by
+ using the 'bindtextdomain()' function.
- 8. At runtime, `guide' looks up each string via a call to
- `gettext()'. The returned string is the translated string if
- available, or the original string if not.
+ 8. At runtime, 'guide' looks up each string via a call to 'gettext()'.
+ The returned string is the translated string if available, or the
+ original string if not.
9. If necessary, it is possible to access messages from a different
text domain than the one belonging to the application, without
@@ -20129,16 +20043,16 @@ in this order:
forth.
In C (or C++), the string marking and dynamic translation lookup are
-accomplished by wrapping each string in a call to `gettext()':
+accomplished by wrapping each string in a call to 'gettext()':
printf("%s", gettext("Don't Panic!\n"));
- The tools that extract messages from source code pull out all
-strings enclosed in calls to `gettext()'.
+ The tools that extract messages from source code pull out all strings
+enclosed in calls to 'gettext()'.
- The GNU `gettext' developers, recognizing that typing `gettext(...)'
+ The GNU 'gettext' developers, recognizing that typing 'gettext(...)'
over and over again is both painful and ugly to look at, use the macro
-`_' (an underscore) to make things easier:
+'_' (an underscore) to make things easier:
/* In the standard header file: */
#define _(str) gettext(str)
@@ -20150,121 +20064,121 @@ This reduces the typing overhead to just three
extra characters per
string and is considerably easier to read as well.
There are locale "categories" for different types of locale-related
-information. The defined locale categories that `gettext' knows about
+information. The defined locale categories that 'gettext' knows about
are:
-`LC_MESSAGES'
- Text messages. This is the default category for `gettext'
+'LC_MESSAGES'
+ Text messages. This is the default category for 'gettext'
operations, but it is possible to supply a different one
explicitly, if necessary. (It is almost never necessary to supply
a different category.)
-`LC_COLLATE'
+'LC_COLLATE'
Text-collation information (i.e., how different characters and/or
groups of characters sort in a given language).
-`LC_CTYPE'
- Character-type information (alphabetic, digit, upper- or
- lowercase, and so on) as well as character encoding. This
- information is accessed via the POSIX character classes in regular
- expressions, such as `/[[:alnum:]]/' (*note Bracket Expressions::).
+'LC_CTYPE'
+ Character-type information (alphabetic, digit, upper- or lowercase,
+ and so on) as well as character encoding. This information is
+ accessed via the POSIX character classes in regular expressions,
+ such as '/[[:alnum:]]/' (*note Bracket Expressions::).
-`LC_MONETARY'
+'LC_MONETARY'
Monetary information, such as the currency symbol, and whether the
symbol goes before or after a number.
-`LC_NUMERIC'
+'LC_NUMERIC'
Numeric information, such as which characters to use for the
decimal point and the thousands separator.(2)
-`LC_TIME'
+'LC_TIME'
Time- and date-related information, such as 12- or 24-hour clock,
month printed before or after the day in a date, local month
abbreviations, and so on.
-`LC_ALL'
- All of the above. (Not too useful in the context of `gettext'.)
+'LC_ALL'
+ All of the above. (Not too useful in the context of 'gettext'.)
---------- Footnotes ----------
- (1) For some operating systems, the `gawk' port doesn't support GNU
-`gettext'. Therefore, these features are not available if you are
-using one of those operating systems. Sorry.
+ (1) For some operating systems, the 'gawk' port doesn't support GNU
+'gettext'. Therefore, these features are not available if you are using
+one of those operating systems. Sorry.
- (2) Americans use a comma every three decimal places and a period
-for the decimal point, while many Europeans do exactly the opposite:
+ (2) Americans use a comma every three decimal places and a period for
+the decimal point, while many Europeans do exactly the opposite:
1,234.56 versus 1.234,56.
File: gawk.info, Node: Programmer i18n, Next: Translator i18n, Prev:
Explaining gettext, Up: Internationalization
-13.3 Internationalizing `awk' Programs
+13.3 Internationalizing 'awk' Programs
======================================
-`gawk' provides the following variables for internationalization:
+'gawk' provides the following variables for internationalization:
-`TEXTDOMAIN'
+'TEXTDOMAIN'
This variable indicates the application's text domain. For
- compatibility with GNU `gettext', the default value is
- `"messages"'.
+ compatibility with GNU 'gettext', the default value is
+ '"messages"'.
-`_"your message here"'
+'_"your message here"'
String constants marked with a leading underscore are candidates
for translation at runtime. String constants without a leading
underscore are not translated.
- `gawk' provides the following functions for internationalization:
+ 'gawk' provides the following functions for internationalization:
-``dcgettext(STRING' [`,' DOMAIN [`,' CATEGORY]]`)''
+'dcgettext(STRING [, DOMAIN [, CATEGORY]])'
Return the translation of STRING in text domain DOMAIN for locale
category CATEGORY. The default value for DOMAIN is the current
- value of `TEXTDOMAIN'. The default value for CATEGORY is
- `"LC_MESSAGES"'.
+ value of 'TEXTDOMAIN'. The default value for CATEGORY is
+ '"LC_MESSAGES"'.
If you supply a value for CATEGORY, it must be a string equal to
one of the known locale categories described in *note Explaining
- gettext::. You must also supply a text domain. Use `TEXTDOMAIN'
+ gettext::. You must also supply a text domain. Use 'TEXTDOMAIN'
if you want to use the current domain.
- CAUTION: The order of arguments to the `awk' version of the
- `dcgettext()' function is purposely different from the order
- for the C version. The `awk' version's order was chosen to
- be simple and to allow for reasonable `awk'-style default
+ CAUTION: The order of arguments to the 'awk' version of the
+ 'dcgettext()' function is purposely different from the order
+ for the C version. The 'awk' version's order was chosen to be
+ simple and to allow for reasonable 'awk'-style default
arguments.
-``dcngettext(STRING1, STRING2, NUMBER' [`,' DOMAIN [`,' CATEGORY]]`)''
+'dcngettext(STRING1, STRING2, NUMBER [, DOMAIN [, CATEGORY]])'
Return the plural form used for NUMBER of the translation of
STRING1 and STRING2 in text domain DOMAIN for locale category
- CATEGORY. STRING1 is the English singular variant of a message,
- and STRING2 is the English plural variant of the same message.
- The default value for DOMAIN is the current value of `TEXTDOMAIN'.
- The default value for CATEGORY is `"LC_MESSAGES"'.
+ CATEGORY. STRING1 is the English singular variant of a message,
+ and STRING2 is the English plural variant of the same message. The
+ default value for DOMAIN is the current value of 'TEXTDOMAIN'. The
+ default value for CATEGORY is '"LC_MESSAGES"'.
- The same remarks about argument order as for the `dcgettext()'
+ The same remarks about argument order as for the 'dcgettext()'
function apply.
-``bindtextdomain(DIRECTORY' [`,' DOMAIN ]`)''
- Change the directory in which `gettext' looks for `.gmo' files, in
+'bindtextdomain(DIRECTORY [, DOMAIN ])'
+ Change the directory in which 'gettext' looks for '.gmo' files, in
case they will not or cannot be placed in the standard locations
(e.g., during testing). Return the directory in which DOMAIN is
"bound."
- The default DOMAIN is the value of `TEXTDOMAIN'. If DIRECTORY is
- the null string (`""'), then `bindtextdomain()' returns the
- current binding for the given DOMAIN.
+ The default DOMAIN is the value of 'TEXTDOMAIN'. If DIRECTORY is
+ the null string ('""'), then 'bindtextdomain()' returns the current
+ binding for the given DOMAIN.
- To use these facilities in your `awk' program, follow these steps:
+ To use these facilities in your 'awk' program, follow these steps:
- 1. Set the variable `TEXTDOMAIN' to the text domain of your program.
- This is best done in a `BEGIN' rule (*note BEGIN/END::), or it can
- also be done via the `-v' command-line option (*note Options::):
+ 1. Set the variable 'TEXTDOMAIN' to the text domain of your program.
+ This is best done in a 'BEGIN' rule (*note BEGIN/END::), or it can
+ also be done via the '-v' command-line option (*note Options::):
BEGIN {
TEXTDOMAIN = "guide"
...
}
- 2. Mark all translatable strings with a leading underscore (`_')
+ 2. Mark all translatable strings with a leading underscore ('_')
character. It _must_ be adjacent to the opening quote of the
string. For example:
@@ -20273,7 +20187,7 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
printf(_"Number of users is %d\n", nusers)
3. If you are creating strings dynamically, you can still translate
- them, using the `dcgettext()' built-in function:(1)
+ them, using the 'dcgettext()' built-in function:(1)
if (groggy)
message = dcgettext("%d customers disturbing me\n", "adminprog")
@@ -20281,12 +20195,12 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
message = dcgettext("enjoying %d customers\n", "adminprog")
printf(message, ncustomers)
- Here, the call to `dcgettext()' supplies a different text domain
- (`"adminprog"') in which to find the message, but it uses the
- default `"LC_MESSAGES"' category.
+ Here, the call to 'dcgettext()' supplies a different text domain
+ ('"adminprog"') in which to find the message, but it uses the
+ default '"LC_MESSAGES"' category.
- The previous example only works if `ncustomers' is greater than
- one. This example would be better done with `dcngettext()':
+ The previous example only works if 'ncustomers' is greater than
+ one. This example would be better done with 'dcngettext()':
if (groggy)
message = dcngettext("%d customer disturbing me\n",
@@ -20296,9 +20210,9 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
"enjoying %d customers\n", "adminprog")
printf(message, ncustomers)
- 4. During development, you might want to put the `.gmo' file in a
+ 4. During development, you might want to put the '.gmo' file in a
private directory for testing. This is done with the
- `bindtextdomain()' built-in function:
+ 'bindtextdomain()' built-in function:
BEGIN {
TEXTDOMAIN = "guide" # our text domain
@@ -20311,9 +20225,8 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
...
}
-
*Note I18N Example::, for an example program showing the steps to
-create and use translations from `awk'.
+create and use translations from 'awk'.
---------- Footnotes ----------
@@ -20322,23 +20235,23 @@ create and use translations from `awk'.
File: gawk.info, Node: Translator i18n, Next: I18N Example, Prev:
Programmer i18n, Up: Internationalization
-13.4 Translating `awk' Programs
+13.4 Translating 'awk' Programs
===============================
Once a program's translatable strings have been marked, they must be
-extracted to create the initial `.pot' file. As part of translation,
-it is often helpful to rearrange the order in which arguments to
-`printf' are output.
+extracted to create the initial '.pot' file. As part of translation, it
+is often helpful to rearrange the order in which arguments to 'printf'
+are output.
- `gawk''s `--gen-pot' command-line option extracts the messages and
-is discussed next. After that, `printf''s ability to rearrange the
-order for `printf' arguments at runtime is covered.
+ 'gawk''s '--gen-pot' command-line option extracts the messages and is
+discussed next. After that, 'printf''s ability to rearrange the order
+for 'printf' arguments at runtime is covered.
* Menu:
* String Extraction:: Extracting marked strings.
-* Printf Ordering:: Rearranging `printf' arguments.
-* I18N Portability:: `awk'-level portability issues.
+* Printf Ordering:: Rearranging 'printf' arguments.
+* I18N Portability:: 'awk'-level portability issues.
File: gawk.info, Node: String Extraction, Next: Printf Ordering, Up:
Translator i18n
@@ -20346,36 +20259,36 @@ File: gawk.info, Node: String Extraction, Next:
Printf Ordering, Up: Translat
13.4.1 Extracting Marked Strings
--------------------------------
-Once your `awk' program is working, and all the strings have been
-marked and you've set (and perhaps bound) the text domain, it is time
-to produce translations. First, use the `--gen-pot' command-line
-option to create the initial `.pot' file:
+Once your 'awk' program is working, and all the strings have been marked
+and you've set (and perhaps bound) the text domain, it is time to
+produce translations. First, use the '--gen-pot' command-line option to
+create the initial '.pot' file:
gawk --gen-pot -f guide.awk > guide.pot
- When run with `--gen-pot', `gawk' does not execute your program.
-Instead, it parses it as usual and prints all marked strings to
-standard output in the format of a GNU `gettext' Portable Object file.
-Also included in the output are any constant strings that appear as the
-first argument to `dcgettext()' or as the first and second argument to
-`dcngettext()'.(1) You should distribute the generated `.pot' file with
-your `awk' program; translators will eventually use it to provide you
+ When run with '--gen-pot', 'gawk' does not execute your program.
+Instead, it parses it as usual and prints all marked strings to standard
+output in the format of a GNU 'gettext' Portable Object file. Also
+included in the output are any constant strings that appear as the first
+argument to 'dcgettext()' or as the first and second argument to
+'dcngettext()'.(1) You should distribute the generated '.pot' file with
+your 'awk' program; translators will eventually use it to provide you
translations that you can also then distribute. *Note I18N Example::,
-for the full list of steps to go through to create and test
-translations for `guide'.
+for the full list of steps to go through to create and test translations
+for 'guide'.
---------- Footnotes ----------
- (1) The `xgettext' utility that comes with GNU `gettext' can handle
-`.awk' files.
+ (1) The 'xgettext' utility that comes with GNU 'gettext' can handle
+'.awk' files.
File: gawk.info, Node: Printf Ordering, Next: I18N Portability, Prev:
String Extraction, Up: Translator i18n
-13.4.2 Rearranging `printf' Arguments
+13.4.2 Rearranging 'printf' Arguments
-------------------------------------
-Format strings for `printf' and `sprintf()' (*note Printf::) present a
+Format strings for 'printf' and 'sprintf()' (*note Printf::) present a
special problem for translation. Consider the following:(1)
printf(_"String `%s' has %d characters\n",
@@ -20385,21 +20298,21 @@ special problem for translation. Consider the
following:(1)
"%d Zeichen lang ist die Zeichenkette `%s'\n"
- The problem should be obvious: the order of the format
-specifications is different from the original! Even though `gettext()'
-can return the translated string at runtime, it cannot change the
-argument order in the call to `printf'.
+ The problem should be obvious: the order of the format specifications
+is different from the original! Even though 'gettext()' can return the
+translated string at runtime, it cannot change the argument order in the
+call to 'printf'.
- To solve this problem, `printf' format specifiers may have an
+ To solve this problem, 'printf' format specifiers may have an
additional optional element, which we call a "positional specifier".
For example:
"%2$d Zeichen lang ist die Zeichenkette `%1$s'\n"
Here, the positional specifier consists of an integer count, which
-indicates which argument to use, and a `$'. Counts are one-based, and
+indicates which argument to use, and a '$'. Counts are one-based, and
the format string itself is _not_ included. Thus, in the following
-example, `string' is the first argument and `length(string)' is the
+example, 'string' is the first argument and 'length(string)' is the
second:
$ gawk 'BEGIN {
@@ -20422,39 +20335,39 @@ precision capability:
-| hello
-| hello
- NOTE: When using `*' with a positional specifier, the `*' comes
- first, then the integer position, and then the `$'. This is
+ NOTE: When using '*' with a positional specifier, the '*' comes
+ first, then the integer position, and then the '$'. This is
somewhat counterintuitive.
- `gawk' does not allow you to mix regular format specifiers and those
+ 'gawk' does not allow you to mix regular format specifiers and those
with positional specifiers in the same string:
$ gawk 'BEGIN { printf "%d %3$s\n", 1, 2, "hi" }'
- error--> gawk: cmd. line:1: fatal: must use `count$' on all formats or
none
+ error-> gawk: cmd. line:1: fatal: must use `count$' on all formats or none
- NOTE: There are some pathological cases that `gawk' may fail to
+ NOTE: There are some pathological cases that 'gawk' may fail to
diagnose. In such cases, the output may not be what you expect.
- It's still a bad idea to try mixing them, even if `gawk' doesn't
+ It's still a bad idea to try mixing them, even if 'gawk' doesn't
detect it.
- Although positional specifiers can be used directly in `awk'
+ Although positional specifiers can be used directly in 'awk'
programs, their primary purpose is to help in producing correct
translations of format strings into languages different from the one in
which the program is first written.
---------- Footnotes ----------
- (1) This example is borrowed from the GNU `gettext' manual.
+ (1) This example is borrowed from the GNU 'gettext' manual.
File: gawk.info, Node: I18N Portability, Prev: Printf Ordering, Up:
Translator i18n
-13.4.3 `awk' Portability Issues
+13.4.3 'awk' Portability Issues
-------------------------------
-`gawk''s internationalization features were purposely chosen to have as
-little impact as possible on the portability of `awk' programs that use
-them to other versions of `awk'. Consider this program:
+'gawk''s internationalization features were purposely chosen to have as
+little impact as possible on the portability of 'awk' programs that use
+them to other versions of 'awk'. Consider this program:
BEGIN {
TEXTDOMAIN = "guide"
@@ -20463,19 +20376,19 @@ them to other versions of `awk'. Consider this
program:
print _"don't panic!"
}
-As written, it won't work on other versions of `awk'. However, it is
+As written, it won't work on other versions of 'awk'. However, it is
actually almost portable, requiring very little change:
- * Assignments to `TEXTDOMAIN' won't have any effect, because
- `TEXTDOMAIN' is not special in other `awk' implementations.
+ * Assignments to 'TEXTDOMAIN' won't have any effect, because
+ 'TEXTDOMAIN' is not special in other 'awk' implementations.
- * Non-GNU versions of `awk' treat marked strings as the
- concatenation of a variable named `_' with the string following
- it.(1) Typically, the variable `_' has the null string (`""') as
- its value, leaving the original string constant as the result.
+ * Non-GNU versions of 'awk' treat marked strings as the concatenation
+ of a variable named '_' with the string following it.(1)
+ Typically, the variable '_' has the null string ('""') as its
+ value, leaving the original string constant as the result.
- * By defining "dummy" functions to replace `dcgettext()',
- `dcngettext()', and `bindtextdomain()', the `awk' program can be
+ * By defining "dummy" functions to replace 'dcgettext()',
+ 'dcngettext()', and 'bindtextdomain()', the 'awk' program can be
made to run, but all the messages are output in the original
language. For example:
@@ -20494,22 +20407,22 @@ actually almost portable, requiring very little
change:
return (number == 1 ? string1 : string2)
}
- * The use of positional specifications in `printf' or `sprintf()' is
- _not_ portable. To support `gettext()' at the C level, many
- systems' C versions of `sprintf()' do support positional
+ * The use of positional specifications in 'printf' or 'sprintf()' is
+ _not_ portable. To support 'gettext()' at the C level, many
+ systems' C versions of 'sprintf()' do support positional
specifiers. But it works only if enough arguments are supplied in
- the function call. Many versions of `awk' pass `printf' formats
+ the function call. Many versions of 'awk' pass 'printf' formats
and arguments unchanged to the underlying C library version of
- `sprintf()', but only one format and argument at a time. What
+ 'sprintf()', but only one format and argument at a time. What
happens if a positional specification is used is anybody's guess.
However, because the positional specifications are primarily for
- use in _translated_ format strings, and because non-GNU `awk's
+ use in _translated_ format strings, and because non-GNU 'awk's
never retrieve the translated string, this should not be a problem
in practice.
---------- Footnotes ----------
- (1) This is good fodder for an "Obfuscated `awk'" contest.
+ (1) This is good fodder for an "Obfuscated 'awk'" contest.
File: gawk.info, Node: I18N Example, Next: Gawk I18N, Prev: Translator
i18n, Up: Internationalization
@@ -20518,7 +20431,7 @@ File: gawk.info, Node: I18N Example, Next: Gawk I18N,
Prev: Translator i18n,
==========================================
Now let's look at a step-by-step example of how to internationalize and
-localize a simple `awk' program, using `guide.awk' as our original
+localize a simple 'awk' program, using 'guide.awk' as our original
source:
BEGIN {
@@ -20529,7 +20442,7 @@ source:
print "Pardon me, Zaphod who?"
}
-Run `gawk --gen-pot' to create the `.pot' file:
+Run 'gawk --gen-pot' to create the '.pot' file:
$ gawk --gen-pot -f guide.awk > guide.pot
@@ -20543,12 +20456,13 @@ This produces:
msgid "The Answer Is"
msgstr ""
+
This original portable object template file is saved and reused for
-each language into which the application is translated. The `msgid' is
-the original string and the `msgstr' is the translation.
+each language into which the application is translated. The 'msgid' is
+the original string and the 'msgstr' is the translation.
- NOTE: Strings not marked with a leading underscore do not appear
- in the `guide.pot' file.
+ NOTE: Strings not marked with a leading underscore do not appear in
+ the 'guide.pot' file.
Next, the messages must be translated. Here is a translation to a
hypothetical dialect of English, called "Mellow":(1)
@@ -20566,19 +20480,20 @@ Following are the translations:
msgid "The Answer Is"
msgstr "Like, the scoop is"
+
The next step is to make the directory to hold the binary message
-object file and then to create the `guide.mo' file. We pretend that
-our file is to be used in the `en_US.UTF-8' locale, because we have to
-use a locale name known to the C `gettext' routines. The directory
-layout shown here is standard for GNU `gettext' on GNU/Linux systems.
-Other versions of `gettext' may use a different layout:
+object file and then to create the 'guide.mo' file. We pretend that our
+file is to be used in the 'en_US.UTF-8' locale, because we have to use a
+locale name known to the C 'gettext' routines. The directory layout
+shown here is standard for GNU 'gettext' on GNU/Linux systems. Other
+versions of 'gettext' may use a different layout:
$ mkdir en_US.UTF-8 en_US.UTF-8/LC_MESSAGES
- The `msgfmt' utility does the conversion from human-readable `.po'
-file to machine-readable `.mo' file. By default, `msgfmt' creates a
-file named `messages'. This file must be renamed and placed in the
-proper directory (using the `-o' option) so that `gawk' can find it:
+ The 'msgfmt' utility does the conversion from human-readable '.po'
+file to machine-readable '.mo' file. By default, 'msgfmt' creates a
+file named 'messages'. This file must be renamed and placed in the
+proper directory (using the '-o' option) so that 'gawk' can find it:
$ msgfmt guide-mellow.po -o en_US.UTF-8/LC_MESSAGES/guide.mo
@@ -20589,9 +20504,9 @@ proper directory (using the `-o' option) so that `gawk'
can find it:
-| Like, the scoop is 42
-| Pardon me, Zaphod who?
- If the three replacement functions for `dcgettext()', `dcngettext()',
-and `bindtextdomain()' (*note I18N Portability::) are in a file named
-`libintl.awk', then we can run `guide.awk' unchanged as follows:
+ If the three replacement functions for 'dcgettext()', 'dcngettext()',
+and 'bindtextdomain()' (*note I18N Portability::) are in a file named
+'libintl.awk', then we can run 'guide.awk' unchanged as follows:
$ gawk --posix -f guide.awk -f libintl.awk
-| Don't Panic
@@ -20600,21 +20515,21 @@ and `bindtextdomain()' (*note I18N Portability::) are
in a file named
---------- Footnotes ----------
- (1) Perhaps it would be better if it were called "Hippy." Ah, well.
+ (1) Perhaps it would be better if it were called "Hippy." Ah, well.
File: gawk.info, Node: Gawk I18N, Next: I18N Summary, Prev: I18N Example,
Up: Internationalization
-13.6 `gawk' Can Speak Your Language
+13.6 'gawk' Can Speak Your Language
===================================
-`gawk' itself has been internationalized using the GNU `gettext'
-package. (GNU `gettext' is described in complete detail in *note (GNU
-`gettext' utilities)Top:: gettext, GNU `gettext' utilities.) As of
-this writing, the latest version of GNU `gettext' is version 0.19.4
+'gawk' itself has been internationalized using the GNU 'gettext'
+package. (GNU 'gettext' is described in complete detail in *note (GNU
+'gettext' utilities, gettext, GNU 'gettext' utilities)Top::.) As of
+this writing, the latest version of GNU 'gettext' is version 0.19.4
(ftp://ftp.gnu.org/gnu/gettext/gettext-0.19.4.tar.gz).
- If a translation of `gawk''s messages exists, then `gawk' produces
+ If a translation of 'gawk''s messages exists, then 'gawk' produces
usage messages, warnings, and fatal errors in the local language.
@@ -20628,47 +20543,46 @@ File: gawk.info, Node: I18N Summary, Prev: Gawk
I18N, Up: Internationalizatio
Localization means providing the data necessary for an
internationalized program to work in a particular language.
- * `gawk' uses GNU `gettext' to let you internationalize and localize
- `awk' programs. A program's text domain identifies the program
- for grouping all messages and other data together.
+ * 'gawk' uses GNU 'gettext' to let you internationalize and localize
+ 'awk' programs. A program's text domain identifies the program for
+ grouping all messages and other data together.
* You mark a program's strings for translation by preceding them with
- an underscore. Once that is done, the strings are extracted into a
- `.pot' file. This file is copied for each language into a `.po'
- file, and the `.po' files are compiled into `.gmo' files for use
- at runtime.
-
- * You can use positional specifications with `sprintf()' and
- `printf' to rearrange the placement of argument values in formatted
- strings and output. This is useful for the translation of format
- control strings.
+ an underscore. Once that is done, the strings are extracted into a
+ '.pot' file. This file is copied for each language into a '.po'
+ file, and the '.po' files are compiled into '.gmo' files for use at
+ runtime.
+
+ * You can use positional specifications with 'sprintf()' and 'printf'
+ to rearrange the placement of argument values in formatted strings
+ and output. This is useful for the translation of format control
+ strings.
* The internationalization features have been designed so that they
- can be easily worked around in a standard `awk'.
-
- * `gawk' itself has been internationalized and ships with a number
- of translations for its messages.
+ can be easily worked around in a standard 'awk'.
+ * 'gawk' itself has been internationalized and ships with a number of
+ translations for its messages.
File: gawk.info, Node: Debugger, Next: Arbitrary Precision Arithmetic,
Prev: Internationalization, Up: Top
-14 Debugging `awk' Programs
+14 Debugging 'awk' Programs
***************************
It would be nice if computer programs worked perfectly the first time
-they were run, but in real life, this rarely happens for programs of
-any complexity. Thus, most programming languages have facilities
-available for "debugging" programs, and now `awk' is no exception.
+they were run, but in real life, this rarely happens for programs of any
+complexity. Thus, most programming languages have facilities available
+for "debugging" programs, and now 'awk' is no exception.
- The `gawk' debugger is purposely modeled after the GNU Debugger
-(GDB) (http://www.gnu.org/software/gdb/) command-line debugger. If you
-are familiar with GDB, learning how to use `gawk' for debugging your
-program is easy.
+ The 'gawk' debugger is purposely modeled after the GNU Debugger (GDB)
+(http://www.gnu.org/software/gdb/) command-line debugger. If you are
+familiar with GDB, learning how to use 'gawk' for debugging your program
+is easy.
* Menu:
-* Debugging:: Introduction to `gawk' debugger.
+* Debugging:: Introduction to 'gawk' debugger.
* Sample Debugging Session:: Sample debugging session.
* List of Debugger Commands:: Main debugger commands.
* Readline Support:: Readline support.
@@ -20678,11 +20592,11 @@ program is easy.
File: gawk.info, Node: Debugging, Next: Sample Debugging Session, Up:
Debugger
-14.1 Introduction to the `gawk' Debugger
+14.1 Introduction to the 'gawk' Debugger
========================================
This minor node introduces debugging in general and begins the
-discussion of debugging in `gawk'.
+discussion of debugging in 'gawk'.
* Menu:
@@ -20699,12 +20613,12 @@ File: gawk.info, Node: Debugging Concepts, Next:
Debugging Terms, Up: Debuggi
(If you have used debuggers in other languages, you may want to skip
ahead to *note Awk Debugging::.)
- Of course, a debugging program cannot remove bugs for you, because
-it has no way of knowing what you or your users consider a "bug" versus
-a "feature." (Sometimes, we humans have a hard time with this
-ourselves.) In that case, what can you expect from such a tool? The
-answer to that depends on the language being debugged, but in general,
-you can expect at least the following:
+ Of course, a debugging program cannot remove bugs for you, because it
+has no way of knowing what you or your users consider a "bug" versus a
+"feature." (Sometimes, we humans have a hard time with this ourselves.)
+In that case, what can you expect from such a tool? The answer to that
+depends on the language being debugged, but in general, you can expect
+at least the following:
* The ability to watch a program execute its instructions one by one,
giving you, the programmer, the opportunity to think about what is
@@ -20743,21 +20657,21 @@ defines terms used throughout the rest of this major
node:
Programs generally call functions during the course of their
execution. One function can call another, or a function can call
itself (recursion). You can view the chain of called functions
- (main program calls A, which calls B, which calls C), as a stack
- of executing functions: the currently running function is the
- topmost one on the stack, and when it finishes (returns), the next
- one down then becomes the active function. Such a stack is termed
- a "call stack".
+ (main program calls A, which calls B, which calls C), as a stack of
+ executing functions: the currently running function is the topmost
+ one on the stack, and when it finishes (returns), the next one down
+ then becomes the active function. Such a stack is termed a "call
+ stack".
For each function on the call stack, the system maintains a data
area that contains the function's parameters, local variables, and
- return value, as well as any other "bookkeeping" information
- needed to manage the call stack. This data area is termed a
- "stack frame".
+ return value, as well as any other "bookkeeping" information needed
+ to manage the call stack. This data area is termed a "stack
+ frame".
- `gawk' also follows this model, and gives you access to the call
- stack and to each stack frame. You can see the call stack, as well
- as from where each function on the stack was invoked. Commands
+ 'gawk' also follows this model, and gives you access to the call
+ stack and to each stack frame. You can see the call stack, as well
+ as from where each function on the stack was invoked. Commands
that print the call stack print information about each stack frame
(as detailed later on).
@@ -20772,11 +20686,11 @@ defines terms used throughout the rest of this major
node:
"Watchpoint"
A watchpoint is similar to a breakpoint. The difference is that
- breakpoints are oriented around the code: stop when a certain
- point in the code is reached. A watchpoint, however, specifies
- that program execution should stop when a _data value_ is changed.
- This is useful, as sometimes it happens that a variable receives
- an erroneous value, and it's hard to track down where this happens
+ breakpoints are oriented around the code: stop when a certain point
+ in the code is reached. A watchpoint, however, specifies that
+ program execution should stop when a _data value_ is changed. This
+ is useful, as sometimes it happens that a variable receives an
+ erroneous value, and it's hard to track down where this happens
just by looking at the code. By using a watchpoint, you can stop
whenever a variable is assigned to, and usually find the errant
code quite quickly.
@@ -20784,34 +20698,34 @@ defines terms used throughout the rest of this major
node:
File: gawk.info, Node: Awk Debugging, Prev: Debugging Terms, Up: Debugging
-14.1.3 `awk' Debugging
+14.1.3 'awk' Debugging
----------------------
-Debugging an `awk' program has some specific aspects that are not
-shared with programs written in other languages.
+Debugging an 'awk' program has some specific aspects that are not shared
+with programs written in other languages.
- First of all, the fact that `awk' programs usually take input line
-by line from a file or files and operate on those lines using specific
+ First of all, the fact that 'awk' programs usually take input line by
+line from a file or files and operate on those lines using specific
rules makes it especially useful to organize viewing the execution of
-the program in terms of these rules. As we will see, each `awk' rule
-is treated almost like a function call, with its own specific block of
+the program in terms of these rules. As we will see, each 'awk' rule is
+treated almost like a function call, with its own specific block of
instructions.
- In addition, because `awk' is by design a very concise language, it
+ In addition, because 'awk' is by design a very concise language, it
is easy to lose sight of everything that is going on "inside" each line
-of `awk' code. The debugger provides the opportunity to look at the
-individual primitive instructions carried out by the higher-level `awk'
+of 'awk' code. The debugger provides the opportunity to look at the
+individual primitive instructions carried out by the higher-level 'awk'
commands.
File: gawk.info, Node: Sample Debugging Session, Next: List of Debugger
Commands, Prev: Debugging, Up: Debugger
-14.2 Sample `gawk' Debugging Session
+14.2 Sample 'gawk' Debugging Session
====================================
-In order to illustrate the use of `gawk' as a debugger, let's look at a
-sample debugging session. We will use the `awk' implementation of the
-POSIX `uniq' command described earlier (*note Uniq Program::) as our
+In order to illustrate the use of 'gawk' as a debugger, let's look at a
+sample debugging session. We will use the 'awk' implementation of the
+POSIX 'uniq' command described earlier (*note Uniq Program::) as our
example.
* Menu:
@@ -20825,24 +20739,24 @@ File: gawk.info, Node: Debugger Invocation, Next:
Finding The Bug, Up: Sample
14.2.1 How to Start the Debugger
--------------------------------
-Starting the debugger is almost exactly like running `gawk' normally,
-except you have to pass an additional option, `--debug', or the
-corresponding short option, `-D'. The file(s) containing the program
+Starting the debugger is almost exactly like running 'gawk' normally,
+except you have to pass an additional option, '--debug', or the
+corresponding short option, '-D'. The file(s) containing the program
and any supporting code are given on the command line as arguments to
-one or more `-f' options. (`gawk' is not designed to debug command-line
-programs, only programs contained in files.) In our case, we invoke
-the debugger like this:
+one or more '-f' options. ('gawk' is not designed to debug command-line
+programs, only programs contained in files.) In our case, we invoke the
+debugger like this:
$ gawk -D -f getopt.awk -f join.awk -f uniq.awk -1 inputfile
-where both `getopt.awk' and `uniq.awk' are in `$AWKPATH'. (Experienced
+where both 'getopt.awk' and 'uniq.awk' are in '$AWKPATH'. (Experienced
users of GDB or similar debuggers should note that this syntax is
-slightly different from what you are used to. With the `gawk'
-debugger, you give the arguments for running the program in the command
-line to the debugger rather than as part of the `run' command at the
-debugger prompt.) The `-1' is an option to `uniq.awk'.
+slightly different from what you are used to. With the 'gawk' debugger,
+you give the arguments for running the program in the command line to
+the debugger rather than as part of the 'run' command at the debugger
+prompt.) The '-1' is an option to 'uniq.awk'.
- Instead of immediately running the program on `inputfile', as `gawk'
+ Instead of immediately running the program on 'inputfile', as 'gawk'
would ordinarily do, the debugger merely loads all the program source
files, compiles them internally, and then gives us a prompt:
@@ -20858,7 +20772,7 @@ File: gawk.info, Node: Finding The Bug, Prev:
Debugger Invocation, Up: Sample
----------------------
Let's say that we are having a problem using (a faulty version of)
-`uniq.awk' in the "field-skipping" mode, and it doesn't seem to be
+'uniq.awk' in the "field-skipping" mode, and it doesn't seem to be
catching lines which should be identical when skipping the first field,
such as:
@@ -20880,15 +20794,15 @@ we wrote:
The first thing we usually want to do when trying to investigate a
problem like this is to put a breakpoint in the program so that we can
watch it at work and catch what it is doing wrong. A reasonable spot
-for a breakpoint in `uniq.awk' is at the beginning of the function
-`are_equal()', which compares the current line with the previous one.
-To set the breakpoint, use the `b' (breakpoint) command:
+for a breakpoint in 'uniq.awk' is at the beginning of the function
+'are_equal()', which compares the current line with the previous one.
+To set the breakpoint, use the 'b' (breakpoint) command:
gawk> b are_equal
-| Breakpoint 1 set at file `awklib/eg/prog/uniq.awk', line 63
The debugger tells us the file and line number where the breakpoint
-is. Now type `r' or `run' and the program runs until it hits the
+is. Now type 'r' or 'run' and the program runs until it hits the
breakpoint for the first time:
gawk> r
@@ -20900,30 +20814,30 @@ breakpoint for the first time:
gawk>
Now we can look at what's going on inside our program. First of all,
-let's see how we got to where we are. At the prompt, we type `bt'
-(short for "backtrace"), and the debugger responds with a listing of
-the current stack frames:
+let's see how we got to where we are. At the prompt, we type 'bt'
+(short for "backtrace"), and the debugger responds with a listing of the
+current stack frames:
gawk> bt
-| #0 are_equal(n, m, clast, cline, alast, aline)
at `awklib/eg/prog/uniq.awk':68
-| #1 in main() at `awklib/eg/prog/uniq.awk':88
- This tells us that `are_equal()' was called by the main program at
-line 88 of `uniq.awk'. (This is not a big surprise, because this is
-the only call to `are_equal()' in the program, but in more complex
-programs, knowing who called a function and with what parameters can be
-the key to finding the source of the problem.)
+ This tells us that 'are_equal()' was called by the main program at
+line 88 of 'uniq.awk'. (This is not a big surprise, because this is the
+only call to 'are_equal()' in the program, but in more complex programs,
+knowing who called a function and with what parameters can be the key to
+finding the source of the problem.)
- Now that we're in `are_equal()', we can start looking at the values
-of some variables. Let's say we type `p n' (`p' is short for "print").
-We would expect to see the value of `n', a parameter to `are_equal()'.
+ Now that we're in 'are_equal()', we can start looking at the values
+of some variables. Let's say we type 'p n' ('p' is short for "print").
+We would expect to see the value of 'n', a parameter to 'are_equal()'.
Actually, the debugger gives us:
gawk> p n
-| n = untyped variable
-In this case, `n' is an uninitialized local variable, because the
+In this case, 'n' is an uninitialized local variable, because the
function was called without arguments (*note Function Calls::).
A more useful variable to display might be the current record:
@@ -20931,15 +20845,15 @@ function was called without arguments (*note Function
Calls::).
gawk> p $0
-| $0 = "gawk is a wonderful program!"
-This might be a bit puzzling at first, as this is the second line of
-our test input. Let's look at `NR':
+This might be a bit puzzling at first, as this is the second line of our
+test input. Let's look at 'NR':
gawk> p NR
-| NR = 2
-So we can see that `are_equal()' was only called for the second record
+So we can see that 'are_equal()' was only called for the second record
of the file. Of course, this is because our program contains a rule for
-`NR == 1':
+'NR == 1':
NR == 1 {
last = $0
@@ -20952,19 +20866,19 @@ of the file. Of course, this is because our program
contains a rule for
-| last = "awk is a wonderful program!"
Everything we have done so far has verified that the program has
-worked as planned, up to and including the call to `are_equal()', so
-the problem must be inside this function. To investigate further, we
-must begin "stepping through" the lines of `are_equal()'. We start by
-typing `n' (for "next"):
+worked as planned, up to and including the call to 'are_equal()', so the
+problem must be inside this function. To investigate further, we must
+begin "stepping through" the lines of 'are_equal()'. We start by typing
+'n' (for "next"):
gawk> n
-| 66 if (fcount > 0) {
- This tells us that `gawk' is now ready to execute line 66, which
+ This tells us that 'gawk' is now ready to execute line 66, which
decides whether to give the lines the special "field-skipping" treatment
-indicated by the `-1' command-line option. (Notice that we skipped
-from where we were before, at line 63, to here, because the condition
-in line 63, `if (fcount == 0 && charcount == 0)', was false.)
+indicated by the '-1' command-line option. (Notice that we skipped from
+where we were before, at line 63, to here, because the condition in line
+63, 'if (fcount == 0 && charcount == 0)', was false.)
Continuing to step, we now get to the splitting of the current and
last records:
@@ -20983,14 +20897,14 @@ split into, so we try to look:
-| alast = array, 5 elements
-| aline = untyped variable
-(The `p' command can take more than one argument, similar to `awk''s
-`print' statement.)
+(The 'p' command can take more than one argument, similar to 'awk''s
+'print' statement.)
This is kind of disappointing, though. All we found out is that
-there are five elements in `alast'; `m' and `aline' don't have values
-because we are at line 68 but haven't executed it yet. This
-information is useful enough (we now know that none of the words were
-accidentally left out), but what if we want to see inside the array?
+there are five elements in 'alast'; 'm' and 'aline' don't have values
+because we are at line 68 but haven't executed it yet. This information
+is useful enough (we now know that none of the words were accidentally
+left out), but what if we want to see inside the array?
The first choice would be to use subscripts:
@@ -21002,7 +20916,7 @@ Oops!
gawk> p alast[1]
-| alast["1"] = "awk"
- This would be kind of slow for a 100-member array, though, so `gawk'
+ This would be kind of slow for a 100-member array, though, so 'gawk'
provides a shortcut (reminiscent of another language not to be
mentioned):
@@ -21013,7 +20927,7 @@ mentioned):
-| alast["4"] = "wonderful"
-| alast["5"] = "program!"
- It looks like we got this far OK. Let's take another step or two:
+ It looks like we got this far OK. Let's take another step or two:
gawk> n
-| 69 clast = join(alast, fcount, n)
@@ -21022,8 +20936,8 @@ mentioned):
Well, here we are at our error (sorry to spoil the suspense). What
we had in mind was to join the fields starting from the second one to
-make the virtual record to compare, and if the first field were
-numbered zero, this would work. Let's look at what we've got:
+make the virtual record to compare, and if the first field were numbered
+zero, this would work. Let's look at what we've got:
gawk> p cline clast
-| cline = "gawk is a wonderful program!"
@@ -21051,7 +20965,7 @@ File: gawk.info, Node: List of Debugger Commands,
Next: Readline Support, Pre
14.3 Main Debugger Commands
===========================
-The `gawk' debugger command set can be divided into the following
+The 'gawk' debugger command set can be divided into the following
categories:
* Breakpoint control
@@ -21069,10 +20983,10 @@ categories:
Each of these are discussed in the following subsections. In the
following descriptions, commands that may be abbreviated show the
abbreviation on a second description line. A debugger command name may
-also be truncated if that partial name is unambiguous. The debugger has
+also be truncated if that partial name is unambiguous. The debugger has
the built-in capability to automatically repeat the previous command
-just by hitting `Enter'. This works for the commands `list', `next',
-`nexti', `step', `stepi', and `continue' executed without any argument.
+just by hitting 'Enter'. This works for the commands 'list', 'next',
+'nexti', 'step', 'stepi', and 'continue' executed without any argument.
* Menu:
@@ -21095,89 +21009,89 @@ debugging session is to get your breakpoints set up,
because your
program will otherwise just run as if it was not under the debugger.
The commands for controlling breakpoints are:
-`break' [[FILENAME`:']N | FUNCTION] [`"EXPRESSION"']
-`b' [[FILENAME`:']N | FUNCTION] [`"EXPRESSION"']
+'break' [[FILENAME':']N | FUNCTION] ['"EXPRESSION"']
+'b' [[FILENAME':']N | FUNCTION] ['"EXPRESSION"']
Without any argument, set a breakpoint at the next instruction to
be executed in the selected stack frame. Arguments can be one of
the following:
- N
+ N
Set a breakpoint at line number N in the current source file.
- FILENAME`:'N
+ FILENAME':'N
Set a breakpoint at line number N in source file FILENAME.
- FUNCTION
+ FUNCTION
Set a breakpoint at entry to (the first instruction of)
function FUNCTION.
Each breakpoint is assigned a number that can be used to delete it
- from the breakpoint list using the `delete' command.
+ from the breakpoint list using the 'delete' command.
With a breakpoint, you may also supply a condition. This is an
- `awk' expression (enclosed in double quotes) that the debugger
- evaluates whenever the breakpoint is reached. If the condition is
+ 'awk' expression (enclosed in double quotes) that the debugger
+ evaluates whenever the breakpoint is reached. If the condition is
true, then the debugger stops execution and prompts for a command.
Otherwise, it continues executing the program.
-`clear' [[FILENAME`:']N | FUNCTION]
+'clear' [[FILENAME':']N | FUNCTION]
Without any argument, delete any breakpoint at the next instruction
- to be executed in the selected stack frame. If the program stops at
- a breakpoint, this deletes that breakpoint so that the program
+ to be executed in the selected stack frame. If the program stops
+ at a breakpoint, this deletes that breakpoint so that the program
does not stop at that location again. Arguments can be one of the
following:
- N
+ N
Delete breakpoint(s) set at line number N in the current
source file.
- FILENAME`:'N
+ FILENAME':'N
Delete breakpoint(s) set at line number N in source file
FILENAME.
- FUNCTION
+ FUNCTION
Delete breakpoint(s) set at entry to function FUNCTION.
-`condition' N `"EXPRESSION"'
- Add a condition to existing breakpoint or watchpoint N. The
- condition is an `awk' expression _enclosed in double quotes_ that
+'condition' N '"EXPRESSION"'
+ Add a condition to existing breakpoint or watchpoint N. The
+ condition is an 'awk' expression _enclosed in double quotes_ that
the debugger evaluates whenever the breakpoint or watchpoint is
- reached. If the condition is true, then the debugger stops
- execution and prompts for a command. Otherwise, the debugger
- continues executing the program. If the condition expression is
+ reached. If the condition is true, then the debugger stops
+ execution and prompts for a command. Otherwise, the debugger
+ continues executing the program. If the condition expression is
not specified, any existing condition is removed (i.e., the
breakpoint or watchpoint is made unconditional).
-`delete' [N1 N2 ...] [N-M]
-`d' [N1 N2 ...] [N-M]
- Delete specified breakpoints or a range of breakpoints. Delete all
+'delete' [N1 N2 ...] [N-M]
+'d' [N1 N2 ...] [N-M]
+ Delete specified breakpoints or a range of breakpoints. Delete all
defined breakpoints if no argument is supplied.
-`disable' [N1 N2 ... | N-M]
- Disable specified breakpoints or a range of breakpoints. Without
+'disable' [N1 N2 ... | N-M]
+ Disable specified breakpoints or a range of breakpoints. Without
any argument, disable all breakpoints.
-`enable' [`del' | `once'] [N1 N2 ...] [N-M]
-`e' [`del' | `once'] [N1 N2 ...] [N-M]
- Enable specified breakpoints or a range of breakpoints. Without
+'enable' ['del' | 'once'] [N1 N2 ...] [N-M]
+'e' ['del' | 'once'] [N1 N2 ...] [N-M]
+ Enable specified breakpoints or a range of breakpoints. Without
any argument, enable all breakpoints. Optionally, you can specify
how to enable the breakpoints:
- `del'
+ 'del'
Enable the breakpoints temporarily, then delete each one when
the program stops at it.
- `once'
+ 'once'
Enable the breakpoints temporarily, then disable each one when
the program stops at it.
-`ignore' N COUNT
+'ignore' N COUNT
Ignore breakpoint number N the next COUNT times it is hit.
-`tbreak' [[FILENAME`:']N | FUNCTION]
-`t' [[FILENAME`:']N | FUNCTION]
+'tbreak' [[FILENAME':']N | FUNCTION]
+'t' [[FILENAME':']N | FUNCTION]
Set a temporary breakpoint (enabled for only one stop). The
- arguments are the same as for `break'.
+ arguments are the same as for 'break'.
File: gawk.info, Node: Debugger Execution Control, Next: Viewing And
Changing Data, Prev: Breakpoint Control, Up: List of Debugger Commands
@@ -21189,19 +21103,19 @@ Now that your breakpoints are ready, you can start
running the program
and observing its behavior. There are more commands for controlling
execution of the program than we saw in our earlier example:
-`commands' [N]
-`silent'
+'commands' [N]
+'silent'
...
-`end'
- Set a list of commands to be executed upon stopping at a
- breakpoint or watchpoint. N is the breakpoint or watchpoint number.
- Without a number, the last one set is used. The actual commands
- follow, starting on the next line, and terminated by the `end'
- command. If the command `silent' is in the list, the usual
- messages about stopping at a breakpoint and the source line are
- not printed. Any command in the list that resumes execution (e.g.,
- `continue') terminates the list (an implicit `end'), and
- subsequent commands are ignored. For example:
+'end'
+ Set a list of commands to be executed upon stopping at a breakpoint
+ or watchpoint. N is the breakpoint or watchpoint number. Without
+ a number, the last one set is used. The actual commands follow,
+ starting on the next line, and terminated by the 'end' command. If
+ the command 'silent' is in the list, the usual messages about
+ stopping at a breakpoint and the source line are not printed. Any
+ command in the list that resumes execution (e.g., 'continue')
+ terminates the list (an implicit 'end'), and subsequent commands
+ are ignored. For example:
gawk> commands
> silent
@@ -21212,60 +21126,59 @@ execution of the program than we saw in our earlier
example:
> end
gawk>
-`continue' [COUNT]
-`c' [COUNT]
- Resume program execution. If continued from a breakpoint and COUNT
- is specified, ignore the breakpoint at that location the next
- COUNT times before stopping.
+'continue' [COUNT]
+'c' [COUNT]
+ Resume program execution. If continued from a breakpoint and COUNT
+ is specified, ignore the breakpoint at that location the next COUNT
+ times before stopping.
-`finish'
- Execute until the selected stack frame returns. Print the
- returned value.
+'finish'
+ Execute until the selected stack frame returns. Print the returned
+ value.
-`next' [COUNT]
-`n' [COUNT]
+'next' [COUNT]
+'n' [COUNT]
Continue execution to the next source line, stepping over function
calls. The argument COUNT controls how many times to repeat the
- action, as in `step'.
+ action, as in 'step'.
-`nexti' [COUNT]
-`ni' [COUNT]
+'nexti' [COUNT]
+'ni' [COUNT]
Execute one (or COUNT) instruction(s), stepping over function
calls.
-`return' [VALUE]
- Cancel execution of a function call. If VALUE (either a string or a
- number) is specified, it is used as the function's return value.
+'return' [VALUE]
+ Cancel execution of a function call. If VALUE (either a string or
+ a number) is specified, it is used as the function's return value.
If used in a frame other than the innermost one (the currently
- executing function; i.e., frame number 0), discard all inner
- frames in addition to the selected one, and the caller of that
- frame becomes the innermost frame.
+ executing function; i.e., frame number 0), discard all inner frames
+ in addition to the selected one, and the caller of that frame
+ becomes the innermost frame.
-`run'
-`r'
- Start/restart execution of the program. When restarting, the
+'run'
+'r'
+ Start/restart execution of the program. When restarting, the
debugger retains the current breakpoints, watchpoints, command
history, automatic display variables, and debugger options.
-`step' [COUNT]
-`s' [COUNT]
- Continue execution until control reaches a different source line
- in the current stack frame, stepping inside any function called
- within the line. If the argument COUNT is supplied, steps that
- many times before stopping, unless it encounters a breakpoint or
- watchpoint.
+'step' [COUNT]
+'s' [COUNT]
+ Continue execution until control reaches a different source line in
+ the current stack frame, stepping inside any function called within
+ the line. If the argument COUNT is supplied, steps that many times
+ before stopping, unless it encounters a breakpoint or watchpoint.
-`stepi' [COUNT]
-`si' [COUNT]
+'stepi' [COUNT]
+'si' [COUNT]
Execute one (or COUNT) instruction(s), stepping inside function
calls. (For illustration of what is meant by an "instruction" in
- `gawk', see the output shown under `dump' in *note Miscellaneous
+ 'gawk', see the output shown under 'dump' in *note Miscellaneous
Debugger Commands::.)
-`until' [[FILENAME`:']N | FUNCTION]
-`u' [[FILENAME`:']N | FUNCTION]
+'until' [[FILENAME':']N | FUNCTION]
+'u' [[FILENAME':']N | FUNCTION]
Without any argument, continue execution until a line past the
- current line in the current stack frame is reached. With an
+ current line in the current stack frame is reached. With an
argument, continue execution until the specified location is
reached, or the current stack frame returns.
@@ -21275,11 +21188,11 @@ File: gawk.info, Node: Viewing And Changing Data,
Next: Execution Stack, Prev
14.3.3 Viewing and Changing Data
--------------------------------
-The commands for viewing and changing variables inside of `gawk' are:
+The commands for viewing and changing variables inside of 'gawk' are:
-`display' [VAR | `$'N]
- Add variable VAR (or field `$N') to the display list. The value
- of the variable or field is displayed each time the program stops.
+'display' [VAR | '$'N]
+ Add variable VAR (or field '$N') to the display list. The value of
+ the variable or field is displayed each time the program stops.
Each variable added to the list is identified by a unique number:
gawk> display x
@@ -21289,112 +21202,110 @@ The commands for viewing and changing variables
inside of `gawk' are:
current value. If the display variable refers to a function
parameter, it is silently deleted from the list as soon as the
execution reaches a context where no such variable of the given
- name exists. Without argument, `display' displays the current
+ name exists. Without argument, 'display' displays the current
values of items on the list.
-`eval "AWK STATEMENTS"'
- Evaluate AWK STATEMENTS in the context of the running program.
- You can do anything that an `awk' program would do: assign values
- to variables, call functions, and so on.
+'eval "AWK STATEMENTS"'
+ Evaluate AWK STATEMENTS in the context of the running program. You
+ can do anything that an 'awk' program would do: assign values to
+ variables, call functions, and so on.
-`eval' PARAM, ...
+'eval' PARAM, ...
AWK STATEMENTS
-`end'
- This form of `eval' is similar, but it allows you to define "local
- variables" that exist in the context of the AWK STATEMENTS,
- instead of using variables or function parameters defined by the
- program.
-
-`print' VAR1[`,' VAR2 ...]
-`p' VAR1[`,' VAR2 ...]
- Print the value of a `gawk' variable or field. Fields must be
+'end'
+ This form of 'eval' is similar, but it allows you to define "local
+ variables" that exist in the context of the AWK STATEMENTS, instead
+ of using variables or function parameters defined by the program.
+
+'print' VAR1[',' VAR2 ...]
+'p' VAR1[',' VAR2 ...]
+ Print the value of a 'gawk' variable or field. Fields must be
referenced by constants:
gawk> print $3
This prints the third field in the input record (if the specified
- field does not exist, it prints `Null field'). A variable can be
- an array element, with the subscripts being constant string
- values. To print the contents of an array, prefix the name of the
- array with the `@' symbol:
+ field does not exist, it prints 'Null field'). A variable can be
+ an array element, with the subscripts being constant string values.
+ To print the contents of an array, prefix the name of the array
+ with the '@' symbol:
gawk> print @a
This prints the indices and the corresponding values for all
- elements in the array `a'.
+ elements in the array 'a'.
-`printf' FORMAT [`,' ARG ...]
- Print formatted text. The FORMAT may include escape sequences,
- such as `\n' (*note Escape Sequences::). No newline is printed
+'printf' FORMAT [',' ARG ...]
+ Print formatted text. The FORMAT may include escape sequences,
+ such as '\n' (*note Escape Sequences::). No newline is printed
unless one is specified.
-`set' VAR`='VALUE
- Assign a constant (number or string) value to an `awk' variable or
+'set' VAR'='VALUE
+ Assign a constant (number or string) value to an 'awk' variable or
field. String values must be enclosed between double quotes
- (`"'...`"').
+ ('"'...'"').
- You can also set special `awk' variables, such as `FS', `NF',
- `NR', and so on.
+ You can also set special 'awk' variables, such as 'FS', 'NF', 'NR',
+ and so on.
-`watch' VAR | `$'N [`"EXPRESSION"']
-`w' VAR | `$'N [`"EXPRESSION"']
- Add variable VAR (or field `$N') to the watch list. The debugger
+'watch' VAR | '$'N ['"EXPRESSION"']
+'w' VAR | '$'N ['"EXPRESSION"']
+ Add variable VAR (or field '$N') to the watch list. The debugger
then stops whenever the value of the variable or field changes.
Each watched item is assigned a number that can be used to delete
- it from the watch list using the `unwatch' command.
+ it from the watch list using the 'unwatch' command.
With a watchpoint, you may also supply a condition. This is an
- `awk' expression (enclosed in double quotes) that the debugger
- evaluates whenever the watchpoint is reached. If the condition is
+ 'awk' expression (enclosed in double quotes) that the debugger
+ evaluates whenever the watchpoint is reached. If the condition is
true, then the debugger stops execution and prompts for a command.
- Otherwise, `gawk' continues executing the program.
+ Otherwise, 'gawk' continues executing the program.
-`undisplay' [N]
+'undisplay' [N]
Remove item number N (or all items, if no argument) from the
automatic display list.
-`unwatch' [N]
+'unwatch' [N]
Remove item number N (or all items, if no argument) from the watch
list.
-
File: gawk.info, Node: Execution Stack, Next: Debugger Info, Prev: Viewing
And Changing Data, Up: List of Debugger Commands
14.3.4 Working with the Stack
-----------------------------
-Whenever you run a program that contains any function calls, `gawk'
+Whenever you run a program that contains any function calls, 'gawk'
maintains a stack of all of the function calls leading up to where the
program is right now. You can see how you got to where you are, and
also move around in the stack to see what the state of things was in the
functions that called the one you are in. The commands for doing this
are:
-`backtrace' [COUNT]
-`bt' [COUNT]
-`where' [COUNT]
+'backtrace' [COUNT]
+'bt' [COUNT]
+'where' [COUNT]
Print a backtrace of all function calls (stack frames), or
- innermost COUNT frames if COUNT > 0. Print the outermost COUNT
- frames if COUNT < 0. The backtrace displays the name and
- arguments to each function, the source file name, and the line
- number. The alias `where' for `backtrace' is provided for longtime
- GDB users who may be used to that command.
+ innermost COUNT frames if COUNT > 0. Print the outermost COUNT
+ frames if COUNT < 0. The backtrace displays the name and arguments
+ to each function, the source file name, and the line number. The
+ alias 'where' for 'backtrace' is provided for longtime GDB users
+ who may be used to that command.
-`down' [COUNT]
+'down' [COUNT]
Move COUNT (default 1) frames down the stack toward the innermost
frame. Then select and print the frame.
-`frame' [N]
-`f' [N]
+'frame' [N]
+'f' [N]
Select and print stack frame N. Frame 0 is the currently
executing, or "innermost", frame (function call); frame 1 is the
- frame that called the innermost one. The highest-numbered frame is
+ frame that called the innermost one. The highest-numbered frame is
the one for the main program. The printed information consists of
- the frame number, function and argument names, source file, and
- the source line.
+ the frame number, function and argument names, source file, and the
+ source line.
-`up' [COUNT]
+'up' [COUNT]
Move COUNT (default 1) frames up the stack toward the outermost
frame. Then select and print the frame.
@@ -21406,106 +21317,106 @@ File: gawk.info, Node: Debugger Info, Next:
Miscellaneous Debugger Commands,
Besides looking at the values of variables, there is often a need to get
other sorts of information about the state of your program and of the
-debugging environment itself. The `gawk' debugger has one command that
-provides this information, appropriately called `info'. `info' is used
+debugging environment itself. The 'gawk' debugger has one command that
+provides this information, appropriately called 'info'. 'info' is used
with one of a number of arguments that tell it exactly what you want to
know:
-`info' WHAT
-`i' WHAT
+'info' WHAT
+'i' WHAT
The value for WHAT should be one of the following:
- `args'
+ 'args'
List arguments of the selected frame.
- `break'
+ 'break'
List all currently set breakpoints.
- `display'
+ 'display'
List all items in the automatic display list.
- `frame'
+ 'frame'
Give a description of the selected stack frame.
- `functions'
+ 'functions'
List all function definitions including source file names and
line numbers.
- `locals'
+ 'locals'
List local variables of the selected frame.
- `source'
- Print the name of the current source file. Each time the
+ 'source'
+ Print the name of the current source file. Each time the
program stops, the current source file is the file containing
the current instruction. When the debugger first starts, the
- current source file is the first file included via the `-f'
- option. The `list FILENAME:LINENO' command can be used at any
+ current source file is the first file included via the '-f'
+ option. The 'list FILENAME:LINENO' command can be used at any
time to change the current source.
- `sources'
+ 'sources'
List all program sources.
- `variables'
+ 'variables'
List all global variables.
- `watch'
+ 'watch'
List all items in the watch list.
Additional commands give you control over the debugger, the ability
to save the debugger's state, and the ability to run debugger commands
from a file. The commands are:
-`option' [NAME[`='VALUE]]
-`o' [NAME[`='VALUE]]
+'option' [NAME['='VALUE]]
+'o' [NAME['='VALUE]]
Without an argument, display the available debugger options and
- their current values. `option NAME' shows the current value of the
- named option. `option NAME=VALUE' assigns a new value to the named
+ their current values. 'option NAME' shows the current value of the
+ named option. 'option NAME=VALUE' assigns a new value to the named
option. The available options are:
- `history_size'
+ 'history_size'
Set the maximum number of lines to keep in the history file
- `./.gawk_history'. The default is 100.
+ './.gawk_history'. The default is 100.
- `listsize'
- Specify the number of lines that `list' prints. The default
+ 'listsize'
+ Specify the number of lines that 'list' prints. The default
is 15.
- `outfile'
- Send `gawk' output to a file; debugger output still goes to
- standard output. An empty string (`""') resets output to
+ 'outfile'
+ Send 'gawk' output to a file; debugger output still goes to
+ standard output. An empty string ('""') resets output to
standard output.
- `prompt'
- Change the debugger prompt. The default is `gawk> '.
+ 'prompt'
+ Change the debugger prompt. The default is 'gawk> '.
- `save_history' [`on' | `off']
- Save command history to file `./.gawk_history'. The default
- is `on'.
+ 'save_history' ['on' | 'off']
+ Save command history to file './.gawk_history'. The default
+ is 'on'.
- `save_options' [`on' | `off']
- Save current options to file `./.gawkrc' upon exit. The
- default is `on'. Options are read back into the next session
+ 'save_options' ['on' | 'off']
+ Save current options to file './.gawkrc' upon exit. The
+ default is 'on'. Options are read back into the next session
upon startup.
- `trace' [`on' | `off']
- Turn instruction tracing on or off. The default is `off'.
+ 'trace' ['on' | 'off']
+ Turn instruction tracing on or off. The default is 'off'.
-`save' FILENAME
+'save' FILENAME
Save the commands from the current session to the given file name,
- so that they can be replayed using the `source' command.
+ so that they can be replayed using the 'source' command.
-`source' FILENAME
+'source' FILENAME
Run command(s) from a file; an error in any command does not
- terminate execution of subsequent commands. Comments (lines
- starting with `#') are allowed in a command file. Empty lines are
+ terminate execution of subsequent commands. Comments (lines
+ starting with '#') are allowed in a command file. Empty lines are
ignored; they do _not_ repeat the last command. You can't restart
- the program by having more than one `run' command in the file.
- Also, the list of commands may include additional `source'
- commands; however, the `gawk' debugger will not source the same
+ the program by having more than one 'run' command in the file.
+ Also, the list of commands may include additional 'source'
+ commands; however, the 'gawk' debugger will not source the same
file more than once in order to avoid infinite recursion.
- In addition to, or instead of, the `source' command, you can use
- the `-D FILE' or `--debug=FILE' command-line options to execute
+ In addition to, or instead of, the 'source' command, you can use
+ the '-D FILE' or '--debug=FILE' command-line options to execute
commands from a file non-interactively (*note Options::).
@@ -21517,10 +21428,10 @@ File: gawk.info, Node: Miscellaneous Debugger
Commands, Prev: Debugger Info,
There are a few more commands that do not fit into the previous
categories, as follows:
-`dump' [FILENAME]
+'dump' [FILENAME]
Dump byte code of the program to standard output or to the file
named in FILENAME. This prints a representation of the internal
- instructions that `gawk' executes to implement the `awk' commands
+ instructions that 'gawk' executes to implement the 'awk' commands
in a program. This can be very enlightening, as the following
partial dump of Davide Brini's obfuscated code (*note Signature
Program::) demonstrates:
@@ -21574,56 +21485,55 @@ categories, as follows:
-| [ :0xfcc1a0] Op_after_endfile :
gawk>
-`help'
-`h'
- Print a list of all of the `gawk' debugger commands with a short
- summary of their usage. `help COMMAND' prints the information
+'help'
+'h'
+ Print a list of all of the 'gawk' debugger commands with a short
+ summary of their usage. 'help COMMAND' prints the information
about the command COMMAND.
-`list' [`-' | `+' | N | FILENAME`:'N | N-M | FUNCTION]
-`l' [`-' | `+' | N | FILENAME`:'N | N-M | FUNCTION]
+'list' ['-' | '+' | N | FILENAME':'N | N-M | FUNCTION]
+'l' ['-' | '+' | N | FILENAME':'N | N-M | FUNCTION]
Print the specified lines (default 15) from the current source file
- or the file named FILENAME. The possible arguments to `list' are
+ or the file named FILENAME. The possible arguments to 'list' are
as follows:
- `-' (Minus)
+ '-' (Minus)
Print lines before the lines last printed.
- `+'
- Print lines after the lines last printed. `list' without any
+ '+'
+ Print lines after the lines last printed. 'list' without any
argument does the same thing.
- N
+ N
Print lines centered around line number N.
- N-M
+ N-M
Print lines from N to M.
- FILENAME`:'N
+ FILENAME':'N
Print lines centered around line number N in source file
- FILENAME. This command may change the current source file.
+ FILENAME. This command may change the current source file.
- FUNCTION
+ FUNCTION
Print lines centered around the beginning of the function
- FUNCTION. This command may change the current source file.
+ FUNCTION. This command may change the current source file.
-`quit'
-`q'
+'quit'
+'q'
Exit the debugger. Debugging is great fun, but sometimes we all
have to tend to other obligations in life, and sometimes we find
the bug and are free to go on to the next one! As we saw earlier,
if you are running a program, the debugger warns you when you type
- `q' or `quit', to make sure you really want to quit.
+ 'q' or 'quit', to make sure you really want to quit.
-`trace' [`on' | `off']
+'trace' ['on' | 'off']
Turn on or off continuous printing of the instructions that are
- about to be executed, along with the `awk' lines they implement.
- The default is `off'.
+ about to be executed, along with the 'awk' lines they implement.
+ The default is 'off'.
It is to be hoped that most of the "opcodes" in these instructions
- are fairly self-explanatory, and using `stepi' and `nexti' while
- `trace' is on will make them into familiar friends.
-
+ are fairly self-explanatory, and using 'stepi' and 'nexti' while
+ 'trace' is on will make them into familiar friends.
File: gawk.info, Node: Readline Support, Next: Limitations, Prev: List of
Debugger Commands, Up: Debugger
@@ -21631,27 +21541,26 @@ File: gawk.info, Node: Readline Support, Next:
Limitations, Prev: List of Deb
14.4 Readline Support
=====================
-If `gawk' is compiled with the GNU Readline library
+If 'gawk' is compiled with the GNU Readline library
(http://cnswww.cns.cwru.edu/php/chet/readline/readline.html), you can
take advantage of that library's command completion and history
-expansion features. The following types of completion are available:
+expansion features. The following types of completion are available:
Command completion
Command names.
Source file name completion
- Source file names. Relevant commands are `break', `clear', `list',
- `tbreak', and `until'.
+ Source file names. Relevant commands are 'break', 'clear', 'list',
+ 'tbreak', and 'until'.
Argument completion
- Non-numeric arguments to a command. Relevant commands are
- `enable' and `info'.
+ Non-numeric arguments to a command. Relevant commands are 'enable'
+ and 'info'.
Variable name completion
Global variable names, and function arguments in the current
- context if the program is running. Relevant commands are `display',
- `print', `set', and `watch'.
-
+ context if the program is running. Relevant commands are
+ 'display', 'print', 'set', and 'watch'.
File: gawk.info, Node: Limitations, Next: Debugging Summary, Prev: Readline
Support, Up: Debugger
@@ -21659,43 +21568,42 @@ File: gawk.info, Node: Limitations, Next: Debugging
Summary, Prev: Readline S
14.5 Limitations
================
-We hope you find the `gawk' debugger useful and enjoyable to work with,
+We hope you find the 'gawk' debugger useful and enjoyable to work with,
but as with any program, especially in its early releases, it still has
some limitations. A few that it's worth being aware of are:
* At this point, the debugger does not give a detailed explanation of
what you did wrong when you type in something it doesn't like.
- Rather, it just responds `syntax error'. When you do figure out
+ Rather, it just responds 'syntax error'. When you do figure out
what your mistake was, though, you'll feel like a real guru.
* If you perused the dump of opcodes in *note Miscellaneous Debugger
- Commands:: (or if you are already familiar with `gawk' internals),
+ Commands:: (or if you are already familiar with 'gawk' internals),
you will realize that much of the internal manipulation of data in
- `gawk', as in many interpreters, is done on a stack. `Op_push',
- `Op_pop', and the like are the "bread and butter" of most `gawk'
+ 'gawk', as in many interpreters, is done on a stack. 'Op_push',
+ 'Op_pop', and the like are the "bread and butter" of most 'gawk'
code.
- Unfortunately, as of now, the `gawk' debugger does not allow you
- to examine the stack's contents. That is, the intermediate
- results of expression evaluation are on the stack, but cannot be
- printed. Rather, only variables that are defined in the program
- can be printed. Of course, a workaround for this is to use more
- explicit variables at the debugging stage and then change back to
- obscure, perhaps more optimal code later.
+ Unfortunately, as of now, the 'gawk' debugger does not allow you to
+ examine the stack's contents. That is, the intermediate results of
+ expression evaluation are on the stack, but cannot be printed.
+ Rather, only variables that are defined in the program can be
+ printed. Of course, a workaround for this is to use more explicit
+ variables at the debugging stage and then change back to obscure,
+ perhaps more optimal code later.
* There is no way to look "inside" the process of compiling regular
- expressions to see if you got it right. As an `awk' programmer,
- you are expected to know the meaning of `/[^[:alnum:][:blank:]]/'.
+ expressions to see if you got it right. As an 'awk' programmer,
+ you are expected to know the meaning of '/[^[:alnum:][:blank:]]/'.
- * The `gawk' debugger is designed to be used by running a program
+ * The 'gawk' debugger is designed to be used by running a program
(with all its parameters) on the command line, as described in
- *note Debugger Invocation::. There is no way (as of now) to
- attach or "break into" a running program. This seems reasonable
- for a language that is used mainly for quickly executing, short
- programs.
+ *note Debugger Invocation::. There is no way (as of now) to attach
+ or "break into" a running program. This seems reasonable for a
+ language that is used mainly for quickly executing, short programs.
- * The `gawk' debugger only accepts source code supplied with the
- `-f' option.
+ * The 'gawk' debugger only accepts source code supplied with the '-f'
+ option.
File: gawk.info, Node: Debugging Summary, Prev: Limitations, Up: Debugger
@@ -21705,54 +21613,53 @@ File: gawk.info, Node: Debugging Summary, Prev:
Limitations, Up: Debugger
* Programs rarely work correctly the first time. Finding bugs is
called debugging, and a program that helps you find bugs is a
- debugger. `gawk' has a built-in debugger that works very
- similarly to the GNU Debugger, GDB.
+ debugger. 'gawk' has a built-in debugger that works very similarly
+ to the GNU Debugger, GDB.
* Debuggers let you step through your program one statement at a
- time, examine and change variable and array values, and do a
- number of other things that let you understand what your program
- is actually doing (as opposed to what it is supposed to do).
+ time, examine and change variable and array values, and do a number
+ of other things that let you understand what your program is
+ actually doing (as opposed to what it is supposed to do).
- * Like most debuggers, the `gawk' debugger works in terms of stack
+ * Like most debuggers, the 'gawk' debugger works in terms of stack
frames, and lets you set both breakpoints (stop at a point in the
code) and watchpoints (stop when a data value changes).
* The debugger command set is fairly complete, providing control over
- breakpoints, execution, viewing and changing data, working with
- the stack, getting information, and other tasks.
+ breakpoints, execution, viewing and changing data, working with the
+ stack, getting information, and other tasks.
- * If the GNU Readline library is available when `gawk' is compiled,
+ * If the GNU Readline library is available when 'gawk' is compiled,
it is used by the debugger to provide command-line history and
editing.
-
File: gawk.info, Node: Arbitrary Precision Arithmetic, Next: Dynamic
Extensions, Prev: Debugger, Up: Top
-15 Arithmetic and Arbitrary-Precision Arithmetic with `gawk'
+15 Arithmetic and Arbitrary-Precision Arithmetic with 'gawk'
************************************************************
-This major node introduces some basic concepts relating to how
-computers do arithmetic and defines some important terms. It then
-proceeds to describe floating-point arithmetic, which is what `awk'
-uses for all its computations, including a discussion of
-arbitrary-precision floating-point arithmetic, which is a feature
-available only in `gawk'. It continues on to present
-arbitrary-precision integers, and concludes with a description of some
-points where `gawk' and the POSIX standard are not quite in agreement.
-
- NOTE: Most users of `gawk' can safely skip this chapter. But if
- you want to do scientific calculations with `gawk', this is the
+This major node introduces some basic concepts relating to how computers
+do arithmetic and defines some important terms. It then proceeds to
+describe floating-point arithmetic, which is what 'awk' uses for all its
+computations, including a discussion of arbitrary-precision
+floating-point arithmetic, which is a feature available only in 'gawk'.
+It continues on to present arbitrary-precision integers, and concludes
+with a description of some points where 'gawk' and the POSIX standard
+are not quite in agreement.
+
+ NOTE: Most users of 'gawk' can safely skip this chapter. But if
+ you want to do scientific calculations with 'gawk', this is the
place to be.
* Menu:
* Computer Arithmetic:: A quick intro to computer math.
* Math Definitions:: Defining terms used.
-* MPFR features:: The MPFR features in `gawk'.
+* MPFR features:: The MPFR features in 'gawk'.
* FP Math Caution:: Things to know.
* Arbitrary Precision Integers:: Arbitrary Precision Integer Arithmetic with
- `gawk'.
+ 'gawk'.
* POSIX Floating Point Problems:: Standards Versus Existing Practice.
* Floating point summary:: Summary of floating point discussion.
@@ -21778,7 +21685,7 @@ that interest us are:
Decimal arithmetic
This is the kind of arithmetic you learned in elementary school,
- using paper and pencil (and/or a calculator). In theory, numbers
+ using paper and pencil (and/or a calculator). In theory, numbers
can have an arbitrary number of digits on either side (or both
sides) of the decimal point, and the results of a computation are
always exact.
@@ -21788,7 +21695,7 @@ Decimal arithmetic
these instructions. There are also libraries that do decimal
arithmetic entirely in software.
- Despite the fact that some users expect `gawk' to be performing
+ Despite the fact that some users expect 'gawk' to be performing
decimal arithmetic,(1) it does not do so.
Integer arithmetic
@@ -21802,40 +21709,48 @@ Integer arithmetic
unsigned values are always greater than or equal to zero.
In computer systems, integer arithmetic is exact, but the possible
- range of values is limited. Integer arithmetic is generally
- faster than floating-point arithmetic.
+ range of values is limited. Integer arithmetic is generally faster
+ than floating-point arithmetic.
Floating-point arithmetic
Floating-point numbers represent what were called in school "real"
numbers (i.e., those that have a fractional part, such as
3.1415927). The advantage to floating-point numbers is that they
- can represent a much larger range of values than can integers.
- The disadvantage is that there are numbers that they cannot
- represent exactly.
+ can represent a much larger range of values than can integers. The
+ disadvantage is that there are numbers that they cannot represent
+ exactly.
Modern systems support floating-point arithmetic in hardware, with
a limited range of values. There are software libraries that allow
the use of arbitrary-precision floating-point calculations.
- POSIX `awk' uses "double-precision" floating-point numbers, which
+ POSIX 'awk' uses "double-precision" floating-point numbers, which
can hold more digits than "single-precision" floating-point
- numbers. `gawk' has facilities for performing arbitrary-precision
+ numbers. 'gawk' has facilities for performing arbitrary-precision
floating-point arithmetic, which we describe in more detail
shortly.
Computers work with integer and floating-point values of different
-ranges. Integer values are usually either 32 or 64 bits in size.
+ranges. Integer values are usually either 32 or 64 bits in size.
Single-precision floating-point values occupy 32 bits, whereas
double-precision floating-point values occupy 64 bits. Floating-point
-values are always signed. The possible ranges of values are shown in
-*note table-numeric-ranges::.
+values are always signed. The possible ranges of values are shown in
+*note Table 15.1: table-numeric-ranges.
Numeric representation Minimum value Maximum value
----------------------------------------------------------------------------
+---------------------------------------------------------------------------
32-bit signed integer -2,147,483,648 2,147,483,647
-32-bit unsigned integer 0 4,294,967,295
+32-bit unsigned 0 4,294,967,295
+integer
64-bit signed integer -9,223,372,036,854,775,8089,223,372,036,854,775,807
-64-bit unsigned integer 0 18,446,744,073,709,551,615
+64-bit unsigned 0 18,446,744,073,709,551,615
+integer
+Single-precision 1.175494e-38 3.402823e38
+floating point
+(approximate)
+Double-precision 2.225074e-308 1.797693e308
+floating point
+(approximate)
Table 15.1: Value ranges for different numeric representations
@@ -21849,7 +21764,7 @@ File: gawk.info, Node: Math Definitions, Next: MPFR
features, Prev: Computer
15.2 Other Stuff to Know
========================
-The rest of this major node uses a number of terms. Here are some
+The rest of this major node uses a number of terms. Here are some
informal definitions that should help you work your way through the
material here:
@@ -21867,28 +21782,28 @@ material here:
floating-point value store the exponent.
"Inf"
- A special value representing infinity. Operations involving another
- number and infinity produce infinity.
+ A special value representing infinity. Operations involving
+ another number and infinity produce infinity.
"NaN"
- "Not a number."(1) A special value that results from attempting a
+ "Not a number."(1) A special value that results from attempting a
calculation that has no answer as a real number. In such a case,
programs can either receive a floating-point exception, or get
- `NaN' back as the result. The IEEE 754 standard recommends that
- systems return `NaN'. Some examples:
+ 'NaN' back as the result. The IEEE 754 standard recommends that
+ systems return 'NaN'. Some examples:
- `sqrt(-1)'
+ 'sqrt(-1)'
This makes sense in the range of complex numbers, but not in
- the range of real numbers, so the result is `NaN'.
+ the range of real numbers, so the result is 'NaN'.
- `log(-8)'
- -8 is out of the domain of `log()', so the result is `NaN'.
+ 'log(-8)'
+ -8 is out of the domain of 'log()', so the result is 'NaN'.
"Normalized"
- How the significand (see later in this list) is usually stored. The
- value is adjusted so that the first bit is one, and then that
- leading one is assumed instead of physically stored. This
- provides one extra bit of precision.
+ How the significand (see later in this list) is usually stored.
+ The value is adjusted so that the first bit is one, and then that
+ leading one is assumed instead of physically stored. This provides
+ one extra bit of precision.
"Precision"
The number of bits used to represent a floating-point number. The
@@ -21906,8 +21821,8 @@ material here:
"Significand"
A floating-point value consists of the significand multiplied by 10
- to the power of the exponent. For example, in `1.2345e67', the
- significand is `1.2345'.
+ to the power of the exponent. For example, in '1.2345e67', the
+ significand is '1.2345'.
"Stability"
From the Wikipedia article on numerical stability
@@ -21921,17 +21836,17 @@ information on some of those terms.
On modern systems, floating-point hardware uses the representation
and operations defined by the IEEE 754 standard. Three of the standard
-IEEE 754 types are 32-bit single precision, 64-bit double precision,
-and 128-bit quadruple precision. The standard also specifies extended
+IEEE 754 types are 32-bit single precision, 64-bit double precision, and
+128-bit quadruple precision. The standard also specifies extended
precision formats to allow greater precisions and larger exponent
-ranges. (`awk' uses only the 64-bit double-precision format.)
+ranges. ('awk' uses only the 64-bit double-precision format.)
- *note table-ieee-formats:: lists the precision and exponent field
-values for the basic IEEE 754 binary formats.
+ *note Table 15.2: table-ieee-formats. lists the precision and
+exponent field values for the basic IEEE 754 binary formats.
Name Total bits Precision Minimum Maximum
exponent exponent
----------------------------------------------------------------------------
+---------------------------------------------------------------------------
Single 32 24 -126 +127
Double 64 53 -1022 +1023
Quadruple 128 113 -16382 +16383
@@ -21949,12 +21864,12 @@ paraphrased, and for the examples.
File: gawk.info, Node: MPFR features, Next: FP Math Caution, Prev: Math
Definitions, Up: Arbitrary Precision Arithmetic
-15.3 Arbitrary-Precision Arithmetic Features in `gawk'
+15.3 Arbitrary-Precision Arithmetic Features in 'gawk'
======================================================
-By default, `gawk' uses the double-precision floating-point values
+By default, 'gawk' uses the double-precision floating-point values
supplied by the hardware of the system it runs on. However, if it was
-compiled to do so, `gawk' uses the GNU MPFR (http://www.mpfr.org) and
+compiled to do so, 'gawk' uses the GNU MPFR (http://www.mpfr.org) and
GNU MP (http://gmplib.org) (GMP) libraries for arbitrary-precision
arithmetic on numbers. You can see if MPFR support is available like
so:
@@ -21964,25 +21879,25 @@ so:
-| Copyright (C) 1989, 1991-2015 Free Software Foundation.
...
-(You may see different version numbers than what's shown here. That's
+(You may see different version numbers than what's shown here. That's
OK; what's important is to see that GNU MPFR and GNU MP are listed in
the output.)
- Additionally, there are a few elements available in the `PROCINFO'
+ Additionally, there are a few elements available in the 'PROCINFO'
array to provide information about the MPFR and GMP libraries (*note
Auto-set::).
The MPFR library provides precise control over precisions and
rounding modes, and gives correctly rounded, reproducible,
-platform-independent results. With the `-M' command-line option, all
+platform-independent results. With the '-M' command-line option, all
floating-point arithmetic operators and numeric functions can yield
results to any desired precision level supported by MPFR.
- Two predefined variables, `PREC' and `ROUNDMODE', provide control
-over the working precision and the rounding mode. The precision and
-the rounding mode are set globally for every operation to follow.
-*Note Setting precision::, and *note Setting the rounding mode::, for
-more information.
+ Two predefined variables, 'PREC' and 'ROUNDMODE', provide control
+over the working precision and the rounding mode. The precision and the
+rounding mode are set globally for every operation to follow. *Note
+Setting precision::, and *note Setting the rounding mode::, for more
+information.
File: gawk.info, Node: FP Math Caution, Next: Arbitrary Precision Integers,
Prev: MPFR features, Up: Arbitrary Precision Arithmetic
@@ -21990,16 +21905,16 @@ File: gawk.info, Node: FP Math Caution, Next:
Arbitrary Precision Integers, P
15.4 Floating-Point Arithmetic: Caveat Emptor!
==============================================
- Math class is tough! -- Teen Talk Barbie, July 1992
+ Math class is tough!
+ -- _Teen Talk Barbie, July 1992_
- This minor node provides a high-level overview of the issues
-involved when doing lots of floating-point arithmetic.(1) The
-discussion applies to both hardware and arbitrary-precision
-floating-point arithmetic.
+ This minor node provides a high-level overview of the issues involved
+when doing lots of floating-point arithmetic.(1) The discussion applies
+to both hardware and arbitrary-precision floating-point arithmetic.
- CAUTION: The material here is purposely general. If you need to do
- serious computer arithmetic, you should do some research first,
- and not rely just on what we tell you.
+ CAUTION: The material here is purposely general. If you need to do
+ serious computer arithmetic, you should do some research first, and
+ not rely just on what we tell you.
* Menu:
@@ -22014,7 +21929,7 @@ floating-point arithmetic.
(1) There is a very nice paper on floating-point arithmetic
(http://www.validlab.com/goldberg/paper.pdf) by David Goldberg, "What
Every Computer Scientist Should Know About Floating-Point Arithmetic,"
-`ACM Computing Surveys' *23*, 1 (1991-03): 5-48. This is worth reading
+'ACM Computing Surveys' *23*, 1 (1991-03): 5-48. This is worth reading
if you are interested in the details, but it does require a background
in computer science.
@@ -22028,11 +21943,10 @@ Binary floating-point representations and arithmetic
are inexact.
Simple values like 0.1 cannot be precisely represented using binary
floating-point numbers, and the limited precision of floating-point
numbers means that slight changes in the order of operations or the
-precision of intermediate storage can change the result. To make
+precision of intermediate storage can change the result. To make
matters worse, with arbitrary-precision floating-point arithmetic, you
-can set the precision before starting a computation, but then you
-cannot be sure of the number of significant decimal places in the final
-result.
+can set the precision before starting a computation, but then you cannot
+be sure of the number of significant decimal places in the final result.
* Menu:
@@ -22047,20 +21961,20 @@ File: gawk.info, Node: Inexact representation,
Next: Comparing FP Values, Up:
...................................................
So, before you start to write any code, you should think about what you
-really want and what's really happening. Consider the two numbers in
+really want and what's really happening. Consider the two numbers in
the following example:
x = 0.875 # 1/2 + 1/4 + 1/8
y = 0.425
- Unlike the number in `y', the number stored in `x' is exactly
-representable in binary because it can be written as a finite sum of
-one or more fractions whose denominators are all powers of two. When
-`gawk' reads a floating-point number from program source, it
-automatically rounds that number to whatever precision your machine
-supports. If you try to print the numeric content of a variable using
-an output format string of `"%.17g"', it may not produce the same
-number as you assigned to it:
+ Unlike the number in 'y', the number stored in 'x' is exactly
+representable in binary because it can be written as a finite sum of one
+or more fractions whose denominators are all powers of two. When 'gawk'
+reads a floating-point number from program source, it automatically
+rounds that number to whatever precision your machine supports. If you
+try to print the numeric content of a variable using an output format
+string of '"%.17g"', it may not produce the same number as you assigned
+to it:
$ gawk 'BEGIN { x = 0.875; y = 0.425
> printf("%0.17g, %0.17g\n", x, y) }'
@@ -22068,7 +21982,7 @@ number as you assigned to it:
Often the error is so small you do not even notice it, and if you do,
you can always specify how much precision you would like in your output.
-Usually this is a format string like `"%.15g"', which, when used in the
+Usually this is a format string like '"%.15g"', which, when used in the
previous example, produces an output identical to the input.
@@ -22087,8 +22001,8 @@ work like you would expect:
The general wisdom when comparing floating-point values is to see if
they are within some small range of each other (called a "delta", or
-"tolerance"). You have to decide how small a delta is important to
-you. Code to do this looks something like the following:
+"tolerance"). You have to decide how small a delta is important to you.
+Code to do this looks something like the following:
delta = 0.00001 # for example
difference = abs(a) - abs(b) # subtract the two values
@@ -22097,7 +22011,7 @@ you. Code to do this looks something like the following:
else
# not ok
-(We assume that you have a simple absolute value function named `abs()'
+(We assume that you have a simple absolute value function named 'abs()'
defined elsewhere in your program.)
@@ -22107,11 +22021,11 @@ File: gawk.info, Node: Errors accumulate, Prev:
Comparing FP Values, Up: Inex
..........................
The loss of accuracy during a single computation with floating-point
-numbers usually isn't enough to worry about. However, if you compute a
-value that is the result of a sequence of floating-point operations,
-the error can accumulate and greatly affect the computation itself.
-Here is an attempt to compute the value of pi using one of its many
-series representations:
+numbers usually isn't enough to worry about. However, if you compute a
+value that is the result of a sequence of floating-point operations, the
+error can accumulate and greatly affect the computation itself. Here is
+an attempt to compute the value of pi using one of its many series
+representations:
BEGIN {
x = 1.0 / sqrt(3.0)
@@ -22136,7 +22050,7 @@ zero:
-| 3.224515243534819
-| 2.791117213058638
-| 0.000000000000000
- error--> gawk: pi.awk:6: fatal: division by zero attempted
+ error-> gawk: pi.awk:6: fatal: division by zero attempted
Here is an additional example where the inaccuracies in internal
representations yield an unexpected result:
@@ -22154,14 +22068,14 @@ File: gawk.info, Node: Getting Accuracy, Next: Try
To Round, Prev: Inexactnes
15.4.2 Getting the Accuracy You Need
------------------------------------
-Can arbitrary-precision arithmetic give exact results? There are no
-easy answers. The standard rules of algebra often do not apply when
+Can arbitrary-precision arithmetic give exact results? There are no
+easy answers. The standard rules of algebra often do not apply when
using floating-point arithmetic. Among other things, the distributive
and associative laws do not hold completely, and order of operation may
-be important for your computation. Rounding error, cumulative precision
+be important for your computation. Rounding error, cumulative precision
loss, and underflow are often troublesome.
- When `gawk' tests the expressions `0.1 + 12.2' and `12.3' for
+ When 'gawk' tests the expressions '0.1 + 12.2' and '12.3' for
equality using the machine double-precision arithmetic, it decides that
they are not equal! (*Note Comparing FP Values::.) You can get the
result you want by increasing the precision; 56 bits in this case does
@@ -22172,18 +22086,18 @@ the job:
If adding more bits is good, perhaps adding even more bits of
precision is better? Here is what happens if we use an even larger
-value of `PREC':
+value of 'PREC':
$ gawk -M -v PREC=201 'BEGIN { print (0.1 + 12.2 == 12.3) }'
-| 0
- This is not a bug in `gawk' or in the MPFR library. It is easy to
+ This is not a bug in 'gawk' or in the MPFR library. It is easy to
forget that the finite number of bits used to store the value is often
just an approximation after proper rounding. The test for equality
succeeds if and only if _all_ bits in the two operands are exactly the
-same. Because this is not necessarily true after floating-point
+same. Because this is not necessarily true after floating-point
computations with a particular precision and effective rounding mode, a
-straight test for equality may not work. Instead, compare the two
+straight test for equality may not work. Instead, compare the two
numbers to see if they are within the desirable delta of each other.
In applications where 15 or fewer decimal places suffice, hardware
@@ -22206,7 +22120,7 @@ In the example in *note Errors accumulate:::
-| 4
you may or may not succeed in getting the correct result by choosing an
-arbitrarily large value for `PREC'. Reformulation of the problem at
+arbitrarily large value for 'PREC'. Reformulation of the problem at
hand is often the correct approach in such situations.
@@ -22242,24 +22156,24 @@ File: gawk.info, Node: Setting precision, Next:
Setting the rounding mode, Pr
15.4.4 Setting the Precision
----------------------------
-`gawk' uses a global working precision; it does not keep track of the
-precision or accuracy of individual numbers. Performing an arithmetic
+'gawk' uses a global working precision; it does not keep track of the
+precision or accuracy of individual numbers. Performing an arithmetic
operation or calling a built-in function rounds the result to the
-current working precision. The default working precision is 53 bits,
-which you can modify using the predefined variable `PREC'. You can also
-set the value to one of the predefined case-insensitive strings shown
-in *note table-predefined-precision-strings::, to emulate an IEEE 754
-binary format.
-
-`PREC' IEEE 754 binary format
----------------------------------------------------
-`"half"' 16-bit half-precision
-`"single"' Basic 32-bit single precision
-`"double"' Basic 64-bit double precision
-`"quad"' Basic 128-bit quadruple precision
-`"oct"' 256-bit octuple precision
-
-Table 15.3: Predefined precision strings for `PREC'
+current working precision. The default working precision is 53 bits,
+which you can modify using the predefined variable 'PREC'. You can also
+set the value to one of the predefined case-insensitive strings shown in
+*note Table 15.3: table-predefined-precision-strings, to emulate an IEEE
+754 binary format.
+
+'PREC' IEEE 754 binary format
+---------------------------------------------------
+'"half"' 16-bit half-precision
+'"single"' Basic 32-bit single precision
+'"double"' Basic 64-bit double precision
+'"quad"' Basic 128-bit quadruple precision
+'"oct"' 256-bit octuple precision
+
+Table 15.3: Predefined precision strings for 'PREC'
The following example illustrates the effects of changing precision
on arithmetic operations:
@@ -22269,19 +22183,19 @@ on arithmetic operations:
-| 1e-400
-| 0
- CAUTION: Be wary of floating-point constants! When reading a
- floating-point constant from program source code, `gawk' uses the
- default precision (that of a C `double'), unless overridden by an
- assignment to the special variable `PREC' on the command line, to
+ CAUTION: Be wary of floating-point constants! When reading a
+ floating-point constant from program source code, 'gawk' uses the
+ default precision (that of a C 'double'), unless overridden by an
+ assignment to the special variable 'PREC' on the command line, to
store it internally as an MPFR number. Changing the precision
- using `PREC' in the program text does _not_ change the precision
- of a constant.
+ using 'PREC' in the program text does _not_ change the precision of
+ a constant.
If you need to represent a floating-point constant at a higher
- precision than the default and cannot use a command-line
- assignment to `PREC', you should either specify the constant as a
- string, or as a rational number, whenever possible. The following
- example illustrates the differences among various ways to print a
+ precision than the default and cannot use a command-line assignment
+ to 'PREC', you should either specify the constant as a string, or
+ as a rational number, whenever possible. The following example
+ illustrates the differences among various ways to print a
floating-point constant:
$ gawk -M 'BEGIN { PREC = 113; printf("%0.25f\n", 0.1) }'
@@ -22299,39 +22213,39 @@ File: gawk.info, Node: Setting the rounding mode,
Prev: Setting precision, Up
15.4.5 Setting the Rounding Mode
--------------------------------
-The `ROUNDMODE' variable provides program-level control over the
-rounding mode. The correspondence between `ROUNDMODE' and the IEEE
-rounding modes is shown in *note table-gawk-rounding-modes::.
+The 'ROUNDMODE' variable provides program-level control over the
+rounding mode. The correspondence between 'ROUNDMODE' and the IEEE
+rounding modes is shown in *note Table 15.4: table-gawk-rounding-modes.
-Rounding mode IEEE name `ROUNDMODE'
----------------------------------------------------------------------------
-Round to nearest, ties to even `roundTiesToEven' `"N"' or `"n"'
-Round toward positive infinity `roundTowardPositive' `"U"' or `"u"'
-Round toward negative infinity `roundTowardNegative' `"D"' or `"d"'
-Round toward zero `roundTowardZero' `"Z"' or `"z"'
-Round to nearest, ties away `roundTiesToAway' `"A"' or `"a"'
-from zero
+Rounding mode IEEE name 'ROUNDMODE'
+---------------------------------------------------------------------------
+Round to nearest, ties to even 'roundTiesToEven' '"N"' or '"n"'
+Round toward positive infinity 'roundTowardPositive' '"U"' or '"u"'
+Round toward negative infinity 'roundTowardNegative' '"D"' or '"d"'
+Round toward zero 'roundTowardZero' '"Z"' or '"z"'
+Round to nearest, ties away 'roundTiesToAway' '"A"' or '"a"'
+from zero
-Table 15.4: `gawk' rounding modes
+Table 15.4: 'gawk' rounding modes
- `ROUNDMODE' has the default value `"N"', which selects the IEEE 754
-rounding mode `roundTiesToEven'. In *note Table 15.4:
-table-gawk-rounding-modes, the value `"A"' selects `roundTiesToAway'.
+ 'ROUNDMODE' has the default value '"N"', which selects the IEEE 754
+rounding mode 'roundTiesToEven'. In *note Table 15.4:
+table-gawk-rounding-modes, the value '"A"' selects 'roundTiesToAway'.
This is only available if your version of the MPFR library supports it;
-otherwise, setting `ROUNDMODE' to `"A"' has no effect.
+otherwise, setting 'ROUNDMODE' to '"A"' has no effect.
- The default mode `roundTiesToEven' is the most preferred, but the
-least intuitive. This method does the obvious thing for most values, by
+ The default mode 'roundTiesToEven' is the most preferred, but the
+least intuitive. This method does the obvious thing for most values, by
rounding them up or down to the nearest digit. For example, rounding
1.132 to two digits yields 1.13, and rounding 1.157 yields 1.16.
However, when it comes to rounding a value that is exactly halfway
between, things do not work the way you probably learned in school. In
-this case, the number is rounded to the nearest even digit. So
-rounding 0.125 to two digits rounds down to 0.12, but rounding 0.6875
-to three digits rounds up to 0.688. You probably have already
-encountered this rounding mode when using `printf' to format
-floating-point numbers. For example:
+this case, the number is rounded to the nearest even digit. So rounding
+0.125 to two digits rounds down to 0.12, but rounding 0.6875 to three
+digits rounds up to 0.688. You probably have already encountered this
+rounding mode when using 'printf' to format floating-point numbers. For
+example:
BEGIN {
x = -4.5
@@ -22353,49 +22267,49 @@ produces the following output when run on the
author's system:(1)
3.5 => 4
4.5 => 4
- The theory behind `roundTiesToEven' is that it more or less evenly
+ The theory behind 'roundTiesToEven' is that it more or less evenly
distributes upward and downward rounds of exact halves, which might
-cause any accumulating round-off error to cancel itself out. This is the
-default rounding mode for IEEE 754 computing functions and operators.
+cause any accumulating round-off error to cancel itself out. This is
+the default rounding mode for IEEE 754 computing functions and
+operators.
The other rounding modes are rarely used. Rounding toward positive
-infinity (`roundTowardPositive') and toward negative infinity
-(`roundTowardNegative') are often used to implement interval
-arithmetic, where you adjust the rounding mode to calculate upper and
-lower bounds for the range of output. The `roundTowardZero' mode can be
-used for converting floating-point numbers to integers. The rounding
-mode `roundTiesToAway' rounds the result to the nearest number and
-selects the number with the larger magnitude if a tie occurs.
+infinity ('roundTowardPositive') and toward negative infinity
+('roundTowardNegative') are often used to implement interval arithmetic,
+where you adjust the rounding mode to calculate upper and lower bounds
+for the range of output. The 'roundTowardZero' mode can be used for
+converting floating-point numbers to integers. The rounding mode
+'roundTiesToAway' rounds the result to the nearest number and selects
+the number with the larger magnitude if a tie occurs.
Some numerical analysts will tell you that your choice of rounding
-style has tremendous impact on the final outcome, and advise you to
-wait until final output for any rounding. Instead, you can often avoid
+style has tremendous impact on the final outcome, and advise you to wait
+until final output for any rounding. Instead, you can often avoid
round-off error problems by setting the precision initially to some
value sufficiently larger than the final desired precision, so that the
accumulation of round-off error does not influence the outcome. If you
-suspect that results from your computation are sensitive to
-accumulation of round-off error, look for a significant difference in
-output when you change the rounding mode to be sure.
+suspect that results from your computation are sensitive to accumulation
+of round-off error, look for a significant difference in output when you
+change the rounding mode to be sure.
---------- Footnotes ----------
- (1) It is possible for the output to be completely different if the
-C library in your system does not use the IEEE 754 even-rounding rule
-to round halfway cases for `printf'.
+ (1) It is possible for the output to be completely different if the C
+library in your system does not use the IEEE 754 even-rounding rule to
+round halfway cases for 'printf'.
File: gawk.info, Node: Arbitrary Precision Integers, Next: POSIX Floating
Point Problems, Prev: FP Math Caution, Up: Arbitrary Precision Arithmetic
-15.5 Arbitrary-Precision Integer Arithmetic with `gawk'
+15.5 Arbitrary-Precision Integer Arithmetic with 'gawk'
=======================================================
-When given the `-M' option, `gawk' performs all integer arithmetic
-using GMP arbitrary-precision integers. Any number that looks like an
-integer in a source or data file is stored as an arbitrary-precision
-integer. The size of the integer is limited only by the available
-memory. For example, the following computes 5^4^3^2, the result of
-which is beyond the limits of ordinary hardware double-precision
-floating-point values:
+When given the '-M' option, 'gawk' performs all integer arithmetic using
+GMP arbitrary-precision integers. Any number that looks like an integer
+in a source or data file is stored as an arbitrary-precision integer.
+The size of the integer is limited only by the available memory. For
+example, the following computes 5^4^3^2, the result of which is beyond
+the limits of ordinary hardware double-precision floating-point values:
$ gawk -M 'BEGIN {
> x = 5^4^3^2
@@ -22407,13 +22321,13 @@ floating-point values:
If instead you were to compute the same value using
arbitrary-precision floating-point values, the precision needed for
-correct output (using the formula `prec = 3.322 * dps') would be 3.322
-x 183231, or 608693.
+correct output (using the formula 'prec = 3.322 * dps') would be 3.322 x
+183231, or 608693.
The result from an arithmetic operation with an integer and a
-floating-point value is a floating-point value with a precision equal
-to the working precision. The following program calculates the eighth
-term in Sylvester's sequence(1) using a recurrence:
+floating-point value is a floating-point value with a precision equal to
+the working precision. The following program calculates the eighth term
+in Sylvester's sequence(1) using a recurrence:
$ gawk -M 'BEGIN {
> s = 2.0
@@ -22424,14 +22338,13 @@ term in Sylvester's sequence(1) using a recurrence:
-| 113423713055421845118910464
The output differs from the actual number,
-113,423,713,055,421,844,361,000,443, because the default precision of
-53 bits is not enough to represent the floating-point results exactly.
-You can either increase the precision (100 bits is enough in this
-case), or replace the floating-point constant `2.0' with an integer, to
-perform all computations using integer arithmetic to get the correct
-output.
-
- Sometimes `gawk' must implicitly convert an arbitrary-precision
+113,423,713,055,421,844,361,000,443, because the default precision of 53
+bits is not enough to represent the floating-point results exactly. You
+can either increase the precision (100 bits is enough in this case), or
+replace the floating-point constant '2.0' with an integer, to perform
+all computations using integer arithmetic to get the correct output.
+
+ Sometimes 'gawk' must implicitly convert an arbitrary-precision
integer into an arbitrary-precision floating-point value. This is
primarily because the MPFR library does not always provide the relevant
interface to process arbitrary-precision integers or mixed-mode numbers
@@ -22455,9 +22368,8 @@ the following:
---------- Footnotes ----------
- (1) Weisstein, Eric W. `Sylvester's Sequence'. From MathWorld--A
-Wolfram Web Resource
-(`http://mathworld.wolfram.com/SylvestersSequence.html').
+ (1) Weisstein, Eric W. 'Sylvester's Sequence'. From MathWorld--A
+Wolfram Web Resource (<http://mathworld.wolfram.com/SylvestersSequence.html>).
File: gawk.info, Node: POSIX Floating Point Problems, Next: Floating point
summary, Prev: Arbitrary Precision Integers, Up: Arbitrary Precision
Arithmetic
@@ -22465,18 +22377,18 @@ File: gawk.info, Node: POSIX Floating Point
Problems, Next: Floating point sum
15.6 Standards Versus Existing Practice
=======================================
-Historically, `awk' has converted any nonnumeric-looking string to the
-numeric value zero, when required. Furthermore, the original
-definition of the language and the original POSIX standards specified
-that `awk' only understands decimal numbers (base 10), and not octal
-(base 8) or hexadecimal numbers (base 16).
+Historically, 'awk' has converted any nonnumeric-looking string to the
+numeric value zero, when required. Furthermore, the original definition
+of the language and the original POSIX standards specified that 'awk'
+only understands decimal numbers (base 10), and not octal (base 8) or
+hexadecimal numbers (base 16).
Changes in the language of the 2001 and 2004 POSIX standards can be
-interpreted to imply that `awk' should support additional features.
+interpreted to imply that 'awk' should support additional features.
These features are:
* Interpretation of floating-point data values specified in
- hexadecimal notation (e.g., `0xDEADBEEF'). (Note: data values,
+ hexadecimal notation (e.g., '0xDEADBEEF'). (Note: data values,
_not_ source code constants.)
* Support for the special IEEE 754 floating-point values "not a
@@ -22484,40 +22396,39 @@ These features are:
("-inf"). In particular, the format for these values is as
specified by the ISO 1999 C standard, which ignores case and can
allow implementation-dependent additional characters after the
- `nan' and allow either `inf' or `infinity'.
+ 'nan' and allow either 'inf' or 'infinity'.
The first problem is that both of these are clear changes to
historical practice:
- * The `gawk' maintainer feels that supporting hexadecimal
+ * The 'gawk' maintainer feels that supporting hexadecimal
floating-point values, in particular, is ugly, and was never
intended by the original designers to be part of the language.
- * Allowing completely alphabetic strings to have valid numeric
- values is also a very severe departure from historical practice.
+ * Allowing completely alphabetic strings to have valid numeric values
+ is also a very severe departure from historical practice.
- The second problem is that the `gawk' maintainer feels that this
+ The second problem is that the 'gawk' maintainer feels that this
interpretation of the standard, which required a certain amount of
"language lawyering" to arrive at in the first place, was not even
intended by the standard developers. In other words, "We see how you
got where you are, but we don't think that that's where you want to be."
Recognizing these issues, but attempting to provide compatibility
-with the earlier versions of the standard, the 2008 POSIX standard
-added explicit wording to allow, but not require, that `awk' support
+with the earlier versions of the standard, the 2008 POSIX standard added
+explicit wording to allow, but not require, that 'awk' support
hexadecimal floating-point values and special values for "not a number"
and infinity.
- Although the `gawk' maintainer continues to feel that providing
-those features is inadvisable, nevertheless, on systems that support
-IEEE floating point, it seems reasonable to provide _some_ way to
-support NaN and infinity values. The solution implemented in `gawk' is
-as follows:
+ Although the 'gawk' maintainer continues to feel that providing those
+features is inadvisable, nevertheless, on systems that support IEEE
+floating point, it seems reasonable to provide _some_ way to support NaN
+and infinity values. The solution implemented in 'gawk' is as follows:
- * With the `--posix' command-line option, `gawk' becomes "hands
- off." String values are passed directly to the system library's
- `strtod()' function, and if it successfully returns a numeric
- value, that is what's used.(1) By definition, the results are not
+ * With the '--posix' command-line option, 'gawk' becomes "hands off."
+ String values are passed directly to the system library's
+ 'strtod()' function, and if it successfully returns a numeric
+ value, that is what's used.(1) By definition, the results are not
portable across different systems. They are also a little
surprising:
@@ -22526,12 +22437,12 @@ as follows:
$ echo 0xDeadBeef | gawk --posix '{ print $1 + 0 }'
-| 3735928559
- * Without `--posix', `gawk' interprets the four string values `+inf',
- `-inf', `+nan', and `-nan' specially, producing the corresponding
- special numeric values. The leading sign acts a signal to `gawk'
+ * Without '--posix', 'gawk' interprets the four string values '+inf',
+ '-inf', '+nan', and '-nan' specially, producing the corresponding
+ special numeric values. The leading sign acts a signal to 'gawk'
(and the user) that the value is really numeric. Hexadecimal
floating point is not supported (unless you also use
- `--non-decimal-data', which is _not_ recommended). For example:
+ '--non-decimal-data', which is _not_ recommended). For example:
$ echo nanny | gawk '{ print $1 + 0 }'
-| 0
@@ -22540,8 +22451,8 @@ as follows:
$ echo 0xDeadBeef | gawk '{ print $1 + 0 }'
-| 0
- `gawk' ignores case in the four special values. Thus, `+nan' and
- `+NaN' are the same.
+ 'gawk' ignores case in the four special values. Thus, '+nan' and
+ '+NaN' are the same.
---------- Footnotes ----------
@@ -22554,7 +22465,7 @@ File: gawk.info, Node: Floating point summary, Prev:
POSIX Floating Point Prob
============
* Most computer arithmetic is done using either integers or
- floating-point values. Standard `awk' uses double-precision
+ floating-point values. Standard 'awk' uses double-precision
floating-point values.
* In the early 1990s Barbie mistakenly said, "Math class is tough!"
@@ -22564,7 +22475,7 @@ File: gawk.info, Node: Floating point summary, Prev:
POSIX Floating Point Prob
- Not all numbers can be represented exactly.
- Comparing values should use a delta, instead of being done
- directly with `==' and `!='.
+ directly with '==' and '!='.
- Errors accumulate.
@@ -22575,51 +22486,50 @@ File: gawk.info, Node: Floating point summary,
Prev: POSIX Floating Point Prob
* Often, increasing the accuracy and then rounding to the desired
number of digits produces reasonable results.
- * Use `-M' (or `--bignum') to enable MPFR arithmetic. Use `PREC' to
- set the precision in bits, and `ROUNDMODE' to set the IEEE 754
+ * Use '-M' (or '--bignum') to enable MPFR arithmetic. Use 'PREC' to
+ set the precision in bits, and 'ROUNDMODE' to set the IEEE 754
rounding mode.
- * With `-M', `gawk' performs arbitrary-precision integer arithmetic
+ * With '-M', 'gawk' performs arbitrary-precision integer arithmetic
using the GMP library. This is faster and more space-efficient
than using MPFR for the same calculations.
* There are several areas with respect to floating-point numbers
- where `gawk' disagrees with the POSIX standard. It pays to be
+ where 'gawk' disagrees with the POSIX standard. It pays to be
aware of them.
- * Overall, there is no need to be unduly suspicious about the
- results from floating-point arithmetic. The lesson to remember is
- that floating-point arithmetic is always more complex than
- arithmetic using pencil and paper. In order to take advantage of
- the power of floating-point arithmetic, you need to know its
- limitations and work within them. For most casual use of
- floating-point arithmetic, you will often get the expected result
- if you simply round the display of your final results to the
- correct number of significant decimal digits.
+ * Overall, there is no need to be unduly suspicious about the results
+ from floating-point arithmetic. The lesson to remember is that
+ floating-point arithmetic is always more complex than arithmetic
+ using pencil and paper. In order to take advantage of the power of
+ floating-point arithmetic, you need to know its limitations and
+ work within them. For most casual use of floating-point
+ arithmetic, you will often get the expected result if you simply
+ round the display of your final results to the correct number of
+ significant decimal digits.
* As general advice, avoid presenting numerical data in a manner that
implies better precision than is actually the case.
-
File: gawk.info, Node: Dynamic Extensions, Next: Language History, Prev:
Arbitrary Precision Arithmetic, Up: Top
-16 Writing Extensions for `gawk'
+16 Writing Extensions for 'gawk'
********************************
-It is possible to add new functions written in C or C++ to `gawk' using
-dynamically loaded libraries. This facility is available on systems
-that support the C `dlopen()' and `dlsym()' functions. This major node
+It is possible to add new functions written in C or C++ to 'gawk' using
+dynamically loaded libraries. This facility is available on systems
+that support the C 'dlopen()' and 'dlsym()' functions. This major node
describes how to create extensions using code written in C or C++.
If you don't know anything about C programming, you can safely skip
this major node, although you may wish to review the documentation on
-the extensions that come with `gawk' (*note Extension Samples::), and
-the information on the `gawkextlib' project (*note gawkextlib::). The
-sample extensions are automatically built and installed when `gawk' is.
+the extensions that come with 'gawk' (*note Extension Samples::), and
+the information on the 'gawkextlib' project (*note gawkextlib::). The
+sample extensions are automatically built and installed when 'gawk' is.
- NOTE: When `--sandbox' is specified, extensions are disabled
- (*note Options::).
+ NOTE: When '--sandbox' is specified, extensions are disabled (*note
+ Options::).
* Menu:
@@ -22627,11 +22537,11 @@ sample extensions are automatically built and
installed when `gawk' is.
* Plugin License:: A note about licensing.
* Extension Mechanism Outline:: An outline of how it works.
* Extension API Description:: A full description of the API.
-* Finding Extensions:: How `gawk' finds compiled extensions.
+* Finding Extensions:: How 'gawk' finds compiled extensions.
* Extension Example:: Example C code for an extension.
* Extension Samples:: The sample extensions that ship with
- `gawk'.
-* gawkextlib:: The `gawkextlib' project.
+ 'gawk'.
+* gawkextlib:: The 'gawkextlib' project.
* Extension summary:: Extension summary.
* Extension Exercises:: Exercises.
@@ -22642,23 +22552,23 @@ File: gawk.info, Node: Extension Intro, Next:
Plugin License, Up: Dynamic Ext
=================
An "extension" (sometimes called a "plug-in") is a piece of external
-compiled code that `gawk' can load at runtime to provide additional
-functionality, over and above the built-in capabilities described in
-the rest of this Info file.
+compiled code that 'gawk' can load at runtime to provide additional
+functionality, over and above the built-in capabilities described in the
+rest of this Info file.
Extensions are useful because they allow you (of course) to extend
-`gawk''s functionality. For example, they can provide access to system
-calls (such as `chdir()' to change directory) and to other C library
+'gawk''s functionality. For example, they can provide access to system
+calls (such as 'chdir()' to change directory) and to other C library
routines that could be of use. As with most software, "the sky is the
limit"; if you can imagine something that you might want to do and can
write in C or C++, you can write an extension to do it!
Extensions are written in C or C++, using the "application
-programming interface" (API) defined for this purpose by the `gawk'
+programming interface" (API) defined for this purpose by the 'gawk'
developers. The rest of this major node explains the facilities that
the API provides and how to use them, and presents a small example
extension. In addition, it documents the sample extensions included in
-the `gawk' distribution and describes the `gawkextlib' project. *Note
+the 'gawk' distribution and describes the 'gawkextlib' project. *Note
Extension Design::, for a discussion of the extension mechanism goals
and design.
@@ -22671,14 +22581,14 @@ File: gawk.info, Node: Plugin License, Next:
Extension Mechanism Outline, Pre
Every dynamic extension must be distributed under a license that is
compatible with the GNU GPL (*note Copying::).
- In order for the extension to tell `gawk' that it is properly
+ In order for the extension to tell 'gawk' that it is properly
licensed, the extension must define the global symbol
-`plugin_is_GPL_compatible'. If this symbol does not exist, `gawk'
-emits a fatal error and exits when it tries to load your extension.
+'plugin_is_GPL_compatible'. If this symbol does not exist, 'gawk' emits
+a fatal error and exits when it tries to load your extension.
- The declared type of the symbol should be `int'. It does not need
-to be in any allocated section, though. The code merely asserts that
-the symbol exists in the global scope. Something like this is enough:
+ The declared type of the symbol should be 'int'. It does not need to
+be in any allocated section, though. The code merely asserts that the
+symbol exists in the global scope. Something like this is enough:
int plugin_is_GPL_compatible;
@@ -22688,44 +22598,45 @@ File: gawk.info, Node: Extension Mechanism Outline,
Next: Extension API Descri
16.3 How It Works at a High Level
=================================
-Communication between `gawk' and an extension is two-way. First, when
-an extension is loaded, `gawk' passes it a pointer to a `struct' whose
-fields are function pointers. This is shown in *note
-figure-load-extension::.
+Communication between 'gawk' and an extension is two-way. First, when
+an extension is loaded, 'gawk' passes it a pointer to a 'struct' whose
+fields are function pointers. This is shown in *note Figure 16.1:
+figure-load-extension.
- API
+ [image src="api-figure1.txt" alt="Loading the extension" text="
API
Struct
+---+
| |
+---+
+---------------| |
| +---+ dl_load(api_p, id);
- | | | ___________________
+ | | | ___________________
| +---+ |
| +---------| | __________________ |
| | +---+ ||
| | | | ||
| | +---+ ||
| | +---| | ||
- | | | +---+ \ || /
- | | | \ /
- v v v \/
+ | | | +---+ \\ || /
+ | | | \\ /
+ v v v \\/
+-------+-+---+-+---+-+------------------+--------------------+
| |x| |x| |x| |OOOOOOOOOOOOOOOOOOOO|
| |x| |x| |x| |OOOOOOOOOOOOOOOOOOOO|
| |x| |x| |x| |OOOOOOOOOOOOOOOOOOOO|
+-------+-+---+-+---+-+------------------+--------------------+
- gawk Main Program Address Space Extension
+ gawk Main Program Address Space Extension" ]
+
Figure 16.1: Loading the extension
- The extension can call functions inside `gawk' through these
-function pointers, at runtime, without needing (link-time) access to
-`gawk''s symbols. One of these function pointers is to a function for
-"registering" new functions. This is shown in *note
-figure-register-new-function::.
+ The extension can call functions inside 'gawk' through these function
+pointers, at runtime, without needing (link-time) access to 'gawk''s
+symbols. One of these function pointers is to a function for
+"registering" new functions. This is shown in *note Figure 16.2:
+figure-register-new-function.
- register_ext_func({ "chdir", do_chdir, 1 });
+ [image src="api-figure2.txt" alt="Registering a new Function" text="
register_ext_func({ \"chdir\", do_chdir, 1 });
+--------------------------------------------+
| |
@@ -22736,17 +22647,19 @@ figure-register-new-function::.
| |x| |x| |x| |OOOOOOOOOOOOOO|X|OOO|
+-------+-+---+-+---+-+------------------+--------------+-+---+
- gawk Main Program Address Space Extension
+ gawk Main Program Address Space Extension" ]
+
Figure 16.2: Registering a new function
In the other direction, the extension registers its new functions
-with `gawk' by passing function pointers to the functions that provide
-the new feature (`do_chdir()', for example). `gawk' associates the
+with 'gawk' by passing function pointers to the functions that provide
+the new feature ('do_chdir()', for example). 'gawk' associates the
function pointer with a name and can then call it, using a defined
-calling convention. This is shown in *note figure-call-new-function::.
+calling convention. This is shown in *note Figure 16.3:
+figure-call-new-function.
- BEGIN {
- chdir("/path") (*fnptr)(1);
+ [image src="api-figure3.txt" alt="Calling the new function" text=" BEGIN {
+ chdir(\"/path\") (*fnptr)(1);
}
+--------------------------------------------+
| |
@@ -22757,32 +22670,33 @@ calling convention. This is shown in *note
figure-call-new-function::.
| |x| |x| |x| |OOOOOOOOOOOOOO|X|OOO|
+-------+-+---+-+---+-+------------------+--------------+-+---+
- gawk Main Program Address Space Extension
+ gawk Main Program Address Space Extension" ]
+
Figure 16.3: Calling the new function
- The `do_XXX()' function, in turn, then uses the function pointers in
-the API `struct' to do its work, such as updating variables or arrays,
-printing messages, setting `ERRNO', and so on.
+ The 'do_XXX()' function, in turn, then uses the function pointers in
+the API 'struct' to do its work, such as updating variables or arrays,
+printing messages, setting 'ERRNO', and so on.
Convenience macros make calling through the function pointers look
-like regular function calls so that extension code is quite readable
-and understandable.
+like regular function calls so that extension code is quite readable and
+understandable.
Although all of this sounds somewhat complicated, the result is that
-extension code is quite straightforward to write and to read. You can
-see this in the sample extension `filefuncs.c' (*note Extension
-Example::) and also in the `testext.c' code for testing the APIs.
+extension code is quite straightforward to write and to read. You can
+see this in the sample extension 'filefuncs.c' (*note Extension
+Example::) and also in the 'testext.c' code for testing the APIs.
Some other bits and pieces:
- * The API provides access to `gawk''s `do_XXX' values, reflecting
- command-line options, like `do_lint', `do_profiling', and so on
+ * The API provides access to 'gawk''s 'do_XXX' values, reflecting
+ command-line options, like 'do_lint', 'do_profiling', and so on
(*note Extension API Variables::). These are informational: an
- extension cannot affect their values inside `gawk'. In addition,
+ extension cannot affect their values inside 'gawk'. In addition,
attempting to assign to them produces a compile-time error.
* The API also provides major and minor version numbers, so that an
- extension can check if the `gawk' it is loaded with supports the
+ extension can check if the 'gawk' it is loaded with supports the
facilities it was compiled with. (Version mismatches "shouldn't"
happen, but we all know how _that_ goes.) *Note Extension
Versioning::, for details.
@@ -22793,10 +22707,10 @@ File: gawk.info, Node: Extension API Description,
Next: Finding Extensions, P
16.4 API Description
====================
-C or C++ code for an extension must include the header file
-`gawkapi.h', which declares the functions and defines the data types
-used to communicate with `gawk'. This (rather large) minor node
-describes the API in detail.
+C or C++ code for an extension must include the header file 'gawkapi.h',
+which declares the functions and defines the data types used to
+communicate with 'gawk'. This (rather large) minor node describes the
+API in detail.
* Menu:
@@ -22805,9 +22719,9 @@ describes the API in detail.
* Memory Allocation Functions:: Functions for allocating memory.
* Constructor Functions:: Functions for creating values.
* Registration Functions:: Functions to register things with
- `gawk'.
+ 'gawk'.
* Printing Messages:: Functions for printing messages.
-* Updating `ERRNO':: Functions for updating `ERRNO'.
+* Updating 'ERRNO':: Functions for updating 'ERRNO'.
* Requesting Values:: How to get a value.
* Accessing Parameters:: Functions for accessing parameters.
* Symbol Table Access:: Functions for accessing global
@@ -22822,7 +22736,7 @@ File: gawk.info, Node: Extension API Functions
Introduction, Next: General Dat
16.4.1 Introduction
-------------------
-Access to facilities within `gawk' is achieved by calling through
+Access to facilities within 'gawk' is achieved by calling through
function pointers passed into your extension.
API function pointers are provided for the following kinds of
@@ -22830,31 +22744,26 @@ operations:
* Allocating, reallocating, and releasing memory.
- * Registration functions. You may register:
+ * Registration functions. You may register:
- Extension functions
-
- Exit callbacks
-
- A version string
-
- Input parsers
-
- Output wrappers
-
- Two-way processors
All of these are discussed in detail later in this major node.
* Printing fatal, warning, and "lint" warning messages.
- * Updating `ERRNO', or unsetting it.
+ * Updating 'ERRNO', or unsetting it.
* Accessing parameters, including converting an undefined parameter
into an array.
- * Symbol table access: retrieving a global variable, creating one,
- or changing one.
+ * Symbol table access: retrieving a global variable, creating one, or
+ changing one.
* Creating and releasing cached values; this provides an efficient
way to use values for multiple variables and can be a big
@@ -22876,52 +22785,51 @@ operations:
Some points about using the API:
* The following types, macros, and/or functions are referenced in
- `gawkapi.h'. For correct use, you must therefore include the
- corresponding standard header file _before_ including `gawkapi.h':
+ 'gawkapi.h'. For correct use, you must therefore include the
+ corresponding standard header file _before_ including 'gawkapi.h':
C entity Header file
- -------------------------------------------
- `EOF' `<stdio.h>'
- Values for `errno' `<errno.h>'
- `FILE' `<stdio.h>'
- `NULL' `<stddef.h>'
- `memcpy()' `<string.h>'
- `memset()' `<string.h>'
- `size_t' `<sys/types.h>'
- `struct stat' `<sys/stat.h>'
+ -------------------------------------------
+ 'EOF' '<stdio.h>'
+ Values for 'errno' '<errno.h>'
+ 'FILE' '<stdio.h>'
+ 'NULL' '<stddef.h>'
+ 'memcpy()' '<string.h>'
+ 'memset()' '<string.h>'
+ 'size_t' '<sys/types.h>'
+ 'struct stat' '<sys/stat.h>'
Due to portability concerns, especially to systems that are not
- fully standards-compliant, it is your responsibility to include
- the correct files in the correct way. This requirement is
- necessary in order to keep `gawkapi.h' clean, instead of becoming
- a portability hodge-podge as can be seen in some parts of the
- `gawk' source code.
+ fully standards-compliant, it is your responsibility to include the
+ correct files in the correct way. This requirement is necessary in
+ order to keep 'gawkapi.h' clean, instead of becoming a portability
+ hodge-podge as can be seen in some parts of the 'gawk' source code.
- * The `gawkapi.h' file may be included more than once without ill
+ * The 'gawkapi.h' file may be included more than once without ill
effect. Doing so, however, is poor coding practice.
* Although the API only uses ISO C 90 features, there is an
- exception; the "constructor" functions use the `inline' keyword.
+ exception; the "constructor" functions use the 'inline' keyword.
If your compiler does not support this keyword, you should either
- place `-Dinline=''' on your command line or use the GNU Autotools
- and include a `config.h' file in your extensions.
+ place '-Dinline=''' on your command line or use the GNU Autotools
+ and include a 'config.h' file in your extensions.
- * All pointers filled in by `gawk' point to memory managed by `gawk'
+ * All pointers filled in by 'gawk' point to memory managed by 'gawk'
and should be treated by the extension as read-only. Memory for
- _all_ strings passed into `gawk' from the extension _must_ come
- from calling one of `gawk_malloc()', `gawk_calloc()', or
- `gawk_realloc()', and is managed by `gawk' from then on.
+ _all_ strings passed into 'gawk' from the extension _must_ come
+ from calling one of 'gawk_malloc()', 'gawk_calloc()', or
+ 'gawk_realloc()', and is managed by 'gawk' from then on.
- * The API defines several simple `struct's that map values as seen
- from `awk'. A value can be a `double', a string, or an array (as
+ * The API defines several simple 'struct's that map values as seen
+ from 'awk'. A value can be a 'double', a string, or an array (as
in multidimensional arrays, or when creating a new array). String
values maintain both pointer and length, because embedded NUL
characters are allowed.
NOTE: By intent, strings are maintained using the current
- multibyte encoding (as defined by `LC_XXX' environment
+ multibyte encoding (as defined by 'LC_XXX' environment
variables) and not using wide characters. This matches how
- `gawk' stores strings internally and also how characters are
+ 'gawk' stores strings internally and also how characters are
likely to be input into and output from files.
* When retrieving a value (such as a parameter or that of a global
@@ -22935,10 +22843,9 @@ operations:
that is there, so that the extension can, e.g., print an error
message (such as "scalar passed where array expected").
-
You may call the API functions by using the function pointers
-directly, but the interface is not so pretty. To make extension code
-look more like regular code, the `gawkapi.h' header file defines several
+directly, but the interface is not so pretty. To make extension code
+look more like regular code, the 'gawkapi.h' header file defines several
macros that you should use in your code. This minor node presents the
macros as if they were functions.
@@ -22948,139 +22855,138 @@ File: gawk.info, Node: General Data Types, Next:
Memory Allocation Functions,
16.4.2 General-Purpose Data Types
---------------------------------
- I have a true love/hate relationship with unions. -- Arnold
- Robbins
+ I have a true love/hate relationship with unions.
+ -- _Arnold Robbins_
That's the thing about unions: the compiler will arrange things so
- they can accommodate both love and hate. -- Chet Ramey
+ they can accommodate both love and hate.
+ -- _Chet Ramey_
The extension API defines a number of simple types and structures for
-general-purpose use. Additional, more specialized, data structures are
+general-purpose use. Additional, more specialized, data structures are
introduced in subsequent minor nodes, together with the functions that
use them.
The general-purpose types and structures are as follows:
-`typedef void *awk_ext_id_t;'
- A value of this type is received from `gawk' when an extension is
- loaded. That value must then be passed back to `gawk' as the
- first parameter of each API function.
-
-`#define awk_const ...'
- This macro expands to `const' when compiling an extension, and to
- nothing when compiling `gawk' itself. This makes certain fields
- in the API data structures unwritable from extension code, while
- allowing `gawk' to use them as it needs to.
-
-`typedef enum awk_bool {'
-` awk_false = 0,'
-` awk_true'
-`} awk_bool_t;'
+'typedef void *awk_ext_id_t;'
+ A value of this type is received from 'gawk' when an extension is
+ loaded. That value must then be passed back to 'gawk' as the first
+ parameter of each API function.
+
+'#define awk_const ...'
+ This macro expands to 'const' when compiling an extension, and to
+ nothing when compiling 'gawk' itself. This makes certain fields in
+ the API data structures unwritable from extension code, while
+ allowing 'gawk' to use them as it needs to.
+
+'typedef enum awk_bool {'
+' awk_false = 0,'
+' awk_true'
+'} awk_bool_t;'
A simple Boolean type.
-`typedef struct awk_string {'
-` char *str; /* data */'
-` size_t len; /* length thereof, in chars */'
-`} awk_string_t;'
- This represents a mutable string. `gawk' owns the memory pointed
- to if it supplied the value. Otherwise, it takes ownership of the
+'typedef struct awk_string {'
+' char *str; /* data */'
+' size_t len; /* length thereof, in chars */'
+'} awk_string_t;'
+ This represents a mutable string. 'gawk' owns the memory pointed
+ to if it supplied the value. Otherwise, it takes ownership of the
memory pointed to. _Such memory must come from calling one of the
- `gawk_malloc()', `gawk_calloc()', or `gawk_realloc()' functions!_
+ 'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()' functions!_
As mentioned earlier, strings are maintained using the current
multibyte encoding.
-`typedef enum {'
-` AWK_UNDEFINED,'
-` AWK_NUMBER,'
-` AWK_STRING,'
-` AWK_ARRAY,'
-` AWK_SCALAR, /* opaque access to a variable */'
-` AWK_VALUE_COOKIE /* for updating a previously created value */'
-`} awk_valtype_t;'
- This `enum' indicates the type of a value. It is used in the
- following `struct'.
-
-`typedef struct awk_value {'
-` awk_valtype_t val_type;'
-` union {'
-` awk_string_t s;'
-` double d;'
-` awk_array_t a;'
-` awk_scalar_t scl;'
-` awk_value_cookie_t vc;'
-` } u;'
-`} awk_value_t;'
- An "`awk' value." The `val_type' member indicates what kind of
- value the `union' holds, and each member is of the appropriate
+'typedef enum {'
+' AWK_UNDEFINED,'
+' AWK_NUMBER,'
+' AWK_STRING,'
+' AWK_ARRAY,'
+' AWK_SCALAR, /* opaque access to a variable */'
+' AWK_VALUE_COOKIE /* for updating a previously created value */'
+'} awk_valtype_t;'
+ This 'enum' indicates the type of a value. It is used in the
+ following 'struct'.
+
+'typedef struct awk_value {'
+' awk_valtype_t val_type;'
+' union {'
+' awk_string_t s;'
+' double d;'
+' awk_array_t a;'
+' awk_scalar_t scl;'
+' awk_value_cookie_t vc;'
+' } u;'
+'} awk_value_t;'
+ An "'awk' value." The 'val_type' member indicates what kind of
+ value the 'union' holds, and each member is of the appropriate
type.
-`#define str_value u.s'
-`#define num_value u.d'
-`#define array_cookie u.a'
-`#define scalar_cookie u.scl'
-`#define value_cookie u.vc'
- Using these macros makes accessing the fields of the `awk_value_t'
+'#define str_value u.s'
+'#define num_value u.d'
+'#define array_cookie u.a'
+'#define scalar_cookie u.scl'
+'#define value_cookie u.vc'
+ Using these macros makes accessing the fields of the 'awk_value_t'
more readable.
-`typedef void *awk_scalar_t;'
- Scalars can be represented as an opaque type. These values are
- obtained from `gawk' and then passed back into it. This is
- discussed in a general fashion in the text following this list,
- and in more detail in *note Symbol table by cookie::.
+'typedef void *awk_scalar_t;'
+ Scalars can be represented as an opaque type. These values are
+ obtained from 'gawk' and then passed back into it. This is
+ discussed in a general fashion in the text following this list, and
+ in more detail in *note Symbol table by cookie::.
-`typedef void *awk_value_cookie_t;'
+'typedef void *awk_value_cookie_t;'
A "value cookie" is an opaque type representing a cached value.
This is also discussed in a general fashion in the text following
this list, and in more detail in *note Cached values::.
+ Scalar values in 'awk' are either numbers or strings. The
+'awk_value_t' struct represents values. The 'val_type' member indicates
+what is in the 'union'.
- Scalar values in `awk' are either numbers or strings. The
-`awk_value_t' struct represents values. The `val_type' member
-indicates what is in the `union'.
-
- Representing numbers is easy--the API uses a C `double'. Strings
-require more work. Because `gawk' allows embedded NUL bytes in string
-values, a string must be represented as a pair containing a data
-pointer and length. This is the `awk_string_t' type.
+ Representing numbers is easy--the API uses a C 'double'. Strings
+require more work. Because 'gawk' allows embedded NUL bytes in string
+values, a string must be represented as a pair containing a data pointer
+and length. This is the 'awk_string_t' type.
Identifiers (i.e., the names of global variables) can be associated
-with either scalar values or with arrays. In addition, `gawk' provides
+with either scalar values or with arrays. In addition, 'gawk' provides
true arrays of arrays, where any given array element can itself be an
array. Discussion of arrays is delayed until *note Array
Manipulation::.
The various macros listed earlier make it easier to use the elements
-of the `union' as if they were fields in a `struct'; this is a common
-coding practice in C. Such code is easier to write and to read, but it
-remains _your_ responsibility to make sure that the `val_type' member
-correctly reflects the type of the value in the `awk_value_t' struct.
+of the 'union' as if they were fields in a 'struct'; this is a common
+coding practice in C. Such code is easier to write and to read, but it
+remains _your_ responsibility to make sure that the 'val_type' member
+correctly reflects the type of the value in the 'awk_value_t' struct.
- Conceptually, the first three members of the `union' (number, string,
-and array) are all that is needed for working with `awk' values.
+ Conceptually, the first three members of the 'union' (number, string,
+and array) are all that is needed for working with 'awk' values.
However, because the API provides routines for accessing and changing
the value of a global scalar variable only by using the variable's name,
-there is a performance penalty: `gawk' must find the variable each time
-it is accessed and changed. This turns out to be a real issue, not
-just a theoretical one.
+there is a performance penalty: 'gawk' must find the variable each time
+it is accessed and changed. This turns out to be a real issue, not just
+a theoretical one.
Thus, if you know that your extension will spend considerable time
reading and/or changing the value of one or more scalar variables, you
can obtain a "scalar cookie"(1) object for that variable, and then use
the cookie for getting the variable's value or for changing the
-variable's value. The `awk_scalar_t' type holds a scalar cookie, and
-the `scalar_cookie' macro provides access to the value of that type in
-the `awk_value_t' struct. Given a scalar cookie, `gawk' can directly
+variable's value. The 'awk_scalar_t' type holds a scalar cookie, and
+the 'scalar_cookie' macro provides access to the value of that type in
+the 'awk_value_t' struct. Given a scalar cookie, 'gawk' can directly
retrieve or modify the value, as required, without having to find it
first.
- The `awk_value_cookie_t' type and `value_cookie' macro are similar.
+ The 'awk_value_cookie_t' type and 'value_cookie' macro are similar.
If you know that you wish to use the same numeric or string _value_ for
-one or more variables, you can create the value once, retaining a
-"value cookie" for it, and then pass in that value cookie whenever you
-wish to set the value of a variable. This saves storage space within
-the running `gawk' process and reduces the time needed to create the
-value.
+one or more variables, you can create the value once, retaining a "value
+cookie" for it, and then pass in that value cookie whenever you wish to
+set the value of a variable. This saves storage space within the
+running 'gawk' process and reduces the time needed to create the value.
---------- Footnotes ----------
@@ -23097,52 +23003,52 @@ File: gawk.info, Node: Memory Allocation Functions,
Next: Constructor Function
---------------------------------------------------------
The API provides a number of "memory allocation" functions for
-allocating memory that can be passed to `gawk', as well as a number of
-convenience macros. This node presents them all as function
-prototypes, in the way that extension code would use them:
+allocating memory that can be passed to 'gawk', as well as a number of
+convenience macros. This node presents them all as function prototypes,
+in the way that extension code would use them:
-`void *gawk_malloc(size_t size);'
- Call the correct version of `malloc()' to allocate storage that may
- be passed to `gawk'.
+'void *gawk_malloc(size_t size);'
+ Call the correct version of 'malloc()' to allocate storage that may
+ be passed to 'gawk'.
-`void *gawk_calloc(size_t nmemb, size_t size);'
- Call the correct version of `calloc()' to allocate storage that may
- be passed to `gawk'.
+'void *gawk_calloc(size_t nmemb, size_t size);'
+ Call the correct version of 'calloc()' to allocate storage that may
+ be passed to 'gawk'.
-`void *gawk_realloc(void *ptr, size_t size);'
- Call the correct version of `realloc()' to allocate storage that
- may be passed to `gawk'.
+'void *gawk_realloc(void *ptr, size_t size);'
+ Call the correct version of 'realloc()' to allocate storage that
+ may be passed to 'gawk'.
-`void gawk_free(void *ptr);'
- Call the correct version of `free()' to release storage that was
- allocated with `gawk_malloc()', `gawk_calloc()', or
- `gawk_realloc()'.
+'void gawk_free(void *ptr);'
+ Call the correct version of 'free()' to release storage that was
+ allocated with 'gawk_malloc()', 'gawk_calloc()', or
+ 'gawk_realloc()'.
The API has to provide these functions because it is possible for an
-extension to be compiled and linked against a different version of the
-C library than was used for the `gawk' executable.(1) If `gawk' were to
-use its version of `free()' when the memory came from an unrelated
-version of `malloc()', unexpected behavior would likely result.
+extension to be compiled and linked against a different version of the C
+library than was used for the 'gawk' executable.(1) If 'gawk' were to
+use its version of 'free()' when the memory came from an unrelated
+version of 'malloc()', unexpected behavior would likely result.
Two convenience macros may be used for allocating storage from
-`gawk_malloc()' and `gawk_realloc()'. If the allocation fails, they
-cause `gawk' to exit with a fatal error message. They should be used
-as if they were procedure calls that do not return a value:
+'gawk_malloc()' and 'gawk_realloc()'. If the allocation fails, they
+cause 'gawk' to exit with a fatal error message. They should be used as
+if they were procedure calls that do not return a value:
-`#define emalloc(pointer, type, size, message) ...'
+'#define emalloc(pointer, type, size, message) ...'
The arguments to this macro are as follows:
- `pointer'
+ 'pointer'
The pointer variable to point at the allocated storage.
- `type'
+ 'type'
The type of the pointer variable. This is used to create a
- cast for the call to `gawk_malloc()'.
+ cast for the call to 'gawk_malloc()'.
- `size'
+ 'size'
The total number of bytes to be allocated.
- `message'
+ 'message'
A message to be prefixed to the fatal error message.
Typically this is the name of the function using the macro.
@@ -23156,10 +23062,10 @@ as if they were procedure calls that do not return a
value:
strcpy(message, greet);
make_malloced_string(message, strlen(message), & result);
-`#define erealloc(pointer, type, size, message) ...'
- This is like `emalloc()', but it calls `gawk_realloc()' instead of
- `gawk_malloc()'. The arguments are the same as for the
- `emalloc()' macro.
+'#define erealloc(pointer, type, size, message) ...'
+ This is like 'emalloc()', but it calls 'gawk_realloc()' instead of
+ 'gawk_malloc()'. The arguments are the same as for the 'emalloc()'
+ macro.
---------- Footnotes ----------
@@ -23172,37 +23078,37 @@ File: gawk.info, Node: Constructor Functions, Next:
Registration Functions, P
16.4.4 Constructor Functions
----------------------------
-The API provides a number of "constructor" functions for creating
-string and numeric values, as well as a number of convenience macros.
-This node presents them all as function prototypes, in the way that
-extension code would use them:
-
-`static inline awk_value_t *'
-`make_const_string(const char *string, size_t length, awk_value_t *result);'
- This function creates a string value in the `awk_value_t' variable
- pointed to by `result'. It expects `string' to be a C string
- constant (or other string data), and automatically creates a
- _copy_ of the data for storage in `result'. It returns `result'.
-
-`static inline awk_value_t *'
-`make_malloced_string(const char *string, size_t length, awk_value_t *result);'
- This function creates a string value in the `awk_value_t' variable
- pointed to by `result'. It expects `string' to be a `char *' value
- pointing to data previously obtained from `gawk_malloc()',
- `gawk_calloc()', or `gawk_realloc()'. The idea here is that the
- data is passed directly to `gawk', which assumes responsibility
- for it. It returns `result'.
-
-`static inline awk_value_t *'
-`make_null_string(awk_value_t *result);'
+The API provides a number of "constructor" functions for creating string
+and numeric values, as well as a number of convenience macros. This
+node presents them all as function prototypes, in the way that extension
+code would use them:
+
+'static inline awk_value_t *'
+'make_const_string(const char *string, size_t length, awk_value_t *result);'
+ This function creates a string value in the 'awk_value_t' variable
+ pointed to by 'result'. It expects 'string' to be a C string
+ constant (or other string data), and automatically creates a _copy_
+ of the data for storage in 'result'. It returns 'result'.
+
+'static inline awk_value_t *'
+'make_malloced_string(const char *string, size_t length, awk_value_t *result);'
+ This function creates a string value in the 'awk_value_t' variable
+ pointed to by 'result'. It expects 'string' to be a 'char *' value
+ pointing to data previously obtained from 'gawk_malloc()',
+ 'gawk_calloc()', or 'gawk_realloc()'. The idea here is that the
+ data is passed directly to 'gawk', which assumes responsibility for
+ it. It returns 'result'.
+
+'static inline awk_value_t *'
+'make_null_string(awk_value_t *result);'
This specialized function creates a null string (the "undefined"
- value) in the `awk_value_t' variable pointed to by `result'. It
- returns `result'.
+ value) in the 'awk_value_t' variable pointed to by 'result'. It
+ returns 'result'.
-`static inline awk_value_t *'
-`make_number(double num, awk_value_t *result);'
- This function simply creates a numeric value in the `awk_value_t'
- variable pointed to by `result'.
+'static inline awk_value_t *'
+'make_number(double num, awk_value_t *result);'
+ This function simply creates a numeric value in the 'awk_value_t'
+ variable pointed to by 'result'.
File: gawk.info, Node: Registration Functions, Next: Printing Messages,
Prev: Constructor Functions, Up: Extension API Description
@@ -23211,7 +23117,7 @@ File: gawk.info, Node: Registration Functions, Next:
Printing Messages, Prev:
-----------------------------
This minor node describes the API functions for registering parts of
-your extension with `gawk'.
+your extension with 'gawk'.
* Menu:
@@ -23238,42 +23144,42 @@ Extension functions are described by the following
record:
The fields are:
-`const char *name;'
- The name of the new function. `awk'-level code calls the function
+'const char *name;'
+ The name of the new function. 'awk'-level code calls the function
by this name. This is a regular C string.
- Function names must obey the rules for `awk' identifiers. That is,
+ Function names must obey the rules for 'awk' identifiers. That is,
they must begin with either an English letter or an underscore,
which may be followed by any number of letters, digits, and
underscores. Letter case in function names is significant.
-`awk_value_t *(*function)(int num_actual_args, awk_value_t *result);'
+'awk_value_t *(*function)(int num_actual_args, awk_value_t *result);'
This is a pointer to the C function that provides the extension's
- functionality. The function must fill in `*result' with either a
- number or a string. `gawk' takes ownership of any string memory.
+ functionality. The function must fill in '*result' with either a
+ number or a string. 'gawk' takes ownership of any string memory.
As mentioned earlier, string memory _must_ come from one of
- `gawk_malloc()', `gawk_calloc()', or `gawk_realloc()'.
+ 'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()'.
- The `num_actual_args' argument tells the C function how many
- actual parameters were passed from the calling `awk' code.
+ The 'num_actual_args' argument tells the C function how many actual
+ parameters were passed from the calling 'awk' code.
- The function must return the value of `result'. This is for the
- convenience of the calling code inside `gawk'.
+ The function must return the value of 'result'. This is for the
+ convenience of the calling code inside 'gawk'.
-`size_t num_expected_args;'
+'size_t num_expected_args;'
This is the number of arguments the function expects to receive.
Each extension function may decide what to do if the number of
- arguments isn't what it expected. As with real `awk' functions, it
+ arguments isn't what it expected. As with real 'awk' functions, it
is likely OK to ignore extra arguments.
Once you have a record representing your extension function, you
-register it with `gawk' using this API function:
+register it with 'gawk' using this API function:
-`awk_bool_t add_ext_func(const char *namespace, const awk_ext_func_t *func);'
+'awk_bool_t add_ext_func(const char *namespace, const awk_ext_func_t *func);'
This function returns true upon success, false otherwise. The
- `namespace' parameter is currently not used; you should pass in an
- empty string (`""'). The `func' pointer is the address of a
- `struct' representing your function, as just described.
+ 'namespace' parameter is currently not used; you should pass in an
+ empty string ('""'). The 'func' pointer is the address of a
+ 'struct' representing your function, as just described.
File: gawk.info, Node: Exit Callback Functions, Next: Extension Version
String, Prev: Extension Functions, Up: Registration Functions
@@ -23281,29 +23187,29 @@ File: gawk.info, Node: Exit Callback Functions,
Next: Extension Version String
16.4.5.2 Registering An Exit Callback Function
..............................................
-An "exit callback" function is a function that `gawk' calls before it
+An "exit callback" function is a function that 'gawk' calls before it
exits. Such functions are useful if you have general "cleanup" tasks
that should be performed in your extension (such as closing database
connections or other resource deallocations). You can register such a
-function with `gawk' using the following function:
+function with 'gawk' using the following function:
-`void awk_atexit(void (*funcp)(void *data, int exit_status),'
-` void *arg0);'
+'void awk_atexit(void (*funcp)(void *data, int exit_status),'
+' void *arg0);'
The parameters are:
- `funcp'
- A pointer to the function to be called before `gawk' exits.
- The `data' parameter will be the original value of `arg0'.
- The `exit_status' parameter is the exit status value that
- `gawk' intends to pass to the `exit()' system call.
+ 'funcp'
+ A pointer to the function to be called before 'gawk' exits.
+ The 'data' parameter will be the original value of 'arg0'.
+ The 'exit_status' parameter is the exit status value that
+ 'gawk' intends to pass to the 'exit()' system call.
- `arg0'
- A pointer to private data that `gawk' saves in order to pass
- to the function pointed to by `funcp'.
+ 'arg0'
+ A pointer to private data that 'gawk' saves in order to pass
+ to the function pointed to by 'funcp'.
Exit callback functions are called in last-in, first-out (LIFO)
order--that is, in the reverse order in which they are registered with
-`gawk'.
+'gawk'.
File: gawk.info, Node: Extension Version String, Next: Input Parsers, Prev:
Exit Callback Functions, Up: Registration Functions
@@ -23311,16 +23217,16 @@ File: gawk.info, Node: Extension Version String,
Next: Input Parsers, Prev: E
16.4.5.3 Registering An Extension Version String
................................................
-You can register a version string that indicates the name and version
-of your extension with `gawk', as follows:
+You can register a version string that indicates the name and version of
+your extension with 'gawk', as follows:
-`void register_ext_version(const char *version);'
- Register the string pointed to by `version' with `gawk'. Note
- that `gawk' does _not_ copy the `version' string, so it should not
- be changed.
+'void register_ext_version(const char *version);'
+ Register the string pointed to by 'version' with 'gawk'. Note that
+ 'gawk' does _not_ copy the 'version' string, so it should not be
+ changed.
- `gawk' prints all registered extension version strings when it is
-invoked with the `--version' option.
+ 'gawk' prints all registered extension version strings when it is
+invoked with the '--version' option.
File: gawk.info, Node: Input Parsers, Next: Output Wrappers, Prev:
Extension Version String, Up: Registration Functions
@@ -23328,38 +23234,37 @@ File: gawk.info, Node: Input Parsers, Next: Output
Wrappers, Prev: Extension
16.4.5.4 Customized Input Parsers
.................................
-By default, `gawk' reads text files as its input. It uses the value of
-`RS' to find the end of the record, and then uses `FS' (or
-`FIELDWIDTHS' or `FPAT') to split it into fields (*note Reading
-Files::). Additionally, it sets the value of `RT' (*note Built-in
-Variables::).
+By default, 'gawk' reads text files as its input. It uses the value of
+'RS' to find the end of the record, and then uses 'FS' (or 'FIELDWIDTHS'
+or 'FPAT') to split it into fields (*note Reading Files::).
+Additionally, it sets the value of 'RT' (*note Built-in Variables::).
If you want, you can provide your own custom input parser. An input
-parser's job is to return a record to the `gawk' record-processing
-code, along with indicators for the value and length of the data to be
-used for `RT', if any.
+parser's job is to return a record to the 'gawk' record-processing code,
+along with indicators for the value and length of the data to be used
+for 'RT', if any.
To provide an input parser, you must first provide two functions
(where XXX is a prefix name for your extension):
-`awk_bool_t XXX_can_take_file(const awk_input_buf_t *iobuf);'
- This function examines the information available in `iobuf' (which
- we discuss shortly). Based on the information there, it decides
- if the input parser should be used for this file. If so, it
- should return true. Otherwise, it should return false. It should
- not change any state (variable values, etc.) within `gawk'.
-
-`awk_bool_t XXX_take_control_of(awk_input_buf_t *iobuf);'
- When `gawk' decides to hand control of the file over to the input
- parser, it calls this function. This function in turn must fill
- in certain fields in the `awk_input_buf_t' structure and ensure
- that certain conditions are true. It should then return true. If
- an error of some kind occurs, it should not fill in any fields and
- should return false; then `gawk' will not use the input parser.
+'awk_bool_t XXX_can_take_file(const awk_input_buf_t *iobuf);'
+ This function examines the information available in 'iobuf' (which
+ we discuss shortly). Based on the information there, it decides if
+ the input parser should be used for this file. If so, it should
+ return true. Otherwise, it should return false. It should not
+ change any state (variable values, etc.) within 'gawk'.
+
+'awk_bool_t XXX_take_control_of(awk_input_buf_t *iobuf);'
+ When 'gawk' decides to hand control of the file over to the input
+ parser, it calls this function. This function in turn must fill in
+ certain fields in the 'awk_input_buf_t' structure and ensure that
+ certain conditions are true. It should then return true. If an
+ error of some kind occurs, it should not fill in any fields and
+ should return false; then 'gawk' will not use the input parser.
The details are presented shortly.
Your extension should package these functions inside an
-`awk_input_parser_t', which looks like this:
+'awk_input_parser_t', which looks like this:
typedef struct awk_input_parser {
const char *name; /* name of parser */
@@ -23370,29 +23275,29 @@ used for `RT', if any.
The fields are:
-`const char *name;'
- The name of the input parser. This is a regular C string.
+'const char *name;'
+ The name of the input parser. This is a regular C string.
-`awk_bool_t (*can_take_file)(const awk_input_buf_t *iobuf);'
- A pointer to your `XXX_can_take_file()' function.
+'awk_bool_t (*can_take_file)(const awk_input_buf_t *iobuf);'
+ A pointer to your 'XXX_can_take_file()' function.
-`awk_bool_t (*take_control_of)(awk_input_buf_t *iobuf);'
- A pointer to your `XXX_take_control_of()' function.
+'awk_bool_t (*take_control_of)(awk_input_buf_t *iobuf);'
+ A pointer to your 'XXX_take_control_of()' function.
-`awk_const struct input_parser *awk_const next;'
- This is for use by `gawk'; therefore it is marked `awk_const' so
+'awk_const struct input_parser *awk_const next;'
+ This is for use by 'gawk'; therefore it is marked 'awk_const' so
that the extension cannot modify it.
The steps are as follows:
- 1. Create a `static awk_input_parser_t' variable and initialize it
+ 1. Create a 'static awk_input_parser_t' variable and initialize it
appropriately.
2. When your extension is loaded, register your input parser with
- `gawk' using the `register_input_parser()' API function (described
+ 'gawk' using the 'register_input_parser()' API function (described
next).
- An `awk_input_buf_t' looks like this:
+ An 'awk_input_buf_t' looks like this:
typedef struct awk_input {
const char *name; /* filename */
@@ -23407,143 +23312,143 @@ used for `RT', if any.
} awk_input_buf_t;
The fields can be divided into two categories: those for use
-(initially, at least) by `XXX_can_take_file()', and those for use by
-`XXX_take_control_of()'. The first group of fields and their uses are
+(initially, at least) by 'XXX_can_take_file()', and those for use by
+'XXX_take_control_of()'. The first group of fields and their uses are
as follows:
-`const char *name;'
+'const char *name;'
The name of the file.
-`int fd;'
- A file descriptor for the file. If `gawk' was able to open the
- file, then `fd' will _not_ be equal to `INVALID_HANDLE'.
+'int fd;'
+ A file descriptor for the file. If 'gawk' was able to open the
+ file, then 'fd' will _not_ be equal to 'INVALID_HANDLE'.
Otherwise, it will.
-`struct stat sbuf;'
- If the file descriptor is valid, then `gawk' will have filled in
- this structure via a call to the `fstat()' system call.
+'struct stat sbuf;'
+ If the file descriptor is valid, then 'gawk' will have filled in
+ this structure via a call to the 'fstat()' system call.
- The `XXX_can_take_file()' function should examine these fields and
+ The 'XXX_can_take_file()' function should examine these fields and
decide if the input parser should be used for the file. The decision
-can be made based upon `gawk' state (the value of a variable defined
-previously by the extension and set by `awk' code), the name of the
+can be made based upon 'gawk' state (the value of a variable defined
+previously by the extension and set by 'awk' code), the name of the
file, whether or not the file descriptor is valid, the information in
-the `struct stat', or any combination of these factors.
+the 'struct stat', or any combination of these factors.
- Once `XXX_can_take_file()' has returned true, and `gawk' has decided
-to use your input parser, it calls `XXX_take_control_of()'. That
-function then fills either the `get_record' field or the `read_func'
-field in the `awk_input_buf_t'. It must also ensure that `fd' is _not_
-set to `INVALID_HANDLE'. The following list describes the fields that
-may be filled by `XXX_take_control_of()':
+ Once 'XXX_can_take_file()' has returned true, and 'gawk' has decided
+to use your input parser, it calls 'XXX_take_control_of()'. That
+function then fills either the 'get_record' field or the 'read_func'
+field in the 'awk_input_buf_t'. It must also ensure that 'fd' is _not_
+set to 'INVALID_HANDLE'. The following list describes the fields that
+may be filled by 'XXX_take_control_of()':
-`void *opaque;'
+'void *opaque;'
This is used to hold any state information needed by the input
- parser for this file. It is "opaque" to `gawk'. The input parser
+ parser for this file. It is "opaque" to 'gawk'. The input parser
is not required to use this pointer.
-`int (*get_record)(char **out,'
-` struct awk_input *iobuf,'
-` int *errcode,'
-` char **rt_start,'
-` size_t *rt_len);'
+'int (*get_record)(char **out,'
+' struct awk_input *iobuf,'
+' int *errcode,'
+' char **rt_start,'
+' size_t *rt_len);'
This function pointer should point to a function that creates the
- input records. Said function is the core of the input parser.
- Its behavior is described in the text following this list.
+ input records. Said function is the core of the input parser. Its
+ behavior is described in the text following this list.
-`ssize_t (*read_func)();'
+'ssize_t (*read_func)();'
This function pointer should point to a function that has the same
- behavior as the standard POSIX `read()' system call. It is an
- alternative to the `get_record' pointer. Its behavior is also
+ behavior as the standard POSIX 'read()' system call. It is an
+ alternative to the 'get_record' pointer. Its behavior is also
described in the text following this list.
-`void (*close_func)(struct awk_input *iobuf);'
+'void (*close_func)(struct awk_input *iobuf);'
This function pointer should point to a function that does the
- "teardown." It should release any resources allocated by
- `XXX_take_control_of()'. It may also close the file. If it does
- so, it should set the `fd' field to `INVALID_HANDLE'.
+ "teardown." It should release any resources allocated by
+ 'XXX_take_control_of()'. It may also close the file. If it does
+ so, it should set the 'fd' field to 'INVALID_HANDLE'.
- If `fd' is still not `INVALID_HANDLE' after the call to this
- function, `gawk' calls the regular `close()' system call.
+ If 'fd' is still not 'INVALID_HANDLE' after the call to this
+ function, 'gawk' calls the regular 'close()' system call.
- Having a "teardown" function is optional. If your input parser does
- not need it, do not set this field. Then, `gawk' calls the
- regular `close()' system call on the file descriptor, so it should
+ Having a "teardown" function is optional. If your input parser
+ does not need it, do not set this field. Then, 'gawk' calls the
+ regular 'close()' system call on the file descriptor, so it should
be valid.
- The `XXX_get_record()' function does the work of creating input
+ The 'XXX_get_record()' function does the work of creating input
records. The parameters are as follows:
-`char **out'
- This is a pointer to a `char *' variable that is set to point to
- the record. `gawk' makes its own copy of the data, so the
+'char **out'
+ This is a pointer to a 'char *' variable that is set to point to
+ the record. 'gawk' makes its own copy of the data, so the
extension must manage this storage.
-`struct awk_input *iobuf'
- This is the `awk_input_buf_t' for the file. The fields should be
- used for reading data (`fd') and for managing private state
- (`opaque'), if any.
+'struct awk_input *iobuf'
+ This is the 'awk_input_buf_t' for the file. The fields should be
+ used for reading data ('fd') and for managing private state
+ ('opaque'), if any.
-`int *errcode'
- If an error occurs, `*errcode' should be set to an appropriate
- code from `<errno.h>'.
+'int *errcode'
+ If an error occurs, '*errcode' should be set to an appropriate code
+ from '<errno.h>'.
-`char **rt_start'
-`size_t *rt_len'
+'char **rt_start'
+'size_t *rt_len'
If the concept of a "record terminator" makes sense, then
- `*rt_start' should be set to point to the data to be used for
- `RT', and `*rt_len' should be set to the length of the data.
- Otherwise, `*rt_len' should be set to zero. `gawk' makes its own
- copy of this data, so the extension must manage this storage.
+ '*rt_start' should be set to point to the data to be used for 'RT',
+ and '*rt_len' should be set to the length of the data. Otherwise,
+ '*rt_len' should be set to zero. 'gawk' makes its own copy of this
+ data, so the extension must manage this storage.
- The return value is the length of the buffer pointed to by `*out',
-or `EOF' if end-of-file was reached or an error occurred.
+ The return value is the length of the buffer pointed to by '*out', or
+'EOF' if end-of-file was reached or an error occurred.
- It is guaranteed that `errcode' is a valid pointer, so there is no
-need to test for a `NULL' value. `gawk' sets `*errcode' to zero, so
+ It is guaranteed that 'errcode' is a valid pointer, so there is no
+need to test for a 'NULL' value. 'gawk' sets '*errcode' to zero, so
there is no need to set it unless an error occurs.
- If an error does occur, the function should return `EOF' and set
-`*errcode' to a value greater than zero. In that case, if `*errcode'
-does not equal zero, `gawk' automatically updates the `ERRNO' variable
-based on the value of `*errcode'. (In general, setting `*errcode =
+ If an error does occur, the function should return 'EOF' and set
+'*errcode' to a value greater than zero. In that case, if '*errcode'
+does not equal zero, 'gawk' automatically updates the 'ERRNO' variable
+based on the value of '*errcode'. (In general, setting '*errcode =
errno' should do the right thing.)
As an alternative to supplying a function that returns an input
record, you may instead supply a function that simply reads bytes, and
-let `gawk' parse the data into records. If you do so, the data should
+let 'gawk' parse the data into records. If you do so, the data should
be returned in the multibyte encoding of the current locale. Such a
-function should follow the same behavior as the `read()' system call,
-and you fill in the `read_func' pointer with its address in the
-`awk_input_buf_t' structure.
+function should follow the same behavior as the 'read()' system call,
+and you fill in the 'read_func' pointer with its address in the
+'awk_input_buf_t' structure.
- By default, `gawk' sets the `read_func' pointer to point to the
-`read()' system call. So your extension need not set this field
+ By default, 'gawk' sets the 'read_func' pointer to point to the
+'read()' system call. So your extension need not set this field
explicitly.
NOTE: You must choose one method or the other: either a function
that returns a record, or one that returns raw data. In
- particular, if you supply a function to get a record, `gawk' will
+ particular, if you supply a function to get a record, 'gawk' will
call it, and will never call the raw read function.
- `gawk' ships with a sample extension that reads directories,
+ 'gawk' ships with a sample extension that reads directories,
returning records for each entry in a directory (*note Extension Sample
Readdir::). You may wish to use that code as a guide for writing your
own input parser.
When writing an input parser, you should think about (and document)
-how it is expected to interact with `awk' code. You may want it to
-always be called, and to take effect as appropriate (as the `readdir'
-extension does). Or you may want it to take effect based upon the
-value of an `awk' variable, as the XML extension from the `gawkextlib'
-project does (*note gawkextlib::). In the latter case, code in a
-`BEGINFILE' section can look at `FILENAME' and `ERRNO' to decide
-whether or not to activate an input parser (*note BEGINFILE/ENDFILE::).
+how it is expected to interact with 'awk' code. You may want it to
+always be called, and to take effect as appropriate (as the 'readdir'
+extension does). Or you may want it to take effect based upon the value
+of an 'awk' variable, as the XML extension from the 'gawkextlib' project
+does (*note gawkextlib::). In the latter case, code in a 'BEGINFILE'
+section can look at 'FILENAME' and 'ERRNO' to decide whether or not to
+activate an input parser (*note BEGINFILE/ENDFILE::).
You register your input parser with the following function:
-`void register_input_parser(awk_input_parser_t *input_parser);'
- Register the input parser pointed to by `input_parser' with `gawk'.
+'void register_input_parser(awk_input_parser_t *input_parser);'
+ Register the input parser pointed to by 'input_parser' with 'gawk'.
File: gawk.info, Node: Output Wrappers, Next: Two-way processors, Prev:
Input Parsers, Up: Registration Functions
@@ -23552,8 +23457,8 @@ File: gawk.info, Node: Output Wrappers, Next: Two-way
processors, Prev: Input
...................................
An "output wrapper" is the mirror image of an input parser. It allows
-an extension to take over the output to a file opened with the `>' or
-`>>' I/O redirection operators (*note Redirection::).
+an extension to take over the output to a file opened with the '>' or
+'>>' I/O redirection operators (*note Redirection::).
The output wrapper is very similar to the input parser structure:
@@ -23566,28 +23471,27 @@ an extension to take over the output to a file opened
with the `>' or
The members are as follows:
-`const char *name;'
+'const char *name;'
This is the name of the output wrapper.
-`awk_bool_t (*can_take_file)(const awk_output_buf_t *outbuf);'
+'awk_bool_t (*can_take_file)(const awk_output_buf_t *outbuf);'
This points to a function that examines the information in the
- `awk_output_buf_t' structure pointed to by `outbuf'. It should
+ 'awk_output_buf_t' structure pointed to by 'outbuf'. It should
return true if the output wrapper wants to take over the file, and
false otherwise. It should not change any state (variable values,
- etc.) within `gawk'.
+ etc.) within 'gawk'.
-`awk_bool_t (*take_control_of)(awk_output_buf_t *outbuf);'
- The function pointed to by this field is called when `gawk'
- decides to let the output wrapper take control of the file. It
- should fill in appropriate members of the `awk_output_buf_t'
- structure, as described next, and return true if successful, false
- otherwise.
+'awk_bool_t (*take_control_of)(awk_output_buf_t *outbuf);'
+ The function pointed to by this field is called when 'gawk' decides
+ to let the output wrapper take control of the file. It should fill
+ in appropriate members of the 'awk_output_buf_t' structure, as
+ described next, and return true if successful, false otherwise.
-`awk_const struct output_wrapper *awk_const next;'
- This is for use by `gawk'; therefore it is marked `awk_const' so
+'awk_const struct output_wrapper *awk_const next;'
+ This is for use by 'gawk'; therefore it is marked 'awk_const' so
that the extension cannot modify it.
- The `awk_output_buf_t' structure looks like this:
+ The 'awk_output_buf_t' structure looks like this:
typedef struct awk_output_buf {
const char *name; /* name of output file */
@@ -23602,55 +23506,55 @@ an extension to take over the output to a file opened
with the `>' or
int (*gawk_fclose)(FILE *fp, void *opaque);
} awk_output_buf_t;
- Here too, your extension will define `XXX_can_take_file()' and
-`XXX_take_control_of()' functions that examine and update data members
-in the `awk_output_buf_t'. The data members are as follows:
+ Here too, your extension will define 'XXX_can_take_file()' and
+'XXX_take_control_of()' functions that examine and update data members
+in the 'awk_output_buf_t'. The data members are as follows:
-`const char *name;'
+'const char *name;'
The name of the output file.
-`const char *mode;'
+'const char *mode;'
The mode string (as would be used in the second argument to
- `fopen()') with which the file was opened.
+ 'fopen()') with which the file was opened.
-`FILE *fp;'
- The `FILE' pointer from `<stdio.h>'. `gawk' opens the file before
+'FILE *fp;'
+ The 'FILE' pointer from '<stdio.h>'. 'gawk' opens the file before
attempting to find an output wrapper.
-`awk_bool_t redirected;'
- This field must be set to true by the `XXX_take_control_of()'
+'awk_bool_t redirected;'
+ This field must be set to true by the 'XXX_take_control_of()'
function.
-`void *opaque;'
- This pointer is opaque to `gawk'. The extension should use it to
+'void *opaque;'
+ This pointer is opaque to 'gawk'. The extension should use it to
store a pointer to any private data associated with the file.
-`size_t (*gawk_fwrite)(const void *buf, size_t size, size_t count,'
-` FILE *fp, void *opaque);'
-`int (*gawk_fflush)(FILE *fp, void *opaque);'
-`int (*gawk_ferror)(FILE *fp, void *opaque);'
-`int (*gawk_fclose)(FILE *fp, void *opaque);'
- These pointers should be set to point to functions that perform
- the equivalent function as the `<stdio.h>' functions do, if
- appropriate. `gawk' uses these function pointers for all output.
- `gawk' initializes the pointers to point to internal "pass-through"
- functions that just call the regular `<stdio.h>' functions, so an
+'size_t (*gawk_fwrite)(const void *buf, size_t size, size_t count,'
+' FILE *fp, void *opaque);'
+'int (*gawk_fflush)(FILE *fp, void *opaque);'
+'int (*gawk_ferror)(FILE *fp, void *opaque);'
+'int (*gawk_fclose)(FILE *fp, void *opaque);'
+ These pointers should be set to point to functions that perform the
+ equivalent function as the '<stdio.h>' functions do, if
+ appropriate. 'gawk' uses these function pointers for all output.
+ 'gawk' initializes the pointers to point to internal "pass-through"
+ functions that just call the regular '<stdio.h>' functions, so an
extension only needs to redefine those functions that are
appropriate for what it does.
- The `XXX_can_take_file()' function should make a decision based upon
-the `name' and `mode' fields, and any additional state (such as `awk'
+ The 'XXX_can_take_file()' function should make a decision based upon
+the 'name' and 'mode' fields, and any additional state (such as 'awk'
variable values) that is appropriate.
- When `gawk' calls `XXX_take_control_of()', that function should fill
-in the other fields as appropriate, except for `fp', which it should
+ When 'gawk' calls 'XXX_take_control_of()', that function should fill
+in the other fields as appropriate, except for 'fp', which it should
just use normally.
You register your output wrapper with the following function:
-`void register_output_wrapper(awk_output_wrapper_t *output_wrapper);'
- Register the output wrapper pointed to by `output_wrapper' with
- `gawk'.
+'void register_output_wrapper(awk_output_wrapper_t *output_wrapper);'
+ Register the output wrapper pointed to by 'output_wrapper' with
+ 'gawk'.
File: gawk.info, Node: Two-way processors, Prev: Output Wrappers, Up:
Registration Functions
@@ -23659,8 +23563,8 @@ File: gawk.info, Node: Two-way processors, Prev:
Output Wrappers, Up: Registr
......................................
A "two-way processor" combines an input parser and an output wrapper for
-two-way I/O with the `|&' operator (*note Redirection::). It makes
-identical use of the `awk_input_parser_t' and `awk_output_buf_t'
+two-way I/O with the '|&' operator (*note Redirection::). It makes
+identical use of the 'awk_input_parser_t' and 'awk_output_buf_t'
structures as described earlier.
A two-way processor is represented by the following structure:
@@ -23676,118 +23580,117 @@ structures as described earlier.
The fields are as follows:
-`const char *name;'
+'const char *name;'
The name of the two-way processor.
-`awk_bool_t (*can_take_two_way)(const char *name);'
+'awk_bool_t (*can_take_two_way)(const char *name);'
The function pointed to by this field should return true if it
wants to take over two-way I/O for this file name. It should not
- change any state (variable values, etc.) within `gawk'.
+ change any state (variable values, etc.) within 'gawk'.
-`awk_bool_t (*take_control_of)(const char *name,'
-` awk_input_buf_t *inbuf,'
-` awk_output_buf_t *outbuf);'
+'awk_bool_t (*take_control_of)(const char *name,'
+' awk_input_buf_t *inbuf,'
+' awk_output_buf_t *outbuf);'
The function pointed to by this field should fill in the
- `awk_input_buf_t' and `awk_outut_buf_t' structures pointed to by
- `inbuf' and `outbuf', respectively. These structures were
+ 'awk_input_buf_t' and 'awk_outut_buf_t' structures pointed to by
+ 'inbuf' and 'outbuf', respectively. These structures were
described earlier.
-`awk_const struct two_way_processor *awk_const next;'
- This is for use by `gawk'; therefore it is marked `awk_const' so
+'awk_const struct two_way_processor *awk_const next;'
+ This is for use by 'gawk'; therefore it is marked 'awk_const' so
that the extension cannot modify it.
- As with the input parser and output processor, you provide "yes I
-can take this" and "take over for this" functions,
-`XXX_can_take_two_way()' and `XXX_take_control_of()'.
+ As with the input parser and output processor, you provide "yes I can
+take this" and "take over for this" functions, 'XXX_can_take_two_way()'
+and 'XXX_take_control_of()'.
You register your two-way processor with the following function:
-`void register_two_way_processor(awk_two_way_processor_t *two_way_processor);'
- Register the two-way processor pointed to by `two_way_processor'
- with `gawk'.
+'void register_two_way_processor(awk_two_way_processor_t *two_way_processor);'
+ Register the two-way processor pointed to by 'two_way_processor'
+ with 'gawk'.
-File: gawk.info, Node: Printing Messages, Next: Updating `ERRNO', Prev:
Registration Functions, Up: Extension API Description
+File: gawk.info, Node: Printing Messages, Next: Updating 'ERRNO', Prev:
Registration Functions, Up: Extension API Description
16.4.6 Printing Messages
------------------------
You can print different kinds of warning messages from your extension,
as described here. Note that for these functions, you must pass in the
-extension ID received from `gawk' when the extension was loaded:(1)
+extension ID received from 'gawk' when the extension was loaded:(1)
-`void fatal(awk_ext_id_t id, const char *format, ...);'
- Print a message and then cause `gawk' to exit immediately.
+'void fatal(awk_ext_id_t id, const char *format, ...);'
+ Print a message and then cause 'gawk' to exit immediately.
-`void warning(awk_ext_id_t id, const char *format, ...);'
+'void warning(awk_ext_id_t id, const char *format, ...);'
Print a warning message.
-`void lintwarn(awk_ext_id_t id, const char *format, ...);'
+'void lintwarn(awk_ext_id_t id, const char *format, ...);'
Print a "lint warning." Normally this is the same as printing a
- warning message, but if `gawk' was invoked with `--lint=fatal',
+ warning message, but if 'gawk' was invoked with '--lint=fatal',
then lint warnings become fatal error messages.
- All of these functions are otherwise like the C `printf()' family of
-functions, where the `format' parameter is a string with literal
+ All of these functions are otherwise like the C 'printf()' family of
+functions, where the 'format' parameter is a string with literal
characters and formatting codes intermixed.
---------- Footnotes ----------
(1) Because the API uses only ISO C 90 features, it cannot make use
-of the ISO C 99 variadic macro feature to hide that parameter. More's
+of the ISO C 99 variadic macro feature to hide that parameter. More's
the pity.
-File: gawk.info, Node: Updating `ERRNO', Next: Requesting Values, Prev:
Printing Messages, Up: Extension API Description
+File: gawk.info, Node: Updating 'ERRNO', Next: Requesting Values, Prev:
Printing Messages, Up: Extension API Description
-16.4.7 Updating `ERRNO'
+16.4.7 Updating 'ERRNO'
-----------------------
-The following functions allow you to update the `ERRNO' variable:
+The following functions allow you to update the 'ERRNO' variable:
-`void update_ERRNO_int(int errno_val);'
- Set `ERRNO' to the string equivalent of the error code in
- `errno_val'. The value should be one of the defined error codes in
- `<errno.h>', and `gawk' turns it into a (possibly translated)
- string using the C `strerror()' function.
+'void update_ERRNO_int(int errno_val);'
+ Set 'ERRNO' to the string equivalent of the error code in
+ 'errno_val'. The value should be one of the defined error codes in
+ '<errno.h>', and 'gawk' turns it into a (possibly translated)
+ string using the C 'strerror()' function.
-`void update_ERRNO_string(const char *string);'
- Set `ERRNO' directly to the string value of `ERRNO'. `gawk' makes
- a copy of the value of `string'.
+'void update_ERRNO_string(const char *string);'
+ Set 'ERRNO' directly to the string value of 'ERRNO'. 'gawk' makes
+ a copy of the value of 'string'.
-`void unset_ERRNO(void);'
- Unset `ERRNO'.
+'void unset_ERRNO(void);'
+ Unset 'ERRNO'.
-File: gawk.info, Node: Requesting Values, Next: Accessing Parameters, Prev:
Updating `ERRNO', Up: Extension API Description
+File: gawk.info, Node: Requesting Values, Next: Accessing Parameters, Prev:
Updating 'ERRNO', Up: Extension API Description
16.4.8 Requesting Values
------------------------
-All of the functions that return values from `gawk' work in the same
-way. You pass in an `awk_valtype_t' value to indicate what kind of
+All of the functions that return values from 'gawk' work in the same
+way. You pass in an 'awk_valtype_t' value to indicate what kind of
value you expect. If the actual value matches what you requested, the
-function returns true and fills in the `awk_value_t' result.
-Otherwise, the function returns false, and the `val_type' member
-indicates the type of the actual value. You may then print an error
-message or reissue the request for the actual value type, as
-appropriate. This behavior is summarized in *note
-table-value-types-returned::.
+function returns true and fills in the 'awk_value_t' result. Otherwise,
+the function returns false, and the 'val_type' member indicates the type
+of the actual value. You may then print an error message or reissue the
+request for the actual value type, as appropriate. This behavior is
+summarized in *note Table 16.1: table-value-types-returned.
Type of Actual Value
---------------------------------------------------------------------------
-
+--------------------------------------------------------------------------
String Number Array Undefined
-------------------------------------------------------------------------------
+------------------------------------------------------------------------------
String String String False False
- Number Number if can Number False False
- be converted,
- else false
+ Number Number if Number False False
+ can be
+ converted,
+ else false
Type Array False False Array False
Requested Scalar Scalar Scalar False False
Undefined String Number Array Undefined
Value False False False False
- cookie
+ cookie
Table 16.1: API value types returned
@@ -23798,22 +23701,22 @@ File: gawk.info, Node: Accessing Parameters, Next:
Symbol Table Access, Prev:
----------------------------------------
Two functions give you access to the arguments (parameters) passed to
-your extension function. They are:
-
-`awk_bool_t get_argument(size_t count,'
-` awk_valtype_t wanted,'
-` awk_value_t *result);'
- Fill in the `awk_value_t' structure pointed to by `result' with
- the `count'th argument. Return true if the actual type matches
- `wanted', and false otherwise. In the latter case,
- `result->val_type' indicates the actual type (*note Table 16.1:
+your extension function. They are:
+
+'awk_bool_t get_argument(size_t count,'
+' awk_valtype_t wanted,'
+' awk_value_t *result);'
+ Fill in the 'awk_value_t' structure pointed to by 'result' with the
+ 'count'th argument. Return true if the actual type matches
+ 'wanted', and false otherwise. In the latter case,
+ 'result->val_type' indicates the actual type (*note Table 16.1:
table-value-types-returned.). Counts are zero-based--the first
- argument is numbered zero, the second one, and so on. `wanted'
+ argument is numbered zero, the second one, and so on. 'wanted'
indicates the type of value expected.
-`awk_bool_t set_argument(size_t count, awk_array_t array);'
+'awk_bool_t set_argument(size_t count, awk_array_t array);'
Convert a parameter that was undefined into an array; this provides
- call by reference for arrays. Return false if `count' is too big,
+ call by reference for arrays. Return false if 'count' is too big,
or if the argument's type is not undefined. *Note Array
Manipulation::, for more information on creating arrays.
@@ -23829,7 +23732,7 @@ allows you to create and release cached values.
* Menu:
* Symbol table by name:: Accessing variables by name.
-* Symbol table by cookie:: Accessing variables by ``cookie''.
+* Symbol table by cookie:: Accessing variables by "cookie".
* Cached values:: Creating and using cached values.
@@ -23839,39 +23742,39 @@ File: gawk.info, Node: Symbol table by name, Next:
Symbol table by cookie, Up
............................................
The following routines provide the ability to access and update global
-`awk'-level variables by name. In compiler terminology, identifiers of
+'awk'-level variables by name. In compiler terminology, identifiers of
different kinds are termed "symbols", thus the "sym" in the routines'
names. The data structure that stores information about symbols is
termed a "symbol table". The functions are as follows:
-`awk_bool_t sym_lookup(const char *name,'
-` awk_valtype_t wanted,'
-` awk_value_t *result);'
- Fill in the `awk_value_t' structure pointed to by `result' with
- the value of the variable named by the string `name', which is a
- regular C string. `wanted' indicates the type of value expected.
- Return true if the actual type matches `wanted', and false
- otherwise. In the latter case, `result->val_type' indicates the
+'awk_bool_t sym_lookup(const char *name,'
+' awk_valtype_t wanted,'
+' awk_value_t *result);'
+ Fill in the 'awk_value_t' structure pointed to by 'result' with the
+ value of the variable named by the string 'name', which is a
+ regular C string. 'wanted' indicates the type of value expected.
+ Return true if the actual type matches 'wanted', and false
+ otherwise. In the latter case, 'result->val_type' indicates the
actual type (*note Table 16.1: table-value-types-returned.).
-`awk_bool_t sym_update(const char *name, awk_value_t *value);'
- Update the variable named by the string `name', which is a regular
- C string. The variable is added to `gawk''s symbol table if it is
+'awk_bool_t sym_update(const char *name, awk_value_t *value);'
+ Update the variable named by the string 'name', which is a regular
+ C string. The variable is added to 'gawk''s symbol table if it is
not there. Return true if everything worked, and false otherwise.
Changing types (scalar to array or vice versa) of an existing
variable is _not_ allowed, nor may this routine be used to update
an array. This routine cannot be used to update any of the
- predefined variables (such as `ARGC' or `NF').
+ predefined variables (such as 'ARGC' or 'NF').
- An extension can look up the value of `gawk''s special variables.
-However, with the exception of the `PROCINFO' array, an extension
-cannot change any of those variables.
+ An extension can look up the value of 'gawk''s special variables.
+However, with the exception of the 'PROCINFO' array, an extension cannot
+change any of those variables.
- CAUTION: It is possible for the lookup of `PROCINFO' to fail. This
- happens if the `awk' program being run does not reference
- `PROCINFO'; in this case, `gawk' doesn't bother to create the
- array and populate it.
+ CAUTION: It is possible for the lookup of 'PROCINFO' to fail. This
+ happens if the 'awk' program being run does not reference
+ 'PROCINFO'; in this case, 'gawk' doesn't bother to create the array
+ and populate it.
File: gawk.info, Node: Symbol table by cookie, Next: Cached values, Prev:
Symbol table by name, Up: Symbol Table Access
@@ -23880,28 +23783,28 @@ File: gawk.info, Node: Symbol table by cookie,
Next: Cached values, Prev: Sym
..............................................
A "scalar cookie" is an opaque handle that provides access to a global
-variable or array. It is an optimization that avoids looking up
-variables in `gawk''s symbol table every time access is needed. This
+variable or array. It is an optimization that avoids looking up
+variables in 'gawk''s symbol table every time access is needed. This
was discussed earlier, in *note General Data Types::.
The following functions let you work with scalar cookies:
-`awk_bool_t sym_lookup_scalar(awk_scalar_t cookie,'
-` awk_valtype_t wanted,'
-` awk_value_t *result);'
+'awk_bool_t sym_lookup_scalar(awk_scalar_t cookie,'
+' awk_valtype_t wanted,'
+' awk_value_t *result);'
Retrieve the current value of a scalar cookie. Once you have
- obtained a scalar cookie using `sym_lookup()', you can use this
+ obtained a scalar cookie using 'sym_lookup()', you can use this
function to get its value more efficiently. Return false if the
value cannot be retrieved.
-`awk_bool_t sym_update_scalar(awk_scalar_t cookie, awk_value_t *value);'
+'awk_bool_t sym_update_scalar(awk_scalar_t cookie, awk_value_t *value);'
Update the value associated with a scalar cookie. Return false if
- the new value is not of type `AWK_STRING' or `AWK_NUMBER'. Here
+ the new value is not of type 'AWK_STRING' or 'AWK_NUMBER'. Here
too, the predefined variables may not be updated.
It is not obvious at first glance how to work with scalar cookies or
-what their raison d'e^tre really is. In theory, the `sym_lookup()' and
-`sym_update()' routines are all you really need to work with variables.
+what their raison d'e^tre really is. In theory, the 'sym_lookup()' and
+'sym_update()' routines are all you really need to work with variables.
For example, you might have code that looks up the value of a variable,
evaluates a condition, and then possibly changes the value of the
variable based on the result of that evaluation, like so:
@@ -23922,13 +23825,13 @@ variable based on the result of that evaluation, like
so:
return make_number(0.0, result);
}
-This code looks (and is) simple and straightforward. So what's the
+This code looks (and is) simple and straightforward. So what's the
problem?
- Well, consider what happens if `awk'-level code associated with your
-extension calls the `magic()' function (implemented in C by
-`do_magic()'), once per record, while processing hundreds of thousands
-or millions of records. The `MAGIC_VAR' variable is looked up in the
+ Well, consider what happens if 'awk'-level code associated with your
+extension calls the 'magic()' function (implemented in C by
+'do_magic()'), once per record, while processing hundreds of thousands
+or millions of records. The 'MAGIC_VAR' variable is looked up in the
symbol table once or twice per function call!
The symbol table lookup is really pure overhead; it is considerably
@@ -23936,8 +23839,8 @@ more efficient to get a cookie that represents the
variable, and use
that to get the variable's value and update it as needed.(1)
Thus, the way to use cookies is as follows. First, install your
-extension's variable in `gawk''s symbol table using `sym_update()', as
-usual. Then get a scalar cookie for the variable using `sym_lookup()':
+extension's variable in 'gawk''s symbol table using 'sym_update()', as
+usual. Then get a scalar cookie for the variable using 'sym_lookup()':
static awk_scalar_t magic_var_cookie; /* cookie for MAGIC_VAR */
@@ -23958,7 +23861,7 @@ usual. Then get a scalar cookie for the variable using
`sym_lookup()':
}
Next, use the routines in this section for retrieving and updating
-the value through the cookie. Thus, `do_magic()' now becomes something
+the value through the cookie. Thus, 'do_magic()' now becomes something
like this:
/* do_magic --- do something really great */
@@ -23984,7 +23887,7 @@ like this:
---------- Footnotes ----------
- (1) The difference is measurable and quite real. Trust us.
+ (1) The difference is measurable and quite real. Trust us.
File: gawk.info, Node: Cached values, Prev: Symbol table by cookie, Up:
Symbol Table Access
@@ -23994,31 +23897,31 @@ File: gawk.info, Node: Cached values, Prev: Symbol
table by cookie, Up: Symbo
The routines in this section allow you to create and release cached
values. Like scalar cookies, in theory, cached values are not
-necessary. You can create numbers and strings using the functions in
-*note Constructor Functions::. You can then assign those values to
-variables using `sym_update()' or `sym_update_scalar()', as you like.
+necessary. You can create numbers and strings using the functions in
+*note Constructor Functions::. You can then assign those values to
+variables using 'sym_update()' or 'sym_update_scalar()', as you like.
However, you can understand the point of cached values if you
remember that _every_ string value's storage _must_ come from
-`gawk_malloc()', `gawk_calloc()', or `gawk_realloc()'. If you have 20
+'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()'. If you have 20
variables, all of which have the same string value, you must create 20
identical copies of the string.(1)
It is clearly more efficient, if possible, to create a value once,
-and then tell `gawk' to reuse the value for multiple variables. That is
+and then tell 'gawk' to reuse the value for multiple variables. That is
what the routines in this section let you do. The functions are as
follows:
-`awk_bool_t create_value(awk_value_t *value, awk_value_cookie_t *result);'
- Create a cached string or numeric value from `value' for efficient
- later assignment. Only values of type `AWK_NUMBER' and
- `AWK_STRING' are allowed. Any other type is rejected.
- `AWK_UNDEFINED' could be allowed, but doing so would result in
+'awk_bool_t create_value(awk_value_t *value, awk_value_cookie_t *result);'
+ Create a cached string or numeric value from 'value' for efficient
+ later assignment. Only values of type 'AWK_NUMBER' and
+ 'AWK_STRING' are allowed. Any other type is rejected.
+ 'AWK_UNDEFINED' could be allowed, but doing so would result in
inferior performance.
-`awk_bool_t release_value(awk_value_cookie_t vc);'
+'awk_bool_t release_value(awk_value_cookie_t vc);'
Release the memory associated with a value cookie obtained from
- `create_value()'.
+ 'create_value()'.
You use value cookies in a fashion similar to the way you use scalar
cookies. In the extension initialization routine, you create the value
@@ -24061,27 +23964,27 @@ of variables:
}
Using value cookies in this way saves considerable storage, as all of
-`VAR1' through `VAR100' share the same value.
+'VAR1' through 'VAR100' share the same value.
You might be wondering, "Is this sharing problematic? What happens
-if `awk' code assigns a new value to `VAR1'; are all the others changed
+if 'awk' code assigns a new value to 'VAR1'; are all the others changed
too?"
- That's a great question. The answer is that no, it's not a problem.
-Internally, `gawk' uses "reference-counted strings". This means that
-many variables can share the same string value, and `gawk' keeps track
-of the usage. When a variable's value changes, `gawk' simply
-decrements the reference count on the old value and updates the
-variable to use the new value.
+ That's a great question. The answer is that no, it's not a problem.
+Internally, 'gawk' uses "reference-counted strings". This means that
+many variables can share the same string value, and 'gawk' keeps track
+of the usage. When a variable's value changes, 'gawk' simply decrements
+the reference count on the old value and updates the variable to use the
+new value.
Finally, as part of your cleanup action (*note Exit Callback
Functions::) you should release any cached values that you created,
-using `release_value()'.
+using 'release_value()'.
---------- Footnotes ----------
(1) Numeric values are clearly less problematic, requiring only a C
-`double' to store.
+'double' to store.
File: gawk.info, Node: Array Manipulation, Next: Extension API Variables,
Prev: Symbol Table Access, Up: Extension API Description
@@ -24089,11 +23992,11 @@ File: gawk.info, Node: Array Manipulation, Next:
Extension API Variables, Pre
16.4.11 Array Manipulation
--------------------------
-The primary data structure(1) in `awk' is the associative array (*note
-Arrays::). Extensions need to be able to manipulate `awk' arrays. The
+The primary data structure(1) in 'awk' is the associative array (*note
+Arrays::). Extensions need to be able to manipulate 'awk' arrays. The
API provides a number of data structures for working with arrays,
functions for working with individual elements, and functions for
-working with arrays as a whole. This includes the ability to "flatten"
+working with arrays as a whole. This includes the ability to "flatten"
an array so that it is easy for C code to traverse every element in an
array. The array data structures integrate nicely with the data
structures for values to make it easy to both work with and create true
@@ -24118,63 +24021,63 @@ File: gawk.info, Node: Array Data Types, Next:
Array Functions, Up: Array Man
The data types associated with arrays are as follows:
-`typedef void *awk_array_t;'
+'typedef void *awk_array_t;'
If you request the value of an array variable, you get back an
- `awk_array_t' value. This value is opaque(1) to the extension; it
+ 'awk_array_t' value. This value is opaque(1) to the extension; it
uniquely identifies the array but can only be used by passing it
- into API functions or receiving it from API functions. This is
- very similar to way `FILE *' values are used with the `<stdio.h>'
+ into API functions or receiving it from API functions. This is
+ very similar to way 'FILE *' values are used with the '<stdio.h>'
library routines.
-`typedef struct awk_element {'
-` /* convenience linked list pointer, not used by gawk */'
-` struct awk_element *next;'
-` enum {'
-` AWK_ELEMENT_DEFAULT = 0, /* set by gawk */'
-` AWK_ELEMENT_DELETE = 1 /* set by extension */'
-` } flags;'
-` awk_value_t index;'
-` awk_value_t value;'
-`} awk_element_t;'
- The `awk_element_t' is a "flattened" array element. `awk' produces
- an array of these inside the `awk_flat_array_t' (see the next
- item). Individual elements may be marked for deletion. New
+'typedef struct awk_element {'
+' /* convenience linked list pointer, not used by gawk */'
+' struct awk_element *next;'
+' enum {'
+' AWK_ELEMENT_DEFAULT = 0, /* set by gawk */'
+' AWK_ELEMENT_DELETE = 1 /* set by extension */'
+' } flags;'
+' awk_value_t index;'
+' awk_value_t value;'
+'} awk_element_t;'
+ The 'awk_element_t' is a "flattened" array element. 'awk' produces
+ an array of these inside the 'awk_flat_array_t' (see the next
+ item). Individual elements may be marked for deletion. New
elements must be added individually, one at a time, using the
separate API for that purpose. The fields are as follows:
- `struct awk_element *next;'
+ 'struct awk_element *next;'
This pointer is for the convenience of extension writers. It
allows an extension to create a linked list of new elements
that can then be added to an array in a loop that traverses
the list.
- `enum { ... } flags;'
+ 'enum { ... } flags;'
A set of flag values that convey information between the
- extension and `gawk'. Currently there is only one:
- `AWK_ELEMENT_DELETE'. Setting it causes `gawk' to delete the
+ extension and 'gawk'. Currently there is only one:
+ 'AWK_ELEMENT_DELETE'. Setting it causes 'gawk' to delete the
element from the original array upon release of the flattened
array.
- `index'
- `value'
+ 'index'
+ 'value'
The index and value of the element, respectively. _All_
- memory pointed to by `index' and `value' belongs to `gawk'.
-
-`typedef struct awk_flat_array {'
-` awk_const void *awk_const opaque1; /* for use by gawk */'
-` awk_const void *awk_const opaque2; /* for use by gawk */'
-` awk_const size_t count; /* how many elements */'
-` awk_element_t elements[1]; /* will be extended */'
-`} awk_flat_array_t;'
- This is a flattened array. When an extension gets one of these
- from `gawk', the `elements' array is of actual size `count'. The
- `opaque1' and `opaque2' pointers are for use by `gawk'; therefore
- they are marked `awk_const' so that the extension cannot modify
+ memory pointed to by 'index' and 'value' belongs to 'gawk'.
+
+'typedef struct awk_flat_array {'
+' awk_const void *awk_const opaque1; /* for use by gawk */'
+' awk_const void *awk_const opaque2; /* for use by gawk */'
+' awk_const size_t count; /* how many elements */'
+' awk_element_t elements[1]; /* will be extended */'
+'} awk_flat_array_t;'
+ This is a flattened array. When an extension gets one of these
+ from 'gawk', the 'elements' array is of actual size 'count'. The
+ 'opaque1' and 'opaque2' pointers are for use by 'gawk'; therefore
+ they are marked 'awk_const' so that the extension cannot modify
them.
---------- Footnotes ----------
- (1) It is also a "cookie," but the `gawk' developers did not wish to
+ (1) It is also a "cookie," but the 'gawk' developers did not wish to
overuse this term.
@@ -24185,75 +24088,74 @@ File: gawk.info, Node: Array Functions, Next:
Flattening Arrays, Prev: Array
The following functions relate to individual array elements:
-`awk_bool_t get_element_count(awk_array_t a_cookie, size_t *count);'
- For the array represented by `a_cookie', place in `*count' the
- number of elements it contains. A subarray counts as a single
+'awk_bool_t get_element_count(awk_array_t a_cookie, size_t *count);'
+ For the array represented by 'a_cookie', place in '*count' the
+ number of elements it contains. A subarray counts as a single
element. Return false if there is an error.
-`awk_bool_t get_array_element(awk_array_t a_cookie,'
-` const awk_value_t *const index,'
-` awk_valtype_t wanted,'
-` awk_value_t *result);'
- For the array represented by `a_cookie', return in `*result' the
- value of the element whose index is `index'. `wanted' specifies
- the type of value you wish to retrieve. Return false if `wanted'
- does not match the actual type or if `index' is not in the array
+'awk_bool_t get_array_element(awk_array_t a_cookie,'
+' const awk_value_t *const index,'
+' awk_valtype_t wanted,'
+' awk_value_t *result);'
+ For the array represented by 'a_cookie', return in '*result' the
+ value of the element whose index is 'index'. 'wanted' specifies
+ the type of value you wish to retrieve. Return false if 'wanted'
+ does not match the actual type or if 'index' is not in the array
(*note Table 16.1: table-value-types-returned.).
- The value for `index' can be numeric, in which case `gawk'
- converts it to a string. Using nonintegral values is possible, but
- requires that you understand how such values are converted to
- strings (*note Conversion::); thus, using integral values is
- safest.
+ The value for 'index' can be numeric, in which case 'gawk' converts
+ it to a string. Using nonintegral values is possible, but requires
+ that you understand how such values are converted to strings (*note
+ Conversion::); thus, using integral values is safest.
- As with _all_ strings passed into `gawk' from an extension, the
- string value of `index' must come from `gawk_malloc()',
- `gawk_calloc()', or `gawk_realloc()', and `gawk' releases the
+ As with _all_ strings passed into 'gawk' from an extension, the
+ string value of 'index' must come from 'gawk_malloc()',
+ 'gawk_calloc()', or 'gawk_realloc()', and 'gawk' releases the
storage.
-`awk_bool_t set_array_element(awk_array_t a_cookie,'
-` const awk_value_t *const index,'
-` const awk_value_t *const value);'
- In the array represented by `a_cookie', create or modify the
- element whose index is given by `index'. The `ARGV' and `ENVIRON'
- arrays may not be changed, although the `PROCINFO' array can be.
+'awk_bool_t set_array_element(awk_array_t a_cookie,'
+' const awk_value_t *const index,'
+' const awk_value_t *const value);'
+ In the array represented by 'a_cookie', create or modify the
+ element whose index is given by 'index'. The 'ARGV' and 'ENVIRON'
+ arrays may not be changed, although the 'PROCINFO' array can be.
-`awk_bool_t set_array_element_by_elem(awk_array_t a_cookie,'
-` awk_element_t element);'
- Like `set_array_element()', but take the `index' and `value' from
- `element'. This is a convenience macro.
+'awk_bool_t set_array_element_by_elem(awk_array_t a_cookie,'
+' awk_element_t element);'
+ Like 'set_array_element()', but take the 'index' and 'value' from
+ 'element'. This is a convenience macro.
-`awk_bool_t del_array_element(awk_array_t a_cookie,'
-` const awk_value_t* const index);'
+'awk_bool_t del_array_element(awk_array_t a_cookie,'
+' const awk_value_t* const index);'
Remove the element with the given index from the array represented
- by `a_cookie'. Return true if the element was removed, or false
- if the element did not exist in the array.
+ by 'a_cookie'. Return true if the element was removed, or false if
+ the element did not exist in the array.
The following functions relate to arrays as a whole:
-`awk_array_t create_array(void);'
+'awk_array_t create_array(void);'
Create a new array to which elements may be added. *Note Creating
Arrays::, for a discussion of how to create a new array and add
elements to it.
-`awk_bool_t clear_array(awk_array_t a_cookie);'
- Clear the array represented by `a_cookie'. Return false if there
+'awk_bool_t clear_array(awk_array_t a_cookie);'
+ Clear the array represented by 'a_cookie'. Return false if there
was some kind of problem, true otherwise. The array remains an
- array, but after calling this function, it has no elements. This
- is equivalent to using the `delete' statement (*note Delete::).
+ array, but after calling this function, it has no elements. This
+ is equivalent to using the 'delete' statement (*note Delete::).
-`awk_bool_t flatten_array(awk_array_t a_cookie, awk_flat_array_t **data);'
- For the array represented by `a_cookie', create an
- `awk_flat_array_t' structure and fill it in. Set the pointer whose
- address is passed as `data' to point to this structure. Return
+'awk_bool_t flatten_array(awk_array_t a_cookie, awk_flat_array_t **data);'
+ For the array represented by 'a_cookie', create an
+ 'awk_flat_array_t' structure and fill it in. Set the pointer whose
+ address is passed as 'data' to point to this structure. Return
true upon success, or false otherwise. *Note Flattening Arrays::,
for a discussion of how to flatten an array and work with it.
-`awk_bool_t release_flattened_array(awk_array_t a_cookie,'
-` awk_flat_array_t *data);'
+'awk_bool_t release_flattened_array(awk_array_t a_cookie,'
+' awk_flat_array_t *data);'
When done with a flattened array, release the storage using this
function. You must pass in both the original array cookie and the
- address of the created `awk_flat_array_t' structure. The function
+ address of the created 'awk_flat_array_t' structure. The function
returns true upon success, false otherwise.
@@ -24264,11 +24166,11 @@ File: gawk.info, Node: Flattening Arrays, Next:
Creating Arrays, Prev: Array
To "flatten" an array is to create a structure that represents the full
array in a fashion that makes it easy for C code to traverse the entire
-array. Some of the code in `extension/testext.c' does this, and also
+array. Some of the code in 'extension/testext.c' does this, and also
serves as a nice example showing how to use the APIs.
- We walk through that part of the code one step at a time. First,
-the `gawk' script that drives the test extension:
+ We walk through that part of the code one step at a time. First, the
+'gawk' script that drives the test extension:
@load "testext"
BEGIN {
@@ -24283,16 +24185,16 @@ the `gawk' script that drives the test extension:
print ""
}
-This code creates an array with `split()' (*note String Functions::)
-and then calls `dump_array_and_delete()'. That function looks up the
-array whose name is passed as the first argument, and deletes the
-element at the index passed in the second argument. The `awk' code
-then prints the return value and checks if the element was indeed
-deleted. Here is the C code that implements `dump_array_and_delete()'.
-It has been edited slightly for presentation.
+This code creates an array with 'split()' (*note String Functions::) and
+then calls 'dump_array_and_delete()'. That function looks up the array
+whose name is passed as the first argument, and deletes the element at
+the index passed in the second argument. The 'awk' code then prints the
+return value and checks if the element was indeed deleted. Here is the
+C code that implements 'dump_array_and_delete()'. It has been edited
+slightly for presentation.
The first part declares variables, sets up the default return value
-in `result', and checks that the function was called with the correct
+in 'result', and checks that the function was called with the correct
number of arguments:
static awk_value_t *
@@ -24313,9 +24215,9 @@ number of arguments:
goto out;
}
- The function then proceeds in steps, as follows. First, retrieve the
+ The function then proceeds in steps, as follows. First, retrieve the
name of the array, passed as the first argument, followed by the array
-itself. If either operation fails, print an error message and return:
+itself. If either operation fails, print an error message and return:
/* get argument named array as flat array and print it */
if (get_argument(0, AWK_STRING, & value)) {
@@ -24334,7 +24236,7 @@ itself. If either operation fails, print an error
message and return:
}
For testing purposes and to make sure that the C code sees the same
-number of elements as the `awk' code, the second step is to get the
+number of elements as the 'awk' code, the second step is to get the
count of elements in the array and print it:
if (! get_element_count(value2.array_cookie, & count)) {
@@ -24346,8 +24248,8 @@ count of elements in the array and print it:
(unsigned long) count);
The third step is to actually flatten the array, and then to
-double-check that the count in the `awk_flat_array_t' is the same as
-the count just retrieved:
+double-check that the count in the 'awk_flat_array_t' is the same as the
+count just retrieved:
if (! flatten_array(value2.array_cookie, & flat_array)) {
printf("dump_array_and_delete: could not flatten array\n");
@@ -24364,7 +24266,7 @@ the count just retrieved:
The fourth step is to retrieve the index of the element to be
deleted, which was passed as the second argument. Remember that
-argument counts passed to `get_argument()' are zero-based, and thus the
+argument counts passed to 'get_argument()' are zero-based, and thus the
second argument is numbered one:
if (! get_argument(1, AWK_STRING, & value3)) {
@@ -24372,11 +24274,11 @@ second argument is numbered one:
goto out;
}
- The fifth step is where the "real work" is done. The function loops
+ The fifth step is where the "real work" is done. The function loops
over every element in the array, printing the index and element values.
-In addition, upon finding the element with the index that is supposed
-to be deleted, the function sets the `AWK_ELEMENT_DELETE' bit in the
-`flags' field of the element. When the array is released, `gawk'
+In addition, upon finding the element with the index that is supposed to
+be deleted, the function sets the 'AWK_ELEMENT_DELETE' bit in the
+'flags' field of the element. When the array is released, 'gawk'
traverses the flattened array, and deletes any elements that have this
flag bit set:
@@ -24396,11 +24298,11 @@ flag bit set:
}
}
- The sixth step is to release the flattened array. This tells `gawk'
+ The sixth step is to release the flattened array. This tells 'gawk'
that the extension is no longer using the array, and that it should
-delete any elements marked for deletion. `gawk' also frees any storage
-that was allocated, so you should not use the pointer (`flat_array' in
-this code) once you have called `release_flattened_array()':
+delete any elements marked for deletion. 'gawk' also frees any storage
+that was allocated, so you should not use the pointer ('flat_array' in
+this code) once you have called 'release_flattened_array()':
if (! release_flattened_array(value2.array_cookie, flat_array)) {
printf("dump_array_and_delete: could not release flattened
array\n");
@@ -24435,30 +24337,30 @@ File: gawk.info, Node: Creating Arrays, Prev:
Flattening Arrays, Up: Array Ma
16.4.11.4 How To Create and Populate Arrays
...........................................
-Besides working with arrays created by `awk' code, you can create
-arrays and populate them as you see fit, and then `awk' code can access
-them and manipulate them.
+Besides working with arrays created by 'awk' code, you can create arrays
+and populate them as you see fit, and then 'awk' code can access them
+and manipulate them.
There are two important points about creating arrays from extension
code:
- * You must install a new array into `gawk''s symbol table
- immediately upon creating it. Once you have done so, you can then
- populate the array.
+ * You must install a new array into 'gawk''s symbol table immediately
+ upon creating it. Once you have done so, you can then populate the
+ array.
Similarly, if installing a new array as a subarray of an existing
array, you must add the new array to its parent before adding any
elements to it.
Thus, the correct way to build an array is to work "top down."
- Create the array, and immediately install it in `gawk''s symbol
- table using `sym_update()', or install it as an element in a
- previously existing array using `set_array_element()'. We show
+ Create the array, and immediately install it in 'gawk''s symbol
+ table using 'sym_update()', or install it as an element in a
+ previously existing array using 'set_array_element()'. We show
example code shortly.
- * Due to `gawk' internals, after using `sym_update()' to install an
- array into `gawk', you have to retrieve the array cookie from the
- value passed in to `sym_update()' before doing anything else with
+ * Due to 'gawk' internals, after using 'sym_update()' to install an
+ array into 'gawk', you have to retrieve the array cookie from the
+ value passed in to 'sym_update()' before doing anything else with
it, like so:
awk_value_t value;
@@ -24474,10 +24376,10 @@ code:
new_array = val.array_cookie; /* YOU MUST DO THIS */
If installing an array as a subarray, you must also retrieve the
- value of the array cookie after the call to `set_element()'.
+ value of the array cookie after the call to 'set_element()'.
The following C code is a simple test extension to create an array
-with two regular elements and with a subarray. The leading `#include'
+with two regular elements and with a subarray. The leading '#include'
directives and boilerplate variable declarations (*note Extension API
Boilerplate::) are omitted for brevity. The first step is to create a
new array and then install it in the symbol table:
@@ -24499,10 +24401,10 @@ new array and then install it in the symbol table:
printf("create_new_array: sym_update(\"new_array\") failed!\n");
a_cookie = value.array_cookie;
-Note how `a_cookie' is reset from the `array_cookie' field in the
-`value' structure.
+Note how 'a_cookie' is reset from the 'array_cookie' field in the
+'value' structure.
- The second step is to install two regular values into `new_array':
+ The second step is to install two regular values into 'new_array':
(void) make_const_string("hello", 5, & index);
(void) make_const_string("world", 5, & value);
@@ -24565,7 +24467,7 @@ array:
-| new_array["hello"] = world
-| new_array["answer"] = 42
-(*Note Finding Extensions::, for more information on the `AWKLIBPATH'
+(*Note Finding Extensions::, for more information on the 'AWKLIBPATH'
environment variable.)
@@ -24576,14 +24478,14 @@ File: gawk.info, Node: Extension API Variables,
Next: Extension API Boilerplat
The API provides two sets of variables. The first provides information
about the version of the API (both with which the extension was
-compiled, and with which `gawk' was compiled). The second provides
-information about how `gawk' was invoked.
+compiled, and with which 'gawk' was compiled). The second provides
+information about how 'gawk' was invoked.
* Menu:
* Extension Versioning:: API Version information.
* Extension API Informational Variables:: Variables providing information about
- `gawk''s invocation.
+ 'gawk''s invocation.
File: gawk.info, Node: Extension Versioning, Next: Extension API
Informational Variables, Up: Extension API Variables
@@ -24594,29 +24496,29 @@ File: gawk.info, Node: Extension Versioning, Next:
Extension API Informational
The API provides both a "major" and a "minor" version number. The API
versions are available at compile time as constants:
-`GAWK_API_MAJOR_VERSION'
+'GAWK_API_MAJOR_VERSION'
The major version of the API
-`GAWK_API_MINOR_VERSION'
+'GAWK_API_MINOR_VERSION'
The minor version of the API
The minor version increases when new functions are added to the API.
-Such new functions are always added to the end of the API `struct'.
+Such new functions are always added to the end of the API 'struct'.
The major version increases (and the minor version is reset to zero)
if any of the data types change size or member order, or if any of the
existing functions change signature.
It could happen that an extension may be compiled against one version
-of the API but loaded by a version of `gawk' using a different version.
-For this reason, the major and minor API versions of the running `gawk'
-are included in the API `struct' as read-only constant integers:
+of the API but loaded by a version of 'gawk' using a different version.
+For this reason, the major and minor API versions of the running 'gawk'
+are included in the API 'struct' as read-only constant integers:
-`api->major_version'
- The major version of the running `gawk'
+'api->major_version'
+ The major version of the running 'gawk'
-`api->minor_version'
- The minor version of the running `gawk'
+'api->minor_version'
+ The minor version of the running 'gawk'
It is up to the extension to decide if there are API
incompatibilities. Typically, a check like this is enough:
@@ -24630,8 +24532,8 @@ incompatibilities. Typically, a check like this is
enough:
exit(1);
}
- Such code is included in the boilerplate `dl_load_func()' macro
-provided in `gawkapi.h' (discussed in *note Extension API
+ Such code is included in the boilerplate 'dl_load_func()' macro
+provided in 'gawkapi.h' (discussed in *note Extension API
Boilerplate::).
@@ -24641,33 +24543,33 @@ File: gawk.info, Node: Extension API Informational
Variables, Prev: Extension
.................................
The API provides access to several variables that describe whether the
-corresponding command-line options were enabled when `gawk' was
-invoked. The variables are:
+corresponding command-line options were enabled when 'gawk' was invoked.
+The variables are:
-`do_debug'
- This variable is true if `gawk' was invoked with `--debug' option.
+'do_debug'
+ This variable is true if 'gawk' was invoked with '--debug' option.
-`do_lint'
- This variable is true if `gawk' was invoked with `--lint' option.
+'do_lint'
+ This variable is true if 'gawk' was invoked with '--lint' option.
-`do_mpfr'
- This variable is true if `gawk' was invoked with `--bignum' option.
+'do_mpfr'
+ This variable is true if 'gawk' was invoked with '--bignum' option.
-`do_profile'
- This variable is true if `gawk' was invoked with `--profile'
+'do_profile'
+ This variable is true if 'gawk' was invoked with '--profile'
option.
-`do_sandbox'
- This variable is true if `gawk' was invoked with `--sandbox'
+'do_sandbox'
+ This variable is true if 'gawk' was invoked with '--sandbox'
option.
-`do_traditional'
- This variable is true if `gawk' was invoked with `--traditional'
+'do_traditional'
+ This variable is true if 'gawk' was invoked with '--traditional'
option.
- The value of `do_lint' can change if `awk' code modifies the `LINT'
-predefined variable (*note Built-in Variables::). The others should
-not change during execution.
+ The value of 'do_lint' can change if 'awk' code modifies the 'LINT'
+predefined variable (*note Built-in Variables::). The others should not
+change during execution.
File: gawk.info, Node: Extension API Boilerplate, Prev: Extension API
Variables, Up: Extension API Description
@@ -24676,11 +24578,11 @@ File: gawk.info, Node: Extension API Boilerplate,
Prev: Extension API Variable
------------------------
As mentioned earlier (*note Extension Mechanism Outline::), the function
-definitions as presented are really macros. To use these macros, your
+definitions as presented are really macros. To use these macros, your
extension must provide a small amount of boilerplate code (variables and
-functions) toward the top of your source file, using predefined names
-as described here. The boilerplate needed is also provided in comments
-in the `gawkapi.h' header file:
+functions) toward the top of your source file, using predefined names as
+described here. The boilerplate needed is also provided in comments in
+the 'gawkapi.h' header file:
/* Boilerplate code: */
int plugin_is_GPL_compatible;
@@ -24712,76 +24614,75 @@ in the `gawkapi.h' header file:
These variables and functions are as follows:
-`int plugin_is_GPL_compatible;'
+'int plugin_is_GPL_compatible;'
This asserts that the extension is compatible with the GNU GPL
- (*note Copying::). If your extension does not have this, `gawk'
+ (*note Copying::). If your extension does not have this, 'gawk'
will not load it (*note Plugin License::).
-`static gawk_api_t *const api;'
- This global `static' variable should be set to point to the
- `gawk_api_t' pointer that `gawk' passes to your `dl_load()'
+'static gawk_api_t *const api;'
+ This global 'static' variable should be set to point to the
+ 'gawk_api_t' pointer that 'gawk' passes to your 'dl_load()'
function. This variable is used by all of the macros.
-`static awk_ext_id_t ext_id;'
- This global static variable should be set to the `awk_ext_id_t'
- value that `gawk' passes to your `dl_load()' function. This
+'static awk_ext_id_t ext_id;'
+ This global static variable should be set to the 'awk_ext_id_t'
+ value that 'gawk' passes to your 'dl_load()' function. This
variable is used by all of the macros.
-`static const char *ext_version = NULL; /* or ... = "some string" */'
- This global `static' variable should be set either to `NULL', or
- to point to a string giving the name and version of your extension.
+'static const char *ext_version = NULL; /* or ... = "some string" */'
+ This global 'static' variable should be set either to 'NULL', or to
+ point to a string giving the name and version of your extension.
-`static awk_ext_func_t func_table[] = { ... };'
- This is an array of one or more `awk_ext_func_t' structures, as
+'static awk_ext_func_t func_table[] = { ... };'
+ This is an array of one or more 'awk_ext_func_t' structures, as
described earlier (*note Extension Functions::). It can then be
- looped over for multiple calls to `add_ext_func()'.
+ looped over for multiple calls to 'add_ext_func()'.
-`static awk_bool_t (*init_func)(void) = NULL;'
-` OR'
-`static awk_bool_t init_my_extension(void) { ... }'
-`static awk_bool_t (*init_func)(void) = init_my_extension;'
+'static awk_bool_t (*init_func)(void) = NULL;'
+' OR'
+'static awk_bool_t init_my_extension(void) { ... }'
+'static awk_bool_t (*init_func)(void) = init_my_extension;'
If you need to do some initialization work, you should define a
function that does it (creates variables, opens files, etc.) and
- then define the `init_func' pointer to point to your function.
- The function should return `awk_false' upon failure, or `awk_true'
- if everything goes well.
+ then define the 'init_func' pointer to point to your function. The
+ function should return 'awk_false' upon failure, or 'awk_true' if
+ everything goes well.
If you don't need to do any initialization, define the pointer and
- initialize it to `NULL'.
+ initialize it to 'NULL'.
-`dl_load_func(func_table, some_name, "name_space_in_quotes")'
- This macro expands to a `dl_load()' function that performs all the
+'dl_load_func(func_table, some_name, "name_space_in_quotes")'
+ This macro expands to a 'dl_load()' function that performs all the
necessary initializations.
- The point of all the variables and arrays is to let the `dl_load()'
-function (from the `dl_load_func()' macro) do all the standard work. It
+ The point of all the variables and arrays is to let the 'dl_load()'
+function (from the 'dl_load_func()' macro) do all the standard work. It
does the following:
- 1. Check the API versions. If the extension major version does not
- match `gawk''s, or if the extension minor version is greater than
- `gawk''s, it prints a fatal error message and exits.
+ 1. Check the API versions. If the extension major version does not
+ match 'gawk''s, or if the extension minor version is greater than
+ 'gawk''s, it prints a fatal error message and exits.
- 2. Load the functions defined in `func_table'. If any of them fails
+ 2. Load the functions defined in 'func_table'. If any of them fails
to load, it prints a warning message but continues on.
- 3. If the `init_func' pointer is not `NULL', call the function it
- points to. If it returns `awk_false', print a warning message.
+ 3. If the 'init_func' pointer is not 'NULL', call the function it
+ points to. If it returns 'awk_false', print a warning message.
- 4. If `ext_version' is not `NULL', register the version string with
- `gawk'.
+ 4. If 'ext_version' is not 'NULL', register the version string with
+ 'gawk'.
File: gawk.info, Node: Finding Extensions, Next: Extension Example, Prev:
Extension API Description, Up: Dynamic Extensions
-16.5 How `gawk' Finds Extensions
+16.5 How 'gawk' Finds Extensions
================================
-Compiled extensions have to be installed in a directory where `gawk'
-can find them. If `gawk' is configured and built in the default
-fashion, the directory in which to find extensions is
-`/usr/local/lib/gawk'. You can also specify a search path with a list
-of directories to search for compiled extensions. *Note AWKLIBPATH
-Variable::, for more information.
+Compiled extensions have to be installed in a directory where 'gawk' can
+find them. If 'gawk' is configured and built in the default fashion,
+the directory in which to find extensions is '/usr/local/lib/gawk'. You
+can also specify a search path with a list of directories to search for
+compiled extensions. *Note AWKLIBPATH Variable::, for more information.
File: gawk.info, Node: Extension Example, Next: Extension Samples, Prev:
Finding Extensions, Up: Dynamic Extensions
@@ -24789,13 +24690,14 @@ File: gawk.info, Node: Extension Example, Next:
Extension Samples, Prev: Find
16.6 Example: Some File Functions
=================================
- No matter where you go, there you are. -- Buckaroo Banzai
+ No matter where you go, there you are.
+ -- _Buckaroo Banzai_
- Two useful functions that are not in `awk' are `chdir()' (so that an
-`awk' program can change its directory) and `stat()' (so that an `awk'
+ Two useful functions that are not in 'awk' are 'chdir()' (so that an
+'awk' program can change its directory) and 'stat()' (so that an 'awk'
program can gather information about a file). In order to illustrate
-the API in action, this minor node implements these functions for
-`gawk' in an extension.
+the API in action, this minor node implements these functions for 'gawk'
+in an extension.
* Menu:
@@ -24806,12 +24708,12 @@ the API in action, this minor node implements these
functions for
File: gawk.info, Node: Internal File Description, Next: Internal File Ops,
Up: Extension Example
-16.6.1 Using `chdir()' and `stat()'
+16.6.1 Using 'chdir()' and 'stat()'
-----------------------------------
-This minor node shows how to use the new functions at the `awk' level
-once they've been integrated into the running `gawk' interpreter.
-Using `chdir()' is very straightforward. It takes one argument, the new
+This minor node shows how to use the new functions at the 'awk' level
+once they've been integrated into the running 'gawk' interpreter. Using
+'chdir()' is very straightforward. It takes one argument, the new
directory to change to:
@load "filefuncs"
@@ -24824,12 +24726,12 @@ directory to change to:
}
...
- The return value is negative if the `chdir()' failed, and `ERRNO'
+ The return value is negative if the 'chdir()' failed, and 'ERRNO'
(*note Built-in Variables::) is set to a string indicating the error.
- Using `stat()' is a bit more complicated. The C `stat()' function
+ Using 'stat()' is a bit more complicated. The C 'stat()' function
fills in a structure that has a fair amount of information. The right
-way to model this in `awk' is to fill in an associative array with the
+way to model this in 'awk' is to fill in an associative array with the
appropriate information:
file = "/home/arnold/.profile"
@@ -24841,94 +24743,94 @@ appropriate information:
}
printf("size of %s is %d bytes\n", file, fdata["size"])
- The `stat()' function always clears the data array, even if the
-`stat()' fails. It fills in the following elements:
+ The 'stat()' function always clears the data array, even if the
+'stat()' fails. It fills in the following elements:
-`"name"'
- The name of the file that was `stat()'ed.
+'"name"'
+ The name of the file that was 'stat()'ed.
-`"dev"'
-`"ino"'
+'"dev"'
+'"ino"'
The file's device and inode numbers, respectively.
-`"mode"'
- The file's mode, as a numeric value. This includes both the file's
+'"mode"'
+ The file's mode, as a numeric value. This includes both the file's
type and its permissions.
-`"nlink"'
+'"nlink"'
The number of hard links (directory entries) the file has.
-`"uid"'
-`"gid"'
+'"uid"'
+'"gid"'
The numeric user and group ID numbers of the file's owner.
-`"size"'
+'"size"'
The size in bytes of the file.
-`"blocks"'
- The number of disk blocks the file actually occupies. This may not
+'"blocks"'
+ The number of disk blocks the file actually occupies. This may not
be a function of the file's size if the file has holes.
-`"atime"'
-`"mtime"'
-`"ctime"'
+'"atime"'
+'"mtime"'
+'"ctime"'
The file's last access, modification, and inode update times,
respectively. These are numeric timestamps, suitable for
- formatting with `strftime()' (*note Time Functions::).
+ formatting with 'strftime()' (*note Time Functions::).
-`"pmode"'
+'"pmode"'
The file's "printable mode." This is a string representation of
- the file's type and permissions, such as is produced by `ls
- -l'--for example, `"drwxr-xr-x"'.
+ the file's type and permissions, such as is produced by 'ls
+ -l'--for example, '"drwxr-xr-x"'.
-`"type"'
- A printable string representation of the file's type. The value
- is one of the following:
+'"type"'
+ A printable string representation of the file's type. The value is
+ one of the following:
- `"blockdev"'
- `"chardev"'
+ '"blockdev"'
+ '"chardev"'
The file is a block or character device ("special file").
- `"directory"'
+ '"directory"'
The file is a directory.
- `"fifo"'
+ '"fifo"'
The file is a named pipe (also known as a FIFO).
- `"file"'
+ '"file"'
The file is just a regular file.
- `"socket"'
- The file is an `AF_UNIX' ("Unix domain") socket in the
+ '"socket"'
+ The file is an 'AF_UNIX' ("Unix domain") socket in the
filesystem.
- `"symlink"'
+ '"symlink"'
The file is a symbolic link.
-`"devbsize"'
- The size of a block for the element indexed by `"blocks"'. This
- information is derived from either the `DEV_BSIZE' constant
- defined in `<sys/param.h>' on most systems, or the `S_BLKSIZE'
- constant in `<sys/stat.h>' on BSD systems. For some other
- systems, "a priori" knowledge is used to provide a value. Where no
- value can be determined, it defaults to 512.
+'"devbsize"'
+ The size of a block for the element indexed by '"blocks"'. This
+ information is derived from either the 'DEV_BSIZE' constant defined
+ in '<sys/param.h>' on most systems, or the 'S_BLKSIZE' constant in
+ '<sys/stat.h>' on BSD systems. For some other systems, "a priori"
+ knowledge is used to provide a value. Where no value can be
+ determined, it defaults to 512.
Several additional elements may be present, depending upon the
operating system and the type of the file. You can test for them in
-your `awk' program by using the `in' operator (*note Reference to
+your 'awk' program by using the 'in' operator (*note Reference to
Elements::):
-`"blksize"'
- The preferred block size for I/O to the file. This field is not
- present on all POSIX-like systems in the C `stat' structure.
+'"blksize"'
+ The preferred block size for I/O to the file. This field is not
+ present on all POSIX-like systems in the C 'stat' structure.
-`"linkval"'
+'"linkval"'
If the file is a symbolic link, this element is the name of the
file the link points to (i.e., the value of the link).
-`"rdev"'
-`"major"'
-`"minor"'
+'"rdev"'
+'"major"'
+'"minor"'
If the file is a block or character device file, then these values
represent the numeric device number and the major and minor
components of that number, respectively.
@@ -24936,13 +24838,13 @@ Elements::):
File: gawk.info, Node: Internal File Ops, Next: Using Internal File Ops,
Prev: Internal File Description, Up: Extension Example
-16.6.2 C Code for `chdir()' and `stat()'
+16.6.2 C Code for 'chdir()' and 'stat()'
----------------------------------------
Here is the C code for these extensions.(1)
The file includes a number of standard header files, and then
-includes the `gawkapi.h' header file, which provides the API
+includes the 'gawkapi.h' header file, which provides the API
definitions. Those are followed by the necessary variable declarations
to make use of the API macros and boilerplate code (*note Extension API
Boilerplate::):
@@ -24978,11 +24880,11 @@ Boilerplate::):
int plugin_is_GPL_compatible;
- By convention, for an `awk' function `foo()', the C function that
-implements it is called `do_foo()'. The function should have two
-arguments. The first is an `int', usually called `nargs', that
+ By convention, for an 'awk' function 'foo()', the C function that
+implements it is called 'do_foo()'. The function should have two
+arguments. The first is an 'int', usually called 'nargs', that
represents the number of actual arguments for the function. The second
-is a pointer to an `awk_value_t' structure, usually named `result':
+is a pointer to an 'awk_value_t' structure, usually named 'result':
/* do_chdir --- provide dynamically loaded chdir() function for gawk */
@@ -24999,12 +24901,12 @@ is a pointer to an `awk_value_t' structure, usually
named `result':
_("chdir: called with incorrect number of arguments, "
"expecting 1"));
- The `newdir' variable represents the new directory to change to,
-which is retrieved with `get_argument()'. Note that the first argument
+ The 'newdir' variable represents the new directory to change to,
+which is retrieved with 'get_argument()'. Note that the first argument
is numbered zero.
If the argument is retrieved successfully, the function calls the
-`chdir()' system call. If the `chdir()' fails, `ERRNO' is updated:
+'chdir()' system call. If the 'chdir()' fails, 'ERRNO' is updated:
if (get_argument(0, AWK_STRING, & newdir)) {
ret = chdir(newdir.str_value.str);
@@ -25012,14 +24914,14 @@ is numbered zero.
update_ERRNO_int(errno);
}
- Finally, the function returns the return value to the `awk' level:
+ Finally, the function returns the return value to the 'awk' level:
return make_number(ret, result);
}
- The `stat()' extension is more involved. First comes a function
-that turns a numeric mode into a printable representation (e.g., octal
-`0644' becomes `-rw-r--r--'). This is omitted here for brevity:
+ The 'stat()' extension is more involved. First comes a function that
+turns a numeric mode into a printable representation (e.g., octal '0644'
+becomes '-rw-r--r--'). This is omitted here for brevity:
/* format_mode --- turn a stat mode field into something readable */
@@ -25042,7 +24944,7 @@ omitted here for brevity:
}
Two helper functions simplify entering values in the array that will
-contain the result of the `stat()':
+contain the result of the 'stat()':
/* array_set --- set an array element */
@@ -25068,9 +24970,9 @@ contain the result of the `stat()':
}
The following function does most of the work to fill in the
-`awk_array_t' result array with values obtained from a valid `struct
-stat'. This work is done in a separate function to support the `stat()'
-function for `gawk' and also to support the `fts()' extension, which is
+'awk_array_t' result array with values obtained from a valid 'struct
+stat'. This work is done in a separate function to support the 'stat()'
+function for 'gawk' and also to support the 'fts()' extension, which is
included in the same file but whose code is not shown here (*note
Extension Sample File Functions::).
@@ -25109,7 +25011,7 @@ table to map file types to strings:
int j, k;
The destination array is cleared, and then code fills in various
-elements based on values in the `struct stat':
+elements based on values in the 'struct stat':
/* empty out the array */
clear_array(array);
@@ -25139,7 +25041,7 @@ elements based on values in the `struct stat':
The latter part of the function makes selective additions to the
destination array, depending upon the availability of certain members
-and/or the type of the file. It then returns zero, for success:
+and/or the type of the file. It then returns zero, for success:
#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
array_set_numeric(array, "blksize", sbuf->st_blksize);
@@ -25177,15 +25079,15 @@ and/or the type of the file. It then returns zero,
for success:
return 0;
}
- The third argument to `stat()' was not discussed previously. This
-argument is optional. If present, it causes `do_stat()' to use the
-`stat()' system call instead of the `lstat()' system call. This is
-done by using a function pointer: `statfunc'. `statfunc' is
-initialized to point to `lstat()' (instead of `stat()') to get the file
-information, in case the file is a symbolic link. However, if the third
-argument is included, `statfunc' is set to point to `stat()', instead.
+ The third argument to 'stat()' was not discussed previously. This
+argument is optional. If present, it causes 'do_stat()' to use the
+'stat()' system call instead of the 'lstat()' system call. This is done
+by using a function pointer: 'statfunc'. 'statfunc' is initialized to
+point to 'lstat()' (instead of 'stat()') to get the file information, in
+case the file is a symbolic link. However, if the third argument is
+included, 'statfunc' is set to point to 'stat()', instead.
- Here is the `do_stat()' function, which starts with variable
+ Here is the 'do_stat()' function, which starts with variable
declarations and argument checking:
/* do_stat --- provide a stat() function for gawk */
@@ -25210,9 +25112,9 @@ declarations and argument checking:
return make_number(-1, result);
}
- Then comes the actual work. First, the function gets the arguments.
+ Then comes the actual work. First, the function gets the arguments.
Next, it gets the information for the file. If the called function
-(`lstat()' or `stat()') returns an error, the code sets `ERRNO' and
+('lstat()' or 'stat()') returns an error, the code sets 'ERRNO' and
returns:
/* file is first arg, array to hold results is second */
@@ -25239,8 +25141,8 @@ returns:
return make_number(ret, result);
}
- The tedious work is done by `fill_stat_array()', shown earlier.
-When done, the function returns the result from `fill_stat_array()':
+ The tedious work is done by 'fill_stat_array()', shown earlier. When
+done, the function returns the result from 'fill_stat_array()':
ret = fill_stat_array(name, array, & sbuf);
@@ -25248,10 +25150,10 @@ When done, the function returns the result from
`fill_stat_array()':
}
Finally, it's necessary to provide the "glue" that loads the new
-function(s) into `gawk'.
+function(s) into 'gawk'.
- The `filefuncs' extension also provides an `fts()' function, which
-we omit here (*note Extension Sample File Functions::). For its sake,
+ The 'filefuncs' extension also provides an 'fts()' function, which we
+omit here (*note Extension Sample File Functions::). For its sake,
there is an initialization function:
/* init_filefuncs --- initialization routine */
@@ -25262,8 +25164,8 @@ there is an initialization function:
...
}
- We are almost done. We need an array of `awk_ext_func_t' structures
-for loading each function into `gawk':
+ We are almost done. We need an array of 'awk_ext_func_t' structures
+for loading each function into 'gawk':
static awk_ext_func_t func_table[] = {
{ "chdir", do_chdir, 1 },
@@ -25273,9 +25175,9 @@ for loading each function into `gawk':
#endif
};
- Each extension must have a routine named `dl_load()' to load
+ Each extension must have a routine named 'dl_load()' to load
everything that needs to be loaded. It is simplest to use the
-`dl_load_func()' macro in `gawkapi.h':
+'dl_load_func()' macro in 'gawkapi.h':
/* define the dl_load() function using the boilerplate macro */
@@ -25286,7 +25188,7 @@ everything that needs to be loaded. It is simplest to
use the
---------- Footnotes ----------
(1) This version is edited slightly for presentation. See
-`extension/filefuncs.c' in the `gawk' distribution for the complete
+'extension/filefuncs.c' in the 'gawk' distribution for the complete
version.
@@ -25296,15 +25198,15 @@ File: gawk.info, Node: Using Internal File Ops,
Prev: Internal File Ops, Up:
---------------------------------
Now that the code is written, it must be possible to add it at runtime
-to the running `gawk' interpreter. First, the code must be compiled.
-Assuming that the functions are in a file named `filefuncs.c', and IDIR
-is the location of the `gawkapi.h' header file, the following steps(1)
+to the running 'gawk' interpreter. First, the code must be compiled.
+Assuming that the functions are in a file named 'filefuncs.c', and IDIR
+is the location of the 'gawkapi.h' header file, the following steps(1)
create a GNU/Linux shared library:
$ gcc -fPIC -shared -DHAVE_CONFIG_H -c -O -g -IIDIR filefuncs.c
$ gcc -o filefuncs.so -shared filefuncs.o
- Once the library exists, it is loaded by using the address@hidden' keyword:
+ Once the library exists, it is loaded by using the '@load' keyword:
# file testff.awk
@load "filefuncs"
@@ -25333,7 +25235,7 @@ create a GNU/Linux shared library:
print "JUNK modified:", strftime("%m %d %Y %H:%M:%S", data["mtime"])
}
- The `AWKLIBPATH' environment variable tells `gawk' where to find
+ The 'AWKLIBPATH' environment variable tells 'gawk' where to find
extensions (*note Finding Extensions::). We set it to the current
directory and run the program:
@@ -25366,38 +25268,38 @@ directory and run the program:
---------- Footnotes ----------
(1) In practice, you would probably want to use the GNU Autotools
-(Automake, Autoconf, Libtool, and `gettext') to configure and build
-your libraries. Instructions for doing so are beyond the scope of this
-Info file. *Note gawkextlib::, for Internet links to the tools.
+(Automake, Autoconf, Libtool, and 'gettext') to configure and build your
+libraries. Instructions for doing so are beyond the scope of this Info
+file. *Note gawkextlib::, for Internet links to the tools.
File: gawk.info, Node: Extension Samples, Next: gawkextlib, Prev: Extension
Example, Up: Dynamic Extensions
-16.7 The Sample Extensions in the `gawk' Distribution
+16.7 The Sample Extensions in the 'gawk' Distribution
=====================================================
This minor node provides a brief overview of the sample extensions that
-come in the `gawk' distribution. Some of them are intended for
-production use (e.g., the `filefuncs', `readdir', and `inplace'
+come in the 'gawk' distribution. Some of them are intended for
+production use (e.g., the 'filefuncs', 'readdir', and 'inplace'
extensions). Others mainly provide example code that shows how to use
the extension API.
* Menu:
* Extension Sample File Functions:: The file functions sample.
-* Extension Sample Fnmatch:: An interface to `fnmatch()'.
-* Extension Sample Fork:: An interface to `fork()' and other
+* Extension Sample Fnmatch:: An interface to 'fnmatch()'.
+* Extension Sample Fork:: An interface to 'fork()' and other
process functions.
* Extension Sample Inplace:: Enabling in-place file editing.
* Extension Sample Ord:: Character to value to character
conversions.
-* Extension Sample Readdir:: An interface to `readdir()'.
+* Extension Sample Readdir:: An interface to 'readdir()'.
* Extension Sample Revout:: Reversing output sample output wrapper.
* Extension Sample Rev2way:: Reversing data sample two-way processor.
* Extension Sample Read write array:: Serializing an array to a file.
* Extension Sample Readfile:: Reading an entire file into a string.
-* Extension Sample Time:: An interface to `gettimeofday()'
- and `sleep()'.
+* Extension Sample Time:: An interface to 'gettimeofday()'
+ and 'sleep()'.
* Extension Sample API Tests:: Tests for the API.
@@ -25406,69 +25308,68 @@ File: gawk.info, Node: Extension Sample File
Functions, Next: Extension Sample
16.7.1 File-Related Functions
-----------------------------
-The `filefuncs' extension provides three different functions, as
+The 'filefuncs' extension provides three different functions, as
follows. The usage is:
address@hidden "filefuncs"'
+'@load "filefuncs"'
This is how you load the extension.
-`result = chdir("/some/directory")'
- The `chdir()' function is a direct hook to the `chdir()' system
- call to change the current directory. It returns zero upon
- success or a value less than zero upon error. In the latter case,
- it updates `ERRNO'.
+'result = chdir("/some/directory")'
+ The 'chdir()' function is a direct hook to the 'chdir()' system
+ call to change the current directory. It returns zero upon success
+ or a value less than zero upon error. In the latter case, it
+ updates 'ERRNO'.
-`result = stat("/some/path", statdata' [`, follow']`)'
- The `stat()' function provides a hook into the `stat()' system
+'result = stat("/some/path", statdata' [', follow']')'
+ The 'stat()' function provides a hook into the 'stat()' system
call. It returns zero upon success or a value less than zero upon
- error. In the latter case, it updates `ERRNO'.
+ error. In the latter case, it updates 'ERRNO'.
- By default, it uses the `lstat()' system call. However, if passed
- a third argument, it uses `stat()' instead.
+ By default, it uses the 'lstat()' system call. However, if passed
+ a third argument, it uses 'stat()' instead.
- In all cases, it clears the `statdata' array. When the call is
- successful, `stat()' fills the `statdata' array with information
+ In all cases, it clears the 'statdata' array. When the call is
+ successful, 'stat()' fills the 'statdata' array with information
retrieved from the filesystem, as follows:
- Subscript Field in `struct stat' File type
- ------------------------------------------------------------
- `"name"' The file name All
- `"dev"' `st_dev' All
- `"ino"' `st_ino' All
- `"mode"' `st_mode' All
- `"nlink"' `st_nlink' All
- `"uid"' `st_uid' All
- `"gid"' `st_gid' All
- `"size"' `st_size' All
- `"atime"' `st_atime' All
- `"mtime"' `st_mtime' All
- `"ctime"' `st_ctime' All
- `"rdev"' `st_rdev' Device files
- `"major"' `st_major' Device files
- `"minor"' `st_minor' Device files
- `"blksize"'`st_blksize' All
- `"pmode"' A human-readable version of the All
- mode value, like that printed by
- `ls' (for example,
- `"-rwxr-xr-x"')
- `"linkval"'The value of the symbolic link Symbolic
- links
- `"type"' The type of the file as a All
- string--one of `"file"',
- `"blockdev"', `"chardev"',
- `"directory"', `"socket"',
- `"fifo"', `"symlink"', `"door"',
- or `"unknown"' (not all systems
- support all file types)
-
-`flags = or(FTS_PHYSICAL, ...)'
-`result = fts(pathlist, flags, filedata)'
- Walk the file trees provided in `pathlist' and fill in the
- `filedata' array, as described next. `flags' is the bitwise OR of
- several predefined values, also described in a moment. Return
- zero if there were no errors, otherwise return -1.
-
- The `fts()' function provides a hook to the C library `fts()'
+ Subscript Field in 'struct stat' File type
+ ----------------------------------------------------------------
+ '"name"' The file name All
+ '"dev"' 'st_dev' All
+ '"ino"' 'st_ino' All
+ '"mode"' 'st_mode' All
+ '"nlink"' 'st_nlink' All
+ '"uid"' 'st_uid' All
+ '"gid"' 'st_gid' All
+ '"size"' 'st_size' All
+ '"atime"' 'st_atime' All
+ '"mtime"' 'st_mtime' All
+ '"ctime"' 'st_ctime' All
+ '"rdev"' 'st_rdev' Device files
+ '"major"' 'st_major' Device files
+ '"minor"' 'st_minor' Device files
+ '"blksize"' 'st_blksize' All
+ '"pmode"' A human-readable version of the All
+ mode value, like that printed by
+ 'ls' (for example, '"-rwxr-xr-x"')
+ '"linkval"' The value of the symbolic link Symbolic
+ links
+ '"type"' The type of the file as a All
+ string--one of '"file"',
+ '"blockdev"', '"chardev"',
+ '"directory"', '"socket"',
+ '"fifo"', '"symlink"', '"door"',
+ or '"unknown"' (not all systems
+ support all file types)
+
+'flags = or(FTS_PHYSICAL, ...)'
+'result = fts(pathlist, flags, filedata)'
+ Walk the file trees provided in 'pathlist' and fill in the
+ 'filedata' array, as described next. 'flags' is the bitwise OR of
+ several predefined values, also described in a moment. Return zero
+ if there were no errors, otherwise return -1.
+
+ The 'fts()' function provides a hook to the C library 'fts()'
routines for traversing file hierarchies. Instead of returning data
about one file at a time in a stream, it fills in a multidimensional
array with data about each file and directory encountered in the
@@ -25476,145 +25377,143 @@ requested hierarchies.
The arguments are as follows:
-`pathlist'
+'pathlist'
An array of file names. The element values are used; the index
values are ignored.
-`flags'
+'flags'
This should be the bitwise OR of one or more of the following
- predefined constant flag values. At least one of `FTS_LOGICAL' or
- `FTS_PHYSICAL' must be provided; otherwise `fts()' returns an
- error value and sets `ERRNO'. The flags are:
+ predefined constant flag values. At least one of 'FTS_LOGICAL' or
+ 'FTS_PHYSICAL' must be provided; otherwise 'fts()' returns an error
+ value and sets 'ERRNO'. The flags are:
- `FTS_LOGICAL'
+ 'FTS_LOGICAL'
Do a "logical" file traversal, where the information returned
for a symbolic link refers to the linked-to file, and not to
the symbolic link itself. This flag is mutually exclusive
- with `FTS_PHYSICAL'.
+ with 'FTS_PHYSICAL'.
- `FTS_PHYSICAL'
- Do a "physical" file traversal, where the information
- returned for a symbolic link refers to the symbolic link
- itself. This flag is mutually exclusive with `FTS_LOGICAL'.
+ 'FTS_PHYSICAL'
+ Do a "physical" file traversal, where the information returned
+ for a symbolic link refers to the symbolic link itself. This
+ flag is mutually exclusive with 'FTS_LOGICAL'.
- `FTS_NOCHDIR'
- As a performance optimization, the C library `fts()' routines
- change directory as they traverse a file hierarchy. This
- flag disables that optimization.
+ 'FTS_NOCHDIR'
+ As a performance optimization, the C library 'fts()' routines
+ change directory as they traverse a file hierarchy. This flag
+ disables that optimization.
- `FTS_COMFOLLOW'
- Immediately follow a symbolic link named in `pathlist',
- whether or not `FTS_LOGICAL' is set.
+ 'FTS_COMFOLLOW'
+ Immediately follow a symbolic link named in 'pathlist',
+ whether or not 'FTS_LOGICAL' is set.
- `FTS_SEEDOT'
- By default, the C library `fts()' routines do not return
- entries for `.' (dot) and `..' (dot-dot). This option causes
+ 'FTS_SEEDOT'
+ By default, the C library 'fts()' routines do not return
+ entries for '.' (dot) and '..' (dot-dot). This option causes
entries for dot-dot to also be included. (The extension
always includes an entry for dot; more on this in a moment.)
- `FTS_XDEV'
+ 'FTS_XDEV'
During a traversal, do not cross onto a different mounted
filesystem.
-`filedata'
- The `filedata' array holds the results. `fts()' first clears it.
- Then it creates an element in `filedata' for every element in
- `pathlist'. The index is the name of the directory or file given
- in `pathlist'. The element for this index is itself an array.
+'filedata'
+ The 'filedata' array holds the results. 'fts()' first clears it.
+ Then it creates an element in 'filedata' for every element in
+ 'pathlist'. The index is the name of the directory or file given
+ in 'pathlist'. The element for this index is itself an array.
There are two cases:
- _The path is a file_
+ _The path is a file_
In this case, the array contains two or three elements:
- `"path"'
- The full path to this file, starting from the "root"
- that was given in the `pathlist' array.
+ '"path"'
+ The full path to this file, starting from the "root" that
+ was given in the 'pathlist' array.
- `"stat"'
+ '"stat"'
This element is itself an array, containing the same
- information as provided by the `stat()' function
- described earlier for its `statdata' argument. The
- element may not be present if the `stat()' system call
+ information as provided by the 'stat()' function
+ described earlier for its 'statdata' argument. The
+ element may not be present if the 'stat()' system call
for the file failed.
- `"error"'
+ '"error"'
If some kind of error was encountered, the array will
- also contain an element named `"error"', which is a
+ also contain an element named '"error"', which is a
string describing the error.
- _The path is a directory_
- In this case, the array contains one element for each entry
- in the directory. If an entry is a file, that element is the
+ _The path is a directory_
+ In this case, the array contains one element for each entry in
+ the directory. If an entry is a file, that element is the
same as for files, just described. If the entry is a
directory, that element is (recursively) an array describing
- the subdirectory. If `FTS_SEEDOT' was provided in the flags,
- then there will also be an element named `".."'. This
- element will be an array containing the data as provided by
- `stat()'.
+ the subdirectory. If 'FTS_SEEDOT' was provided in the flags,
+ then there will also be an element named '".."'. This element
+ will be an array containing the data as provided by 'stat()'.
- In addition, there will be an element whose index is `"."'.
+ In addition, there will be an element whose index is '"."'.
This element is an array containing the same two or three
- elements as for a file: `"path"', `"stat"', and `"error"'.
+ elements as for a file: '"path"', '"stat"', and '"error"'.
- The `fts()' function returns zero if there were no errors.
+ The 'fts()' function returns zero if there were no errors.
Otherwise, it returns -1.
- NOTE: The `fts()' extension does not exactly mimic the interface
- of the C library `fts()' routines, choosing instead to provide an
+ NOTE: The 'fts()' extension does not exactly mimic the interface of
+ the C library 'fts()' routines, choosing instead to provide an
interface that is based on associative arrays, which is more
- comfortable to use from an `awk' program. This includes the lack
- of a comparison function, because `gawk' already provides powerful
- array sorting facilities. Although an `fts_read()'-like interface
+ comfortable to use from an 'awk' program. This includes the lack
+ of a comparison function, because 'gawk' already provides powerful
+ array sorting facilities. Although an 'fts_read()'-like interface
could have been provided, this felt less natural than simply
creating a multidimensional array to represent the file hierarchy
and its information.
- See `test/fts.awk' in the `gawk' distribution for an example use of
-the `fts()' extension function.
+ See 'test/fts.awk' in the 'gawk' distribution for an example use of
+the 'fts()' extension function.
File: gawk.info, Node: Extension Sample Fnmatch, Next: Extension Sample
Fork, Prev: Extension Sample File Functions, Up: Extension Samples
-16.7.2 Interface to `fnmatch()'
+16.7.2 Interface to 'fnmatch()'
-------------------------------
-This extension provides an interface to the C library `fnmatch()'
+This extension provides an interface to the C library 'fnmatch()'
function. The usage is:
address@hidden "fnmatch"'
+'@load "fnmatch"'
This is how you load the extension.
-`result = fnmatch(pattern, string, flags)'
- The return value is zero on success, `FNM_NOMATCH' if the string
- did not match the pattern, or a different nonzero value if an
- error occurred.
+'result = fnmatch(pattern, string, flags)'
+ The return value is zero on success, 'FNM_NOMATCH' if the string
+ did not match the pattern, or a different nonzero value if an error
+ occurred.
- In addition to the `fnmatch()' function, the `fnmatch' extension
-adds one constant (`FNM_NOMATCH'), and an array of flag values named
-`FNM'.
+ In addition to the 'fnmatch()' function, the 'fnmatch' extension adds
+one constant ('FNM_NOMATCH'), and an array of flag values named 'FNM'.
- The arguments to `fnmatch()' are:
+ The arguments to 'fnmatch()' are:
-`pattern'
+'pattern'
The file name wildcard to match
-`string'
+'string'
The file name string
-`flag'
+'flag'
Either zero, or the bitwise OR of one or more of the flags in the
- `FNM' array
+ 'FNM' array
The flags are as follows:
-Array element Corresponding flag defined by `fnmatch()'
---------------------------------------------------------------------------
-`FNM["CASEFOLD"]' `FNM_CASEFOLD'
-`FNM["FILE_NAME"]' `FNM_FILE_NAME'
-`FNM["LEADING_DIR"]'`FNM_LEADING_DIR'
-`FNM["NOESCAPE"]' `FNM_NOESCAPE'
-`FNM["PATHNAME"]' `FNM_PATHNAME'
-`FNM["PERIOD"]' `FNM_PERIOD'
+Array element Corresponding flag defined by 'fnmatch()'
+--------------------------------------------------------------------------
+'FNM["CASEFOLD"]' 'FNM_CASEFOLD'
+'FNM["FILE_NAME"]' 'FNM_FILE_NAME'
+'FNM["LEADING_DIR"]''FNM_LEADING_DIR'
+'FNM["NOESCAPE"]' 'FNM_NOESCAPE'
+'FNM["PATHNAME"]' 'FNM_PATHNAME'
+'FNM["PERIOD"]' 'FNM_PERIOD'
Here is an example:
@@ -25627,30 +25526,30 @@ Array element Corresponding flag defined by
`fnmatch()'
File: gawk.info, Node: Extension Sample Fork, Next: Extension Sample
Inplace, Prev: Extension Sample Fnmatch, Up: Extension Samples
-16.7.3 Interface to `fork()', `wait()', and `waitpid()'
+16.7.3 Interface to 'fork()', 'wait()', and 'waitpid()'
-------------------------------------------------------
-The `fork' extension adds three functions, as follows:
+The 'fork' extension adds three functions, as follows:
address@hidden "fork"'
+'@load "fork"'
This is how you load the extension.
-`pid = fork()'
- This function creates a new process. The return value is zero in
+'pid = fork()'
+ This function creates a new process. The return value is zero in
the child and the process ID number of the child in the parent, or
- -1 upon error. In the latter case, `ERRNO' indicates the problem.
- In the child, `PROCINFO["pid"]' and `PROCINFO["ppid"]' are updated
+ -1 upon error. In the latter case, 'ERRNO' indicates the problem.
+ In the child, 'PROCINFO["pid"]' and 'PROCINFO["ppid"]' are updated
to reflect the correct values.
-`ret = waitpid(pid)'
+'ret = waitpid(pid)'
This function takes a numeric argument, which is the process ID to
- wait for. The return value is that of the `waitpid()' system call.
+ wait for. The return value is that of the 'waitpid()' system call.
-`ret = wait()'
+'ret = wait()'
This function waits for the first child to die. The return value
- is that of the `wait()' system call.
+ is that of the 'wait()' system call.
- There is no corresponding `exec()' function.
+ There is no corresponding 'exec()' function.
Here is an example:
@@ -25667,9 +25566,9 @@ File: gawk.info, Node: Extension Sample Inplace,
Next: Extension Sample Ord,
16.7.4 Enabling In-Place File Editing
-------------------------------------
-The `inplace' extension emulates GNU `sed''s `-i' option, which
-performs "in-place" editing of each input file. It uses the bundled
-`inplace.awk' include file to invoke the extension properly:
+The 'inplace' extension emulates GNU 'sed''s '-i' option, which performs
+"in-place" editing of each input file. It uses the bundled
+'inplace.awk' include file to invoke the extension properly:
# inplace --- load and invoke the inplace extension.
@@ -25693,15 +25592,15 @@ performs "in-place" editing of each input file. It
uses the bundled
For each regular file that is processed, the extension redirects
standard output to a temporary file configured to have the same owner
-and permissions as the original. After the file has been processed,
-the extension restores standard output to its original destination. If
-`INPLACE_SUFFIX' is not an empty string, the original file is linked to
+and permissions as the original. After the file has been processed, the
+extension restores standard output to its original destination. If
+'INPLACE_SUFFIX' is not an empty string, the original file is linked to
a backup file name created by appending that suffix. Finally, the
temporary file is renamed to the original file name.
- The `_inplace_filename' variable serves to keep track of the current
-filename so as to not invoke `inplace_end()' before processing the
-first file.
+ The '_inplace_filename' variable serves to keep track of the current
+filename so as to not invoke 'inplace_end()' before processing the first
+file.
If any error occurs, the extension issues a fatal error to terminate
processing immediately without damaging the original file.
@@ -25718,21 +25617,21 @@ processing immediately without damaging the original
file.
File: gawk.info, Node: Extension Sample Ord, Next: Extension Sample Readdir,
Prev: Extension Sample Inplace, Up: Extension Samples
-16.7.5 Character and Numeric values: `ord()' and `chr()'
+16.7.5 Character and Numeric values: 'ord()' and 'chr()'
--------------------------------------------------------
-The `ordchr' extension adds two functions, named `ord()' and `chr()',
-as follows:
+The 'ordchr' extension adds two functions, named 'ord()' and 'chr()', as
+follows:
address@hidden "ordchr"'
+'@load "ordchr"'
This is how you load the extension.
-`number = ord(string)'
- Return the numeric value of the first character in `string'.
+'number = ord(string)'
+ Return the numeric value of the first character in 'string'.
-`char = chr(number)'
+'char = chr(number)'
Return a string whose first character is that represented by
- `number'.
+ 'number'.
These functions are inspired by the Pascal language functions of the
same name. Here is an example:
@@ -25748,43 +25647,42 @@ File: gawk.info, Node: Extension Sample Readdir,
Next: Extension Sample Revout
16.7.6 Reading Directories
--------------------------
-The `readdir' extension adds an input parser for directories. The
-usage is as follows:
+The 'readdir' extension adds an input parser for directories. The usage
+is as follows:
@load "readdir"
When this extension is in use, instead of skipping directories named
-on the command line (or with `getline'), they are read, with each entry
+on the command line (or with 'getline'), they are read, with each entry
returned as a record.
- The record consists of three fields. The first two are the inode
+ The record consists of three fields. The first two are the inode
number and the file name, separated by a forward slash character. On
-systems where the directory entry contains the file type, the record
-has a third field (also separated by a slash), which is a single letter
-indicating the type of the file. The letters and their corresponding
-file types are shown in *note table-readdir-file-types::.
+systems where the directory entry contains the file type, the record has
+a third field (also separated by a slash), which is a single letter
+indicating the type of the file. The letters and their corresponding
+file types are shown in *note Table 16.2: table-readdir-file-types.
Letter File type
---------------------------------------------------------------------------
-`b' Block device
-`c' Character device
-`d' Directory
-`f' Regular file
-`l' Symbolic link
-`p' Named pipe (FIFO)
-`s' Socket
-`u' Anything else (unknown)
-
-Table 16.2: File types returned by the `readdir' extension
+--------------------------------------------------------------------------
+'b' Block device
+'c' Character device
+'d' Directory
+'f' Regular file
+'l' Symbolic link
+'p' Named pipe (FIFO)
+'s' Socket
+'u' Anything else (unknown)
+
+Table 16.2: File types returned by the 'readdir' extension
On systems without the file type information, the third field is
-always `u'.
+always 'u'.
NOTE: On GNU/Linux systems, there are filesystems that don't
- support the `d_type' entry (see the readdir(3) manual page), and
- so the file type is always `u'. You can use the `filefuncs'
- extension to call `stat()' in order to get correct type
- information.
+ support the 'd_type' entry (see the readdir(3) manual page), and so
+ the file type is always 'u'. You can use the 'filefuncs' extension
+ to call 'stat()' in order to get correct type information.
Here is an example:
@@ -25799,8 +25697,8 @@ File: gawk.info, Node: Extension Sample Revout, Next:
Extension Sample Rev2way
16.7.7 Reversing Output
-----------------------
-The `revoutput' extension adds a simple output wrapper that reverses
-the characters in each output line. Its main purpose is to show how to
+The 'revoutput' extension adds a simple output wrapper that reverses the
+characters in each output line. Its main purpose is to show how to
write an output wrapper, although it may be mildly amusing for the
unwary. Here is an example:
@@ -25811,7 +25709,7 @@ unwary. Here is an example:
print "don't panic" > "/dev/stdout"
}
- The output from this program is `cinap t'nod'.
+ The output from this program is 'cinap t'nod'.
File: gawk.info, Node: Extension Sample Rev2way, Next: Extension Sample Read
write array, Prev: Extension Sample Revout, Up: Extension Samples
@@ -25819,11 +25717,11 @@ File: gawk.info, Node: Extension Sample Rev2way,
Next: Extension Sample Read w
16.7.8 Two-Way I/O Example
--------------------------
-The `revtwoway' extension adds a simple two-way processor that reverses
-the characters in each line sent to it for reading back by the `awk'
+The 'revtwoway' extension adds a simple two-way processor that reverses
+the characters in each line sent to it for reading back by the 'awk'
program. Its main purpose is to show how to write a two-way processor,
-although it may also be mildly amusing. The following example shows
-how to use it:
+although it may also be mildly amusing. The following example shows how
+to use it:
@load "revtwoway"
@@ -25835,7 +25733,7 @@ how to use it:
close(cmd)
}
- The output from this program is: `cinap t'nod'.
+ The output from this program is: 'cinap t'nod'.
File: gawk.info, Node: Extension Sample Read write array, Next: Extension
Sample Readfile, Prev: Extension Sample Rev2way, Up: Extension Samples
@@ -25843,38 +25741,38 @@ File: gawk.info, Node: Extension Sample Read write
array, Next: Extension Samp
16.7.9 Dumping and Restoring an Array
-------------------------------------
-The `rwarray' extension adds two functions, named `writea()' and
-`reada()', as follows:
+The 'rwarray' extension adds two functions, named 'writea()' and
+'reada()', as follows:
address@hidden "rwarray"'
+'@load "rwarray"'
This is how you load the extension.
-`ret = writea(file, array)'
+'ret = writea(file, array)'
This function takes a string argument, which is the name of the
- file to which to dump the array, and the array itself as the
- second argument. `writea()' understands arrays of arrays. It
- returns one on success, or zero upon failure.
+ file to which to dump the array, and the array itself as the second
+ argument. 'writea()' understands arrays of arrays. It returns one
+ on success, or zero upon failure.
-`ret = reada(file, array)'
- `reada()' is the inverse of `writea()'; it reads the file named as
+'ret = reada(file, array)'
+ 'reada()' is the inverse of 'writea()'; it reads the file named as
its first argument, filling in the array named as the second
- argument. It clears the array first. Here too, the return value
+ argument. It clears the array first. Here too, the return value
is one on success, or zero upon failure.
- The array created by `reada()' is identical to that written by
-`writea()' in the sense that the contents are the same. However, due to
-implementation issues, the array traversal order of the re-created
-array is likely to be different from that of the original array. As
-array traversal order in `awk' is by default undefined, this is
-(technically) not a problem. If you need to guarantee a particular
-traversal order, use the array sorting features in `gawk' to do so
-(*note Array Sorting::).
+ The array created by 'reada()' is identical to that written by
+'writea()' in the sense that the contents are the same. However, due to
+implementation issues, the array traversal order of the re-created array
+is likely to be different from that of the original array. As array
+traversal order in 'awk' is by default undefined, this is (technically)
+not a problem. If you need to guarantee a particular traversal order,
+use the array sorting features in 'gawk' to do so (*note Array
+Sorting::).
The file contains binary data. All integral values are written in
-network byte order. However, double-precision floating-point values
-are written as native binary data. Thus, arrays containing only string
-data can theoretically be dumped on systems with one byte order and
-restored on systems with a different one, but this has not been tried.
+network byte order. However, double-precision floating-point values are
+written as native binary data. Thus, arrays containing only string data
+can theoretically be dumped on systems with one byte order and restored
+on systems with a different one, but this has not been tried.
Here is an example:
@@ -25890,21 +25788,21 @@ File: gawk.info, Node: Extension Sample Readfile,
Next: Extension Sample Time,
16.7.10 Reading an Entire File
------------------------------
-The `readfile' extension adds a single function named `readfile()', and
+The 'readfile' extension adds a single function named 'readfile()', and
an input parser:
address@hidden "readfile"'
+'@load "readfile"'
This is how you load the extension.
-`result = readfile("/some/path")'
+'result = readfile("/some/path")'
The argument is the name of the file to read. The return value is
a string containing the entire contents of the requested file.
- Upon error, the function returns the empty string and sets `ERRNO'.
+ Upon error, the function returns the empty string and sets 'ERRNO'.
-`BEGIN { PROCINFO["readfile"] = 1 }'
+'BEGIN { PROCINFO["readfile"] = 1 }'
In addition, the extension adds an input parser that is activated
- if `PROCINFO["readfile"]' exists. When activated, each input file
- is returned in its entirety as `$0'. `RT' is set to the null
+ if 'PROCINFO["readfile"]' exists. When activated, each input file
+ is returned in its entirety as '$0'. 'RT' is set to the null
string.
Here is an example:
@@ -25923,29 +25821,29 @@ File: gawk.info, Node: Extension Sample Time, Next:
Extension Sample API Tests
16.7.11 Extension Time Functions
--------------------------------
-The `time' extension adds two functions, named `gettimeofday()' and
-`sleep()', as follows:
+The 'time' extension adds two functions, named 'gettimeofday()' and
+'sleep()', as follows:
address@hidden "time"'
+'@load "time"'
This is how you load the extension.
-`the_time = gettimeofday()'
- Return the time in seconds that has elapsed since 1970-01-01 UTC
- as a floating-point value. If the time is unavailable on this
- platform, return -1 and set `ERRNO'. The returned time should
- have sub-second precision, but the actual precision may vary based
- on the platform. If the standard C `gettimeofday()' system call
- is available on this platform, then it simply returns the value.
+'the_time = gettimeofday()'
+ Return the time in seconds that has elapsed since 1970-01-01 UTC as
+ a floating-point value. If the time is unavailable on this
+ platform, return -1 and set 'ERRNO'. The returned time should have
+ sub-second precision, but the actual precision may vary based on
+ the platform. If the standard C 'gettimeofday()' system call is
+ available on this platform, then it simply returns the value.
Otherwise, if on MS-Windows, it tries to use
- `GetSystemTimeAsFileTime()'.
+ 'GetSystemTimeAsFileTime()'.
-`result = sleep(SECONDS)'
+'result = sleep(SECONDS)'
Attempt to sleep for SECONDS seconds. If SECONDS is negative, or
- the attempt to sleep fails, return -1 and set `ERRNO'. Otherwise,
+ the attempt to sleep fails, return -1 and set 'ERRNO'. Otherwise,
return zero after sleeping for the indicated amount of time. Note
that SECONDS may be a floating-point (nonintegral) value.
Implementation details: depending on platform availability, this
- function tries to use `nanosleep()' or `select()' to implement the
+ function tries to use 'nanosleep()' or 'select()' to implement the
delay.
@@ -25954,26 +25852,26 @@ File: gawk.info, Node: Extension Sample API Tests,
Prev: Extension Sample Time
16.7.12 API Tests
-----------------
-The `testext' extension exercises parts of the extension API that are
-not tested by the other samples. The `extension/testext.c' file
-contains both the C code for the extension and `awk' test code inside C
-comments that run the tests. The testing framework extracts the `awk'
+The 'testext' extension exercises parts of the extension API that are
+not tested by the other samples. The 'extension/testext.c' file
+contains both the C code for the extension and 'awk' test code inside C
+comments that run the tests. The testing framework extracts the 'awk'
code and runs the tests. See the source file for more information.
File: gawk.info, Node: gawkextlib, Next: Extension summary, Prev: Extension
Samples, Up: Dynamic Extensions
-16.8 The `gawkextlib' Project
+16.8 The 'gawkextlib' Project
=============================
-The `gawkextlib' (http://sourceforge.net/projects/gawkextlib/) project
-provides a number of `gawk' extensions, including one for processing
-XML files. This is the evolution of the original `xgawk' (XML `gawk')
+The 'gawkextlib' (http://sourceforge.net/projects/gawkextlib/) project
+provides a number of 'gawk' extensions, including one for processing XML
+files. This is the evolution of the original 'xgawk' (XML 'gawk')
project.
As of this writing, there are seven extensions:
- * `errno' extension
+ * 'errno' extension
* GD graphics library extension
@@ -25982,15 +25880,15 @@ project.
* PostgreSQL extension
* MPFR library extension (this provides access to a number of MPFR
- functions that `gawk''s native MPFR support does not)
+ functions that 'gawk''s native MPFR support does not)
* Redis extension
* XML parser extension, using the Expat
(http://expat.sourceforge.net) XML parsing library
- You can check out the code for the `gawkextlib' project using the
-Git (http://git-scm.com) distributed source code control system. The
+ You can check out the code for the 'gawkextlib' project using the Git
+(http://git-scm.com) distributed source code control system. The
command is as follows:
git clone git://git.code.sf.net/p/gawkextlib/code gawkextlib-code
@@ -26001,27 +25899,27 @@ parser library installed in order to build and use
the XML extension.
In addition, you must have the GNU Autotools installed (Autoconf
(http://www.gnu.org/software/autoconf), Automake
(http://www.gnu.org/software/automake), Libtool
-(http://www.gnu.org/software/libtool), and GNU `gettext'
+(http://www.gnu.org/software/libtool), and GNU 'gettext'
(http://www.gnu.org/software/gettext)).
- The simple recipe for building and testing `gawkextlib' is as
-follows. First, build and install `gawk':
+ The simple recipe for building and testing 'gawkextlib' is as
+follows. First, build and install 'gawk':
cd .../path/to/gawk/code
./configure --prefix=/tmp/newgawk Install in /tmp/newgawk for now
make && make check Build and check that all is OK
make install Install gawk
- Next, go to `http://sourceforge.net/projects/gawkextlib/files' to
-download `gawkextlib' and any extensions that you would like to build.
-The `README' file at that site explains how to build the code. If you
-installed `gawk' in a non-standard location, you will need to specify
-`./configure --with-gawk=/PATH/TO/GAWK' to find it. You may need to
-use the `sudo' utility to install both `gawk' and `gawkextlib',
-depending upon how your system works.
+ Next, go to <http://sourceforge.net/projects/gawkextlib/files> to
+download 'gawkextlib' and any extensions that you would like to build.
+The 'README' file at that site explains how to build the code. If you
+installed 'gawk' in a non-standard location, you will need to specify
+'./configure --with-gawk=/PATH/TO/GAWK' to find it. You may need to use
+the 'sudo' utility to install both 'gawk' and 'gawkextlib', depending
+upon how your system works.
- If you write an extension that you wish to share with other `gawk'
-users, consider doing so through the `gawkextlib' project. See the
+ If you write an extension that you wish to share with other 'gawk'
+users, consider doing so through the 'gawkextlib' project. See the
project's website for more information.
@@ -26030,27 +25928,27 @@ File: gawk.info, Node: Extension summary, Next:
Extension Exercises, Prev: ga
16.9 Summary
============
- * You can write extensions (sometimes called plug-ins) for `gawk' in
+ * You can write extensions (sometimes called plug-ins) for 'gawk' in
C or C++ using the application programming interface (API) defined
- by the `gawk' developers.
+ by the 'gawk' developers.
* Extensions must have a license compatible with the GNU General
- Public License (GPL), and they must assert that fact by declaring
- a variable named `plugin_is_GPL_compatible'.
+ Public License (GPL), and they must assert that fact by declaring a
+ variable named 'plugin_is_GPL_compatible'.
- * Communication between `gawk' and an extension is two-way. `gawk'
- passes a `struct' to the extension that contains various data
+ * Communication between 'gawk' and an extension is two-way. 'gawk'
+ passes a 'struct' to the extension that contains various data
fields and function pointers. The extension can then call into
- `gawk' via the supplied function pointers to accomplish certain
+ 'gawk' via the supplied function pointers to accomplish certain
tasks.
* One of these tasks is to "register" the name and implementation of
- new `awk'-level functions with `gawk'. The implementation takes
+ new 'awk'-level functions with 'gawk'. The implementation takes
the form of a C function pointer with a defined signature. By
- convention, implementation functions are named `do_XXXX()' for
- some `awk'-level function `XXXX()'.
+ convention, implementation functions are named 'do_XXXX()' for some
+ 'awk'-level function 'XXXX()'.
- * The API is defined in a header file named `gawkapi.h'. You must
+ * The API is defined in a header file named 'gawkapi.h'. You must
include a number of standard header files _before_ including it in
your source file.
@@ -26065,7 +25963,7 @@ File: gawk.info, Node: Extension summary, Next:
Extension Exercises, Prev: ga
* Printing fatal, warning, and "lint" warning messages
- * Updating `ERRNO', or unsetting it
+ * Updating 'ERRNO', or unsetting it
* Accessing parameters, including converting an undefined
parameter into an array
@@ -26084,83 +25982,81 @@ File: gawk.info, Node: Extension summary, Next:
Extension Exercises, Prev: ga
elements)
* The API defines a number of standard data types for representing
- `awk' values, array elements, and arrays.
+ 'awk' values, array elements, and arrays.
- * The API provides convenience functions for constructing values.
- It also provides memory management functions to ensure
- compatibility between memory allocated by `gawk' and memory
- allocated by an extension.
+ * The API provides convenience functions for constructing values. It
+ also provides memory management functions to ensure compatibility
+ between memory allocated by 'gawk' and memory allocated by an
+ extension.
- * _All_ memory passed from `gawk' to an extension must be treated as
+ * _All_ memory passed from 'gawk' to an extension must be treated as
read-only by the extension.
- * _All_ memory passed from an extension to `gawk' must come from the
- API's memory allocation functions. `gawk' takes responsibility for
+ * _All_ memory passed from an extension to 'gawk' must come from the
+ API's memory allocation functions. 'gawk' takes responsibility for
the memory and releases it when appropriate.
- * The API provides information about the running version of `gawk' so
- that an extension can make sure it is compatible with the `gawk'
+ * The API provides information about the running version of 'gawk' so
+ that an extension can make sure it is compatible with the 'gawk'
that loaded it.
* It is easiest to start a new extension by copying the boilerplate
- code described in this major node. Macros in the `gawkapi.h'
+ code described in this major node. Macros in the 'gawkapi.h'
header file make this easier to do.
- * The `gawk' distribution includes a number of small but useful
- sample extensions. The `gawkextlib' project includes several more
+ * The 'gawk' distribution includes a number of small but useful
+ sample extensions. The 'gawkextlib' project includes several more
(larger) extensions. If you wish to write an extension and
- contribute it to the community of `gawk' users, the `gawkextlib'
+ contribute it to the community of 'gawk' users, the 'gawkextlib'
project is the place to do so.
-
File: gawk.info, Node: Extension Exercises, Prev: Extension summary, Up:
Dynamic Extensions
16.10 Exercises
===============
- 1. Add functions to implement system calls such as `chown()',
- `chmod()', and `umask()' to the file operations extension
- presented in *note Internal File Ops::.
+ 1. Add functions to implement system calls such as 'chown()',
+ 'chmod()', and 'umask()' to the file operations extension presented
+ in *note Internal File Ops::.
- 2. Write an input parser that prints a prompt if the input is a from
- a "terminal" device. You can use the `isatty()' function to tell
- if the input file is a terminal. (Hint: this function is usually
+ 2. Write an input parser that prints a prompt if the input is a from a
+ "terminal" device. You can use the 'isatty()' function to tell if
+ the input file is a terminal. (Hint: this function is usually
expensive to call; try to call it just once.) The content of the
- prompt should come from a variable settable by `awk'-level code.
- You can write the prompt to stanard error. However, for best
- results, open a new file descriptor (or file pointer) on
- `/dev/tty' and print the prompt there, in case standard error has
- been redirected.
+ prompt should come from a variable settable by 'awk'-level code.
+ You can write the prompt to stanard error. However, for best
+ results, open a new file descriptor (or file pointer) on '/dev/tty'
+ and print the prompt there, in case standard error has been
+ redirected.
Why is standard error a better choice than standard output for
writing the prompt? Which reading mechanism should you replace,
the one to get a record, or the one to read raw bytes?
- 3. (Hard.) How would you provide namespaces in `gawk', so that the
- names of functions in different extensions don't conflict with
- each other? If you come up with a really good scheme, contact the
- `gawk' maintainer to tell him about it.
-
- 4. Write a wrapper script that provides an interface similar to `sed
- -i' for the "inplace" extension presented in *note Extension
- Sample Inplace::.
+ 3. (Hard.) How would you provide namespaces in 'gawk', so that the
+ names of functions in different extensions don't conflict with each
+ other? If you come up with a really good scheme, contact the
+ 'gawk' maintainer to tell him about it.
+ 4. Write a wrapper script that provides an interface similar to 'sed
+ -i' for the "inplace" extension presented in *note Extension Sample
+ Inplace::.
File: gawk.info, Node: Language History, Next: Installation, Prev: Dynamic
Extensions, Up: Top
-Appendix A The Evolution of the `awk' Language
+Appendix A The Evolution of the 'awk' Language
**********************************************
-This Info file describes the GNU implementation of `awk', which follows
-the POSIX specification. Many longtime `awk' users learned `awk'
-programming with the original `awk' implementation in Version 7 Unix.
-(This implementation was the basis for `awk' in Berkeley Unix, through
+This Info file describes the GNU implementation of 'awk', which follows
+the POSIX specification. Many longtime 'awk' users learned 'awk'
+programming with the original 'awk' implementation in Version 7 Unix.
+(This implementation was the basis for 'awk' in Berkeley Unix, through
4.3-Reno. Subsequent versions of Berkeley Unix, and, for a while, some
-systems derived from 4.4BSD-Lite, used various versions of `gawk' for
-their `awk'.) This major node briefly describes the evolution of the
-`awk' language, with cross-references to other parts of the Info file
+systems derived from 4.4BSD-Lite, used various versions of 'gawk' for
+their 'awk'.) This major node briefly describes the evolution of the
+'awk' language, with cross-references to other parts of the Info file
where you can find more information.
* Menu:
@@ -26171,13 +26067,13 @@ where you can find more information.
and 4.
* POSIX:: New features from the POSIX standard.
* BTL:: New features from Brian Kernighan's version of
- `awk'.
-* POSIX/GNU:: The extensions in `gawk' not in POSIX
- `awk'.
-* Feature History:: The history of the features in `gawk'.
+ 'awk'.
+* POSIX/GNU:: The extensions in 'gawk' not in POSIX
+ 'awk'.
+* Feature History:: The history of the features in 'gawk'.
* Common Extensions:: Common Extensions Summary.
* Ranges and Locales:: How locales used to affect regexp ranges.
-* Contributors:: The major contributors to `gawk'.
+* Contributors:: The major contributors to 'gawk'.
* History summary:: History summary.
@@ -26186,60 +26082,60 @@ File: gawk.info, Node: V7/SVR3.1, Next: SVR4, Up:
Language History
A.1 Major Changes Between V7 and SVR3.1
=======================================
-The `awk' language evolved considerably between the release of Version
-7 Unix (1978) and the new version that was first made generally
-available in System V Release 3.1 (1987). This minor node summarizes
-the changes, with cross-references to further details:
+The 'awk' language evolved considerably between the release of Version 7
+Unix (1978) and the new version that was first made generally available
+in System V Release 3.1 (1987). This minor node summarizes the changes,
+with cross-references to further details:
- * The requirement for `;' to separate rules on a line (*note
+ * The requirement for ';' to separate rules on a line (*note
Statements/Lines::)
- * User-defined functions and the `return' statement (*note
+ * User-defined functions and the 'return' statement (*note
User-defined::)
- * The `delete' statement (*note Delete::).
+ * The 'delete' statement (*note Delete::).
- * The `do'-`while' statement (*note Do Statement::)
+ * The 'do'-'while' statement (*note Do Statement::)
- * The built-in functions `atan2()', `cos()', `sin()', `rand()', and
- `srand()' (*note Numeric Functions::)
+ * The built-in functions 'atan2()', 'cos()', 'sin()', 'rand()', and
+ 'srand()' (*note Numeric Functions::)
- * The built-in functions `gsub()', `sub()', and `match()' (*note
+ * The built-in functions 'gsub()', 'sub()', and 'match()' (*note
String Functions::)
- * The built-in functions `close()' and `system()' (*note I/O
+ * The built-in functions 'close()' and 'system()' (*note I/O
Functions::)
- * The `ARGC', `ARGV', `FNR', `RLENGTH', `RSTART', and `SUBSEP'
+ * The 'ARGC', 'ARGV', 'FNR', 'RLENGTH', 'RSTART', and 'SUBSEP'
predefined variables (*note Built-in Variables::)
- * Assignable `$0' (*note Changing Fields::)
+ * Assignable '$0' (*note Changing Fields::)
- * The conditional expression using the ternary operator `?:' (*note
+ * The conditional expression using the ternary operator '?:' (*note
Conditional Exp::)
- * The expression `INDX in ARRAY' outside of `for' statements (*note
+ * The expression 'INDX in ARRAY' outside of 'for' statements (*note
Reference to Elements::)
- * The exponentiation operator `^' (*note Arithmetic Ops::) and its
- assignment operator form `^=' (*note Assignment Ops::)
+ * The exponentiation operator '^' (*note Arithmetic Ops::) and its
+ assignment operator form '^=' (*note Assignment Ops::)
- * C-compatible operator precedence, which breaks some old `awk'
+ * C-compatible operator precedence, which breaks some old 'awk'
programs (*note Precedence::)
- * Regexps as the value of `FS' (*note Field Separators::) and as the
- third argument to the `split()' function (*note String
- Functions::), rather than using only the first character of `FS'
+ * Regexps as the value of 'FS' (*note Field Separators::) and as the
+ third argument to the 'split()' function (*note String
+ Functions::), rather than using only the first character of 'FS'
- * Dynamic regexps as operands of the `~' and `!~' operators (*note
+ * Dynamic regexps as operands of the '~' and '!~' operators (*note
Computed Regexps::)
- * The escape sequences `\b', `\f', and `\r' (*note Escape
+ * The escape sequences '\b', '\f', and '\r' (*note Escape
Sequences::)
- * Redirection of input for the `getline' function (*note Getline::)
+ * Redirection of input for the 'getline' function (*note Getline::)
- * Multiple `BEGIN' and `END' rules (*note BEGIN/END::)
+ * Multiple 'BEGIN' and 'END' rules (*note BEGIN/END::)
* Multidimensional arrays (*note Multidimensional::)
@@ -26249,36 +26145,36 @@ File: gawk.info, Node: SVR4, Next: POSIX, Prev:
V7/SVR3.1, Up: Language Hist
A.2 Changes Between SVR3.1 and SVR4
===================================
-The System V Release 4 (1989) version of Unix `awk' added these features
-(some of which originated in `gawk'):
+The System V Release 4 (1989) version of Unix 'awk' added these features
+(some of which originated in 'gawk'):
- * The `ENVIRON' array (*note Built-in Variables::)
+ * The 'ENVIRON' array (*note Built-in Variables::)
- * Multiple `-f' options on the command line (*note Options::)
+ * Multiple '-f' options on the command line (*note Options::)
- * The `-v' option for assigning variables before program execution
+ * The '-v' option for assigning variables before program execution
begins (*note Options::)
- * The `--' signal for terminating command-line options
+ * The '--' signal for terminating command-line options
- * The `\a', `\v', and `\x' escape sequences (*note Escape
+ * The '\a', '\v', and '\x' escape sequences (*note Escape
Sequences::)
- * A defined return value for the `srand()' built-in function (*note
+ * A defined return value for the 'srand()' built-in function (*note
Numeric Functions::)
- * The `toupper()' and `tolower()' built-in string functions for case
+ * The 'toupper()' and 'tolower()' built-in string functions for case
translation (*note String Functions::)
- * A cleaner specification for the `%c' format-control letter in the
- `printf' function (*note Control Letters::)
+ * A cleaner specification for the '%c' format-control letter in the
+ 'printf' function (*note Control Letters::)
* The ability to dynamically pass the field width and precision
- (`"%*.*d"') in the argument list of `printf' and `sprintf()'
- (*note Control Letters::)
+ ('"%*.*d"') in the argument list of 'printf' and 'sprintf()' (*note
+ Control Letters::)
- * The use of regexp constants, such as `/foo/', as expressions, where
- they are equivalent to using the matching operator, as in `$0 ~
+ * The use of regexp constants, such as '/foo/', as expressions, where
+ they are equivalent to using the matching operator, as in '$0 ~
/foo/' (*note Using Constant Regexps::)
* Processing of escape sequences inside command-line variable
@@ -26287,16 +26183,16 @@ The System V Release 4 (1989) version of Unix `awk'
added these features
File: gawk.info, Node: POSIX, Next: BTL, Prev: SVR4, Up: Language History
-A.3 Changes Between SVR4 and POSIX `awk'
+A.3 Changes Between SVR4 and POSIX 'awk'
========================================
-The POSIX Command Language and Utilities standard for `awk' (1992)
+The POSIX Command Language and Utilities standard for 'awk' (1992)
introduced the following changes into the language:
- * The use of `-W' for implementation-specific options (*note
+ * The use of '-W' for implementation-specific options (*note
Options::)
- * The use of `CONVFMT' for controlling the conversion of numbers to
+ * The use of 'CONVFMT' for controlling the conversion of numbers to
strings (*note Conversion::)
* The concept of a numeric string and tighter comparison rules to go
@@ -26311,90 +26207,88 @@ introduced the following changes into the language:
In 2012, a number of extensions that had been commonly available for
many years were finally added to POSIX. They are:
- * The `fflush()' built-in function for flushing buffered output
+ * The 'fflush()' built-in function for flushing buffered output
(*note I/O Functions::)
- * The `nextfile' statement (*note Nextfile Statement::)
+ * The 'nextfile' statement (*note Nextfile Statement::)
- * The ability to delete all of an array at once with `delete ARRAY'
+ * The ability to delete all of an array at once with 'delete ARRAY'
(*note Delete::)
-
*Note Common Extensions::, for a list of common extensions not
permitted by the POSIX standard.
The 2008 POSIX standard can be found online at
-`http://www.opengroup.org/onlinepubs/9699919799/'.
+<http://www.opengroup.org/onlinepubs/9699919799/>.
File: gawk.info, Node: BTL, Next: POSIX/GNU, Prev: POSIX, Up: Language
History
-A.4 Extensions in Brian Kernighan's `awk'
+A.4 Extensions in Brian Kernighan's 'awk'
=========================================
Brian Kernighan has made his version available via his home page (*note
Other Versions::).
This minor node describes common extensions that originally appeared
-in his version of `awk':
+in his version of 'awk':
- * The `**' and `**=' operators (*note Arithmetic Ops:: and *note
+ * The '**' and '**=' operators (*note Arithmetic Ops:: and *note
Assignment Ops::)
- * The use of `func' as an abbreviation for `function' (*note
+ * The use of 'func' as an abbreviation for 'function' (*note
Definition Syntax::)
- * The `fflush()' built-in function for flushing buffered output
+ * The 'fflush()' built-in function for flushing buffered output
(*note I/O Functions::)
-
*Note Common Extensions::, for a full list of the extensions
-available in his `awk'.
+available in his 'awk'.
File: gawk.info, Node: POSIX/GNU, Next: Feature History, Prev: BTL, Up:
Language History
-A.5 Extensions in `gawk' Not in POSIX `awk'
+A.5 Extensions in 'gawk' Not in POSIX 'awk'
===========================================
-The GNU implementation, `gawk', adds a large number of features. They
-can all be disabled with either the `--traditional' or `--posix' options
+The GNU implementation, 'gawk', adds a large number of features. They
+can all be disabled with either the '--traditional' or '--posix' options
(*note Options::).
- A number of features have come and gone over the years. This minor
-node summarizes the additional features over POSIX `awk' that are in
-the current version of `gawk'.
+ A number of features have come and gone over the years. This minor
+node summarizes the additional features over POSIX 'awk' that are in the
+current version of 'gawk'.
* Additional predefined variables:
- - The `ARGIND', `BINMODE', `ERRNO', `FIELDWIDTHS', `FPAT',
- `IGNORECASE', `LINT', `PROCINFO', `RT', and `TEXTDOMAIN'
+ - The 'ARGIND', 'BINMODE', 'ERRNO', 'FIELDWIDTHS', 'FPAT',
+ 'IGNORECASE', 'LINT', 'PROCINFO', 'RT', and 'TEXTDOMAIN'
variables (*note Built-in Variables::)
* Special files in I/O redirections:
- - The `/dev/stdin', `/dev/stdout', `/dev/stderr', and
- `/dev/fd/N' special file names (*note Special Files::)
+ - The '/dev/stdin', '/dev/stdout', '/dev/stderr', and
+ '/dev/fd/N' special file names (*note Special Files::)
- - The `/inet', `/inet4', and `/inet6' special files for TCP/IP
- networking using `|&' to specify which version of the IP
+ - The '/inet', '/inet4', and '/inet6' special files for TCP/IP
+ networking using '|&' to specify which version of the IP
protocol to use (*note TCP/IP Networking::)
* Changes and/or additions to the language:
- - The `\x' escape sequence (*note Escape Sequences::)
+ - The '\x' escape sequence (*note Escape Sequences::)
- Full support for both POSIX and GNU regexps (*note Regexp::)
- - The ability for `FS' and for the third argument to `split()'
+ - The ability for 'FS' and for the third argument to 'split()'
to be null strings (*note Single Character Fields::)
- - The ability for `RS' to be a regexp (*note Records::)
+ - The ability for 'RS' to be a regexp (*note Records::)
- - The ability to use octal and hexadecimal constants in `awk'
+ - The ability to use octal and hexadecimal constants in 'awk'
program source code (*note Nondecimal-numbers::)
- - The `|&' operator for two-way I/O to a coprocess (*note
+ - The '|&' operator for two-way I/O to a coprocess (*note
Two-way I/O::)
- Indirect function calls (*note Indirect Calls::)
@@ -26404,76 +26298,76 @@ the current version of `gawk'.
* New keywords:
- - The `BEGINFILE' and `ENDFILE' special patterns (*note
+ - The 'BEGINFILE' and 'ENDFILE' special patterns (*note
BEGINFILE/ENDFILE::)
- - The `switch' statement (*note Switch Statement::)
+ - The 'switch' statement (*note Switch Statement::)
- * Changes to standard `awk' functions:
+ * Changes to standard 'awk' functions:
- - The optional second argument to `close()' that allows closing
+ - The optional second argument to 'close()' that allows closing
one end of a two-way pipe to a coprocess (*note Two-way I/O::)
- - POSIX compliance for `gsub()' and `sub()' with `--posix'
+ - POSIX compliance for 'gsub()' and 'sub()' with '--posix'
- - The `length()' function accepts an array argument and returns
+ - The 'length()' function accepts an array argument and returns
the number of elements in the array (*note String Functions::)
- - The optional third argument to the `match()' function for
+ - The optional third argument to the 'match()' function for
capturing text-matching subexpressions within a regexp (*note
String Functions::)
- - Positional specifiers in `printf' formats for making
+ - Positional specifiers in 'printf' formats for making
translations easier (*note Printf Ordering::)
- - The `split()' function's additional optional fourth argument,
+ - The 'split()' function's additional optional fourth argument,
which is an array to hold the text of the field separators
(*note String Functions::)
- * Additional functions only in `gawk':
+ * Additional functions only in 'gawk':
- - The `gensub()', `patsplit()', and `strtonum()' functions for
+ - The 'gensub()', 'patsplit()', and 'strtonum()' functions for
more powerful text manipulation (*note String Functions::)
- - The `asort()' and `asorti()' functions for sorting arrays
+ - The 'asort()' and 'asorti()' functions for sorting arrays
(*note Array Sorting::)
- - The `mktime()', `systime()', and `strftime()' functions for
+ - The 'mktime()', 'systime()', and 'strftime()' functions for
working with timestamps (*note Time Functions::)
- - The `and()', `compl()', `lshift()', `or()', `rshift()', and
- `xor()' functions for bit manipulation (*note Bitwise
+ - The 'and()', 'compl()', 'lshift()', 'or()', 'rshift()', and
+ 'xor()' functions for bit manipulation (*note Bitwise
Functions::)
- - The `isarray()' function to check if a variable is an array
- or not (*note Type Functions::)
+ - The 'isarray()' function to check if a variable is an array or
+ not (*note Type Functions::)
- - The `bindtextdomain()', `dcgettext()', and `dcngettext()'
+ - The 'bindtextdomain()', 'dcgettext()', and 'dcngettext()'
functions for internationalization (*note Programmer i18n::)
* Changes and/or additions in the command-line options:
- - The `AWKPATH' environment variable for specifying a path
- search for the `-f' command-line option (*note Options::)
-
- - The `AWKLIBPATH' environment variable for specifying a path
- search for the `-l' command-line option (*note Options::)
-
- - The `-b', `-c', `-C', `-d', `-D', `-e', `-E', `-g', `-h',
- `-i', `-l', `-L', `-M', `-n', `-N', `-o', `-O', `-p', `-P',
- `-r', `-S', `-t', and `-V' short options. Also, the ability
- to use GNU-style long-named options that start with `--', and
- the `--assign', `--bignum', `--characters-as-bytes',
- `--copyright', `--debug', `--dump-variables', `--exec',
- `--field-separator', `--file', `--gen-pot', `--help',
- `--include', `--lint', `--lint-old', `--load',
- `--non-decimal-data', `--optimize', `--posix',
- `--pretty-print', `--profile', `--re-interval', `--sandbox',
- `--source', `--traditional', `--use-lc-numeric', and
- `--version' long options (*note Options::).
+ - The 'AWKPATH' environment variable for specifying a path
+ search for the '-f' command-line option (*note Options::)
+
+ - The 'AWKLIBPATH' environment variable for specifying a path
+ search for the '-l' command-line option (*note Options::)
+
+ - The '-b', '-c', '-C', '-d', '-D', '-e', '-E', '-g', '-h',
+ '-i', '-l', '-L', '-M', '-n', '-N', '-o', '-O', '-p', '-P',
+ '-r', '-S', '-t', and '-V' short options. Also, the ability
+ to use GNU-style long-named options that start with '--', and
+ the '--assign', '--bignum', '--characters-as-bytes',
+ '--copyright', '--debug', '--dump-variables', '--exec',
+ '--field-separator', '--file', '--gen-pot', '--help',
+ '--include', '--lint', '--lint-old', '--load',
+ '--non-decimal-data', '--optimize', '--posix',
+ '--pretty-print', '--profile', '--re-interval', '--sandbox',
+ '--source', '--traditional', '--use-lc-numeric', and
+ '--version' long options (*note Options::).
* Support for the following obsolete systems was removed from the
- code and the documentation for `gawk' version 4.0:
+ code and the documentation for 'gawk' version 4.0:
- Amiga
@@ -26499,216 +26393,213 @@ the current version of `gawk'.
- GCC for VAX and Alpha has not been tested for a while.
-
* Support for the following obsolete system was removed from the code
- for `gawk' version 4.1:
+ for 'gawk' version 4.1:
- Ultrix
-
File: gawk.info, Node: Feature History, Next: Common Extensions, Prev:
POSIX/GNU, Up: Language History
-A.6 History of `gawk' Features
+A.6 History of 'gawk' Features
==============================
-This minor node describes the features in `gawk' over and above those
-in POSIX `awk', in the order they were added to `gawk'.
+This minor node describes the features in 'gawk' over and above those in
+POSIX 'awk', in the order they were added to 'gawk'.
- Version 2.10 of `gawk' introduced the following features:
+ Version 2.10 of 'gawk' introduced the following features:
- * The `AWKPATH' environment variable for specifying a path search for
- the `-f' command-line option (*note Options::).
+ * The 'AWKPATH' environment variable for specifying a path search for
+ the '-f' command-line option (*note Options::).
- * The `IGNORECASE' variable and its effects (*note
+ * The 'IGNORECASE' variable and its effects (*note
Case-sensitivity::).
- * The `/dev/stdin', `/dev/stdout', `/dev/stderr' and `/dev/fd/N'
+ * The '/dev/stdin', '/dev/stdout', '/dev/stderr' and '/dev/fd/N'
special file names (*note Special Files::).
- Version 2.13 of `gawk' introduced the following features:
+ Version 2.13 of 'gawk' introduced the following features:
- * The `FIELDWIDTHS' variable and its effects (*note Constant Size::).
+ * The 'FIELDWIDTHS' variable and its effects (*note Constant Size::).
- * The `systime()' and `strftime()' built-in functions for obtaining
+ * The 'systime()' and 'strftime()' built-in functions for obtaining
and printing timestamps (*note Time Functions::).
* Additional command-line options (*note Options::):
- - The `-W lint' option to provide error and portability checking
+ - The '-W lint' option to provide error and portability checking
for both the source code and at runtime.
- - The `-W compat' option to turn off the GNU extensions.
+ - The '-W compat' option to turn off the GNU extensions.
- - The `-W posix' option for full POSIX compliance.
+ - The '-W posix' option for full POSIX compliance.
- Version 2.14 of `gawk' introduced the following feature:
+ Version 2.14 of 'gawk' introduced the following feature:
- * The `next file' statement for skipping to the next data file
- (*note Nextfile Statement::).
+ * The 'next file' statement for skipping to the next data file (*note
+ Nextfile Statement::).
- Version 2.15 of `gawk' introduced the following features:
+ Version 2.15 of 'gawk' introduced the following features:
* New variables (*note Built-in Variables::):
- - `ARGIND', which tracks the movement of `FILENAME' through
- `ARGV'.
+ - 'ARGIND', which tracks the movement of 'FILENAME' through
+ 'ARGV'.
- - `ERRNO', which contains the system error message when
- `getline' returns -1 or `close()' fails.
+ - 'ERRNO', which contains the system error message when
+ 'getline' returns -1 or 'close()' fails.
- * The `/dev/pid', `/dev/ppid', `/dev/pgrpid', and `/dev/user'
- special file names. These have since been removed.
+ * The '/dev/pid', '/dev/ppid', '/dev/pgrpid', and '/dev/user' special
+ file names. These have since been removed.
- * The ability to delete all of an array at once with `delete ARRAY'
+ * The ability to delete all of an array at once with 'delete ARRAY'
(*note Delete::).
* Command-line option changes (*note Options::):
- The ability to use GNU-style long-named options that start
- with `--'.
+ with '--'.
- - The `--source' option for mixing command-line and library-file
+ - The '--source' option for mixing command-line and library-file
source code.
- Version 3.0 of `gawk' introduced the following features:
+ Version 3.0 of 'gawk' introduced the following features:
* New or changed variables:
- - `IGNORECASE' changed, now applying to string comparison as
+ - 'IGNORECASE' changed, now applying to string comparison as
well as regexp operations (*note Case-sensitivity::).
- - `RT', which contains the input text that matched `RS' (*note
+ - 'RT', which contains the input text that matched 'RS' (*note
Records::).
* Full support for both POSIX and GNU regexps (*note Regexp::).
- * The `gensub()' function for more powerful text manipulation (*note
+ * The 'gensub()' function for more powerful text manipulation (*note
String Functions::).
- * The `strftime()' function acquired a default time format, allowing
+ * The 'strftime()' function acquired a default time format, allowing
it to be called with no arguments (*note Time Functions::).
- * The ability for `FS' and for the third argument to `split()' to be
+ * The ability for 'FS' and for the third argument to 'split()' to be
null strings (*note Single Character Fields::).
- * The ability for `RS' to be a regexp (*note Records::).
+ * The ability for 'RS' to be a regexp (*note Records::).
- * The `next file' statement became `nextfile' (*note Nextfile
+ * The 'next file' statement became 'nextfile' (*note Nextfile
Statement::).
- * The `fflush()' function from BWK `awk' (then at Bell Laboratories;
+ * The 'fflush()' function from BWK 'awk' (then at Bell Laboratories;
*note I/O Functions::).
* New command-line options:
- - The `--lint-old' option to warn about constructs that are not
- available in the original Version 7 Unix version of `awk'
+ - The '--lint-old' option to warn about constructs that are not
+ available in the original Version 7 Unix version of 'awk'
(*note V7/SVR3.1::).
- - The `-m' option from BWK `awk'. (Brian was still at Bell
+ - The '-m' option from BWK 'awk'. (Brian was still at Bell
Laboratories at the time.) This was later removed from both
- his `awk' and from `gawk'.
+ his 'awk' and from 'gawk'.
- - The `--re-interval' option to provide interval expressions in
+ - The '--re-interval' option to provide interval expressions in
regexps (*note Regexp Operators::).
- - The `--traditional' option was added as a better name for
- `--compat' (*note Options::).
+ - The '--traditional' option was added as a better name for
+ '--compat' (*note Options::).
- * The use of GNU Autoconf to control the configuration process
- (*note Quick Installation::).
+ * The use of GNU Autoconf to control the configuration process (*note
+ Quick Installation::).
* Amiga support. This has since been removed.
-
- Version 3.1 of `gawk' introduced the following features:
+ Version 3.1 of 'gawk' introduced the following features:
* New variables (*note Built-in Variables::):
- - `BINMODE', for non-POSIX systems, which allows binary I/O for
+ - 'BINMODE', for non-POSIX systems, which allows binary I/O for
input and/or output files (*note PC Using::).
- - `LINT', which dynamically controls lint warnings.
+ - 'LINT', which dynamically controls lint warnings.
- - `PROCINFO', an array for providing process-related
+ - 'PROCINFO', an array for providing process-related
information.
- - `TEXTDOMAIN', for setting an application's
+ - 'TEXTDOMAIN', for setting an application's
internationalization text domain (*note
Internationalization::).
- * The ability to use octal and hexadecimal constants in `awk'
- program source code (*note Nondecimal-numbers::).
+ * The ability to use octal and hexadecimal constants in 'awk' program
+ source code (*note Nondecimal-numbers::).
- * The `|&' operator for two-way I/O to a coprocess (*note Two-way
+ * The '|&' operator for two-way I/O to a coprocess (*note Two-way
I/O::).
- * The `/inet' special files for TCP/IP networking using `|&' (*note
+ * The '/inet' special files for TCP/IP networking using '|&' (*note
TCP/IP Networking::).
- * The optional second argument to `close()' that allows closing one
+ * The optional second argument to 'close()' that allows closing one
end of a two-way pipe to a coprocess (*note Two-way I/O::).
- * The optional third argument to the `match()' function for
- capturing text-matching subexpressions within a regexp (*note
- String Functions::).
+ * The optional third argument to the 'match()' function for capturing
+ text-matching subexpressions within a regexp (*note String
+ Functions::).
- * Positional specifiers in `printf' formats for making translations
+ * Positional specifiers in 'printf' formats for making translations
easier (*note Printf Ordering::).
* A number of new built-in functions:
- - The `asort()' and `asorti()' functions for sorting arrays
+ - The 'asort()' and 'asorti()' functions for sorting arrays
(*note Array Sorting::).
- - The `bindtextdomain()', `dcgettext()' and `dcngettext()'
+ - The 'bindtextdomain()', 'dcgettext()' and 'dcngettext()'
functions for internationalization (*note Programmer i18n::).
- - The `extension()' function and the ability to add new
- built-in functions dynamically (*note Dynamic Extensions::).
+ - The 'extension()' function and the ability to add new built-in
+ functions dynamically (*note Dynamic Extensions::).
- - The `mktime()' function for creating timestamps (*note Time
+ - The 'mktime()' function for creating timestamps (*note Time
Functions::).
- - The `and()', `or()', `xor()', `compl()', `lshift()',
- `rshift()', and `strtonum()' functions (*note Bitwise
+ - The 'and()', 'or()', 'xor()', 'compl()', 'lshift()',
+ 'rshift()', and 'strtonum()' functions (*note Bitwise
Functions::).
- * The support for `next file' as two words was removed completely
+ * The support for 'next file' as two words was removed completely
(*note Nextfile Statement::).
* Additional command-line options (*note Options::):
- - The `--dump-variables' option to print a list of all global
+ - The '--dump-variables' option to print a list of all global
variables.
- - The `--exec' option, for use in CGI scripts.
+ - The '--exec' option, for use in CGI scripts.
- - The `--gen-po' command-line option and the use of a leading
+ - The '--gen-po' command-line option and the use of a leading
underscore to mark strings that should be translated (*note
String Extraction::).
- - The `--non-decimal-data' option to allow non-decimal input
+ - The '--non-decimal-data' option to allow non-decimal input
data (*note Nondecimal Data::).
- - The `--profile' option and `pgawk', the profiling version of
- `gawk', for producing execution profiles of `awk' programs
+ - The '--profile' option and 'pgawk', the profiling version of
+ 'gawk', for producing execution profiles of 'awk' programs
(*note Profiling::).
- - The `--use-lc-numeric' option to force `gawk' to use the
+ - The '--use-lc-numeric' option to force 'gawk' to use the
locale's decimal point for parsing input data (*note
Conversion::).
* The use of GNU Automake to help in standardizing the configuration
process (*note Quick Installation::).
- * The use of GNU `gettext' for `gawk''s own message output (*note
+ * The use of GNU 'gettext' for 'gawk''s own message output (*note
Gawk I18N::).
- * BeOS support. This was later removed.
+ * BeOS support. This was later removed.
- * Tandem support. This was later removed.
+ * Tandem support. This was later removed.
* The Atari port became officially unsupported and was later removed
entirely.
@@ -26716,119 +26607,119 @@ in POSIX `awk', in the order they were added to
`gawk'.
* The source code changed to use ISO C standard-style function
definitions.
- * POSIX compliance for `sub()' and `gsub()' (*note Gory Details::).
+ * POSIX compliance for 'sub()' and 'gsub()' (*note Gory Details::).
- * The `length()' function was extended to accept an array argument
+ * The 'length()' function was extended to accept an array argument
and return the number of elements in the array (*note String
Functions::).
- * The `strftime()' function acquired a third argument to enable
+ * The 'strftime()' function acquired a third argument to enable
printing times as UTC (*note Time Functions::).
- Version 4.0 of `gawk' introduced the following features:
+ Version 4.0 of 'gawk' introduced the following features:
* Variable additions:
- - `FPAT', which allows you to specify a regexp that matches the
+ - 'FPAT', which allows you to specify a regexp that matches the
fields, instead of matching the field separator (*note
Splitting By Content::).
- - If `PROCINFO["sorted_in"]' exists, `for(iggy in foo)' loops
+ - If 'PROCINFO["sorted_in"]' exists, 'for(iggy in foo)' loops
sort the indices before looping over them. The value of this
element provides control over how the indices are sorted
before the loop traversal starts (*note Controlling
Scanning::).
- - `PROCINFO["strftime"]', which holds the default format for
- `strftime()' (*note Time Functions::).
+ - 'PROCINFO["strftime"]', which holds the default format for
+ 'strftime()' (*note Time Functions::).
- * The special files `/dev/pid', `/dev/ppid', `/dev/pgrpid' and
- `/dev/user' were removed.
+ * The special files '/dev/pid', '/dev/ppid', '/dev/pgrpid' and
+ '/dev/user' were removed.
- * Support for IPv6 was added via the `/inet6' special file.
- `/inet4' forces IPv4 and `/inet' chooses the system default, which
- is probably IPv4 (*note TCP/IP Networking::).
+ * Support for IPv6 was added via the '/inet6' special file. '/inet4'
+ forces IPv4 and '/inet' chooses the system default, which is
+ probably IPv4 (*note TCP/IP Networking::).
- * The use of `\s' and `\S' escape sequences in regular expressions
+ * The use of '\s' and '\S' escape sequences in regular expressions
(*note GNU Regexp Operators::).
* Interval expressions became part of default regular expressions
(*note Regexp Operators::).
- * POSIX character classes work even with `--traditional' (*note
+ * POSIX character classes work even with '--traditional' (*note
Regexp Operators::).
- * `break' and `continue' became invalid outside a loop, even with
- `--traditional' (*note Break Statement::, and also see *note
+ * 'break' and 'continue' became invalid outside a loop, even with
+ '--traditional' (*note Break Statement::, and also see *note
Continue Statement::).
- * `fflush()', `nextfile', and `delete ARRAY' are allowed if
- `--posix' or `--traditional', since they are all now part of POSIX.
+ * 'fflush()', 'nextfile', and 'delete ARRAY' are allowed if '--posix'
+ or '--traditional', since they are all now part of POSIX.
- * An optional third argument to `asort()' and `asorti()', specifying
+ * An optional third argument to 'asort()' and 'asorti()', specifying
how to sort (*note String Functions::).
- * The behavior of `fflush()' changed to match BWK `awk' and for
- POSIX; now both `fflush()' and `fflush("")' flush all open output
+ * The behavior of 'fflush()' changed to match BWK 'awk' and for
+ POSIX; now both 'fflush()' and 'fflush("")' flush all open output
redirections (*note I/O Functions::).
- * The `isarray()' function which distinguishes if an item is an array
+ * The 'isarray()' function which distinguishes if an item is an array
or not, to make it possible to traverse arrays of arrays (*note
Type Functions::).
- * The `patsplit()' function which gives the same capability as
- `FPAT', for splitting (*note String Functions::).
+ * The 'patsplit()' function which gives the same capability as
+ 'FPAT', for splitting (*note String Functions::).
- * An optional fourth argument to the `split()' function, which is an
+ * An optional fourth argument to the 'split()' function, which is an
array to hold the values of the separators (*note String
Functions::).
* Arrays of arrays (*note Arrays of Arrays::).
- * The `BEGINFILE' and `ENDFILE' special patterns (*note
+ * The 'BEGINFILE' and 'ENDFILE' special patterns (*note
BEGINFILE/ENDFILE::).
* Indirect function calls (*note Indirect Calls::).
- * `switch' / `case' are enabled by default (*note Switch
+ * 'switch' / 'case' are enabled by default (*note Switch
Statement::).
* Command-line option changes (*note Options::):
- - The `-b' and `--characters-as-bytes' options which prevent
- `gawk' from treating input as a multibyte string.
+ - The '-b' and '--characters-as-bytes' options which prevent
+ 'gawk' from treating input as a multibyte string.
- - The redundant `--compat', `--copyleft', and `--usage' long
+ - The redundant '--compat', '--copyleft', and '--usage' long
options were removed.
- - The `--gen-po' option was finally renamed to the correct
- `--gen-pot'.
+ - The '--gen-po' option was finally renamed to the correct
+ '--gen-pot'.
- - The `--sandbox' option which disables certain features.
+ - The '--sandbox' option which disables certain features.
- - All long options acquired corresponding short options, for
- use in `#!' scripts.
+ - All long options acquired corresponding short options, for use
+ in '#!' scripts.
* Directories named on the command line now produce a warning, not a
- fatal error, unless `--posix' or `--traditional' are used (*note
+ fatal error, unless '--posix' or '--traditional' are used (*note
Command-line directories::).
- * The `gawk' internals were rewritten, bringing the `dgawk' debugger
+ * The 'gawk' internals were rewritten, bringing the 'dgawk' debugger
and possibly improved performance (*note Debugger::).
* Per the GNU Coding Standards, dynamic extensions must now define a
- global symbol indicating that they are GPL-compatible (*note
- Plugin License::).
+ global symbol indicating that they are GPL-compatible (*note Plugin
+ License::).
- * In POSIX mode, string comparisons use `strcoll()' / `wcscoll()'
+ * In POSIX mode, string comparisons use 'strcoll()' / 'wcscoll()'
(*note POSIX String Comparison::).
* The option for raw sockets was removed, since it was never
implemented (*note TCP/IP Networking::).
- * Ranges of the form `[d-h]' are treated as if they were in the C
+ * Ranges of the form '[d-h]' are treated as if they were in the C
locale, no matter what kind of regexp is being used, and even if
- `--posix' (*note Ranges and Locales::).
+ '--posix' (*note Ranges and Locales::).
* Support was removed for the following systems:
@@ -26854,49 +26745,48 @@ in POSIX `awk', in the order they were added to
`gawk'.
- Prestandard VAX C compiler for VAX/VMS
- Version 4.1 of `gawk' introduced the following features:
+ Version 4.1 of 'gawk' introduced the following features:
- * Three new arrays: `SYMTAB', `FUNCTAB', and
- `PROCINFO["identifiers"]' (*note Auto-set::).
+ * Three new arrays: 'SYMTAB', 'FUNCTAB', and
+ 'PROCINFO["identifiers"]' (*note Auto-set::).
- * The three executables `gawk', `pgawk', and `dgawk', were merged
- into one, named just `gawk'. As a result the command-line options
+ * The three executables 'gawk', 'pgawk', and 'dgawk', were merged
+ into one, named just 'gawk'. As a result the command-line options
changed.
* Command-line option changes (*note Options::):
- - The `-D' option invokes the debugger.
+ - The '-D' option invokes the debugger.
- - The `-i' and `--include' options load `awk' library files.
+ - The '-i' and '--include' options load 'awk' library files.
- - The `-l' and `--load' options load compiled dynamic
+ - The '-l' and '--load' options load compiled dynamic
extensions.
- - The `-M' and `--bignum' options enable MPFR.
+ - The '-M' and '--bignum' options enable MPFR.
- - The `-o' option only does pretty-printing.
+ - The '-o' option only does pretty-printing.
- - The `-p' option is used for profiling.
+ - The '-p' option is used for profiling.
- - The `-R' option was removed.
+ - The '-R' option was removed.
- * Support for high precision arithmetic with MPFR. (*note Arbitrary
+ * Support for high precision arithmetic with MPFR. (*note Arbitrary
Precision Arithmetic::).
- * The `and()', `or()' and `xor()' functions changed to allow any
+ * The 'and()', 'or()' and 'xor()' functions changed to allow any
number of arguments, with a minimum of two (*note Bitwise
Functions::).
* The dynamic extension interface was completely redone (*note
Dynamic Extensions::).
- * Redirected `getline' became allowed inside `BEGINFILE' and
- `ENDFILE' (*note BEGINFILE/ENDFILE::).
+ * Redirected 'getline' became allowed inside 'BEGINFILE' and
+ 'ENDFILE' (*note BEGINFILE/ENDFILE::).
- * The `where' command was added to the debugger (*note Execution
+ * The 'where' command was added to the debugger (*note Execution
Stack::).
-
File: gawk.info, Node: Common Extensions, Next: Ranges and Locales, Prev:
Feature History, Up: Language History
@@ -26904,25 +26794,25 @@ A.7 Common Extensions Summary
=============================
The following table summarizes the common extensions supported by
-`gawk', Brian Kernighan's `awk', and `mawk', the three most widely used
-freely available versions of `awk' (*note Other Versions::).
-
-Feature BWK `awk' `mawk' `gawk' Now standard
---------------------------------------------------------------------------
-`\x' escape sequence X X X
-`FS' as null string X X X
-`/dev/stdin' special file X X X
-`/dev/stdout' special file X X X
-`/dev/stderr' special file X X X
-`delete' without subscript X X X X
-`fflush()' function X X X X
-`length()' of an array X X X
-`nextfile' statement X X X X
-`**' and `**=' operators X X
-`func' keyword X X
-`BINMODE' variable X X
-`RS' as regexp X X
-Time-related functions X X
+'gawk', Brian Kernighan's 'awk', and 'mawk', the three most widely used
+freely available versions of 'awk' (*note Other Versions::).
+
+Feature BWK 'awk' 'mawk' 'gawk' Now standard
+--------------------------------------------------------------------------
+'\x' escape sequence X X X
+'FS' as null string X X X
+'/dev/stdin' special file X X X
+'/dev/stdout' special file X X X
+'/dev/stderr' special file X X X
+'delete' without subscript X X X X
+'fflush()' function X X X X
+'length()' of an array X X X
+'nextfile' statement X X X X
+'**' and '**=' operators X X
+'func' keyword X X
+'BINMODE' variable X X
+'RS' as regexp X X
+Time-related functions X X
File: gawk.info, Node: Ranges and Locales, Next: Contributors, Prev: Common
Extensions, Up: Language History
@@ -26930,24 +26820,24 @@ File: gawk.info, Node: Ranges and Locales, Next:
Contributors, Prev: Common E
A.8 Regexp Ranges and Locales: A Long Sad Story
===============================================
-This minor node describes the confusing history of ranges within
-regular expressions and their interactions with locales, and how this
-affected different versions of `gawk'.
+This minor node describes the confusing history of ranges within regular
+expressions and their interactions with locales, and how this affected
+different versions of 'gawk'.
The original Unix tools that worked with regular expressions defined
-character ranges (such as `[a-z]') to match any character between the
+character ranges (such as '[a-z]') to match any character between the
first character in the range and the last character in the range,
-inclusive. Ordering was based on the numeric value of each character
-in the machine's native character set. Thus, on ASCII-based systems,
-`[a-z]' matched all the lowercase letters, and only the lowercase
-letters, as the numeric values for the letters from `a' through `z'
-were contiguous. (On an EBCDIC system, the range `[a-z]' includes
-additional nonalphabetic characters as well.)
+inclusive. Ordering was based on the numeric value of each character in
+the machine's native character set. Thus, on ASCII-based systems,
+'[a-z]' matched all the lowercase letters, and only the lowercase
+letters, as the numeric values for the letters from 'a' through 'z' were
+contiguous. (On an EBCDIC system, the range '[a-z]' includes additional
+nonalphabetic characters as well.)
Almost all introductory Unix literature explained range expressions
as working in this fashion, and in particular, would teach that the
-"correct" way to match lowercase letters was with `[a-z]', and that
-`[A-Z]' was the "correct" way to match uppercase letters. And indeed,
+"correct" way to match lowercase letters was with '[a-z]', and that
+'[A-Z]' was the "correct" way to match uppercase letters. And indeed,
this was true.(1)
The 1992 POSIX standard introduced the idea of locales (*note
@@ -26958,72 +26848,72 @@ different kinds of characters besides the traditional
ones in the ASCII
character set.
However, the standard _changed_ the interpretation of range
-expressions. In the `"C"' and `"POSIX"' locales, a range expression
-like `[a-dx-z]' is still equivalent to `[abcdxyz]', as in ASCII. But
+expressions. In the '"C"' and '"POSIX"' locales, a range expression
+like '[a-dx-z]' is still equivalent to '[abcdxyz]', as in ASCII. But
outside those locales, the ordering was defined to be based on
"collation order".
- What does that mean? In many locales, `A' and `a' are both less
-than `B'. In other words, these locales sort characters in dictionary
-order, and `[a-dx-z]' is typically not equivalent to `[abcdxyz]';
-instead, it might be equivalent to `[ABCXYabcdxyz]', for example.
+ What does that mean? In many locales, 'A' and 'a' are both less than
+'B'. In other words, these locales sort characters in dictionary order,
+and '[a-dx-z]' is typically not equivalent to '[abcdxyz]'; instead, it
+might be equivalent to '[ABCXYabcdxyz]', for example.
This point needs to be emphasized: much literature teaches that you
-should use `[a-z]' to match a lowercase character. But on systems with
+should use '[a-z]' to match a lowercase character. But on systems with
non-ASCII locales, this also matches all of the uppercase characters
-except `A' or `Z'! This was a continuous cause of confusion, even well
+except 'A' or 'Z'! This was a continuous cause of confusion, even well
into the twenty-first century.
- To demonstrate these issues, the following example uses the `sub()'
+ To demonstrate these issues, the following example uses the 'sub()'
function, which does text replacement (*note String Functions::). Here,
the intent is to remove trailing uppercase characters:
$ echo something1234abc | gawk-3.1.8 '{ sub("[A-Z]*$", ""); print }'
-| something1234a
-This output is unexpected, as the `bc' at the end of `something1234abc'
-should not normally match `[A-Z]*'. This result is due to the locale
+This output is unexpected, as the 'bc' at the end of 'something1234abc'
+should not normally match '[A-Z]*'. This result is due to the locale
setting (and thus you may not see it on your system).
- Similar considerations apply to other ranges. For example, `["-/]'
+ Similar considerations apply to other ranges. For example, '["-/]'
is perfectly valid in ASCII, but is not valid in many Unicode locales,
-such as `en_US.UTF-8'.
+such as 'en_US.UTF-8'.
- Early versions of `gawk' used regexp matching code that was not
+ Early versions of 'gawk' used regexp matching code that was not
locale-aware, so ranges had their traditional interpretation.
- When `gawk' switched to using locale-aware regexp matchers, the
-problems began; especially as both GNU/Linux and commercial Unix
-vendors started implementing non-ASCII locales, _and making them the
-default_. Perhaps the most frequently asked question became something
-like, "Why does `[A-Z]' match lowercase letters?!?"
+ When 'gawk' switched to using locale-aware regexp matchers, the
+problems began; especially as both GNU/Linux and commercial Unix vendors
+started implementing non-ASCII locales, _and making them the default_.
+Perhaps the most frequently asked question became something like, "Why
+does '[A-Z]' match lowercase letters?!?"
This situation existed for close to 10 years, if not more, and the
-`gawk' maintainer grew weary of trying to explain that `gawk' was being
-nicely standards-compliant, and that the issue was in the user's
-locale. During the development of version 4.0, he modified `gawk' to
-always treat ranges in the original, pre-POSIX fashion, unless
-`--posix' was used (*note Options::).(2)
+'gawk' maintainer grew weary of trying to explain that 'gawk' was being
+nicely standards-compliant, and that the issue was in the user's locale.
+During the development of version 4.0, he modified 'gawk' to always
+treat ranges in the original, pre-POSIX fashion, unless '--posix' was
+used (*note Options::).(2)
- Fortunately, shortly before the final release of `gawk' 4.0, the
+ Fortunately, shortly before the final release of 'gawk' 4.0, the
maintainer learned that the 2008 standard had changed the definition of
-ranges, such that outside the `"C"' and `"POSIX"' locales, the meaning
+ranges, such that outside the '"C"' and '"POSIX"' locales, the meaning
of range expressions was _undefined_.(3)
By using this lovely technical term, the standard gives license to
implementors to implement ranges in whatever way they choose. The
-`gawk' maintainer chose to apply the pre-POSIX meaning both with the
-default regexp matching and when `--traditional' or `--posix' are used.
-In all cases `gawk' remains POSIX-compliant.
+'gawk' maintainer chose to apply the pre-POSIX meaning both with the
+default regexp matching and when '--traditional' or '--posix' are used.
+In all cases 'gawk' remains POSIX-compliant.
---------- Footnotes ----------
(1) And Life was good.
(2) And thus was born the Campaign for Rational Range Interpretation
-(or RRI). A number of GNU tools have already implemented this change,
-or will soon. Thanks to Karl Berry for coining the phrase "Rational
-Range Interpretation."
+(or RRI). A number of GNU tools have already implemented this change, or
+will soon. Thanks to Karl Berry for coining the phrase "Rational Range
+Interpretation."
(3) See the standard
(http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05)
@@ -27033,17 +26923,18 @@ and its rationale
File: gawk.info, Node: Contributors, Next: History summary, Prev: Ranges
and Locales, Up: Language History
-A.9 Major Contributors to `gawk'
+A.9 Major Contributors to 'gawk'
================================
- Always give credit where credit is due. -- Anonymous
+ Always give credit where credit is due.
+ -- _Anonymous_
- This minor node names the major contributors to `gawk' and/or this
+ This minor node names the major contributors to 'gawk' and/or this
Info file, in approximate chronological order:
* Dr. Alfred V. Aho, Dr. Peter J. Weinberger, and Dr. Brian W.
Kernighan, all of Bell Laboratories, designed and implemented Unix
- `awk', from which `gawk' gets the majority of its feature set.
+ 'awk', from which 'gawk' gets the majority of its feature set.
* Paul Rubin did the initial design and implementation in 1986, and
wrote the first draft (around 40 pages) of this Info file.
@@ -27054,14 +26945,14 @@ Info file, in approximate chronological order:
to around 90 pages.
* Richard Stallman helped finish the implementation and the initial
- draft of this Info file. He is also the founder of the FSF and
- the GNU Project.
+ draft of this Info file. He is also the founder of the FSF and the
+ GNU Project.
* John Woods contributed parts of the code (mostly fixes) in the
- initial version of `gawk'.
+ initial version of 'gawk'.
- * In 1988, David Trueman took over primary maintenance of `gawk',
- making it compatible with "new" `awk', and greatly improving its
+ * In 1988, David Trueman took over primary maintenance of 'gawk',
+ making it compatible with "new" 'awk', and greatly improving its
performance.
* Conrad Kwok, Scott Garfinkle, and Kent Williams did the initial
@@ -27069,7 +26960,7 @@ Info file, in approximate chronological order:
* Pat Rankin provided the VMS port and its documentation.
- * Hal Peterson provided help in porting `gawk' to Cray systems.
+ * Hal Peterson provided help in porting 'gawk' to Cray systems.
(This is no longer supported.)
* Kai Uwe Rommel provided the initial port to OS/2 and its
@@ -27077,8 +26968,8 @@ Info file, in approximate chronological order:
* Michal Jaegermann provided the port to Atari systems and its
documentation. (This port is no longer supported.) He continues
- to provide portability checking, and has done a lot of work to
- make sure `gawk' works on non-32-bit systems.
+ to provide portability checking, and has done a lot of work to make
+ sure 'gawk' works on non-32-bit systems.
* Fred Fish provided the port to Amiga systems and its documentation.
(With Fred's sad passing, this is no longer supported.)
@@ -27096,18 +26987,18 @@ Info file, in approximate chronological order:
instrumental in keeping the documentation up to date for the
various PC platforms.
- * Christos Zoulas provided the `extension()' built-in function for
- dynamically adding new functions. (This was obsoleted at `gawk'
+ * Christos Zoulas provided the 'extension()' built-in function for
+ dynamically adding new functions. (This was obsoleted at 'gawk'
4.1.)
* Ju"rgen Kahrs contributed the initial version of the TCP/IP
networking code and documentation, and motivated the inclusion of
- the `|&' operator.
+ the '|&' operator.
* Stephen Davies provided the initial port to Tandem systems and its
documentation. (However, this is no longer supported.) He was
also instrumental in the initial work to integrate the byte-code
- internals into the `gawk' code base.
+ internals into the 'gawk' code base.
* Matthew Woehlke provided improvements for Tandem's POSIX-compliant
systems.
@@ -27115,19 +27006,19 @@ Info file, in approximate chronological order:
* Martin Brown provided the port to BeOS and its documentation.
(This is no longer supported.)
- * Arno Peters did the initial work to convert `gawk' to use GNU
- Automake and GNU `gettext'.
+ * Arno Peters did the initial work to convert 'gawk' to use GNU
+ Automake and GNU 'gettext'.
- * Alan J. Broder provided the initial version of the `asort()'
+ * Alan J. Broder provided the initial version of the 'asort()'
function as well as the code for the optional third argument to the
- `match()' function.
+ 'match()' function.
- * Andreas Buening updated the `gawk' port for OS/2.
+ * Andreas Buening updated the 'gawk' port for OS/2.
* Isamu Hasegawa, of IBM in Japan, contributed support for multibyte
characters.
- * Michael Benzinger contributed the initial code for `switch'
+ * Michael Benzinger contributed the initial code for 'switch'
statements.
* Patrick T.J. McPhee contributed the code for dynamic loading in
@@ -27135,12 +27026,12 @@ Info file, in approximate chronological order:
* Anders Wallin helped keep the VMS port going for several years.
- * Assaf Gordon contributed the code to implement the `--sandbox'
+ * Assaf Gordon contributed the code to implement the '--sandbox'
option.
* John Haque made the following contributions:
- - The modifications to convert `gawk' into a byte-code
+ - The modifications to convert 'gawk' into a byte-code
interpreter, including the debugger
- The addition of true arrays of arrays
@@ -27150,7 +27041,7 @@ Info file, in approximate chronological order:
- The initial text of *note Arbitrary Precision Arithmetic::
- - The work to merge the three versions of `gawk' into one, for
+ - The work to merge the three versions of 'gawk' into one, for
the 4.1 release
- Improved array internals for arrays indexed by integers
@@ -27163,8 +27054,8 @@ Info file, in approximate chronological order:
* Efraim Yawitz contributed the original text for *note Debugger::.
- * The development of the extension API first released with `gawk'
- 4.1 was driven primarily by Arnold Robbins and Andrew Schorr, with
+ * The development of the extension API first released with 'gawk' 4.1
+ was driven primarily by Arnold Robbins and Andrew Schorr, with
notable contributions from the rest of the development team.
* John Malmberg contributed significant improvements to the OpenVMS
@@ -27174,7 +27065,7 @@ Info file, in approximate chronological order:
chapters that were severely dated, for which I am incredibly
grateful.
- * Arnold Robbins has been working on `gawk' since 1988, at first
+ * Arnold Robbins has been working on 'gawk' since 1988, at first
helping David Trueman, and as the primary maintainer since around
1994.
@@ -27184,62 +27075,61 @@ File: gawk.info, Node: History summary, Prev:
Contributors, Up: Language Hist
A.10 Summary
============
- * The `awk' language has evolved over time. The first release was
- with V7 Unix, circa 1978. In 1987, for System V Release 3.1,
- major additions, including user-defined functions, were made to
- the language. Additional changes were made for System V Release
- 4, in 1989. Since then, further minor changes have happened under
- the auspices of the POSIX standard.
+ * The 'awk' language has evolved over time. The first release was
+ with V7 Unix, circa 1978. In 1987, for System V Release 3.1, major
+ additions, including user-defined functions, were made to the
+ language. Additional changes were made for System V Release 4, in
+ 1989. Since then, further minor changes have happened under the
+ auspices of the POSIX standard.
- * Brian Kernighan's `awk' provides a small number of extensions that
- are implemented in common with other versions of `awk'.
+ * Brian Kernighan's 'awk' provides a small number of extensions that
+ are implemented in common with other versions of 'awk'.
- * `gawk' provides a large number of extensions over POSIX `awk'.
- They can be disabled with either the `--traditional' or `--posix'
+ * 'gawk' provides a large number of extensions over POSIX 'awk'.
+ They can be disabled with either the '--traditional' or '--posix'
options.
- * The interaction of POSIX locales and regexp matching in `gawk' has
- been confusing over the years. Today, `gawk' implements Rational
- Range Interpretation, where ranges of the form `[a-z]' match
- _only_ the characters numerically between `a' through `z' in the
- machine's native character set. Usually this is ASCII, but it can
- be EBCDIC on IBM S/390 systems.
+ * The interaction of POSIX locales and regexp matching in 'gawk' has
+ been confusing over the years. Today, 'gawk' implements Rational
+ Range Interpretation, where ranges of the form '[a-z]' match _only_
+ the characters numerically between 'a' through 'z' in the machine's
+ native character set. Usually this is ASCII, but it can be EBCDIC
+ on IBM S/390 systems.
- * Many people have contributed to `gawk' development over the years.
+ * Many people have contributed to 'gawk' development over the years.
We hope that the list provided in this major node is complete and
gives the appropriate credit where credit is due.
-
File: gawk.info, Node: Installation, Next: Notes, Prev: Language History,
Up: Top
-Appendix B Installing `gawk'
+Appendix B Installing 'gawk'
****************************
-This appendix provides instructions for installing `gawk' on the
-various platforms that are supported by the developers. The primary
-developer supports GNU/Linux (and Unix), whereas the other ports are
-contributed. *Note Bugs::, for the email addresses of the people who
-maintain the respective ports.
+This appendix provides instructions for installing 'gawk' on the various
+platforms that are supported by the developers. The primary developer
+supports GNU/Linux (and Unix), whereas the other ports are contributed.
+*Note Bugs::, for the email addresses of the people who maintain the
+respective ports.
* Menu:
-* Gawk Distribution:: What is in the `gawk' distribution.
-* Unix Installation:: Installing `gawk' under various
+* Gawk Distribution:: What is in the 'gawk' distribution.
+* Unix Installation:: Installing 'gawk' under various
versions of Unix.
* Non-Unix Installation:: Installation on Other Operating Systems.
* Bugs:: Reporting Problems and Bugs.
-* Other Versions:: Other freely available `awk'
+* Other Versions:: Other freely available 'awk'
implementations.
* Installation summary:: Summary of installation.
File: gawk.info, Node: Gawk Distribution, Next: Unix Installation, Up:
Installation
-B.1 The `gawk' Distribution
+B.1 The 'gawk' Distribution
===========================
-This minor node describes how to get the `gawk' distribution, how to
+This minor node describes how to get the 'gawk' distribution, how to
extract it, and then what is in the various files and subdirectories.
* Menu:
@@ -27251,16 +27141,16 @@ extract it, and then what is in the various files and
subdirectories.
File: gawk.info, Node: Getting, Next: Extracting, Up: Gawk Distribution
-B.1.1 Getting the `gawk' Distribution
+B.1.1 Getting the 'gawk' Distribution
-------------------------------------
There are two ways to get GNU software:
* Copy it from someone else who already has it.
- * Retrieve `gawk' from the Internet host `ftp.gnu.org', in the
- directory `/gnu/gawk'. Both anonymous `ftp' and `http' access are
- supported. If you have the `wget' program, you can use a command
+ * Retrieve 'gawk' from the Internet host 'ftp.gnu.org', in the
+ directory '/gnu/gawk'. Both anonymous 'ftp' and 'http' access are
+ supported. If you have the 'wget' program, you can use a command
like the following:
wget http://ftp.gnu.org/gnu/gawk/gawk-4.1.2.tar.gz
@@ -27277,283 +27167,281 @@ File: gawk.info, Node: Extracting, Next:
Distribution contents, Prev: Getting
B.1.2 Extracting the Distribution
---------------------------------
-`gawk' is distributed as several `tar' files compressed with different
-compression programs: `gzip', `bzip2', and `xz'. For simplicity, the
+'gawk' is distributed as several 'tar' files compressed with different
+compression programs: 'gzip', 'bzip2', and 'xz'. For simplicity, the
rest of these instructions assume you are using the one compressed with
-the GNU Gzip program (`gzip').
+the GNU Gzip program ('gzip').
- Once you have the distribution (e.g., `gawk-4.1.2.tar.gz'), use
-`gzip' to expand the file and then use `tar' to extract it. You can
-use the following pipeline to produce the `gawk' distribution:
+ Once you have the distribution (e.g., 'gawk-4.1.2.tar.gz'), use
+'gzip' to expand the file and then use 'tar' to extract it. You can use
+the following pipeline to produce the 'gawk' distribution:
gzip -d -c gawk-4.1.2.tar.gz | tar -xvpf -
- On a system with GNU `tar', you can let `tar' do the decompression
+ On a system with GNU 'tar', you can let 'tar' do the decompression
for you:
tar -xvpzf gawk-4.1.2.tar.gz
-Extracting the archive creates a directory named `gawk-4.1.2' in the
+Extracting the archive creates a directory named 'gawk-4.1.2' in the
current directory.
- The distribution file name is of the form `gawk-V.R.P.tar.gz'. The
-V represents the major version of `gawk', the R represents the current
-release of version V, and the P represents a "patch level", meaning
-that minor bugs have been fixed in the release. The current patch
-level is 2, but when retrieving distributions, you should get the
-version with the highest version, release, and patch level. (Note,
-however, that patch levels greater than or equal to 70 denote "beta" or
-nonproduction software; you might not want to retrieve such a version
-unless you don't mind experimenting.) If you are not on a Unix or
-GNU/Linux system, you need to make other arrangements for getting and
-extracting the `gawk' distribution. You should consult a local expert.
+ The distribution file name is of the form 'gawk-V.R.P.tar.gz'. The V
+represents the major version of 'gawk', the R represents the current
+release of version V, and the P represents a "patch level", meaning that
+minor bugs have been fixed in the release. The current patch level is
+2, but when retrieving distributions, you should get the version with
+the highest version, release, and patch level. (Note, however, that
+patch levels greater than or equal to 70 denote "beta" or nonproduction
+software; you might not want to retrieve such a version unless you don't
+mind experimenting.) If you are not on a Unix or GNU/Linux system, you
+need to make other arrangements for getting and extracting the 'gawk'
+distribution. You should consult a local expert.
File: gawk.info, Node: Distribution contents, Prev: Extracting, Up: Gawk
Distribution
-B.1.3 Contents of the `gawk' Distribution
+B.1.3 Contents of the 'gawk' Distribution
-----------------------------------------
-The `gawk' distribution has a number of C source files, documentation
+The 'gawk' distribution has a number of C source files, documentation
files, subdirectories, and files related to the configuration process
(*note Unix Installation::), as well as several subdirectories related
to different non-Unix operating systems:
-Various `.c', `.y', and `.h' files
- These files contain the actual `gawk' source code.
+Various '.c', '.y', and '.h' files
+ These files contain the actual 'gawk' source code.
-`ABOUT-NLS'
- A file containing information about GNU `gettext' and translations.
+'ABOUT-NLS'
+ A file containing information about GNU 'gettext' and translations.
-`AUTHORS'
- A file with some information about the authorship of `gawk'. It
+'AUTHORS'
+ A file with some information about the authorship of 'gawk'. It
exists only to satisfy the pedants at the Free Software Foundation.
-`README'
-`README_d/README.*'
- Descriptive files: `README' for `gawk' under Unix and the rest for
+'README'
+'README_d/README.*'
+ Descriptive files: 'README' for 'gawk' under Unix and the rest for
the various hardware and software combinations.
-`INSTALL'
+'INSTALL'
A file providing an overview of the configuration and installation
process.
-`ChangeLog'
+'ChangeLog'
A detailed list of source code changes as bugs are fixed or
improvements made.
-`ChangeLog.0'
+'ChangeLog.0'
An older list of source code changes.
-`NEWS'
- A list of changes to `gawk' since the last release or patch.
+'NEWS'
+ A list of changes to 'gawk' since the last release or patch.
-`NEWS.0'
- An older list of changes to `gawk'.
+'NEWS.0'
+ An older list of changes to 'gawk'.
-`COPYING'
+'COPYING'
The GNU General Public License.
-`POSIX.STD'
- A description of behaviors in the POSIX standard for `awk' that
- are left undefined, or where `gawk' may not comply fully, as well
- as a list of things that the POSIX standard should describe but
- does not.
+'POSIX.STD'
+ A description of behaviors in the POSIX standard for 'awk' that are
+ left undefined, or where 'gawk' may not comply fully, as well as a
+ list of things that the POSIX standard should describe but does
+ not.
-`doc/awkforai.txt'
+'doc/awkforai.txt'
Pointers to the original draft of a short article describing why
- `gawk' is a good language for artificial intelligence (AI)
+ 'gawk' is a good language for artificial intelligence (AI)
programming.
-`doc/bc_notes'
- A brief description of `gawk''s "byte code" internals.
-
-`doc/README.card'
-`doc/ad.block'
-`doc/awkcard.in'
-`doc/cardfonts'
-`doc/colors'
-`doc/macros'
-`doc/no.colors'
-`doc/setter.outline'
- The `troff' source for a five-color `awk' reference card. A
- modern version of `troff' such as GNU `troff' (`groff') is needed
- to produce the color version. See the file `README.card' for
- instructions if you have an older `troff'.
-
-`doc/gawk.1'
- The `troff' source for a manual page describing `gawk'. This is
+'doc/bc_notes'
+ A brief description of 'gawk''s "byte code" internals.
+
+'doc/README.card'
+'doc/ad.block'
+'doc/awkcard.in'
+'doc/cardfonts'
+'doc/colors'
+'doc/macros'
+'doc/no.colors'
+'doc/setter.outline'
+ The 'troff' source for a five-color 'awk' reference card. A modern
+ version of 'troff' such as GNU 'troff' ('groff') is needed to
+ produce the color version. See the file 'README.card' for
+ instructions if you have an older 'troff'.
+
+'doc/gawk.1'
+ The 'troff' source for a manual page describing 'gawk'. This is
distributed for the convenience of Unix users.
-`doc/gawktexi.in'
-`doc/sidebar.awk'
- The Texinfo source file for this Info file. It should be
- processed by `doc/sidebar.awk' before processing with `texi2dvi'
- or `texi2pdf' to produce a printed document, and with `makeinfo'
- to produce an Info or HTML file. The `Makefile' takes care of
- this processing and produces printable output via `texi2dvi' or
- `texi2pdf'.
+'doc/gawktexi.in'
+'doc/sidebar.awk'
+ The Texinfo source file for this Info file. It should be processed
+ by 'doc/sidebar.awk' before processing with 'texi2dvi' or
+ 'texi2pdf' to produce a printed document, and with 'makeinfo' to
+ produce an Info or HTML file. The 'Makefile' takes care of this
+ processing and produces printable output via 'texi2dvi' or
+ 'texi2pdf'.
-`doc/gawk.texi'
- The file produced after processing `gawktexi.in' with
- `sidebar.awk'.
+'doc/gawk.texi'
+ The file produced after processing 'gawktexi.in' with
+ 'sidebar.awk'.
-`doc/gawk.info'
+'doc/gawk.info'
The generated Info file for this Info file.
-`doc/gawkinet.texi'
- The Texinfo source file for *note (General Introduction)Top::
- gawkinet, TCP/IP Internetworking with `gawk'. It should be
- processed with TeX (via `texi2dvi' or `texi2pdf') to produce a
- printed document and with `makeinfo' to produce an Info or HTML
- file.
+'doc/gawkinet.texi'
+ The Texinfo source file for *note (General Introduction, gawkinet,
+ TCP/IP Internetworking with 'gawk')Top::. It should be processed
+ with TeX (via 'texi2dvi' or 'texi2pdf') to produce a printed
+ document and with 'makeinfo' to produce an Info or HTML file.
-`doc/gawkinet.info'
- The generated Info file for `TCP/IP Internetworking with `gawk''.
+'doc/gawkinet.info'
+ The generated Info file for 'TCP/IP Internetworking with 'gawk''.
-`doc/igawk.1'
- The `troff' source for a manual page describing the `igawk'
- program presented in *note Igawk Program::.
+'doc/igawk.1'
+ The 'troff' source for a manual page describing the 'igawk' program
+ presented in *note Igawk Program::.
-`doc/Makefile.in'
+'doc/Makefile.in'
The input file used during the configuration process to generate
- the actual `Makefile' for creating the documentation.
+ the actual 'Makefile' for creating the documentation.
-`Makefile.am'
-`*/Makefile.am'
+'Makefile.am'
+'*/Makefile.am'
Files used by the GNU Automake software for generating the
- `Makefile.in' files used by Autoconf and `configure'.
-
-`Makefile.in'
-`aclocal.m4'
-`bisonfix.awk'
-`config.guess'
-`configh.in'
-`configure.ac'
-`configure'
-`custom.h'
-`depcomp'
-`install-sh'
-`missing_d/*'
-`mkinstalldirs'
-`m4/*'
+ 'Makefile.in' files used by Autoconf and 'configure'.
+
+'Makefile.in'
+'aclocal.m4'
+'bisonfix.awk'
+'config.guess'
+'configh.in'
+'configure.ac'
+'configure'
+'custom.h'
+'depcomp'
+'install-sh'
+'missing_d/*'
+'mkinstalldirs'
+'m4/*'
These files and subdirectories are used when configuring and
- compiling `gawk' for various Unix systems. Most of them are
- explained in *note Unix Installation::. The rest are there to
+ compiling 'gawk' for various Unix systems. Most of them are
+ explained in *note Unix Installation::. The rest are there to
support the main infrastructure.
-`po/*'
- The `po' library contains message translations.
+'po/*'
+ The 'po' library contains message translations.
-`awklib/extract.awk'
-`awklib/Makefile.am'
-`awklib/Makefile.in'
-`awklib/eg/*'
- The `awklib' directory contains a copy of `extract.awk' (*note
+'awklib/extract.awk'
+'awklib/Makefile.am'
+'awklib/Makefile.in'
+'awklib/eg/*'
+ The 'awklib' directory contains a copy of 'extract.awk' (*note
Extract Program::), which can be used to extract the sample
- programs from the Texinfo source file for this Info file. It also
- contains a `Makefile.in' file, which `configure' uses to generate
- a `Makefile'. `Makefile.am' is used by GNU Automake to create
- `Makefile.in'. The library functions from *note Library
- Functions::, and the `igawk' program from *note Igawk Program::,
- are included as ready-to-use files in the `gawk' distribution.
+ programs from the Texinfo source file for this Info file. It also
+ contains a 'Makefile.in' file, which 'configure' uses to generate a
+ 'Makefile'. 'Makefile.am' is used by GNU Automake to create
+ 'Makefile.in'. The library functions from *note Library
+ Functions::, and the 'igawk' program from *note Igawk Program::,
+ are included as ready-to-use files in the 'gawk' distribution.
They are installed as part of the installation process. The rest
of the programs in this Info file are available in appropriate
- subdirectories of `awklib/eg'.
+ subdirectories of 'awklib/eg'.
-`extension/*'
+'extension/*'
The source code, manual pages, and infrastructure files for the
- sample extensions included with `gawk'. *Note Dynamic
+ sample extensions included with 'gawk'. *Note Dynamic
Extensions::, for more information.
-`posix/*'
- Files needed for building `gawk' on POSIX-compliant systems.
+'posix/*'
+ Files needed for building 'gawk' on POSIX-compliant systems.
-`pc/*'
- Files needed for building `gawk' under MS-Windows and OS/2 (*note
+'pc/*'
+ Files needed for building 'gawk' under MS-Windows and OS/2 (*note
PC Installation::, for details).
-`vms/*'
- Files needed for building `gawk' under Vax/VMS and OpenVMS (*note
+'vms/*'
+ Files needed for building 'gawk' under Vax/VMS and OpenVMS (*note
VMS Installation::, for details).
-`test/*'
- A test suite for `gawk'. You can use `make check' from the
- top-level `gawk' directory to run your version of `gawk' against
- the test suite. If `gawk' successfully passes `make check', then
+'test/*'
+ A test suite for 'gawk'. You can use 'make check' from the
+ top-level 'gawk' directory to run your version of 'gawk' against
+ the test suite. If 'gawk' successfully passes 'make check', then
you can be confident of a successful port.
File: gawk.info, Node: Unix Installation, Next: Non-Unix Installation,
Prev: Gawk Distribution, Up: Installation
-B.2 Compiling and Installing `gawk' on Unix-Like Systems
+B.2 Compiling and Installing 'gawk' on Unix-Like Systems
========================================================
-Usually, you can compile and install `gawk' by typing only two
-commands. However, if you use an unusual system, you may need to
-configure `gawk' for your system yourself.
+Usually, you can compile and install 'gawk' by typing only two commands.
+However, if you use an unusual system, you may need to configure 'gawk'
+for your system yourself.
* Menu:
-* Quick Installation:: Compiling `gawk' under Unix.
+* Quick Installation:: Compiling 'gawk' under Unix.
* Additional Configuration Options:: Other compile-time options.
* Configuration Philosophy:: How it's all supposed to work.
File: gawk.info, Node: Quick Installation, Next: Additional Configuration
Options, Up: Unix Installation
-B.2.1 Compiling `gawk' for Unix-Like Systems
+B.2.1 Compiling 'gawk' for Unix-Like Systems
--------------------------------------------
The normal installation steps should work on all modern commercial
Unix-derived systems, GNU/Linux, BSD-based systems, and the Cygwin
environment for MS-Windows.
- After you have extracted the `gawk' distribution, `cd' to
-`gawk-4.1.2'. As with most GNU software, you configure `gawk' for your
-system by running the `configure' program. This program is a Bourne
+ After you have extracted the 'gawk' distribution, 'cd' to
+'gawk-4.1.2'. As with most GNU software, you configure 'gawk' for your
+system by running the 'configure' program. This program is a Bourne
shell script that is generated automatically using GNU Autoconf. (The
-Autoconf software is described fully starting with *note
-(Autoconf)Top:: autoconf,Autoconf--Generating Automatic Configuration
-Scripts.)
+Autoconf software is described fully starting with *note (Autoconf,
+autoconf,Autoconf---Generating Automatic Configuration Scripts)Top::.)
- To configure `gawk', simply run `configure':
+ To configure 'gawk', simply run 'configure':
sh ./configure
- This produces a `Makefile' and `config.h' tailored to your system.
-The `config.h' file describes various facts about your system. You
-might want to edit the `Makefile' to change the `CFLAGS' variable,
-which controls the command-line options that are passed to the C
-compiler (such as optimization levels or compiling for debugging).
+ This produces a 'Makefile' and 'config.h' tailored to your system.
+The 'config.h' file describes various facts about your system. You
+might want to edit the 'Makefile' to change the 'CFLAGS' variable, which
+controls the command-line options that are passed to the C compiler
+(such as optimization levels or compiling for debugging).
- Alternatively, you can add your own values for most `make' variables
-on the command line, such as `CC' and `CFLAGS', when running
-`configure':
+ Alternatively, you can add your own values for most 'make' variables
+on the command line, such as 'CC' and 'CFLAGS', when running
+'configure':
CC=cc CFLAGS=-g sh ./configure
-See the file `INSTALL' in the `gawk' distribution for all the details.
+See the file 'INSTALL' in the 'gawk' distribution for all the details.
- After you have run `configure' and possibly edited the `Makefile',
+ After you have run 'configure' and possibly edited the 'Makefile',
type:
make
-Shortly thereafter, you should have an executable version of `gawk'.
-That's all there is to it! To verify that `gawk' is working properly,
-run `make check'. All of the tests should succeed. If these steps do
-not work, or if any of the tests fail, check the files in the
-`README_d' directory to see if you've found a known problem. If the
-failure is not described there, send in a bug report (*note Bugs::).
-
- Of course, once you've built `gawk', it is likely that you will wish
-to install it. To do so, you need to run the command `make install',
-as a user with the appropriate permissions. How to do this varies by
-system, but on many systems you can use the `sudo' command to do so.
-The command then becomes `sudo make install'. It is likely that you
+Shortly thereafter, you should have an executable version of 'gawk'.
+That's all there is to it! To verify that 'gawk' is working properly,
+run 'make check'. All of the tests should succeed. If these steps do
+not work, or if any of the tests fail, check the files in the 'README_d'
+directory to see if you've found a known problem. If the failure is not
+described there, send in a bug report (*note Bugs::).
+
+ Of course, once you've built 'gawk', it is likely that you will wish
+to install it. To do so, you need to run the command 'make install', as
+a user with the appropriate permissions. How to do this varies by
+system, but on many systems you can use the 'sudo' command to do so.
+The command then becomes 'sudo make install'. It is likely that you
will be asked for your password, and you will have to have been set up
-previously as a user who is allowed to run the `sudo' command.
+previously as a user who is allowed to run the 'sudo' command.
File: gawk.info, Node: Additional Configuration Options, Next: Configuration
Philosophy, Prev: Quick Installation, Up: Unix Installation
@@ -27561,43 +27449,43 @@ File: gawk.info, Node: Additional Configuration
Options, Next: Configuration P
B.2.2 Additional Configuration Options
--------------------------------------
-There are several additional options you may use on the `configure'
-command line when compiling `gawk' from scratch, including:
+There are several additional options you may use on the 'configure'
+command line when compiling 'gawk' from scratch, including:
-`--disable-extensions'
+'--disable-extensions'
Disable configuring and building the sample extensions in the
- `extension' directory. This is useful for cross-compiling. The
+ 'extension' directory. This is useful for cross-compiling. The
default action is to dynamically check if the extensions can be
configured and compiled.
-`--disable-lint'
- Disable all lint checking within `gawk'. The `--lint' and
- `--lint-old' options (*note Options::) are accepted, but silently
- do nothing. Similarly, setting the `LINT' variable (*note
- User-modified::) has no effect on the running `awk' program.
+'--disable-lint'
+ Disable all lint checking within 'gawk'. The '--lint' and
+ '--lint-old' options (*note Options::) are accepted, but silently
+ do nothing. Similarly, setting the 'LINT' variable (*note
+ User-modified::) has no effect on the running 'awk' program.
When used with the GNU Compiler Collection's (GCC's) automatic
dead-code-elimination, this option cuts almost 23K bytes off the
- size of the `gawk' executable on GNU/Linux x86_64 systems.
- Results on other systems and with other compilers are likely to
- vary. Using this option may bring you some slight performance
+ size of the 'gawk' executable on GNU/Linux x86_64 systems. Results
+ on other systems and with other compilers are likely to vary.
+ Using this option may bring you some slight performance
improvement.
- CAUTION: Using this option will cause some of the tests in
- the test suite to fail. This option may be removed at a
- later date.
+ CAUTION: Using this option will cause some of the tests in the
+ test suite to fail. This option may be removed at a later
+ date.
-`--disable-nls'
+'--disable-nls'
Disable all message-translation facilities. This is usually not
desirable, but it may bring you some slight performance
improvement.
-`--with-whiny-user-strftime'
- Force use of the included version of the C `strftime()' function
+'--with-whiny-user-strftime'
+ Force use of the included version of the C 'strftime()' function
for deficient systems.
- Use the command `./configure --help' to see the full list of options
-supplied by `configure'.
+ Use the command './configure --help' to see the full list of options
+supplied by 'configure'.
File: gawk.info, Node: Configuration Philosophy, Prev: Additional
Configuration Options, Up: Unix Installation
@@ -27608,42 +27496,42 @@ B.2.3 The Configuration Process
This minor node is of interest only if you know something about using
the C language and Unix-like operating systems.
- The source code for `gawk' generally attempts to adhere to formal
-standards wherever possible. This means that `gawk' uses library
+ The source code for 'gawk' generally attempts to adhere to formal
+standards wherever possible. This means that 'gawk' uses library
routines that are specified by the ISO C standard and by the POSIX
-operating system interface standard. The `gawk' source code requires
+operating system interface standard. The 'gawk' source code requires
using an ISO C compiler (the 1990 standard).
Many Unix systems do not support all of either the ISO or the POSIX
-standards. The `missing_d' subdirectory in the `gawk' distribution
-contains replacement versions of those functions that are most likely
-to be missing.
+standards. The 'missing_d' subdirectory in the 'gawk' distribution
+contains replacement versions of those functions that are most likely to
+be missing.
- The `config.h' file that `configure' creates contains definitions
+ The 'config.h' file that 'configure' creates contains definitions
that describe features of the particular operating system where you are
-attempting to compile `gawk'. The three things described by this file
+attempting to compile 'gawk'. The three things described by this file
are: what header files are available, so that they can be correctly
-included, what (supposedly) standard functions are actually available
-in your C libraries, and various miscellaneous facts about your
-operating system. For example, there may not be an `st_blksize'
-element in the `stat' structure. In this case,
-`HAVE_STRUCT_STAT_ST_BLKSIZE' is undefined.
+included, what (supposedly) standard functions are actually available in
+your C libraries, and various miscellaneous facts about your operating
+system. For example, there may not be an 'st_blksize' element in the
+'stat' structure. In this case, 'HAVE_STRUCT_STAT_ST_BLKSIZE' is
+undefined.
- It is possible for your C compiler to lie to `configure'. It may do
+ It is possible for your C compiler to lie to 'configure'. It may do
so by not exiting with an error when a library function is not
-available. To get around this, edit the `custom.h' file. Use an
-`#ifdef' that is appropriate for your system, and either `#define' any
-constants that `configure' should have defined but didn't, or `#undef'
-any constants that `configure' defined and should not have. The
-`custom.h' file is automatically included by the `config.h' file.
+available. To get around this, edit the 'custom.h' file. Use an
+'#ifdef' that is appropriate for your system, and either '#define' any
+constants that 'configure' should have defined but didn't, or '#undef'
+any constants that 'configure' defined and should not have. The
+'custom.h' file is automatically included by the 'config.h' file.
- It is also possible that the `configure' program generated by
+ It is also possible that the 'configure' program generated by
Autoconf will not work on your system in some other fashion. If you do
-have a problem, the `configure.ac' file is the input for Autoconf. You
+have a problem, the 'configure.ac' file is the input for Autoconf. You
may be able to change this file and generate a new version of
-`configure' that works on your system (*note Bugs::, for information on
-how to report problems in configuring `gawk'). The same mechanism may
-be used to send in updates to `configure.ac' and/or `custom.h'.
+'configure' that works on your system (*note Bugs::, for information on
+how to report problems in configuring 'gawk'). The same mechanism may
+be used to send in updates to 'configure.ac' and/or 'custom.h'.
File: gawk.info, Node: Non-Unix Installation, Next: Bugs, Prev: Unix
Installation, Up: Installation
@@ -27651,14 +27539,14 @@ File: gawk.info, Node: Non-Unix Installation, Next:
Bugs, Prev: Unix Installa
B.3 Installation on Other Operating Systems
===========================================
-This minor node describes how to install `gawk' on various non-Unix
+This minor node describes how to install 'gawk' on various non-Unix
systems.
* Menu:
-* PC Installation:: Installing and Compiling `gawk' on
+* PC Installation:: Installing and Compiling 'gawk' on
MS-DOS and OS/2.
-* VMS Installation:: Installing `gawk' on VMS.
+* VMS Installation:: Installing 'gawk' on VMS.
File: gawk.info, Node: PC Installation, Next: VMS Installation, Up:
Non-Unix Installation
@@ -27666,29 +27554,29 @@ File: gawk.info, Node: PC Installation, Next: VMS
Installation, Up: Non-Unix
B.3.1 Installation on PC Operating Systems
------------------------------------------
-This minor node covers installation and usage of `gawk' on Intel
+This minor node covers installation and usage of 'gawk' on Intel
architecture machines running MS-DOS, any version of MS-Windows, or
OS/2. In this minor node, the term "Windows32" refers to any of
Microsoft Windows 95/98/ME/NT/2000/XP/Vista/7/8.
The limitations of MS-DOS (and MS-DOS shells under the other
operating systems) have meant that various "DOS extenders" are often
-used with programs such as `gawk'. The varying capabilities of
+used with programs such as 'gawk'. The varying capabilities of
Microsoft Windows 3.1 and Windows32 can add to the confusion. For an
-overview of the considerations, refer to `README_d/README.pc' in the
+overview of the considerations, refer to 'README_d/README.pc' in the
distribution.
* Menu:
* PC Binary Installation:: Installing a prepared distribution.
-* PC Compiling:: Compiling `gawk' for MS-DOS,
+* PC Compiling:: Compiling 'gawk' for MS-DOS,
Windows32, and OS/2.
-* PC Testing:: Testing `gawk' on PC systems.
-* PC Using:: Running `gawk' on MS-DOS, Windows32
+* PC Testing:: Testing 'gawk' on PC systems.
+* PC Using:: Running 'gawk' on MS-DOS, Windows32
and OS/2.
-* Cygwin:: Building and running `gawk' for
+* Cygwin:: Building and running 'gawk' for
Cygwin.
-* MSYS:: Using `gawk' In The MSYS Environment.
+* MSYS:: Using 'gawk' In The MSYS Environment.
File: gawk.info, Node: PC Binary Installation, Next: PC Compiling, Up: PC
Installation
@@ -27697,30 +27585,30 @@ B.3.1.1 Installing a Prepared Distribution for PC
Systems
.........................................................
If you have received a binary distribution prepared by the MS-DOS
-maintainers, then `gawk' and the necessary support files appear under
-the `gnu' directory, with executables in `gnu/bin', libraries in
-`gnu/lib/awk', and manual pages under `gnu/man'. This is designed for
-easy installation to a `/gnu' directory on your drive--however, the
-files can be installed anywhere provided `AWKPATH' is set properly.
-Regardless of the installation directory, the first line of `igawk.cmd'
-and `igawk.bat' (in `gnu/bin') may need to be edited.
+maintainers, then 'gawk' and the necessary support files appear under
+the 'gnu' directory, with executables in 'gnu/bin', libraries in
+'gnu/lib/awk', and manual pages under 'gnu/man'. This is designed for
+easy installation to a '/gnu' directory on your drive--however, the
+files can be installed anywhere provided 'AWKPATH' is set properly.
+Regardless of the installation directory, the first line of 'igawk.cmd'
+and 'igawk.bat' (in 'gnu/bin') may need to be edited.
The binary distribution contains a separate file describing the
-contents. In particular, it may include more than one version of the
-`gawk' executable.
-
- OS/2 (32 bit, EMX) binary distributions are prepared for the `/usr'
-directory of your preferred drive. Set `UNIXROOT' to your installation
-drive (e.g., `e:') if you want to install `gawk' onto another drive
-than the hardcoded default `c:'. Executables appear in `/usr/bin',
-libraries under `/usr/share/awk', manual pages under `/usr/man',
-Texinfo documentation under `/usr/info', and NLS files under
-`/usr/share/locale'. Note that the files can be installed anywhere
-provided `AWKPATH' is set properly.
-
- If you already have a file `/usr/info/dir' from another package _do
-not overwrite it!_ Instead enter the following commands at your prompt
-(replace `x:' by your installation drive):
+contents. In particular, it may include more than one version of the
+'gawk' executable.
+
+ OS/2 (32 bit, EMX) binary distributions are prepared for the '/usr'
+directory of your preferred drive. Set 'UNIXROOT' to your installation
+drive (e.g., 'e:') if you want to install 'gawk' onto another drive than
+the hardcoded default 'c:'. Executables appear in '/usr/bin', libraries
+under '/usr/share/awk', manual pages under '/usr/man', Texinfo
+documentation under '/usr/info', and NLS files under
+'/usr/share/locale'. Note that the files can be installed anywhere
+provided 'AWKPATH' is set properly.
+
+ If you already have a file '/usr/info/dir' from another package _do
+not overwrite it!_ Instead enter the following commands at your prompt
+(replace 'x:' by your installation drive):
install-info --info-dir=x:/usr/info x:/usr/info/gawk.info
install-info --info-dir=x:/usr/info x:/usr/info/gawkinet.info
@@ -27731,40 +27619,40 @@ additional or more detailed installation instructions.
File: gawk.info, Node: PC Compiling, Next: PC Testing, Prev: PC Binary
Installation, Up: PC Installation
-B.3.1.2 Compiling `gawk' for PC Operating Systems
+B.3.1.2 Compiling 'gawk' for PC Operating Systems
.................................................
-`gawk' can be compiled for MS-DOS, Windows32, and OS/2 using the GNU
+'gawk' can be compiled for MS-DOS, Windows32, and OS/2 using the GNU
development tools from DJ Delorie (DJGPP: MS-DOS only), MinGW
(Windows32) or Eberhard Mattes (EMX: MS-DOS, Windows32 and OS/2). The
-file `README_d/README.pc' in the `gawk' distribution contains
-additional notes, and `pc/Makefile' contains important information on
-compilation options.
-
-To build `gawk' for MS-DOS and Windows32, copy the files in the `pc'
-directory (_except_ for `ChangeLog') to the directory with the rest of
-the `gawk' sources, then invoke `make' with the appropriate target name
-as an argument to build `gawk'. The `Makefile' copied from the `pc'
-directory contains a configuration section with comments and may need
-to be edited in order to work with your `make' utility.
-
- The `Makefile' supports a number of targets for building various
+file 'README_d/README.pc' in the 'gawk' distribution contains additional
+notes, and 'pc/Makefile' contains important information on compilation
+options.
+
+ To build 'gawk' for MS-DOS and Windows32, copy the files in the 'pc'
+directory (_except_ for 'ChangeLog') to the directory with the rest of
+the 'gawk' sources, then invoke 'make' with the appropriate target name
+as an argument to build 'gawk'. The 'Makefile' copied from the 'pc'
+directory contains a configuration section with comments and may need to
+be edited in order to work with your 'make' utility.
+
+ The 'Makefile' supports a number of targets for building various
MS-DOS and Windows32 versions. A list of targets is printed if the
-`make' command is given without a target. As an example, to build
-`gawk' using the DJGPP tools, enter `make djgpp'. (The DJGPP tools
+'make' command is given without a target. As an example, to build
+'gawk' using the DJGPP tools, enter 'make djgpp'. (The DJGPP tools
needed for the build may be found at
-`ftp://ftp.delorie.com/pub/djgpp/current/v2gnu/'.) To build a native
-MS-Windows binary of `gawk' using the MinGW tools, type `make mingw32'.
+<ftp://ftp.delorie.com/pub/djgpp/current/v2gnu/>.) To build a native
+MS-Windows binary of 'gawk' using the MinGW tools, type 'make mingw32'.
- The 32 bit EMX version of `gawk' works "out of the box" under OS/2.
+ The 32 bit EMX version of 'gawk' works "out of the box" under OS/2.
However, it is highly recommended to use GCC 2.95.3 for the compilation.
-In principle, it is possible to compile `gawk' the following way:
+In principle, it is possible to compile 'gawk' the following way:
$ ./configure
$ make
This is not recommended, though. To get an OMF executable you should
-use the following commands at your `sh' prompt:
+use the following commands at your 'sh' prompt:
$ CFLAGS="-O2 -Zomf -Zmt"
$ export CFLAGS
@@ -27783,7 +27671,7 @@ other set of (self-consistent) environment variables
and compiler flags.
$ LIBS="-lgcc"
$ export LIBS
- You can also get an `a.out' executable if you prefer:
+ You can also get an 'a.out' executable if you prefer:
$ CFLAGS="-O2 -Zmt"
$ export CFLAGS
@@ -27793,15 +27681,15 @@ other set of (self-consistent) environment variables
and compiler flags.
$ ./configure --prefix=c:/usr
$ make
- NOTE: Compilation of `a.out' executables also works with GCC 3.2.
+ NOTE: Compilation of 'a.out' executables also works with GCC 3.2.
Versions later than GCC 3.2 have not been tested successfully.
- `make install' works as expected with the EMX build.
+ 'make install' works as expected with the EMX build.
- NOTE: Ancient OS/2 ports of GNU `make' are not able to handle the
+ NOTE: Ancient OS/2 ports of GNU 'make' are not able to handle the
Makefiles of this package. If you encounter any problems with
- `make', try GNU Make 3.79.1 or later versions. You should find
- the latest version on `ftp://hobbes.nmsu.edu/pub/os2/'.(1)
+ 'make', try GNU Make 3.79.1 or later versions. You should find the
+ latest version on <ftp://hobbes.nmsu.edu/pub/os2/>.(1)
---------- Footnotes ----------
@@ -27811,99 +27699,99 @@ could not find a package for GNU Make.
File: gawk.info, Node: PC Testing, Next: PC Using, Prev: PC Compiling, Up:
PC Installation
-B.3.1.3 Testing `gawk' on PC Operating Systems
+B.3.1.3 Testing 'gawk' on PC Operating Systems
..............................................
-Using `make' to run the standard tests and to install `gawk' requires
-additional Unix-like tools, including `sh', `sed', and `cp'. In order
-to run the tests, the `test/*.ok' files may need to be converted so
-that they have the usual MS-DOS-style end-of-line markers.
-Alternatively, run `make check CMP="diff -a"' to use GNU `diff' in text
-mode instead of `cmp' to compare the resulting files.
+Using 'make' to run the standard tests and to install 'gawk' requires
+additional Unix-like tools, including 'sh', 'sed', and 'cp'. In order
+to run the tests, the 'test/*.ok' files may need to be converted so that
+they have the usual MS-DOS-style end-of-line markers. Alternatively,
+run 'make check CMP="diff -a"' to use GNU 'diff' in text mode instead of
+'cmp' to compare the resulting files.
Most of the tests work properly with Stewartson's shell along with
the companion utilities or appropriate GNU utilities. However, some
-editing of `test/Makefile' is required. It is recommended that you copy
-the file `pc/Makefile.tst' over the file `test/Makefile' as a
-replacement. Details can be found in `README_d/README.pc' and in the
-file `pc/Makefile.tst'.
-
- On OS/2 the `pid' test fails because `spawnl()' is used instead of
-`fork()'/`execl()' to start child processes. Also the `mbfw1' and
-`mbprintf1' tests fail because the needed multibyte functionality is
-not available.
+editing of 'test/Makefile' is required. It is recommended that you copy
+the file 'pc/Makefile.tst' over the file 'test/Makefile' as a
+replacement. Details can be found in 'README_d/README.pc' and in the
+file 'pc/Makefile.tst'.
+
+ On OS/2 the 'pid' test fails because 'spawnl()' is used instead of
+'fork()'/'execl()' to start child processes. Also the 'mbfw1' and
+'mbprintf1' tests fail because the needed multibyte functionality is not
+available.
File: gawk.info, Node: PC Using, Next: Cygwin, Prev: PC Testing, Up: PC
Installation
-B.3.1.4 Using `gawk' on PC Operating Systems
+B.3.1.4 Using 'gawk' on PC Operating Systems
............................................
Under MS-DOS and MS-Windows, the Cygwin and MinGW environments support
-both the `|&' operator and TCP/IP networking (*note TCP/IP
-Networking::). EMX (OS/2 only) supports at least the `|&' operator.
+both the '|&' operator and TCP/IP networking (*note TCP/IP
+Networking::). EMX (OS/2 only) supports at least the '|&' operator.
- The MS-DOS and MS-Windows versions of `gawk' search for program
-files as described in *note AWKPATH Variable::. However, semicolons
-(rather than colons) separate elements in the `AWKPATH' variable. If
-`AWKPATH' is not set or is empty, then the default search path is
-`.;c:/lib/awk;c:/gnu/lib/awk'.
+ The MS-DOS and MS-Windows versions of 'gawk' search for program files
+as described in *note AWKPATH Variable::. However, semicolons (rather
+than colons) separate elements in the 'AWKPATH' variable. If 'AWKPATH'
+is not set or is empty, then the default search path is
+'.;c:/lib/awk;c:/gnu/lib/awk'.
The search path for OS/2 (32 bit, EMX) is determined by the prefix
-directory (most likely `/usr' or `c:/usr') that has been specified as
-an option of the `configure' script as is the case for the Unix
-versions. If `c:/usr' is the prefix directory then the default search
-path contains `.' and `c:/usr/share/awk'. Additionally, to support
-binary distributions of `gawk' for OS/2 systems whose drive `c:' might
-not support long file names or might not exist at all, there is a
-special environment variable. If `UNIXROOT' specifies a drive then
-this specific drive is also searched for program files. E.g., if
-`UNIXROOT' is set to `e:' the complete default search path is
-`.;c:/usr/share/awk;e:/usr/share/awk'.
-
- An `sh'-like shell (as opposed to `command.com' under MS-DOS or
-`cmd.exe' under MS-Windows or OS/2) may be useful for `awk' programming.
+directory (most likely '/usr' or 'c:/usr') that has been specified as an
+option of the 'configure' script as is the case for the Unix versions.
+If 'c:/usr' is the prefix directory then the default search path
+contains '.' and 'c:/usr/share/awk'. Additionally, to support binary
+distributions of 'gawk' for OS/2 systems whose drive 'c:' might not
+support long file names or might not exist at all, there is a special
+environment variable. If 'UNIXROOT' specifies a drive then this
+specific drive is also searched for program files. E.g., if 'UNIXROOT'
+is set to 'e:' the complete default search path is
+'.;c:/usr/share/awk;e:/usr/share/awk'.
+
+ An 'sh'-like shell (as opposed to 'command.com' under MS-DOS or
+'cmd.exe' under MS-Windows or OS/2) may be useful for 'awk' programming.
The DJGPP collection of tools includes an MS-DOS port of Bash, and
-several shells are available for OS/2, including `ksh'.
+several shells are available for OS/2, including 'ksh'.
- Under MS-Windows, OS/2 and MS-DOS, `gawk' (and many other text
-programs) silently translates end-of-line `\r\n' to `\n' on input and
-`\n' to `\r\n' on output. A special `BINMODE' variable (c.e.) allows
+ Under MS-Windows, OS/2 and MS-DOS, 'gawk' (and many other text
+programs) silently translates end-of-line '\r\n' to '\n' on input and
+'\n' to '\r\n' on output. A special 'BINMODE' variable (c.e.) allows
control over these translations and is interpreted as follows:
- * If `BINMODE' is `"r"' or one, then binary mode is set on read
+ * If 'BINMODE' is '"r"' or one, then binary mode is set on read
(i.e., no translations on reads).
- * If `BINMODE' is `"w"' or two, then binary mode is set on write
+ * If 'BINMODE' is '"w"' or two, then binary mode is set on write
(i.e., no translations on writes).
- * If `BINMODE' is `"rw"' or `"wr"' or three, binary mode is set for
+ * If 'BINMODE' is '"rw"' or '"wr"' or three, binary mode is set for
both read and write.
- * `BINMODE=NON-NULL-STRING' is the same as `BINMODE=3' (i.e., no
- translations on reads or writes). However, `gawk' issues a warning
- message if the string is not one of `"rw"' or `"wr"'.
+ * 'BINMODE=NON-NULL-STRING' is the same as 'BINMODE=3' (i.e., no
+ translations on reads or writes). However, 'gawk' issues a warning
+ message if the string is not one of '"rw"' or '"wr"'.
The modes for standard input and standard output are set one time only
-(after the command line is read, but before processing any of the `awk'
-program). Setting `BINMODE' for standard input or standard output is
-accomplished by using an appropriate `-v BINMODE=N' option on the
-command line. `BINMODE' is set at the time a file or pipe is opened
-and cannot be changed midstream.
-
- The name `BINMODE' was chosen to match `mawk' (*note Other
-Versions::). `mawk' and `gawk' handle `BINMODE' similarly; however,
-`mawk' adds a `-W BINMODE=N' option and an environment variable that
-can set `BINMODE', `RS', and `ORS'. The files `binmode[1-3].awk'
-(under `gnu/lib/awk' in some of the prepared binary distributions) have
-been chosen to match `mawk''s `-W BINMODE=N' option. These can be
-changed or discarded; in particular, the setting of `RS' giving the
-fewest "surprises" is open to debate. `mawk' uses `RS = "\r\n"' if
-binary mode is set on read, which is appropriate for files with the
-MS-DOS-style end-of-line.
+(after the command line is read, but before processing any of the 'awk'
+program). Setting 'BINMODE' for standard input or standard output is
+accomplished by using an appropriate '-v BINMODE=N' option on the
+command line. 'BINMODE' is set at the time a file or pipe is opened and
+cannot be changed midstream.
+
+ The name 'BINMODE' was chosen to match 'mawk' (*note Other
+Versions::). 'mawk' and 'gawk' handle 'BINMODE' similarly; however,
+'mawk' adds a '-W BINMODE=N' option and an environment variable that can
+set 'BINMODE', 'RS', and 'ORS'. The files 'binmode[1-3].awk' (under
+'gnu/lib/awk' in some of the prepared binary distributions) have been
+chosen to match 'mawk''s '-W BINMODE=N' option. These can be changed or
+discarded; in particular, the setting of 'RS' giving the fewest
+"surprises" is open to debate. 'mawk' uses 'RS = "\r\n"' if binary mode
+is set on read, which is appropriate for files with the MS-DOS-style
+end-of-line.
To illustrate, the following examples set binary mode on writes for
-standard output and other files, and set `ORS' as the "usual"
+standard output and other files, and set 'ORS' as the "usual"
MS-DOS-style end-of-line:
gawk -v BINMODE=2 -v ORS="\r\n" ...
@@ -27912,8 +27800,8 @@ or:
gawk -v BINMODE=w -f binmode2.awk ...
-These give the same result as the `-W BINMODE=2' option in `mawk'. The
-following changes the record separator to `"\r\n"' and sets binary mode
+These give the same result as the '-W BINMODE=2' option in 'mawk'. The
+following changes the record separator to '"\r\n"' and sets binary mode
on reads, but does not affect the mode on standard input:
gawk -v RS="\r\n" -e "BEGIN { BINMODE = 1 }" ...
@@ -27922,72 +27810,72 @@ or:
gawk -f binmode1.awk ...
-With proper quoting, in the first example the setting of `RS' can be
-moved into the `BEGIN' rule.
+With proper quoting, in the first example the setting of 'RS' can be
+moved into the 'BEGIN' rule.
File: gawk.info, Node: Cygwin, Next: MSYS, Prev: PC Using, Up: PC
Installation
-B.3.1.5 Using `gawk' In The Cygwin Environment
+B.3.1.5 Using 'gawk' In The Cygwin Environment
..............................................
-`gawk' can be built and used "out of the box" under MS-Windows if you
+'gawk' can be built and used "out of the box" under MS-Windows if you
are using the Cygwin environment (http://www.cygwin.com). This
environment provides an excellent simulation of GNU/Linux, using Bash,
-GCC, GNU Make, and other GNU programs. Compilation and installation
-for Cygwin is the same as for a Unix system:
+GCC, GNU Make, and other GNU programs. Compilation and installation for
+Cygwin is the same as for a Unix system:
tar -xvpzf gawk-4.1.2.tar.gz
cd gawk-4.1.2
./configure
make && make check
- When compared to GNU/Linux on the same system, the `configure' step
+ When compared to GNU/Linux on the same system, the 'configure' step
on Cygwin takes considerably longer. However, it does finish, and then
-the `make' proceeds as usual.
+the 'make' proceeds as usual.
File: gawk.info, Node: MSYS, Prev: Cygwin, Up: PC Installation
-B.3.1.6 Using `gawk' In The MSYS Environment
+B.3.1.6 Using 'gawk' In The MSYS Environment
............................................
-In the MSYS environment under MS-Windows, `gawk' automatically uses
+In the MSYS environment under MS-Windows, 'gawk' automatically uses
binary mode for reading and writing files. Thus, there is no need to
-use the `BINMODE' variable.
+use the 'BINMODE' variable.
This can cause problems with other Unix-like components that have
-been ported to MS-Windows that expect `gawk' to do automatic
-translation of `"\r\n"', because it won't.
+been ported to MS-Windows that expect 'gawk' to do automatic translation
+of '"\r\n"', because it won't.
File: gawk.info, Node: VMS Installation, Prev: PC Installation, Up:
Non-Unix Installation
-B.3.2 Compiling and Installing `gawk' on Vax/VMS and OpenVMS
+B.3.2 Compiling and Installing 'gawk' on Vax/VMS and OpenVMS
------------------------------------------------------------
-This node describes how to compile and install `gawk' under VMS. The
+This node describes how to compile and install 'gawk' under VMS. The
older designation "VMS" is used throughout to refer to OpenVMS.
* Menu:
-* VMS Compilation:: How to compile `gawk' under VMS.
-* VMS Dynamic Extensions:: Compiling `gawk' dynamic extensions on
+* VMS Compilation:: How to compile 'gawk' under VMS.
+* VMS Dynamic Extensions:: Compiling 'gawk' dynamic extensions on
VMS.
-* VMS Installation Details:: How to install `gawk' under VMS.
-* VMS Running:: How to run `gawk' under VMS.
+* VMS Installation Details:: How to install 'gawk' under VMS.
+* VMS Running:: How to run 'gawk' under VMS.
* VMS GNV:: The VMS GNV Project.
* VMS Old Gawk:: An old version comes with some VMS systems.
File: gawk.info, Node: VMS Compilation, Next: VMS Dynamic Extensions, Up:
VMS Installation
-B.3.2.1 Compiling `gawk' on VMS
+B.3.2.1 Compiling 'gawk' on VMS
...............................
-To compile `gawk' under VMS, there is a `DCL' command procedure that
-issues all the necessary `CC' and `LINK' commands. There is also a
-`Makefile' for use with the `MMS' and `MMK' utilities. From the source
+To compile 'gawk' under VMS, there is a 'DCL' command procedure that
+issues all the necessary 'CC' and 'LINK' commands. There is also a
+'Makefile' for use with the 'MMS' and 'MMK' utilities. From the source
directory, use either:
$ @[.vms]vmsbuild.com
@@ -28000,19 +27888,19 @@ or:
$ MMK/DESCRIPTION=[.vms]descrip.mms gawk
- `MMK' is an open source, free, near-clone of `MMS' and can better
-handle ODS-5 volumes with upper- and lowercase file names. `MMK' is
-available from `https://github.com/endlesssoftware/mmk'.
+ 'MMK' is an open source, free, near-clone of 'MMS' and can better
+handle ODS-5 volumes with upper- and lowercase file names. 'MMK' is
+available from <https://github.com/endlesssoftware/mmk>.
With ODS-5 volumes and extended parsing enabled, the case of the
target parameter may need to be exact.
- `gawk' has been tested under VAX/VMS 7.3 and Alpha/VMS 7.3-1 using
+ 'gawk' has been tested under VAX/VMS 7.3 and Alpha/VMS 7.3-1 using
Compaq C V6.4, and under Alpha/VMS 7.3, Alpha/VMS 7.3-2, and IA64/VMS
8.3. The most recent builds used HP C V7.3 on Alpha VMS 8.3 and both
Alpha and IA64 VMS 8.4 used HP C 7.3.(1)
- *Note VMS GNV::, for information on building `gawk' as a PCSI kit
+ *Note VMS GNV::, for information on building 'gawk' as a PCSI kit
that is compatible with the GNV product.
---------- Footnotes ----------
@@ -28022,7 +27910,7 @@ that is compatible with the GNV product.
File: gawk.info, Node: VMS Dynamic Extensions, Next: VMS Installation
Details, Prev: VMS Compilation, Up: VMS Installation
-B.3.2.2 Compiling `gawk' Dynamic Extensions on VMS
+B.3.2.2 Compiling 'gawk' Dynamic Extensions on VMS
..................................................
The extensions that have been ported to VMS can be built using one of
@@ -28034,15 +27922,14 @@ or:
$ MMK/DESCRIPTION=[.vms]descrip.mms extensions
- `gawk' uses `AWKLIBPATH' as either an environment variable or a
+ 'gawk' uses 'AWKLIBPATH' as either an environment variable or a
logical name to find the dynamic extensions.
- Dynamic extensions need to be compiled with the same compiler
-options for floating-point, pointer size, and symbol name handling as
-were used to compile `gawk' itself. Alpha and Itanium should use IEEE
-floating point. The pointer size is 32 bits, and the symbol name
-handling should be exact case with CRC shortening for symbols longer
-than 32 bits.
+ Dynamic extensions need to be compiled with the same compiler options
+for floating-point, pointer size, and symbol name handling as were used
+to compile 'gawk' itself. Alpha and Itanium should use IEEE floating
+point. The pointer size is 32 bits, and the symbol name handling should
+be exact case with CRC shortening for symbols longer than 32 bits.
For Alpha and Itanium:
@@ -28068,79 +27955,78 @@ header file is included, as follows:
#endif
#endif
- If you are writing your own extensions to run on VMS, you must
-supply these definitions yourself. The `config.h' file created when
-building `gawk' on VMS does this for you; if instead you use that file
-or a similar one, then you must remember to include it before any
+ If you are writing your own extensions to run on VMS, you must supply
+these definitions yourself. The 'config.h' file created when building
+'gawk' on VMS does this for you; if instead you use that file or a
+similar one, then you must remember to include it before any
VMS-supplied header files.
File: gawk.info, Node: VMS Installation Details, Next: VMS Running, Prev:
VMS Dynamic Extensions, Up: VMS Installation
-B.3.2.3 Installing `gawk' on VMS
+B.3.2.3 Installing 'gawk' on VMS
................................
-To use `gawk', all you need is a "foreign" command, which is a `DCL'
-symbol whose value begins with a dollar sign. For example:
+To use 'gawk', all you need is a "foreign" command, which is a 'DCL'
+symbol whose value begins with a dollar sign. For example:
$ GAWK :== $disk1:[gnubin]gawk
-Substitute the actual location of `gawk.exe' for `$disk1:[gnubin]'. The
-symbol should be placed in the `login.com' of any user who wants to run
-`gawk', so that it is defined every time the user logs on.
-Alternatively, the symbol may be placed in the system-wide
-`sylogin.com' procedure, which allows all users to run `gawk'.
+Substitute the actual location of 'gawk.exe' for '$disk1:[gnubin]'. The
+symbol should be placed in the 'login.com' of any user who wants to run
+'gawk', so that it is defined every time the user logs on.
+Alternatively, the symbol may be placed in the system-wide 'sylogin.com'
+procedure, which allows all users to run 'gawk'.
- If your `gawk' was installed by a PCSI kit into the `GNV$GNU:'
-directory tree, the program will be known as
-`GNV$GNU:[bin]gnv$gawk.exe' and the help file will be
-`GNV$GNU:[vms_help]gawk.hlp'.
+ If your 'gawk' was installed by a PCSI kit into the 'GNV$GNU:'
+directory tree, the program will be known as 'GNV$GNU:[bin]gnv$gawk.exe'
+and the help file will be 'GNV$GNU:[vms_help]gawk.hlp'.
- The PCSI kit also installs a `GNV$GNU:[vms_bin]gawk_verb.cld' file
-that can be used to add `gawk' and `awk' as DCL commands.
+ The PCSI kit also installs a 'GNV$GNU:[vms_bin]gawk_verb.cld' file
+that can be used to add 'gawk' and 'awk' as DCL commands.
For just the current process you can use:
$ set command gnv$gnu:[vms_bin]gawk_verb.cld
- Or the system manager can use `GNV$GNU:[vms_bin]gawk_verb.cld' to
-add the `gawk' and `awk' to the system-wide `DCLTABLES'.
+ Or the system manager can use 'GNV$GNU:[vms_bin]gawk_verb.cld' to add
+the 'gawk' and 'awk' to the system-wide 'DCLTABLES'.
- The DCL syntax is documented in the `gawk.hlp' file.
+ The DCL syntax is documented in the 'gawk.hlp' file.
- Optionally, the `gawk.hlp' entry can be loaded into a VMS help
+ Optionally, the 'gawk.hlp' entry can be loaded into a VMS help
library:
$ LIBRARY/HELP sys$help:helplib [.vms]gawk.hlp
-(You may want to substitute a site-specific help library rather than
-the standard VMS library `HELPLIB'.) After loading the help text, the
+(You may want to substitute a site-specific help library rather than the
+standard VMS library 'HELPLIB'.) After loading the help text, the
command:
$ HELP GAWK
-provides information about both the `gawk' implementation and the `awk'
+provides information about both the 'gawk' implementation and the 'awk'
programming language.
- The logical name `AWK_LIBRARY' can designate a default location for
-`awk' program files. For the `-f' option, if the specified file name
-has no device or directory path information in it, `gawk' looks in the
+ The logical name 'AWK_LIBRARY' can designate a default location for
+'awk' program files. For the '-f' option, if the specified file name
+has no device or directory path information in it, 'gawk' looks in the
current directory first, then in the directory specified by the
-translation of `AWK_LIBRARY' if the file is not found. If, after
-searching in both directories, the file still is not found, `gawk'
-appends the suffix `.awk' to the file name and retries the file search.
-If `AWK_LIBRARY' has no definition, a default value of `SYS$LIBRARY:'
-is used for it.
+translation of 'AWK_LIBRARY' if the file is not found. If, after
+searching in both directories, the file still is not found, 'gawk'
+appends the suffix '.awk' to the file name and retries the file search.
+If 'AWK_LIBRARY' has no definition, a default value of 'SYS$LIBRARY:' is
+used for it.
File: gawk.info, Node: VMS Running, Next: VMS GNV, Prev: VMS Installation
Details, Up: VMS Installation
-B.3.2.4 Running `gawk' on VMS
+B.3.2.4 Running 'gawk' on VMS
.............................
Command-line parsing and quoting conventions are significantly different
on VMS, so examples in this Info file or from other sources often need
-minor changes. They _are_ minor though, and all `awk' programs should
+minor changes. They _are_ minor though, and all 'awk' programs should
run correctly.
Here are a couple of trivial tests:
@@ -28151,50 +28037,50 @@ run correctly.
Note that uppercase and mixed-case text must be quoted.
- The VMS port of `gawk' includes a `DCL'-style interface in addition
+ The VMS port of 'gawk' includes a 'DCL'-style interface in addition
to the original shell-style interface (see the help entry for details).
One side effect of dual command-line parsing is that if there is only a
single parameter (as in the quoted string program), the command becomes
-ambiguous. To work around this, the normally optional `--' flag is
-required to force Unix-style parsing rather than `DCL' parsing. If any
+ambiguous. To work around this, the normally optional '--' flag is
+required to force Unix-style parsing rather than 'DCL' parsing. If any
other dash-type options (or multiple parameters such as data files to
-process) are present, there is no ambiguity and `--' can be omitted.
+process) are present, there is no ambiguity and '--' can be omitted.
- The `exit' value is a Unix-style value and is encoded into a VMS exit
+ The 'exit' value is a Unix-style value and is encoded into a VMS exit
status value when the program exits.
- The VMS severity bits will be set based on the `exit' value. A
-failure is indicated by 1, and VMS sets the `ERROR' status. A fatal
-error is indicated by 2, and VMS sets the `FATAL' status. All other
-values will have the `SUCCESS' status. The exit value is encoded to
-comply with VMS coding standards and will have the `C_FACILITY_NO' of
-`0x350000' with the constant `0xA000' added to the number shifted over
+ The VMS severity bits will be set based on the 'exit' value. A
+failure is indicated by 1, and VMS sets the 'ERROR' status. A fatal
+error is indicated by 2, and VMS sets the 'FATAL' status. All other
+values will have the 'SUCCESS' status. The exit value is encoded to
+comply with VMS coding standards and will have the 'C_FACILITY_NO' of
+'0x350000' with the constant '0xA000' added to the number shifted over
by 3 bits to make room for the severity codes.
- To extract the actual `gawk' exit code from the VMS status, use:
+ To extract the actual 'gawk' exit code from the VMS status, use:
unix_status = (vms_status .and. &x7f8) / 8
-A C program that uses `exec()' to call `gawk' will get the original
+A C program that uses 'exec()' to call 'gawk' will get the original
Unix-style exit value.
- Older versions of `gawk' for VMS treated a Unix exit code 0 as 1, a
+ Older versions of 'gawk' for VMS treated a Unix exit code 0 as 1, a
failure as 2, a fatal error as 4, and passed all the other numbers
through. This violated the VMS exit status coding requirements.
- VAX/VMS floating point uses unbiased rounding. *Note Round
+ VAX/VMS floating point uses unbiased rounding. *Note Round
Function::.
- VMS reports time values in GMT unless one of the `SYS$TIMEZONE_RULE'
-or `TZ' logical names is set. Older versions of VMS, such as VAX/VMS
+ VMS reports time values in GMT unless one of the 'SYS$TIMEZONE_RULE'
+or 'TZ' logical names is set. Older versions of VMS, such as VAX/VMS
7.3, do not set these logical names.
- The default search path, when looking for `awk' program files
-specified by the `-f' option, is `"SYS$DISK:[],AWK_LIBRARY:"'. The
-logical name `AWKPATH' can be used to override this default. The format
-of `AWKPATH' is a comma-separated list of directory specifications.
+ The default search path, when looking for 'awk' program files
+specified by the '-f' option, is '"SYS$DISK:[],AWK_LIBRARY:"'. The
+logical name 'AWKPATH' can be used to override this default. The format
+of 'AWKPATH' is a comma-separated list of directory specifications.
When defining it, the value should be quoted so that it retains a single
-translation and not a multitranslation `RMS' searchlist.
+translation and not a multitranslation 'RMS' searchlist.
File: gawk.info, Node: VMS GNV, Next: VMS Old Gawk, Prev: VMS Running, Up:
VMS Installation
@@ -28203,29 +28089,28 @@ B.3.2.5 The VMS GNV Project
...........................
The VMS GNV package provides a build environment similar to POSIX with
-ports of a collection of open source tools. The `gawk' found in the GNV
+ports of a collection of open source tools. The 'gawk' found in the GNV
base kit is an older port. Currently, the GNV project is being
-reorganized to supply individual PCSI packages for each component. See
-`https://sourceforge.net/p/gnv/wiki/InstallingGNVPackages/'.
+reorganized to supply individual PCSI packages for each component. See
<https://sourceforge.net/p/gnv/wiki/InstallingGNVPackages/>.
- The normal build procedure for `gawk' produces a program that is
+ The normal build procedure for 'gawk' produces a program that is
suitable for use with GNV.
- The file `vms/gawk_build_steps.txt' in the distribution documents
-the procedure for building a VMS PCSI kit that is compatible with GNV.
+ The file 'vms/gawk_build_steps.txt' in the distribution documents the
+procedure for building a VMS PCSI kit that is compatible with GNV.
File: gawk.info, Node: VMS Old Gawk, Prev: VMS GNV, Up: VMS Installation
-B.3.2.6 Some VMS Systems Have An Old Version of `gawk'
+B.3.2.6 Some VMS Systems Have An Old Version of 'gawk'
......................................................
-Some versions of VMS have an old version of `gawk'. To access it,
+Some versions of VMS have an old version of 'gawk'. To access it,
define a symbol, as follows:
$ gawk :== $sys$common:[syshlp.examples.tcpip.snmp]gawk.exe
- This is apparently version 2.15.6, which is extremely old. We
+ This is apparently version 2.15.6, which is extremely old. We
recommend compiling and using the current version.
@@ -28234,10 +28119,10 @@ File: gawk.info, Node: Bugs, Next: Other Versions,
Prev: Non-Unix Installatio
B.4 Reporting Problems and Bugs
===============================
- There is nothing more dangerous than a bored archaeologist. --
- Douglas Adams, `The Hitchhiker's Guide to the Galaxy'
+ There is nothing more dangerous than a bored archaeologist.
+ -- _Douglas Adams, 'The Hitchhiker's Guide to the Galaxy'_
- If you have problems with `gawk' or think that you have found a bug,
+ If you have problems with 'gawk' or think that you have found a bug,
report it to the developers; we cannot promise to do anything, but we
might well want to fix it.
@@ -28248,30 +28133,32 @@ to do something or not, report that too; it's a bug
in the
documentation!
Before reporting a bug or trying to fix it yourself, try to isolate
-it to the smallest possible `awk' program and input data file that
+it to the smallest possible 'awk' program and input data file that
reproduce the problem. Then send us the program and data file, some
idea of what kind of Unix system you're using, the compiler you used to
-compile `gawk', and the exact results `gawk' gave you. Also say what
+compile 'gawk', and the exact results 'gawk' gave you. Also say what
you expected to occur; this helps us decide whether the problem is
really in the documentation.
- Make sure to include the version number of `gawk' you are using.
-You can get this information with the command `gawk --version'.
+ Make sure to include the version number of 'gawk' you are using. You
+can get this information with the command 'gawk --version'.
Once you have a precise problem description, send email to
<address@hidden>.
- The `gawk' maintainers subscribe to this address, and thus they will
+ The 'gawk' maintainers subscribe to this address, and thus they will
receive your bug report. Although you can send mail to the maintainers
directly, the bug reporting address is preferred because the email list
-is archived at the GNU Project. _All email must be in English. This is
-the only language understood in common by all the maintainers._
+is archived at the GNU Project. _All email must be in English. This is
+the only language understood in common by all the maintainers._ In
+addition, please be sure to send all mail in _plain text_, not (or not
+exclusively) in HTML.
- CAUTION: Do _not_ try to report bugs in `gawk' by posting to the
- Usenet/Internet newsgroup `comp.lang.awk'. The `gawk' developers
- do occasionally read this newsgroup, but there is no guarantee
- that we will see your posting. The steps described here are the
- only officially recognized way for reporting bugs. Really.
+ CAUTION: Do _not_ try to report bugs in 'gawk' by posting to the
+ Usenet/Internet newsgroup 'comp.lang.awk'. The 'gawk' developers
+ do occasionally read this newsgroup, but there is no guarantee that
+ we will see your posting. The steps described here are the only
+ officially recognized way for reporting bugs. Really.
NOTE: Many distributions of GNU/Linux and the various BSD-based
operating systems have their own bug reporting systems. If you
@@ -28279,31 +28166,36 @@ the only language understood in common by all the
maintainers._
should also send a copy to <address@hidden>.
This is for two reasons. First, although some distributions
- forward bug reports "upstream" to the GNU mailing list, many
- don't, so there is a good chance that the `gawk' maintainers
- won't even see the bug report! Second, mail to the GNU list is
- archived, and having everything at the GNU Project keeps things
- self-contained and not dependent on other organizations.
+ forward bug reports "upstream" to the GNU mailing list, many don't,
+ so there is a good chance that the 'gawk' maintainers won't even
+ see the bug report! Second, mail to the GNU list is archived, and
+ having everything at the GNU Project keeps things self-contained
+ and not dependent on other organizations.
Non-bug suggestions are always welcome as well. If you have
-questions about things that are unclear in the documentation or are
-just obscure features, ask on the bug list; we will try to help you out
-if we can.
+questions about things that are unclear in the documentation or are just
+obscure features, ask on the bug list; we will try to help you out if we
+can.
- If you find bugs in one of the non-Unix ports of `gawk', send an
+ If you find bugs in one of the non-Unix ports of 'gawk', send an
email to the bug list, with a copy to the person who maintains that
port. The maintainers are named in the following list, as well as in
-the `README' file in the `gawk' distribution. Information in the
-`README' file should be considered authoritative if it conflicts with
+the 'README' file in the 'gawk' distribution. Information in the
+'README' file should be considered authoritative if it conflicts with
this Info file.
- The people maintaining the various `gawk' ports are:
+ The people maintaining the various 'gawk' ports are:
-Unix and POSIX systems Arnold Robbins, <address@hidden>
+Unix and POSIX Arnold Robbins, <address@hidden>
+systems
MS-DOS with DJGPP Scott Deifik, <address@hidden>
+
MS-Windows with MinGW Eli Zaretskii, <address@hidden>
+
OS/2 Andreas Buening, <address@hidden>
+
VMS John Malmberg, <address@hidden>
+
z/OS (OS/390) Dave Pitts, <address@hidden>
If your bug is also reproducible under Unix, send a copy of your
@@ -28312,108 +28204,108 @@ report to the <address@hidden> email list as well.
File: gawk.info, Node: Other Versions, Next: Installation summary, Prev:
Bugs, Up: Installation
-B.5 Other Freely Available `awk' Implementations
+B.5 Other Freely Available 'awk' Implementations
================================================
It's kind of fun to put comments like this in your awk code:
- `// Do C++ comments work? answer: yes! of course' -- Michael
- Brennan
+ '// Do C++ comments work? answer: yes! of course'
+ -- _Michael Brennan_
-There are a number of other freely available `awk' implementations.
+ There are a number of other freely available 'awk' implementations.
This minor node briefly describes where to get them:
-Unix `awk'
- Brian Kernighan, one of the original designers of Unix `awk', has
- made his implementation of `awk' freely available. You can
+Unix 'awk'
+ Brian Kernighan, one of the original designers of Unix 'awk', has
+ made his implementation of 'awk' freely available. You can
retrieve this version via his home page
(http://www.cs.princeton.edu/~bwk). It is available in several
archive formats:
- Shell archive
- `http://www.cs.princeton.edu/~bwk/btl.mirror/awk.shar'
+ Shell archive
+ <http://www.cs.princeton.edu/~bwk/btl.mirror/awk.shar>
- Compressed `tar' file
- `http://www.cs.princeton.edu/~bwk/btl.mirror/awk.tar.gz'
+ Compressed 'tar' file
+ <http://www.cs.princeton.edu/~bwk/btl.mirror/awk.tar.gz>
- Zip file
- `http://www.cs.princeton.edu/~bwk/btl.mirror/awk.zip'
+ Zip file
+ <http://www.cs.princeton.edu/~bwk/btl.mirror/awk.zip>
You can also retrieve it from GitHub:
git clone git://github.com/onetrueawk/awk bwkawk
This command creates a copy of the Git (http://git-scm.com)
- repository in a directory named `bwkawk'. If you leave that
- argument off the `git' command line, the repository copy is
- created in a directory named `awk'.
+ repository in a directory named 'bwkawk'. If you leave that
+ argument off the 'git' command line, the repository copy is created
+ in a directory named 'awk'.
This version requires an ISO C (1990 standard) compiler; the C
compiler from GCC (the GNU Compiler Collection) works quite nicely.
- *Note Common Extensions::, for a list of extensions in this `awk'
- that are not in POSIX `awk'.
+ *Note Common Extensions::, for a list of extensions in this 'awk'
+ that are not in POSIX 'awk'.
As a side note, Dan Bornstein has created a Git repository tracking
- all the versions of BWK `awk' that he could find. It's available
- at `git://github.com/danfuzz/one-true-awk'.
+ all the versions of BWK 'awk' that he could find. It's available
+ at <git://github.com/danfuzz/one-true-awk>.
-`mawk'
- Michael Brennan wrote an independent implementation of `awk',
- called `mawk'. It is available under the GPL (*note Copying::),
- just as `gawk' is.
+'mawk'
+ Michael Brennan wrote an independent implementation of 'awk',
+ called 'mawk'. It is available under the GPL (*note Copying::),
+ just as 'gawk' is.
- The original distribution site for the `mawk' source code no
- longer has it. A copy is available at
- `http://www.skeeve.com/gawk/mawk1.3.3.tar.gz'.
+ The original distribution site for the 'mawk' source code no longer
+ has it. A copy is available at
+ <http://www.skeeve.com/gawk/mawk1.3.3.tar.gz>.
- In 2009, Thomas Dickey took on `mawk' maintenance. Basic
+ In 2009, Thomas Dickey took on 'mawk' maintenance. Basic
information is available on the project's web page
(http://www.invisible-island.net/mawk). The download URL is
- `http://invisible-island.net/datafiles/release/mawk.tar.gz'.
+ <http://invisible-island.net/datafiles/release/mawk.tar.gz>.
- Once you have it, `gunzip' may be used to decompress this file.
- Installation is similar to `gawk''s (*note Unix Installation::).
+ Once you have it, 'gunzip' may be used to decompress this file.
+ Installation is similar to 'gawk''s (*note Unix Installation::).
- *Note Common Extensions::, for a list of extensions in `mawk' that
- are not in POSIX `awk'.
+ *Note Common Extensions::, for a list of extensions in 'mawk' that
+ are not in POSIX 'awk'.
-`awka'
- Written by Andrew Sumner, `awka' translates `awk' programs into C,
+'awka'
+ Written by Andrew Sumner, 'awka' translates 'awk' programs into C,
compiles them, and links them with a library of functions that
- provide the core `awk' functionality. It also has a number of
+ provide the core 'awk' functionality. It also has a number of
extensions.
- The `awk' translator is released under the GPL, and the library is
+ The 'awk' translator is released under the GPL, and the library is
under the LGPL.
- To get `awka', go to `http://sourceforge.net/projects/awka'.
+ To get 'awka', go to <http://sourceforge.net/projects/awka>.
The project seems to be frozen; no new code changes have been made
since approximately 2001.
-`pawk'
- Nelson H.F. Beebe at the University of Utah has modified BWK `awk'
+'pawk'
+ Nelson H.F. Beebe at the University of Utah has modified BWK 'awk'
to provide timing and profiling information. It is different from
- `gawk' with the `--profile' option (*note Profiling::) in that it
+ 'gawk' with the '--profile' option (*note Profiling::) in that it
uses CPU-based profiling, not line-count profiling. You may find
it at either
- `ftp://ftp.math.utah.edu/pub/pawk/pawk-20030606.tar.gz' or
- `http://www.math.utah.edu/pub/pawk/pawk-20030606.tar.gz'.
+ <ftp://ftp.math.utah.edu/pub/pawk/pawk-20030606.tar.gz> or
+ <http://www.math.utah.edu/pub/pawk/pawk-20030606.tar.gz>.
-BusyBox `awk'
+BusyBox 'awk'
BusyBox is a GPL-licensed program providing small versions of many
- applications within a single executable. It is aimed at embedded
- systems. It includes a full implementation of POSIX `awk'. When
- building it, be careful not to do `make install' as it will
- overwrite copies of other applications in your `/usr/local/bin'.
+ applications within a single executable. It is aimed at embedded
+ systems. It includes a full implementation of POSIX 'awk'. When
+ building it, be careful not to do 'make install' as it will
+ overwrite copies of other applications in your '/usr/local/bin'.
For more information, see the project's home page
(http://busybox.net).
-The OpenSolaris POSIX `awk'
- The versions of `awk' in `/usr/xpg4/bin' and `/usr/xpg6/bin' on
+The OpenSolaris POSIX 'awk'
+ The versions of 'awk' in '/usr/xpg4/bin' and '/usr/xpg6/bin' on
Solaris are more or less POSIX-compliant. They are based on the
- `awk' from Mortice Kern Systems for PCs. We were able to make
- this code compile and work under GNU/Linux with 1-2 hours of work.
+ 'awk' from Mortice Kern Systems for PCs. We were able to make this
+ code compile and work under GNU/Linux with 1-2 hours of work.
Making it more generally portable (using GNU Autoconf and/or
Automake) would take more work, and this has not been done, at
least to our knowledge.
@@ -28424,34 +28316,34 @@ The OpenSolaris POSIX `awk'
(http://wiki.illumos.org/display/illumos/illumos+Home) makes this
implementation available. You can view the files one at a time
from
-
`https://github.com/joyent/illumos-joyent/blob/master/usr/src/cmd/awk_xpg4'.
+
<https://github.com/joyent/illumos-joyent/blob/master/usr/src/cmd/awk_xpg4>.
-`jawk'
- This is an interpreter for `awk' written in Java. It claims to be
+'jawk'
+ This is an interpreter for 'awk' written in Java. It claims to be
a full interpreter, although because it uses Java facilities for
I/O and for regexp matching, the language it supports is different
- from POSIX `awk'. More information is available on the project's
+ from POSIX 'awk'. More information is available on the project's
home page (http://jawk.sourceforge.net).
Libmawk
- This is an embeddable `awk' interpreter derived from `mawk'. For
- more information, see `http://repo.hu/projects/libmawk/'.
-
-`pawk'
- This is a Python module that claims to bring `awk'-like features
- to Python. See `https://github.com/alecthomas/pawk' for more
- information. (This is not related to Nelson Beebe's modified
- version of BWK `awk', described earlier.)
-
-QSE `awk'
- This is an embeddable `awk' interpreter. For more information, see
- `http://code.google.com/p/qse/' and `http://awk.info/?tools/qse'.
-
-`QTawk'
- This is an independent implementation of `awk' distributed under
- the GPL. It has a large number of extensions over standard `awk'
+ This is an embeddable 'awk' interpreter derived from 'mawk'. For
+ more information, see <http://repo.hu/projects/libmawk/>.
+
+'pawk'
+ This is a Python module that claims to bring 'awk'-like features to
+ Python. See <https://github.com/alecthomas/pawk> for more
+ information. (This is not related to Nelson Beebe's modified
+ version of BWK 'awk', described earlier.)
+
+QSE 'awk'
+ This is an embeddable 'awk' interpreter. For more information, see
+ <http://code.google.com/p/qse/> and <http://awk.info/?tools/qse>.
+
+'QTawk'
+ This is an independent implementation of 'awk' distributed under
+ the GPL. It has a large number of extensions over standard 'awk'
and may not be 100% syntactically compatible with it. See
- `http://www.quiktrim.org/QTawk.html' for more information,
+ <http://www.quiktrim.org/QTawk.html> for more information,
including the manual and a download link.
The project may also be frozen; no new code changes have been made
@@ -28461,8 +28353,7 @@ Other versions
See also the "Versions and implementations" section of the
Wikipedia article
(http://en.wikipedia.org/wiki/Awk_language#Versions_and_implementations)
- on `awk' for information on additional versions.
-
+ on 'awk' for information on additional versions.
File: gawk.info, Node: Installation summary, Prev: Other Versions, Up:
Installation
@@ -28470,27 +28361,26 @@ File: gawk.info, Node: Installation summary, Prev:
Other Versions, Up: Instal
B.6 Summary
===========
- * The `gawk' distribution is available from the GNU Project's main
- distribution site, `ftp.gnu.org'. The canonical build recipe is:
+ * The 'gawk' distribution is available from the GNU Project's main
+ distribution site, 'ftp.gnu.org'. The canonical build recipe is:
wget http://ftp.gnu.org/gnu/gawk/gawk-4.1.2.tar.gz
tar -xvpzf gawk-4.1.2.tar.gz
cd gawk-4.1.2
./configure && make && make check
- * `gawk' may be built on non-POSIX systems as well. The currently
+ * 'gawk' may be built on non-POSIX systems as well. The currently
supported systems are MS-Windows using DJGPP, MSYS, MinGW, and
- Cygwin, OS/2 using EMX, and both Vax/VMS and OpenVMS.
- Instructions for each system are included in this major node.
+ Cygwin, OS/2 using EMX, and both Vax/VMS and OpenVMS. Instructions
+ for each system are included in this major node.
* Bug reports should be sent via email to <address@hidden>. Bug
reports should be in English and should include the version of
- `gawk', how it was compiled, and a short program and data file
- that demonstrate the problem.
-
- * There are a number of other freely available `awk'
- implementations. Many are POSIX-compliant; others are less so.
+ 'gawk', how it was compiled, and a short program and data file that
+ demonstrate the problem.
+ * There are a number of other freely available 'awk' implementations.
+ Many are POSIX-compliant; others are less so.
File: gawk.info, Node: Notes, Next: Basic Concepts, Prev: Installation,
Up: Top
@@ -28499,14 +28389,14 @@ Appendix C Implementation Notes
*******************************
This appendix contains information mainly of interest to implementers
-and maintainers of `gawk'. Everything in it applies specifically to
-`gawk' and not to other implementations.
+and maintainers of 'gawk'. Everything in it applies specifically to
+'gawk' and not to other implementations.
* Menu:
-* Compatibility Mode:: How to disable certain `gawk'
+* Compatibility Mode:: How to disable certain 'gawk'
extensions.
-* Additions:: Making Additions To `gawk'.
+* Additions:: Making Additions To 'gawk'.
* Future Extensions:: New features that may be implemented one day.
* Implementation Limitations:: Some limitations of the implementation.
* Extension Design:: Design notes about the extension API.
@@ -28519,43 +28409,43 @@ File: gawk.info, Node: Compatibility Mode, Next:
Additions, Up: Notes
C.1 Downward Compatibility and Debugging
========================================
-*Note POSIX/GNU::, for a summary of the GNU extensions to the `awk'
+*Note POSIX/GNU::, for a summary of the GNU extensions to the 'awk'
language and program. All of these features can be turned off by
-invoking `gawk' with the `--traditional' option or with the `--posix'
+invoking 'gawk' with the '--traditional' option or with the '--posix'
option.
- If `gawk' is compiled for debugging with `-DDEBUG', then there is
-one more option available on the command line:
+ If 'gawk' is compiled for debugging with '-DDEBUG', then there is one
+more option available on the command line:
-`-Y'
-`--parsedebug'
+'-Y'
+'--parsedebug'
Print out the parse stack information as the program is being
parsed.
- This option is intended only for serious `gawk' developers and not
+ This option is intended only for serious 'gawk' developers and not
for the casual user. It probably has not even been compiled into your
-version of `gawk', since it slows down execution.
+version of 'gawk', since it slows down execution.
File: gawk.info, Node: Additions, Next: Future Extensions, Prev:
Compatibility Mode, Up: Notes
-C.2 Making Additions to `gawk'
+C.2 Making Additions to 'gawk'
==============================
-If you find that you want to enhance `gawk' in a significant fashion,
+If you find that you want to enhance 'gawk' in a significant fashion,
you are perfectly free to do so. That is the point of having free
software; the source code is available and you are free to change it as
you want (*note Copying::).
- This minor node discusses the ways you might want to change `gawk'
-as well as any considerations you should bear in mind.
+ This minor node discusses the ways you might want to change 'gawk' as
+well as any considerations you should bear in mind.
* Menu:
* Accessing The Source:: Accessing the Git repository.
* Adding Code:: Adding code to the main body of
- `gawk'.
-* New Ports:: Porting `gawk' to a new operating
+ 'gawk'.
+* New Ports:: Porting 'gawk' to a new operating
system.
* Derived Files:: Why derived files are kept in the Git
repository.
@@ -28563,34 +28453,34 @@ as well as any considerations you should bear in mind.
File: gawk.info, Node: Accessing The Source, Next: Adding Code, Up:
Additions
-C.2.1 Accessing The `gawk' Git Repository
+C.2.1 Accessing The 'gawk' Git Repository
-----------------------------------------
-As `gawk' is Free Software, the source code is always available. *note
-Gawk Distribution::, describes how to get and build the formal,
-released versions of `gawk'.
+As 'gawk' is Free Software, the source code is always available. *note
+Gawk Distribution::, describes how to get and build the formal, released
+versions of 'gawk'.
- However, if you want to modify `gawk' and contribute back your
+ However, if you want to modify 'gawk' and contribute back your
changes, you will probably wish to work with the development version.
-To do so, you will need to access the `gawk' source code repository.
+To do so, you will need to access the 'gawk' source code repository.
The code is maintained using the Git distributed version control system
(http://git-scm.com). You will need to install it if your system
doesn't have it. Once you have done so, use the command:
git clone git://git.savannah.gnu.org/gawk.git
-This clones the `gawk' repository. If you are behind a firewall that
+This clones the 'gawk' repository. If you are behind a firewall that
does not allow you to use the Git native protocol, you can still access
the repository using:
git clone http://git.savannah.gnu.org/r/gawk.git
- Once you have made changes, you can use `git diff' to produce a
-patch, and send that to the `gawk' maintainer; see *note Bugs::, for
-how to do that.
+ Once you have made changes, you can use 'git diff' to produce a
+patch, and send that to the 'gawk' maintainer; see *note Bugs::, for how
+to do that.
Once upon a time there was Git-CVS gateway for use by people who
-could not install Git. However, this gateway no longer works, so you
+could not install Git. However, this gateway no longer works, so you
may have better luck using a more modern version control system like
Bazaar, that has a Git plug-in for working with Git repositories.
@@ -28600,216 +28490,215 @@ File: gawk.info, Node: Adding Code, Next: New
Ports, Prev: Accessing The Sour
C.2.2 Adding New Features
-------------------------
-You are free to add any new features you like to `gawk'. However, if
-you want your changes to be incorporated into the `gawk' distribution,
+You are free to add any new features you like to 'gawk'. However, if
+you want your changes to be incorporated into the 'gawk' distribution,
there are several steps that you need to take in order to make it
possible to include them:
- 1. Before building the new feature into `gawk' itself, consider
- writing it as an extension (*note Dynamic Extensions::). If
- that's not possible, continue with the rest of the steps in this
- list.
+ 1. Before building the new feature into 'gawk' itself, consider
+ writing it as an extension (*note Dynamic Extensions::). If that's
+ not possible, continue with the rest of the steps in this list.
2. Be prepared to sign the appropriate paperwork. In order for the
- FSF to distribute your changes, you must either place those
- changes in the public domain and submit a signed statement to that
- effect, or assign the copyright in your changes to the FSF. Both
- of these actions are easy to do and _many_ people have done so
- already. If you have questions, please contact me (*note Bugs::),
- or <address@hidden>.
+ FSF to distribute your changes, you must either place those changes
+ in the public domain and submit a signed statement to that effect,
+ or assign the copyright in your changes to the FSF. Both of these
+ actions are easy to do and _many_ people have done so already. If
+ you have questions, please contact me (*note Bugs::), or
+ <address@hidden>.
3. Get the latest version. It is much easier for me to integrate
- changes if they are relative to the most recent distributed
- version of `gawk', or better yet, relative to the latest code in
- the Git repository. If your version of `gawk' is very old, I may
- not be able to integrate your changes at all. (*Note Getting::,
- for information on getting the latest version of `gawk'.)
-
- 4. See *note (Version)Top:: standards, GNU Coding Standards. This
- document describes how GNU software should be written. If you
+ changes if they are relative to the most recent distributed version
+ of 'gawk', or better yet, relative to the latest code in the Git
+ repository. If your version of 'gawk' is very old, I may not be
+ able to integrate your changes at all. (*Note Getting::, for
+ information on getting the latest version of 'gawk'.)
+
+ 4. See *note (Version, standards, GNU Coding Standards)Top::. This
+ document describes how GNU software should be written. If you
haven't read it, please do so, preferably _before_ starting to
- modify `gawk'. (The `GNU Coding Standards' are available from the
+ modify 'gawk'. (The 'GNU Coding Standards' are available from the
GNU Project's website (http://www.gnu.org/prep/standards/).
Texinfo, Info, and DVI versions are also available.)
- 5. Use the `gawk' coding style. The C code for `gawk' follows the
- instructions in the `GNU Coding Standards', with minor exceptions.
+ 5. Use the 'gawk' coding style. The C code for 'gawk' follows the
+ instructions in the 'GNU Coding Standards', with minor exceptions.
The code is formatted using the traditional "K&R" style,
particularly as regards to the placement of braces and the use of
- TABs. In brief, the coding rules for `gawk' are as follows:
+ TABs. In brief, the coding rules for 'gawk' are as follows:
* Use ANSI/ISO style (prototype) function headers when defining
functions.
* Put the name of the function at the beginning of its own line.
- * Put the return type of the function, even if it is `int', on
+ * Put the return type of the function, even if it is 'int', on
the line above the line with the name and arguments of the
function.
* Put spaces around parentheses used in control structures
- (`if', `while', `for', `do', `switch', and `return').
+ ('if', 'while', 'for', 'do', 'switch', and 'return').
* Do not put spaces in front of parentheses used in function
calls.
- * Put spaces around all C operators and after commas in
- function calls.
+ * Put spaces around all C operators and after commas in function
+ calls.
* Do not use the comma operator to produce multiple side
- effects, except in `for' loop initialization and increment
+ effects, except in 'for' loop initialization and increment
parts, and in macro bodies.
* Use real TABs for indenting, not spaces.
* Use the "K&R" brace layout style.
- * Use comparisons against `NULL' and `'\0'' in the conditions of
- `if', `while', and `for' statements, as well as in the `case's
- of `switch' statements, instead of just the plain pointer or
+ * Use comparisons against 'NULL' and ''\0'' in the conditions of
+ 'if', 'while', and 'for' statements, as well as in the 'case's
+ of 'switch' statements, instead of just the plain pointer or
character value.
- * Use `true' and `false' for `bool' values, the `NULL' symbolic
- constant for pointer values, and the character constant
- `'\0'' where appropriate, instead of `1' and `0'.
+ * Use 'true' and 'false' for 'bool' values, the 'NULL' symbolic
+ constant for pointer values, and the character constant ''\0''
+ where appropriate, instead of '1' and '0'.
* Provide one-line descriptive comments for each function.
- * Do not use the `alloca()' function for allocating memory off
+ * Do not use the 'alloca()' function for allocating memory off
the stack. Its use causes more portability trouble than is
worth the minor benefit of not having to free the storage.
- Instead, use `malloc()' and `free()'.
+ Instead, use 'malloc()' and 'free()'.
- * Do not use comparisons of the form `! strcmp(a, b)' or
- similar. As Henry Spencer once said, "`strcmp()' is not a
- boolean!" Instead, use `strcmp(a, b) == 0'.
+ * Do not use comparisons of the form '! strcmp(a, b)' or
+ similar. As Henry Spencer once said, "'strcmp()' is not a
+ boolean!" Instead, use 'strcmp(a, b) == 0'.
* If adding new bit flag values, use explicit hexadecimal
- constants (`0x001', `0x002', `0x004', and son on) instead of
- shifting one left by successive amounts (`(1<<0)', `(1<<1)',
+ constants ('0x001', '0x002', '0x004', and son on) instead of
+ shifting one left by successive amounts ('(1<<0)', '(1<<1)',
and so on).
NOTE: If I have to reformat your code to follow the coding
- style used in `gawk', I may not bother to integrate your
+ style used in 'gawk', I may not bother to integrate your
changes at all.
6. Update the documentation. Along with your new code, please supply
new sections and/or chapters for this Info file. If at all
possible, please use real Texinfo, instead of just supplying
unformatted ASCII text (although even that is better than no
- documentation at all). Conventions to be followed in `GAWK:
- Effective AWK Programming' are provided after the address@hidden' at the
- end of the Texinfo source file. If possible, please update the
- `man' page as well.
+ documentation at all). Conventions to be followed in 'GAWK:
+ Effective AWK Programming' are provided after the '@bye' at the end
+ of the Texinfo source file. If possible, please update the 'man'
+ page as well.
You will also have to sign paperwork for your documentation
changes.
- 7. Submit changes as unified diffs. Use `diff -u -r -N' to compare
- the original `gawk' source tree with your version. I recommend
- using the GNU version of `diff', or best of all, `git diff' or
- `git format-patch'. Send the output produced by `diff' to me when
- you submit your changes. (*Note Bugs::, for the electronic mail
+ 7. Submit changes as unified diffs. Use 'diff -u -r -N' to compare
+ the original 'gawk' source tree with your version. I recommend
+ using the GNU version of 'diff', or best of all, 'git diff' or 'git
+ format-patch'. Send the output produced by 'diff' to me when you
+ submit your changes. (*Note Bugs::, for the electronic mail
information.)
Using this format makes it easy for me to apply your changes to the
- master version of the `gawk' source code (using `patch'). If I
+ master version of the 'gawk' source code (using 'patch'). If I
have to apply the changes manually, using a text editor, I may not
do so, particularly if there are lots of changes.
- 8. Include an entry for the `ChangeLog' file with your submission.
- This helps further minimize the amount of work I have to do,
- making it easier for me to accept patches. It is simplest if you
- just make this part of your diff.
+ 8. Include an entry for the 'ChangeLog' file with your submission.
+ This helps further minimize the amount of work I have to do, making
+ it easier for me to accept patches. It is simplest if you just
+ make this part of your diff.
Although this sounds like a lot of work, please remember that while
-you may write the new code, I have to maintain it and support it. If it
+you may write the new code, I have to maintain it and support it. If it
isn't possible for me to do that with a minimum of extra work, then I
probably will not.
File: gawk.info, Node: New Ports, Next: Derived Files, Prev: Adding Code,
Up: Additions
-C.2.3 Porting `gawk' to a New Operating System
+C.2.3 Porting 'gawk' to a New Operating System
----------------------------------------------
-If you want to port `gawk' to a new operating system, there are several
+If you want to port 'gawk' to a new operating system, there are several
steps:
1. Follow the guidelines in *note Adding Code::, concerning coding
style, submission of diffs, and so on.
2. Be prepared to sign the appropriate paperwork. In order for the
- FSF to distribute your code, you must either place your code in
- the public domain and submit a signed statement to that effect, or
- assign the copyright in your code to the FSF. Both of these
- actions are easy to do and _many_ people have done so already. If
- you have questions, please contact me, or <address@hidden>.
+ FSF to distribute your code, you must either place your code in the
+ public domain and submit a signed statement to that effect, or
+ assign the copyright in your code to the FSF. Both of these actions
+ are easy to do and _many_ people have done so already. If you have
+ questions, please contact me, or <address@hidden>.
3. When doing a port, bear in mind that your code must coexist
- peacefully with the rest of `gawk' and the other ports. Avoid
- gratuitous changes to the system-independent parts of the code. If
- at all possible, avoid sprinkling `#ifdef's just for your port
+ peacefully with the rest of 'gawk' and the other ports. Avoid
+ gratuitous changes to the system-independent parts of the code. If
+ at all possible, avoid sprinkling '#ifdef's just for your port
throughout the code.
If the changes needed for a particular system affect too much of
the code, I probably will not accept them. In such a case, you
- can, of course, distribute your changes on your own, as long as
- you comply with the GPL (*note Copying::).
+ can, of course, distribute your changes on your own, as long as you
+ comply with the GPL (*note Copying::).
- 4. A number of the files that come with `gawk' are maintained by other
+ 4. A number of the files that come with 'gawk' are maintained by other
people. Thus, you should not change them unless it is for a very
- good reason; i.e., changes are not out of the question, but
- changes to these files are scrutinized extra carefully. The files
- are `dfa.c', `dfa.h', `getopt.c', `getopt.h', `getopt1.c',
- `getopt_int.h', `gettext.h', `regcomp.c', `regex.c', `regex.h',
- `regex_internal.c', `regex_internal.h', and `regexec.c'.
+ good reason; i.e., changes are not out of the question, but changes
+ to these files are scrutinized extra carefully. The files are
+ 'dfa.c', 'dfa.h', 'getopt.c', 'getopt.h', 'getopt1.c',
+ 'getopt_int.h', 'gettext.h', 'regcomp.c', 'regex.c', 'regex.h',
+ 'regex_internal.c', 'regex_internal.h', and 'regexec.c'.
5. A number of other files are provided by the GNU Autotools
- (Autoconf, Automake, and GNU `gettext'). You should not change
- them either, unless it is for a very good reason. The files are
- `ABOUT-NLS', `config.guess', `config.rpath', `config.sub',
- `depcomp', `INSTALL', `install-sh', `missing', `mkinstalldirs',
- `xalloc.h', and `ylwrap'.
+ (Autoconf, Automake, and GNU 'gettext'). You should not change
+ them either, unless it is for a very good reason. The files are
+ 'ABOUT-NLS', 'config.guess', 'config.rpath', 'config.sub',
+ 'depcomp', 'INSTALL', 'install-sh', 'missing', 'mkinstalldirs',
+ 'xalloc.h', and 'ylwrap'.
6. Be willing to continue to maintain the port. Non-Unix operating
- systems are supported by volunteers who maintain the code needed
- to compile and run `gawk' on their systems. If no-one volunteers
- to maintain a port, it becomes unsupported and it may be necessary
- to remove it from the distribution.
-
- 7. Supply an appropriate `gawkmisc.???' file. Each port has its own
- `gawkmisc.???' that implements certain operating system specific
- functions. This is cleaner than a plethora of `#ifdef's scattered
- throughout the code. The `gawkmisc.c' in the main source
- directory includes the appropriate `gawkmisc.???' file from each
+ systems are supported by volunteers who maintain the code needed to
+ compile and run 'gawk' on their systems. If no-one volunteers to
+ maintain a port, it becomes unsupported and it may be necessary to
+ remove it from the distribution.
+
+ 7. Supply an appropriate 'gawkmisc.???' file. Each port has its own
+ 'gawkmisc.???' that implements certain operating system specific
+ functions. This is cleaner than a plethora of '#ifdef's scattered
+ throughout the code. The 'gawkmisc.c' in the main source directory
+ includes the appropriate 'gawkmisc.???' file from each
subdirectory. Be sure to update it as well.
- Each port's `gawkmisc.???' file has a suffix reminiscent of the
+ Each port's 'gawkmisc.???' file has a suffix reminiscent of the
machine or operating system for the port--for example,
- `pc/gawkmisc.pc' and `vms/gawkmisc.vms'. The use of separate
- suffixes, instead of plain `gawkmisc.c', makes it possible to move
+ 'pc/gawkmisc.pc' and 'vms/gawkmisc.vms'. The use of separate
+ suffixes, instead of plain 'gawkmisc.c', makes it possible to move
files from a port's subdirectory into the main subdirectory,
- without accidentally destroying the real `gawkmisc.c' file.
+ without accidentally destroying the real 'gawkmisc.c' file.
(Currently, this is only an issue for the PC operating system
ports.)
- 8. Supply a `Makefile' as well as any other C source and header files
- that are necessary for your operating system. All your code
- should be in a separate subdirectory, with a name that is the same
- as, or reminiscent of, either your operating system or the
- computer system. If possible, try to structure things so that it
- is not necessary to move files out of the subdirectory into the
- main source directory. If that is not possible, then be sure to
- avoid using names for your files that duplicate the names of files
- in the main source directory.
+ 8. Supply a 'Makefile' as well as any other C source and header files
+ that are necessary for your operating system. All your code should
+ be in a separate subdirectory, with a name that is the same as, or
+ reminiscent of, either your operating system or the computer
+ system. If possible, try to structure things so that it is not
+ necessary to move files out of the subdirectory into the main
+ source directory. If that is not possible, then be sure to avoid
+ using names for your files that duplicate the names of files in the
+ main source directory.
- 9. Update the documentation. Please write a section (or sections)
- for this Info file describing the installation and compilation
- steps needed to compile and/or install `gawk' for your system.
+ 9. Update the documentation. Please write a section (or sections) for
+ this Info file describing the installation and compilation steps
+ needed to compile and/or install 'gawk' for your system.
Following these steps makes it much easier to integrate your changes
-into `gawk' and have them coexist happily with other operating systems'
+into 'gawk' and have them coexist happily with other operating systems'
code that is already there.
In the code that you supply and maintain, feel free to use a coding
@@ -28821,48 +28710,48 @@ File: gawk.info, Node: Derived Files, Prev: New
Ports, Up: Additions
C.2.4 Why Generated Files Are Kept In Git
-----------------------------------------
-If you look at the `gawk' source in the Git repository, you will notice
+If you look at the 'gawk' source in the Git repository, you will notice
that it includes files that are automatically generated by GNU
-infrastructure tools, such as `Makefile.in' from Automake and even
-`configure' from Autoconf.
+infrastructure tools, such as 'Makefile.in' from Automake and even
+'configure' from Autoconf.
This is different from many Free Software projects that do not store
-the derived files, because that keeps the repository less cluttered,
-and it is easier to see the substantive changes when comparing versions
-and trying to understand what changed between commits.
+the derived files, because that keeps the repository less cluttered, and
+it is easier to see the substantive changes when comparing versions and
+trying to understand what changed between commits.
- However, there are several reasons why the `gawk' maintainer likes
-to have everything in the repository.
+ However, there are several reasons why the 'gawk' maintainer likes to
+have everything in the repository.
First, because it is then easy to reproduce any given version
completely, without relying upon the availability of (older, likely
obsolete, and maybe even impossible to find) other tools.
As an extreme example, if you ever even think about trying to
-compile, oh, say, the V7 `awk', you will discover that not only do you
-have to bootstrap the V7 `yacc' to do so, but you also need the V7
-`lex'. And the latter is pretty much impossible to bring up on a
-modern GNU/Linux system.(1)
-
- (Or, let's say `gawk' 1.2 required `bison' whatever-it-was in 1989
-and that there was no `awkgram.c' file in the repository. Is there a
-guarantee that we could find that `bison' version? Or that _it_ would
+compile, oh, say, the V7 'awk', you will discover that not only do you
+have to bootstrap the V7 'yacc' to do so, but you also need the V7
+'lex'. And the latter is pretty much impossible to bring up on a modern
+GNU/Linux system.(1)
+
+ (Or, let's say 'gawk' 1.2 required 'bison' whatever-it-was in 1989
+and that there was no 'awkgram.c' file in the repository. Is there a
+guarantee that we could find that 'bison' version? Or that _it_ would
build?)
- If the repository has all the generated files, then it's easy to
-just check them out and build. (Or _easier_, depending upon how far
-back we go.)
+ If the repository has all the generated files, then it's easy to just
+check them out and build. (Or _easier_, depending upon how far back we
+go.)
And that brings us to the second (and stronger) reason why all the
files really need to be in Git. It boils down to who do you cater
-to--the `gawk' developer(s), or the user who just wants to check out a
+to--the 'gawk' developer(s), or the user who just wants to check out a
version and try it out?
- The `gawk' maintainer wants it to be possible for any interested
-`awk' user in the world to just clone the repository, check out the
-branch of interest and build it. Without their having to have the
-correct version(s) of the autotools.(2) That is the point of the
-`bootstrap.sh' file. It touches the various other files in the right
+ The 'gawk' maintainer wants it to be possible for any interested
+'awk' user in the world to just clone the repository, check out the
+branch of interest and build it. Without their having to have the
+correct version(s) of the autotools.(2) That is the point of the
+'bootstrap.sh' file. It touches the various other files in the right
order such that
# The canonical incantation for building GNU software:
@@ -28870,27 +28759,27 @@ order such that
will _just work_.
- This is extremely important for the `master' and `gawk-X.Y-stable'
+ This is extremely important for the 'master' and 'gawk-X.Y-stable'
branches.
- Further, the `gawk' maintainer would argue that it's also important
-for the `gawk' developers. When he tried to check out the `xgawk'
-branch(3) to build it, he couldn't. (No `ltmain.sh' file, and he had no
+ Further, the 'gawk' maintainer would argue that it's also important
+for the 'gawk' developers. When he tried to check out the 'xgawk'
+branch(3) to build it, he couldn't. (No 'ltmain.sh' file, and he had no
idea how to create it, and that was not the only problem.)
He felt _extremely_ frustrated. With respect to that branch, the
maintainer is no different than Jane User who wants to try to build
-`gawk-4.1-stable' or `master' from the repository.
+'gawk-4.1-stable' or 'master' from the repository.
Thus, the maintainer thinks that it's not just important, but
critical, that for any given branch, the above incantation _just works_.
- A third reason to have all the files is that without them, using `git
+ A third reason to have all the files is that without them, using 'git
bisect' to try to find the commit that introduced a bug is exceedingly
-difficult. The maintainer tried to do that on another project that
-requires running bootstrapping scripts just to create `configure' and
-so on; it was really painful. When the repository is self-contained,
-using `git bisect' in it is very easy.
+difficult. The maintainer tried to do that on another project that
+requires running bootstrapping scripts just to create 'configure' and so
+on; it was really painful. When the repository is self-contained, using
+'git bisect' in it is very easy.
What are some of the consequences and/or actions to take?
@@ -28900,17 +28789,17 @@ using `git bisect' in it is very easy.
A. It's the maintainer's job to merge them and he will deal with
it.
- B. He is really good at `git diff x y > /tmp/diff1 ; gvim
+ B. He is really good at 'git diff x y > /tmp/diff1 ; gvim
/tmp/diff1' to remove the diffs that aren't of interest in
order to review code.
2. It would certainly help if everyone used the same versions of the
GNU tools as he does, which in general are the latest released
- versions of Automake, Autoconf, `bison', and GNU `gettext'.
+ versions of Automake, Autoconf, 'bison', and GNU 'gettext'.
- Installing from source is quite easy. It's how the maintainer
- worked for years (and still works). He had `/usr/local/bin' at
- the front of his `PATH' and just did:
+ Installing from source is quite easy. It's how the maintainer
+ worked for years (and still works). He had '/usr/local/bin' at the
+ front of his 'PATH' and just did:
wget http://ftp.gnu.org/gnu/PACKAGE/PACKAGE-X.Y.Z.tar.gz
tar -xpzvf PACKAGE-X.Y.Z.tar.gz
@@ -28918,23 +28807,22 @@ using `git bisect' in it is very easy.
./configure && make && make check
make install # as root
-
Most of the above was originally written by the maintainer to other
-`gawk' developers. It raised the objection from one of the developers
+'gawk' developers. It raised the objection from one of the developers
"... that anybody pulling down the source from Git is not an end user."
- However, this is not true. There are "power `awk' users" who can
-build `gawk' (using the magic incantation shown previously) but who
-can't program in C. Thus, the major branches should be kept buildable
+ However, this is not true. There are "power 'awk' users" who can
+build 'gawk' (using the magic incantation shown previously) but who
+can't program in C. Thus, the major branches should be kept buildable
all the time.
- It was then suggested that there be a `cron' job to create nightly
+ It was then suggested that there be a 'cron' job to create nightly
tarballs of "the source." Here, the problem is that there are source
-trees, corresponding to the various branches! So, nightly tarballs
-aren't the answer, especially as the repository can go for weeks
-without significant change being introduced.
+trees, corresponding to the various branches! So, nightly tarballs
+aren't the answer, especially as the repository can go for weeks without
+significant change being introduced.
- Fortunately, the Git server can meet this need. For any given branch
+ Fortunately, the Git server can meet this need. For any given branch
named BRANCHNAME, use:
wget
http://git.savannah.gnu.org/cgit/gawk.git/snapshot/gawk-BRANCHNAME.tar.gz
@@ -28943,18 +28831,18 @@ to retrieve a snapshot of the given branch.
---------- Footnotes ----------
- (1) We tried. It was painful.
+ (1) We tried. It was painful.
(2) There is one GNU program that is (in our opinion) severely
-difficult to bootstrap from the Git repository. For example, on the
+difficult to bootstrap from the Git repository. For example, on the
author's old (but still working) PowerPC Macintosh with Mac OS X 10.5,
it was necessary to bootstrap a ton of software, starting with Git
itself, in order to try to work with the latest code. It's not
pleasant, and especially on older systems, it's a big waste of time.
- Starting with the latest tarball was no picnic either. The
-maintainers had dropped `.gz' and `.bz2' files and only distribute
-`.tar.xz' files. It was necessary to bootstrap `xz' first!
+ Starting with the latest tarball was no picnic either. The
+maintainers had dropped '.gz' and '.bz2' files and only distribute
+'.tar.xz' files. It was necessary to bootstrap 'xz' first!
(3) A branch (since removed) created by one of the other developers
that did not include the generated files.
@@ -28966,15 +28854,16 @@ C.3 Probable Future Extensions
==============================
AWK is a language similar to PERL, only considerably more elegant.
- -- Arnold Robbins
+ -- _Arnold Robbins_
- Hey! -- Larry Wall
+ Hey!
+ -- _Larry Wall_
- The `TODO' file in the `master' branch of the `gawk' Git repository
+ The 'TODO' file in the 'master' branch of the 'gawk' Git repository
lists possible future enhancements. Some of these relate to the source
-code, and others to possible new features. Please see that file for
-the list. *Note Additions::, if you are interested in tackling any of
-the projects listed there.
+code, and others to possible new features. Please see that file for the
+list. *Note Additions::, if you are interested in tackling any of the
+projects listed there.
File: gawk.info, Node: Implementation Limitations, Next: Extension Design,
Prev: Future Extensions, Up: Notes
@@ -28982,30 +28871,31 @@ File: gawk.info, Node: Implementation Limitations,
Next: Extension Design, Pr
C.4 Some Limitations of the Implementation
==========================================
-This following table describes limits of `gawk' on a Unix-like system
-(although it is variable even then). Other systems may have different
+This following table describes limits of 'gawk' on a Unix-like system
+(although it is variable even then). Other systems may have different
limits.
Item Limit
---------------------------------------------------------------------------
+--------------------------------------------------------------------------
Characters in a character 2^(number of bits per byte)
-class
-Length of input record `MAX_INT'
+class
+Length of input record 'MAX_INT'
Length of output record Unlimited
Length of source line Unlimited
-Number of fields in a record `MAX_LONG'
+Number of fields in a 'MAX_LONG'
+record
Number of file redirections Unlimited
-Number of input records in `MAX_LONG'
-one file
-Number of input records `MAX_LONG'
-total
+Number of input records in 'MAX_LONG'
+one file
+Number of input records 'MAX_LONG'
+total
Number of pipe redirections min(number of processes per user, number
of open files)
Numeric values Double-precision floating point (if not
using MPFR)
-Size of a field `MAX_INT'
-Size of a literal string `MAX_INT'
-Size of a printf string `MAX_INT'
+Size of a field 'MAX_INT'
+Size of a literal string 'MAX_INT'
+Size of a printf string 'MAX_INT'
File: gawk.info, Node: Extension Design, Next: Old Extension Mechanism,
Prev: Implementation Limitations, Up: Notes
@@ -29016,15 +28906,15 @@ C.5 Extension API Design
This minor node documents the design of the extension API, including a
discussion of some of the history and problems that needed to be solved.
- The first version of extensions for `gawk' was developed in the
-mid-1990s and released with `gawk' 3.1 in the late 1990s. The basic
+ The first version of extensions for 'gawk' was developed in the
+mid-1990s and released with 'gawk' 3.1 in the late 1990s. The basic
mechanisms and design remained unchanged for close to 15 years, until
2012.
- The old extension mechanism used data types and functions from
-`gawk' itself, with a "clever hack" to install extension functions.
+ The old extension mechanism used data types and functions from 'gawk'
+itself, with a "clever hack" to install extension functions.
- `gawk' included some sample extensions, of which a few were really
+ 'gawk' included some sample extensions, of which a few were really
useful. However, it was clear from the outset that the extension
mechanism was bolted onto the side and was not really well thought out.
@@ -29043,33 +28933,33 @@ C.5.1 Problems With The Old Mechanism
The old extension mechanism had several problems:
- * It depended heavily upon `gawk' internals. Any time the `NODE'
+ * It depended heavily upon 'gawk' internals. Any time the 'NODE'
structure(1) changed, an extension would have to be recompiled.
Furthermore, to really write extensions required understanding
- something about `gawk''s internal functions. There was some
+ something about 'gawk''s internal functions. There was some
documentation in this Info file, but it was quite minimal.
- * Being able to call into `gawk' from an extension required linker
- facilities that are common on Unix-derived systems but that did
- not work on MS-Windows systems; users wanting extensions on
- MS-Windows had to statically link them into `gawk', even though
- MS-Windows supports dynamic loading of shared objects.
+ * Being able to call into 'gawk' from an extension required linker
+ facilities that are common on Unix-derived systems but that did not
+ work on MS-Windows systems; users wanting extensions on MS-Windows
+ had to statically link them into 'gawk', even though MS-Windows
+ supports dynamic loading of shared objects.
- * The API would change occasionally as `gawk' changed; no
+ * The API would change occasionally as 'gawk' changed; no
compatibility between versions was ever offered or planned for.
- Despite the drawbacks, the `xgawk' project developers forked `gawk'
-and developed several significant extensions. They also enhanced
-`gawk''s facilities relating to file inclusion and shared object access.
+ Despite the drawbacks, the 'xgawk' project developers forked 'gawk'
+and developed several significant extensions. They also enhanced
+'gawk''s facilities relating to file inclusion and shared object access.
A new API was desired for a long time, but only in 2012 did the
-`gawk' maintainer and the `xgawk' developers finally start working on
-it together. More information about the `xgawk' project is provided in
+'gawk' maintainer and the 'xgawk' developers finally start working on it
+together. More information about the 'xgawk' project is provided in
*note gawkextlib::.
---------- Footnotes ----------
- (1) A critical central data structure inside `gawk'.
+ (1) A critical central data structure inside 'gawk'.
File: gawk.info, Node: Extension New Mechanism Goals, Next: Extension Other
Design Decisions, Prev: Old Extension Problems, Up: Extension Design
@@ -29079,21 +28969,21 @@ C.5.2 Goals For A New Mechanism
Some goals for the new API were:
- * The API should be independent of `gawk' internals. Changes in
- `gawk' internals should not be visible to the writer of an
+ * The API should be independent of 'gawk' internals. Changes in
+ 'gawk' internals should not be visible to the writer of an
extension function.
- * The API should provide _binary_ compatibility across `gawk'
+ * The API should provide _binary_ compatibility across 'gawk'
releases as long as the API itself does not change.
* The API should enable extensions written in C or C++ to have
- roughly the same "appearance" to `awk'-level code as `awk'
- functions do. This means that extensions should have:
+ roughly the same "appearance" to 'awk'-level code as 'awk'
+ functions do. This means that extensions should have:
- The ability to access function parameters.
- - The ability to turn an undefined parameter into an array
- (call by reference).
+ - The ability to turn an undefined parameter into an array (call
+ by reference).
- The ability to create, access and update global variables.
@@ -29101,20 +28991,20 @@ Some goals for the new API were:
flattening") in order to loop over all the element in an easy
fashion for C code.
- - The ability to create arrays (including `gawk''s true arrays
+ - The ability to create arrays (including 'gawk''s true arrays
of arrays).
Some additional important goals were:
* The API should use only features in ISO C 90, so that extensions
- can be written using the widest range of C and C++ compilers. The
- header should include the appropriate `#ifdef __cplusplus' and
- `extern "C"' magic so that a C++ compiler could be used. (If
- using C++, the runtime system has to be smart enough to call any
- constructors and destructors, as `gawk' is a C program. As of this
+ can be written using the widest range of C and C++ compilers. The
+ header should include the appropriate '#ifdef __cplusplus' and
+ 'extern "C"' magic so that a C++ compiler could be used. (If using
+ C++, the runtime system has to be smart enough to call any
+ constructors and destructors, as 'gawk' is a C program. As of this
writing, this has not been tested.)
- * The API mechanism should not require access to `gawk''s symbols(1)
+ * The API mechanism should not require access to 'gawk''s symbols(1)
by the compile-time or dynamic linker, in order to enable creation
of extensions that also work on MS-Windows.
@@ -29122,29 +29012,29 @@ Some goals for the new API were:
that should be available to extensions, which were also subsequently
provided:
- * Extensions should have the ability to hook into `gawk''s I/O
- redirection mechanism. In particular, the `xgawk' developers
+ * Extensions should have the ability to hook into 'gawk''s I/O
+ redirection mechanism. In particular, the 'xgawk' developers
provided a so-called "open hook" to take over reading records.
During development, this was generalized to allow extensions to
hook into input processing, output processing, and two-way I/O.
* An extension should be able to provide a "call back" function to
- perform cleanup actions when `gawk' exits.
+ perform cleanup actions when 'gawk' exits.
* An extension should be able to provide a version string so that
- `gawk''s `--version' option can provide information about
+ 'gawk''s '--version' option can provide information about
extensions as well.
- The requirement to avoid access to `gawk''s symbols is, at first
+ The requirement to avoid access to 'gawk''s symbols is, at first
glance, a difficult one to meet.
One design, apparently used by Perl and Ruby and maybe others, would
-be to make the mainline `gawk' code into a library, with the `gawk'
-utility a small C `main()' function linked against the library.
+be to make the mainline 'gawk' code into a library, with the 'gawk'
+utility a small C 'main()' function linked against the library.
This seemed like the tail wagging the dog, complicating build and
-installation and making a simple copy of the `gawk' executable from one
-system to another (or one place to another on the same system!) into a
+installation and making a simple copy of the 'gawk' executable from one
+system to another (or one place to another on the same system!) into a
chancy operation.
Pat Rankin suggested the solution that was adopted. *Note Extension
@@ -29153,7 +29043,7 @@ Mechanism Outline::, for the details.
---------- Footnotes ----------
(1) The "symbols" are the variables and functions defined inside
-`gawk'. Access to these symbols by code external to `gawk' loaded
+'gawk'. Access to these symbols by code external to 'gawk' loaded
dynamically at runtime is problematic on MS-Windows.
@@ -29163,40 +29053,40 @@ C.5.3 Other Design Decisions
----------------------------
As an arbitrary design decision, extensions can read the values of
-predefined variables and arrays (such as `ARGV' and `FS'), but cannot
-change them, with the exception of `PROCINFO'.
+predefined variables and arrays (such as 'ARGV' and 'FS'), but cannot
+change them, with the exception of 'PROCINFO'.
The reason for this is to prevent an extension function from
-affecting the flow of an `awk' program outside its control. While a
-real `awk' function can do what it likes, that is at the discretion of
+affecting the flow of an 'awk' program outside its control. While a
+real 'awk' function can do what it likes, that is at the discretion of
the programmer. An extension function should provide a service or make
-a C API available for use within `awk', and not mess with `FS' or
-`ARGC' and `ARGV'.
+a C API available for use within 'awk', and not mess with 'FS' or 'ARGC'
+and 'ARGV'.
- In addition, it becomes easy to start down a slippery slope. How
-much access to `gawk' facilities do extensions need? Do they need
-`getline'? What about calling `gsub()' or compiling regular
-expressions? What about calling into `awk' functions? (_That_ would be
+ In addition, it becomes easy to start down a slippery slope. How
+much access to 'gawk' facilities do extensions need? Do they need
+'getline'? What about calling 'gsub()' or compiling regular
+expressions? What about calling into 'awk' functions? (_That_ would be
messy.)
- In order to avoid these issues, the `gawk' developers chose to start
+ In order to avoid these issues, the 'gawk' developers chose to start
with the simplest, most basic features that are still truly useful.
- Another decision is that although `gawk' provides nice things like
+ Another decision is that although 'gawk' provides nice things like
MPFR, and arrays indexed internally by integers, these features are not
being brought out to the API in order to keep things simple and close to
-traditional `awk' semantics. (In fact, arrays indexed internally by
+traditional 'awk' semantics. (In fact, arrays indexed internally by
integers are so transparent that they aren't even documented!)
- Additionally, all functions in the API check that their pointer
-input parameters are not `NULL'. If they are, they return an error.
-(It is a good idea for extension code to verify that pointers received
-from `gawk' are not `NULL'. Such a thing should not happen, but the
-`gawk' developers are only human, and they have been known to
-occasionally make mistakes.)
+ Additionally, all functions in the API check that their pointer input
+parameters are not 'NULL'. If they are, they return an error. (It is a
+good idea for extension code to verify that pointers received from
+'gawk' are not 'NULL'. Such a thing should not happen, but the 'gawk'
+developers are only human, and they have been known to occasionally make
+mistakes.)
- With time, the API will undoubtedly evolve; the `gawk' developers
-expect this to be driven by user needs. For now, the current API seems
+ With time, the API will undoubtedly evolve; the 'gawk' developers
+expect this to be driven by user needs. For now, the current API seems
to provide a minimal yet powerful set of features for creating
extensions.
@@ -29208,12 +29098,12 @@ C.5.4 Room For Future Growth
The API can later be expanded, in two ways:
- * `gawk' passes an "extension id" into the extension when it first
+ * 'gawk' passes an "extension id" into the extension when it first
loads the extension. The extension then passes this id back to
- `gawk' with each function call. This mechanism allows `gawk' to
+ 'gawk' with each function call. This mechanism allows 'gawk' to
identify the extension calling into it, should it need to know.
- * Similarly, the extension passes a "name space" into `gawk' when it
+ * Similarly, the extension passes a "name space" into 'gawk' when it
registers each extension function. This accommodates a possible
future mechanism for grouping extension functions and possibly
avoiding name conflicts.
@@ -29228,34 +29118,34 @@ C.6 Compatibility For Old Extensions
====================================
*note Dynamic Extensions::, describes the supported API and mechanisms
-for writing extensions for `gawk'. This API was introduced in version
-4.1. However, for many years `gawk' provided an extension mechanism
-that required knowledge of `gawk' internals and that was not as well
+for writing extensions for 'gawk'. This API was introduced in version
+4.1. However, for many years 'gawk' provided an extension mechanism
+that required knowledge of 'gawk' internals and that was not as well
designed.
- In order to provide a transition period, `gawk' version 4.1
-continues to support the original extension mechanism. This will be
-true for the life of exactly one major release. This support will be
-withdrawn, and removed from the source code, at the next major release.
+ In order to provide a transition period, 'gawk' version 4.1 continues
+to support the original extension mechanism. This will be true for the
+life of exactly one major release. This support will be withdrawn, and
+removed from the source code, at the next major release.
Briefly, original-style extensions should be compiled by including
-the `awk.h' header file in the extension source code. Additionally, you
-must define the identifier `GAWK' when building (use `-DGAWK' with
-Unix-style compilers). Otherwise, the definitions in `gawkapi.h' will
-cause conflicts with those in `awk.h' and your extension will not
+the 'awk.h' header file in the extension source code. Additionally, you
+must define the identifier 'GAWK' when building (use '-DGAWK' with
+Unix-style compilers). Otherwise, the definitions in 'gawkapi.h' will
+cause conflicts with those in 'awk.h' and your extension will not
compile.
Just as in previous versions, you load an old-style extension with
-the `extension()' built-in function (which is not otherwise documented).
+the 'extension()' built-in function (which is not otherwise documented).
This function in turn finds and loads the shared object file containing
-the extension and calls its `dl_load()' C routine.
+the extension and calls its 'dl_load()' C routine.
Because original-style and new-style extensions use different
-initialization routines (`dl_load()' versus `dlload()'), they may safely
-be installed in the same directory (to be found by `AWKLIBPATH')
-without conflict.
+initialization routines ('dl_load()' versus 'dlload()'), they may safely
+be installed in the same directory (to be found by 'AWKLIBPATH') without
+conflict.
- The `gawk' development team strongly recommends that you convert any
+ The 'gawk' development team strongly recommends that you convert any
old extensions that you may have to use the new API described in *note
Dynamic Extensions::.
@@ -29265,30 +29155,28 @@ File: gawk.info, Node: Notes summary, Prev: Old
Extension Mechanism, Up: Note
C.7 Summary
===========
- * `gawk''s extensions can be disabled with either the
- `--traditional' option or with the `--posix' option. The
- `--parsedebug' option is available if `gawk' is compiled with
- `-DDEBUG'.
+ * 'gawk''s extensions can be disabled with either the '--traditional'
+ option or with the '--posix' option. The '--parsedebug' option is
+ available if 'gawk' is compiled with '-DDEBUG'.
- * The source code for `gawk' is maintained in a publicly accessible
- Git repository. Anyone may check it out and view the source.
+ * The source code for 'gawk' is maintained in a publicly accessible
+ Git repository. Anyone may check it out and view the source.
- * Contributions to `gawk' are welcome. Following the steps outlined
+ * Contributions to 'gawk' are welcome. Following the steps outlined
in this major node will make it easier to integrate your
- contributions into the code base. This applies both to new
- feature contributions and to ports to additional operating systems.
+ contributions into the code base. This applies both to new feature
+ contributions and to ports to additional operating systems.
- * `gawk' has some limits--generally those that are imposed by the
+ * 'gawk' has some limits--generally those that are imposed by the
machine architecture.
* The extension API design was intended to solve a number of problems
with the previous extension mechanism, enable features needed by
- the `xgawk' project, and provide binary compatibility going
+ the 'xgawk' project, and provide binary compatibility going
forward.
* The previous extension mechanism is still supported in version 4.1
- of `gawk', but it _will_ be removed in the next major release.
-
+ of 'gawk', but it _will_ be removed in the next major release.
File: gawk.info, Node: Basic Concepts, Next: Glossary, Prev: Notes, Up: Top
@@ -29298,7 +29186,7 @@ Appendix D Basic Programming Concepts
This major node attempts to define some of the basic concepts and terms
that are used throughout the rest of this Info file. As this Info file
-is specifically about `awk', and not about computer programming in
+is specifically about 'awk', and not about computer programming in
general, the coverage here is by necessity fairly cursory and
simplistic. (If you need more background, there are many other
introductory texts that you should refer to instead.)
@@ -29315,39 +29203,41 @@ D.1 What a Program Does
=======================
At the most basic level, the job of a program is to process some input
-data and produce results. See *note figure-general-flow::.
+data and produce results. See *note Figure D.1: figure-general-flow.
- _______
-+------+ / \ +---------+
+ [image src="general-program.txt" alt="General program flow" text="
_______
++------+ / \\ +---------+
| Data | -----> < Program > -----> | Results |
-+------+ \_______/ +---------+
++------+ \\_______/ +---------+" ]
+
Figure D.1: General Program Flow
- The "program" in the figure can be either a compiled program(1)
-(such as `ls'), or it may be "interpreted". In the latter case, a
-machine-executable program such as `awk' reads your program, and then
+ The "program" in the figure can be either a compiled program(1) (such
+as 'ls'), or it may be "interpreted". In the latter case, a
+machine-executable program such as 'awk' reads your program, and then
uses the instructions in your program to process the data.
When you write a program, it usually consists of the following, very
-basic set of steps, as shown in *note figure-process-flow:::
+basic set of steps, as shown in *note Figure D.2: figure-process-flow.:
- ______
-+----------------+ / More \ No +----------+
+ [image src="process-flow.txt" alt="Basic Program Stages" text="
______
++----------------+ / More \\ No +----------+
| Initialization | -------> < Data > -------> | Clean Up |
-+----------------+ ^ \ ? / +----------+
++----------------+ ^ \\ ? / +----------+
| +--+-+
| | Yes
| |
| V
| +---------+
+-----+ Process |
- +---------+
+ +---------+" ]
+
Figure D.2: Basic Program Steps
Initialization
These are the things you do before actually starting to process
- data, such as checking arguments, initializing any data you need
- to work with, and so on. This step corresponds to `awk''s `BEGIN'
+ data, such as checking arguments, initializing any data you need to
+ work with, and so on. This step corresponds to 'awk''s 'BEGIN'
rule (*note BEGIN/END::).
If you were baking a cake, this might consist of laying out all the
@@ -29360,7 +29250,7 @@ Processing
In most programming languages, you have to manually manage the
reading of data, checking to see if there is more each time you
- read a chunk. `awk''s pattern-action paradigm (*note Getting
+ read a chunk. 'awk''s pattern-action paradigm (*note Getting
Started::) handles the mechanics of this for you.
In baking a cake, the processing corresponds to the actual labor:
@@ -29369,7 +29259,7 @@ Processing
Clean Up
Once you've processed all the data, you may have things you need to
- do before exiting. This step corresponds to `awk''s `END' rule
+ do before exiting. This step corresponds to 'awk''s 'END' rule
(*note BEGIN/END::).
After the cake comes out of the oven, you still have to wrap it in
@@ -29377,9 +29267,9 @@ Clean Up
mixing bowls and utensils.
An "algorithm" is a detailed set of instructions necessary to
-accomplish a task, or process data. It is much the same as a recipe
-for baking a cake. Programs implement algorithms. Often, it is up to
-you to design the algorithm and implement it, simultaneously.
+accomplish a task, or process data. It is much the same as a recipe for
+baking a cake. Programs implement algorithms. Often, it is up to you
+to design the algorithm and implement it, simultaneously.
The "logical chunks" we talked about previously are called "records",
similar to the records a company keeps on employees, a school keeps for
@@ -29393,12 +29283,12 @@ results, not too surprisingly, is termed "output".
They are often
referred to together as "input/output," and even more often, as "I/O"
for short. (You will also see "input" and "output" used as verbs.)
- `awk' manages the reading of data for you, as well as the breaking
-it up into records and fields. Your program's job is to tell `awk'
-what to do with the data. You do this by describing "patterns" in the
-data to look for, and "actions" to execute when those patterns are
-seen. This "data-driven" nature of `awk' programs usually makes them
-both easier to write and easier to read.
+ 'awk' manages the reading of data for you, as well as the breaking it
+up into records and fields. Your program's job is to tell 'awk' what to
+do with the data. You do this by describing "patterns" in the data to
+look for, and "actions" to execute when those patterns are seen. This
+"data-driven" nature of 'awk' programs usually makes them both easier to
+write and easier to read.
---------- Footnotes ----------
@@ -29414,18 +29304,18 @@ D.2 Data Values in a Computer
In a program, you keep track of information and values in things called
"variables". A variable is just a name for a given value, such as
-`first_name', `last_name', `address', and so on. `awk' has several
+'first_name', 'last_name', 'address', and so on. 'awk' has several
predefined variables, and it has special names to refer to the current
input record and the fields of the record. You may also group multiple
associated values under one name, as an array.
- Data, particularly in `awk', consists of either numeric values, such
+ Data, particularly in 'awk', consists of either numeric values, such
as 42 or 3.1415927, or string values. String values are essentially
anything that's not a number, such as a name. Strings are sometimes
referred to as "character data", since they store the individual
-characters that comprise them. Individual variables, as well as
-numeric and string variables, are referred to as "scalar" values.
-Groups of values, such as arrays, are not scalars.
+characters that comprise them. Individual variables, as well as numeric
+and string variables, are referred to as "scalar" values. Groups of
+values, such as arrays, are not scalars.
*note Computer Arithmetic::, provided a basic introduction to numeric
types (integer and floating-point) and how they are used in a computer.
@@ -29435,41 +29325,41 @@ presented.
While you are probably used to the idea of a number without a value
(i.e., zero), it takes a bit more getting used to the idea of
zero-length character data. Nevertheless, such a thing exists. It is
-called the "null string". The null string is character data that has
-no value. In other words, it is empty. It is written in `awk' programs
-like this: `""'.
+called the "null string". The null string is character data that has no
+value. In other words, it is empty. It is written in 'awk' programs
+like this: '""'.
Humans are used to working in decimal; i.e., base 10. In base 10,
numbers go from 0 to 9, and then "roll over" into the next column.
-(Remember grade school? 42 = 4 x 10 + 2.)
+(Remember grade school? 42 = 4 x 10 + 2.)
There are other number bases though. Computers commonly use base 2
or "binary", base 8 or "octal", and base 16 or "hexadecimal". In
binary, each column represents two times the value in the column to its
-right. Each column may contain either a 0 or a 1. Thus, binary 1010
+right. Each column may contain either a 0 or a 1. Thus, binary 1010
represents (1 x 8) + (0 x 4) + (1 x 2) + (0 x 1), or decimal 10. Octal
and hexadecimal are discussed more in *note Nondecimal-numbers::.
At the very lowest level, computers store values as groups of binary
digits, or "bits". Modern computers group bits into groups of eight,
-called "bytes". Advanced applications sometimes have to manipulate
-bits directly, and `gawk' provides functions for doing so.
+called "bytes". Advanced applications sometimes have to manipulate bits
+directly, and 'gawk' provides functions for doing so.
Programs are written in programming languages. Hundreds, if not
thousands, of programming languages exist. One of the most popular is
the C programming language. The C language had a very strong influence
-on the design of the `awk' language.
+on the design of the 'awk' language.
- There have been several versions of C. The first is often referred
-to as "K&R" C, after the initials of Brian Kernighan and Dennis Ritchie,
-the authors of the first book on C. (Dennis Ritchie created the
-language, and Brian Kernighan was one of the creators of `awk'.)
+ There have been several versions of C. The first is often referred to
+as "K&R" C, after the initials of Brian Kernighan and Dennis Ritchie,
+the authors of the first book on C. (Dennis Ritchie created the
+language, and Brian Kernighan was one of the creators of 'awk'.)
In the mid-1980s, an effort began to produce an international
-standard for C. This work culminated in 1989, with the production of
-the ANSI standard for C. This standard became an ISO standard in 1990.
-In 1999, a revised ISO C standard was approved and released. Where it
-makes sense, POSIX `awk' is compatible with 1999 ISO C.
+standard for C. This work culminated in 1989, with the production of the
+ANSI standard for C. This standard became an ISO standard in 1990. In
+1999, a revised ISO C standard was approved and released. Where it
+makes sense, POSIX 'awk' is compatible with 1999 ISO C.
File: gawk.info, Node: Glossary, Next: Copying, Prev: Basic Concepts, Up:
Top
@@ -29478,44 +29368,44 @@ Glossary
********
Action
- A series of `awk' statements attached to a rule. If the rule's
- pattern matches an input record, `awk' executes the rule's action.
+ A series of 'awk' statements attached to a rule. If the rule's
+ pattern matches an input record, 'awk' executes the rule's action.
Actions are always enclosed in braces. (*Note Action Overview::.)
Ada
A programming language originally defined by the U.S. Department of
- Defense for embedded programming. It was designed to enforce good
+ Defense for embedded programming. It was designed to enforce good
Software Engineering practices.
-Amazing `awk' Assembler
+Amazing 'awk' Assembler
Henry Spencer at the University of Toronto wrote a retargetable
- assembler completely as `sed' and `awk' scripts. It is thousands
+ assembler completely as 'sed' and 'awk' scripts. It is thousands
of lines long, including machine descriptions for several eight-bit
microcomputers. It is a good example of a program that would have
been better written in another language. You can get it from
- `http://awk.info/?awk100/aaa'.
+ <http://awk.info/?awk100/aaa>.
-Amazingly Workable Formatter (`awf')
+Amazingly Workable Formatter ('awf')
Henry Spencer at the University of Toronto wrote a formatter that
- accepts a large subset of the `nroff -ms' and `nroff -man'
- formatting commands, using `awk' and `sh'. It is available from
- `http://awk.info/?tools/awf'.
+ accepts a large subset of the 'nroff -ms' and 'nroff -man'
+ formatting commands, using 'awk' and 'sh'. It is available from
+ <http://awk.info/?tools/awf>.
Anchor
- The regexp metacharacters `^' and `$', which force the match to
- the beginning or end of the string, respectively.
+ The regexp metacharacters '^' and '$', which force the match to the
+ beginning or end of the string, respectively.
ANSI
The American National Standards Institute. This organization
- produces many standards, among them the standards for the C and
- C++ programming languages. These standards often become
- international standards as well. See also "ISO."
+ produces many standards, among them the standards for the C and C++
+ programming languages. These standards often become international
+ standards as well. See also "ISO."
Argument
An argument can be two different things. It can be an option or a
file name passed to a command while invoking it from the command
line, or it can be something passed to a "function" inside a
- program, e.g. inside `awk'.
+ program, e.g. inside 'awk'.
In the latter case, an argument can be passed to a function in two
ways. Either it is given to the called function by value, i.e., a
@@ -29523,12 +29413,12 @@ Argument
function, but the original variable cannot be modified by the
function itself; or it is given by reference, i.e., a pointer to
the interested variable is passed to the function, which can then
- directly modify it. In `awk' scalars are passed by value, and
+ directly modify it. In 'awk' scalars are passed by value, and
arrays are passed by reference. See "Pass By Value/Reference."
Array
A grouping of multiple values under the same name. Most languages
- just provide sequential arrays. `awk' provides associative arrays.
+ just provide sequential arrays. 'awk' provides associative arrays.
Assertion
A statement in a program that a condition is true at this point in
@@ -29536,7 +29426,7 @@ Assertion
to behave.
Assignment
- An `awk' expression that changes the value of some `awk' variable
+ An 'awk' expression that changes the value of some 'awk' variable
or data object. An object that you can assign to is called an
"lvalue". The assigned values are called "rvalues". *Note
Assignment Ops::.
@@ -29545,49 +29435,48 @@ Associative Array
Arrays in which the indices may be numbers or strings, not just
sequential integers in a fixed range.
-`awk' Language
- The language in which `awk' programs are written.
+'awk' Language
+ The language in which 'awk' programs are written.
-`awk' Program
- An `awk' program consists of a series of "patterns" and "actions",
+'awk' Program
+ An 'awk' program consists of a series of "patterns" and "actions",
collectively known as "rules". For each input record given to the
- program, the program's rules are all processed in turn. `awk'
+ program, the program's rules are all processed in turn. 'awk'
programs may also contain function definitions.
-`awk' Script
- Another name for an `awk' program.
+'awk' Script
+ Another name for an 'awk' program.
Bash
The GNU version of the standard shell (the Bourne-Again SHell).
See also "Bourne Shell."
Binary
- Base-two notation, where the digits are `0'-`1'. Since electronic
+ Base-two notation, where the digits are '0'-'1'. Since electronic
circuitry works "naturally" in base 2 (just think of Off/On),
- everything inside a computer is calculated using base 2. Each digit
- represents the presence (or absence) of a power of 2 and is called
- a "bit". So, for example, the base-two number `10101' is the same
- as decimal 21, ((1 x 16) + (1 x 4) + (1 x 1)).
+ everything inside a computer is calculated using base 2. Each
+ digit represents the presence (or absence) of a power of 2 and is
+ called a "bit". So, for example, the base-two number '10101' is
+ the same as decimal 21, ((1 x 16) + (1 x 4) + (1 x 1)).
Since base-two numbers quickly become very long to read and write,
they are usually grouped by 3 (i.e., they are read as octal
numbers), or by 4 (i.e., they are read as hexadecimal numbers).
- There is no direct way to insert base 2 numbers in a C program.
- If need arises, such numbers are usually inserted as octal or
- hexadecimal numbers. The number of base-two digits that fit into
+ There is no direct way to insert base 2 numbers in a C program. If
+ need arises, such numbers are usually inserted as octal or
+ hexadecimal numbers. The number of base-two digits that fit into
registers used for representing integer numbers in computers is a
rough indication of the computing power of the computer itself.
Most computers nowadays use 64 bits for representing integer
numbers in their registers, but 32-bit, 16-bit and 8-bit registers
have been widely used in the past. *Note Nondecimal-numbers::.
-
Bit
- Short for "Binary Digit." All values in computer memory
- ultimately reduce to binary digits: values that are either zero or
- one. Groups of bits may be interpreted differently--as integers,
+ Short for "Binary Digit." All values in computer memory ultimately
+ reduce to binary digits: values that are either zero or one.
+ Groups of bits may be interpreted differently--as integers,
floating-point numbers, character data, addresses of other memory
- objects, or other data. `awk' lets you work with floating-point
- numbers and strings. `gawk' lets you manipulate bit values with
+ objects, or other data. 'awk' lets you work with floating-point
+ numbers and strings. 'gawk' lets you manipulate bit values with
the built-in functions described in *note Bitwise Functions::.
Computers are often defined by how many bits they use to represent
@@ -29596,68 +29485,68 @@ Bit
essentially disappeared.
Boolean Expression
- Named after the English mathematician Boole. See also "Logical
+ Named after the English mathematician Boole. See also "Logical
Expression."
Bourne Shell
- The standard shell (`/bin/sh') on Unix and Unix-like systems,
+ The standard shell ('/bin/sh') on Unix and Unix-like systems,
originally written by Steven R. Bourne at Bell Laboratories. Many
- shells (Bash, `ksh', `pdksh', `zsh') are generally upwardly
+ shells (Bash, 'ksh', 'pdksh', 'zsh') are generally upwardly
compatible with the Bourne shell.
Braces
- The characters `{' and `}'. Braces are used in `awk' for
+ The characters '{' and '}'. Braces are used in 'awk' for
delimiting actions, compound statements, and function bodies.
Bracket Expression
Inside a "regular expression", an expression included in square
brackets, meant to designate a single character as belonging to a
- specified character class. A bracket expression can contain a list
- of one or more characters, like `[abc]', a range of characters,
- like `[A-Z]', or a name, delimited by `:', that designates a known
- set of characters, like `[:digit:]'. The form of bracket expression
- enclosed between `:' is independent of the underlying
- representation of the character themselves, which could utilize
- the ASCII, ECBDIC, or Unicode codesets, depending on the
- architecture of the computer system, and on localization. See
- also "Regular Expression."
+ specified character class. A bracket expression can contain a list
+ of one or more characters, like '[abc]', a range of characters,
+ like '[A-Z]', or a name, delimited by ':', that designates a known
+ set of characters, like '[:digit:]'. The form of bracket
+ expression enclosed between ':' is independent of the underlying
+ representation of the character themselves, which could utilize the
+ ASCII, ECBDIC, or Unicode codesets, depending on the architecture
+ of the computer system, and on localization. See also "Regular
+ Expression."
Built-in Function
- The `awk' language provides built-in functions that perform various
+ The 'awk' language provides built-in functions that perform various
numerical, I/O-related, and string computations. Examples are
- `sqrt()' (for the square root of a number) and `substr()' (for a
- substring of a string). `gawk' provides functions for timestamp
+ 'sqrt()' (for the square root of a number) and 'substr()' (for a
+ substring of a string). 'gawk' provides functions for timestamp
management, bit manipulation, array sorting, type checking, and
runtime string translation. (*Note Built-in::.)
Built-in Variable
- `ARGC', `ARGV', `CONVFMT', `ENVIRON', `FILENAME', `FNR', `FS',
- `NF', `NR', `OFMT', `OFS', `ORS', `RLENGTH', `RSTART', `RS', and
- `SUBSEP' are the variables that have special meaning to `awk'. In
- addition, `ARGIND', `BINMODE', `ERRNO', `FIELDWIDTHS', `FPAT',
- `IGNORECASE', `LINT', `PROCINFO', `RT', and `TEXTDOMAIN' are the
- variables that have special meaning to `gawk'. Changing some of
- them affects `awk''s running environment. (*Note Built-in
+ 'ARGC', 'ARGV', 'CONVFMT', 'ENVIRON', 'FILENAME', 'FNR', 'FS',
+ 'NF', 'NR', 'OFMT', 'OFS', 'ORS', 'RLENGTH', 'RSTART', 'RS', and
+ 'SUBSEP' are the variables that have special meaning to 'awk'. In
+ addition, 'ARGIND', 'BINMODE', 'ERRNO', 'FIELDWIDTHS', 'FPAT',
+ 'IGNORECASE', 'LINT', 'PROCINFO', 'RT', and 'TEXTDOMAIN' are the
+ variables that have special meaning to 'gawk'. Changing some of
+ them affects 'awk''s running environment. (*Note Built-in
Variables::.)
C
The system programming language that most GNU software is written
- in. The `awk' programming language has C-like syntax, and this
- Info file points out similarities between `awk' and C when
+ in. The 'awk' programming language has C-like syntax, and this
+ Info file points out similarities between 'awk' and C when
appropriate.
- In general, `gawk' attempts to be as similar to the 1990 version
- of ISO C as makes sense.
+ In general, 'gawk' attempts to be as similar to the 1990 version of
+ ISO C as makes sense.
C Shell
- The C Shell (`csh' or its improved version, `tcsh') is a Unix
- shell that was created by Bill Joy in the late 1970s. The C shell
- was differentiated from other shells by its interactive features
- and overall style, which looks more like C. The C Shell is not
- backward compatible with the Bourne Shell, so special attention is
- required when converting scripts written for other Unix shells to
- the C shell, especially with regard to the management of shell
- variables. See also "Bourne Shell."
+ The C Shell ('csh' or its improved version, 'tcsh') is a Unix shell
+ that was created by Bill Joy in the late 1970s. The C shell was
+ differentiated from other shells by its interactive features and
+ overall style, which looks more like C. The C Shell is not backward
+ compatible with the Bourne Shell, so special attention is required
+ when converting scripts written for other Unix shells to the C
+ shell, especially with regard to the management of shell variables.
+ See also "Bourne Shell."
C++
A popular object-oriented programming language derived from C.
@@ -29670,8 +29559,8 @@ Character List
Character Set
The set of numeric codes used by a computer system to represent the
- characters (letters, numbers, punctuation, etc.) of a particular
- country or place. The most common character set in use today is
+ characters (letters, numbers, punctuation, etc.) of a particular
+ country or place. The most common character set in use today is
ASCII (American Standard Code for Information Interchange). Many
European countries use an extension of ASCII known as ISO-8859-1
(ISO Latin-1). The Unicode character set (http://www.unicode.org)
@@ -29679,14 +29568,14 @@ Character Set
used on GNU/Linux systems.
CHEM
- A preprocessor for `pic' that reads descriptions of molecules and
- produces `pic' input for drawing them. It was written in `awk' by
+ A preprocessor for 'pic' that reads descriptions of molecules and
+ produces 'pic' input for drawing them. It was written in 'awk' by
Brian Kernighan and Jon Bentley, and is available from
- `http://netlib.org/typesetting/chem'.
+ <http://netlib.org/typesetting/chem>.
Comparison Expression
- A relation that is either true or false, such as `a < b'.
- Comparison expressions are used in `if', `while', `do', and `for'
+ A relation that is either true or false, such as 'a < b'.
+ Comparison expressions are used in 'if', 'while', 'do', and 'for'
statements, and in patterns to select which input records to
process. (*Note Typing and Comparison::.)
@@ -29697,14 +29586,14 @@ Compiler
Complemented Bracket Expression
The negation of a "bracket expression". All that is _not_
- described by a given bracket expression. The symbol `^' precedes
- the negated bracket expression. E.g.: `[[^:digit:]' designates
- whatever character is not a digit. `[^bad]' designates whatever
- character is not one of the letters `b', `a', or `d'. See
- "Bracket Expression."
+ described by a given bracket expression. The symbol '^' precedes
+ the negated bracket expression. E.g.: '[[^:digit:]' designates
+ whatever character is not a digit. '[^bad]' designates whatever
+ character is not one of the letters 'b', 'a', or 'd'. See "Bracket
+ Expression."
Compound Statement
- A series of `awk' statements, enclosed in curly braces. Compound
+ A series of 'awk' statements, enclosed in curly braces. Compound
statements may be nested. (*Note Statements::.)
Computed Regexps
@@ -29712,26 +29601,26 @@ Computed Regexps
Concatenation
Concatenating two strings means sticking them together, one after
- another, producing a new string. For example, the string `foo'
- concatenated with the string `bar' gives the string `foobar'.
+ another, producing a new string. For example, the string 'foo'
+ concatenated with the string 'bar' gives the string 'foobar'.
(*Note Concatenation::.)
Conditional Expression
- An expression using the `?:' ternary operator, such as `EXPR1 ?
+ An expression using the '?:' ternary operator, such as 'EXPR1 ?
EXPR2 : EXPR3'. The expression EXPR1 is evaluated; if the result
is true, the value of the whole expression is the value of EXPR2;
otherwise the value is EXPR3. In either case, only one of EXPR2
- and EXPR3 is evaluated. (*Note Conditional Exp::.)
+ and EXPR3 is evaluated. (*Note Conditional Exp::.)
Control Statement
A control statement is an instruction to perform a given operation
- or a set of operations inside an `awk' program, if a given
- condition is true. Control statements are: `if', `for', `while',
- and `do' (*note Statements::).
+ or a set of operations inside an 'awk' program, if a given
+ condition is true. Control statements are: 'if', 'for', 'while',
+ and 'do' (*note Statements::).
Cookie
A peculiar goodie, token, saying or remembrance produced by or
- presented to a program. (With thanks to Professor Doug McIlroy.)
+ presented to a program. (With thanks to Professor Doug McIlroy.)
Coprocess
A subordinate program with which two-way communications is
@@ -29743,48 +29632,46 @@ Curly Braces
Dark Corner
An area in the language where specifications often were (or still
are) not clear, leading to unexpected or undesirable behavior.
- Such areas are marked in this Info file with "(d.c.)" in the text
+ Such areas are marked in this Info file with "(d.c.)" in the text
and are indexed under the heading "dark corner."
Data Driven
- A description of `awk' programs, where you specify the data you
- are interested in processing, and what to do when that data is
- seen.
+ A description of 'awk' programs, where you specify the data you are
+ interested in processing, and what to do when that data is seen.
Data Objects
- These are numbers and strings of characters. Numbers are
- converted into strings and vice versa, as needed. (*Note
- Conversion::.)
+ These are numbers and strings of characters. Numbers are converted
+ into strings and vice versa, as needed. (*Note Conversion::.)
Deadlock
The situation in which two communicating processes are each waiting
for the other to perform an action.
Debugger
- A program used to help developers remove "bugs" from (de-bug)
- their programs.
+ A program used to help developers remove "bugs" from (de-bug) their
+ programs.
Double Precision
An internal representation of numbers that can have fractional
parts. Double precision numbers keep track of more digits than do
- single precision numbers, but operations on them are sometimes
- more expensive. This is the way `awk' stores numeric values. It
- is the C type `double'.
+ single precision numbers, but operations on them are sometimes more
+ expensive. This is the way 'awk' stores numeric values. It is the
+ C type 'double'.
Dynamic Regular Expression
A dynamic regular expression is a regular expression written as an
ordinary expression. It could be a string constant, such as
- `"foo"', but it may also be an expression whose value can vary.
+ '"foo"', but it may also be an expression whose value can vary.
(*Note Computed Regexps::.)
Empty String
See "Null String."
Environment
- A collection of strings, of the form `NAME=VAL', that each program
- has available to it. Users generally place values into the
+ A collection of strings, of the form 'NAME=VAL', that each program
+ has available to it. Users generally place values into the
environment in order to provide information to various programs.
- Typical examples are the environment variables `HOME' and `PATH'.
+ Typical examples are the environment variables 'HOME' and 'PATH'.
Epoch
The date used as the "beginning of time" for timestamps. Time
@@ -29792,30 +29679,30 @@ Epoch
with library functions available for converting these values into
standard date and time formats.
- The epoch on Unix and POSIX systems is 1970-01-01 00:00:00 UTC.
- See also "GMT" and "UTC."
+ The epoch on Unix and POSIX systems is 1970-01-01 00:00:00 UTC. See
+ also "GMT" and "UTC."
Escape Sequences
A special sequence of characters used for describing nonprinting
- characters, such as `\n' for newline or `\033' for the ASCII ESC
- (Escape) character. (*Note Escape Sequences::.)
+ characters, such as '\n' for newline or '\033' for the ASCII ESC
+ (Escape) character. (*Note Escape Sequences::.)
Extension
An additional feature or change to a programming language or
utility not defined by that language's or utility's standard.
- `gawk' has (too) many extensions over POSIX `awk'.
+ 'gawk' has (too) many extensions over POSIX 'awk'.
FDL
See "Free Documentation License."
Field
- When `awk' reads an input record, it splits the record into pieces
+ When 'awk' reads an input record, it splits the record into pieces
separated by whitespace (or by a separator regexp that you can
- change by setting the predefined variable `FS'). Such pieces are
+ change by setting the predefined variable 'FS'). Such pieces are
called fields. If the pieces are of fixed length, you can use the
- built-in variable `FIELDWIDTHS' to describe their lengths. If you
+ built-in variable 'FIELDWIDTHS' to describe their lengths. If you
wish to specify the contents of fields instead of the field
- separator, you can use the predefined variable `FPAT' to do so.
+ separator, you can use the predefined variable 'FPAT' to do so.
(*Note Field Separators::, *note Constant Size::, and *note
Splitting By Content::.)
@@ -29825,25 +29712,25 @@ Flag
Floating-Point Number
Often referred to in mathematical terms as a "rational" or real
- number, this is just a number that can have a fractional part.
- See also "Double Precision" and "Single Precision."
+ number, this is just a number that can have a fractional part. See
+ also "Double Precision" and "Single Precision."
Format
- Format strings control the appearance of output in the
- `strftime()' and `sprintf()' functions, and in the `printf'
- statement as well. Also, data conversions from numbers to strings
- are controlled by the format strings contained in the predefined
- variables `CONVFMT' and `OFMT'. (*Note Control Letters::.)
+ Format strings control the appearance of output in the 'strftime()'
+ and 'sprintf()' functions, and in the 'printf' statement as well.
+ Also, data conversions from numbers to strings are controlled by
+ the format strings contained in the predefined variables 'CONVFMT'
+ and 'OFMT'. (*Note Control Letters::.)
Fortran
Shorthand for FORmula TRANslator, one of the first programming
- languages available for scientific calculations. It was created by
- John Backus, and has been available since 1957. It is still in use
+ languages available for scientific calculations. It was created by
+ John Backus, and has been available since 1957. It is still in use
today.
Free Documentation License
This document describes the terms under which this Info file is
- published and may be copied. (*Note GNU Free Documentation
+ published and may be copied. (*Note GNU Free Documentation
License::.)
Free Software Foundation
@@ -29856,26 +29743,26 @@ FSF
See "Free Software Foundation."
Function
- A part of an `awk' program that can be invoked from every point of
- the program, to perform a task. `awk' has several built-in
+ A part of an 'awk' program that can be invoked from every point of
+ the program, to perform a task. 'awk' has several built-in
functions. Users can define their own functions in every part of
the program. Function can be recursive, i.e., they may invoke
- themselves. *Note Functions::. In `gawk' it is also possible to
+ themselves. *Note Functions::. In 'gawk' it is also possible to
have functions shared among different programs, and included where
- required using the address@hidden' directive (*note Include Files::).
- In `gawk' the name of the function that should be invoked can be
- generated at run time, i.e., dynamically. The `gawk' extension
- API provides constructor functions (*note Constructor Functions::).
+ required using the '@include' directive (*note Include Files::).
+ In 'gawk' the name of the function that should be invoked can be
+ generated at run time, i.e., dynamically. The 'gawk' extension API
+ provides constructor functions (*note Constructor Functions::).
-`gawk'
- The GNU implementation of `awk'.
+'gawk'
+ The GNU implementation of 'awk'.
General Public License
- This document describes the terms under which `gawk' and its source
- code may be distributed. (*Note Copying::.)
+ This document describes the terms under which 'gawk' and its source
+ code may be distributed. (*Note Copying::.)
GMT
- "Greenwich Mean Time." This is the old term for UTC. It is the
+ "Greenwich Mean Time." This is the old term for UTC. It is the
time of day used internally for Unix and POSIX systems. See also
"Epoch" and "UTC."
@@ -29887,21 +29774,20 @@ GNU
GNU/Linux
A variant of the GNU system using the Linux kernel, instead of the
Free Software Foundation's Hurd kernel. The Linux kernel is a
- stable, efficient, full-featured clone of Unix that has been
- ported to a variety of architectures. It is most popular on
- PC-class systems, but runs well on a variety of other systems too.
- The Linux kernel source code is available under the terms of the
- GNU General Public License, which is perhaps its most important
- aspect.
+ stable, efficient, full-featured clone of Unix that has been ported
+ to a variety of architectures. It is most popular on PC-class
+ systems, but runs well on a variety of other systems too. The
+ Linux kernel source code is available under the terms of the GNU
+ General Public License, which is perhaps its most important aspect.
GPL
See "General Public License."
Hexadecimal
- Base 16 notation, where the digits are `0'-`9' and `A'-`F', with
- `A' representing 10, `B' representing 11, and so on, up to `F' for
- 15. Hexadecimal numbers are written in C using a leading `0x', to
- indicate their base. Thus, `0x12' is 18 ((1 x 16) + 2). *Note
+ Base 16 notation, where the digits are '0'-'9' and 'A'-'F', with
+ 'A' representing 10, 'B' representing 11, and so on, up to 'F' for
+ 15. Hexadecimal numbers are written in C using a leading '0x', to
+ indicate their base. Thus, '0x12' is 18 ((1 x 16) + 2). *Note
Nondecimal-numbers::.
I/O
@@ -29909,9 +29795,8 @@ I/O
out of a running program.
Input Record
- A single chunk of data that is read in by `awk'. Usually, an
- `awk' input record consists of one line of text. (*Note
- Records::.)
+ A single chunk of data that is read in by 'awk'. Usually, an 'awk'
+ input record consists of one line of text. (*Note Records::.)
Integer
A whole number, i.e., a number that does not have a fractional
@@ -29923,23 +29808,23 @@ Internationalization
Interpreter
A program that reads human-readable source code directly, and uses
- the instructions in it to process data and produce results. `awk'
+ the instructions in it to process data and produce results. 'awk'
is typically (but not always) implemented as an interpreter. See
also "Compiler."
Interval Expression
A component of a regular expression that lets you specify repeated
matches of some part of the regexp. Interval expressions were not
- originally available in `awk' programs.
+ originally available in 'awk' programs.
ISO
The International Organization for Standardization. This
organization produces international standards for many things,
including programming languages, such as C and C++. In the
computer arena, important standards like those for C, C++, and
- POSIX become both American national and ISO international
- standards simultaneously. This Info file refers to Standard C as
- "ISO C" throughout. See the ISO website
+ POSIX become both American national and ISO international standards
+ simultaneously. This Info file refers to Standard C as "ISO C"
+ throughout. See the ISO website
(http://www.iso.org/iso/home/about.htm) for more information about
the name of the organization and its language-independent
three-letter acronym.
@@ -29947,24 +29832,24 @@ ISO
Java
A modern programming language originally developed by Sun
Microsystems (now Oracle) supporting Object-Oriented programming.
- Although usually implemented by compiling to the instructions for
- a standard virtual machine (the JVM), the language can be compiled
- to native code.
+ Although usually implemented by compiling to the instructions for a
+ standard virtual machine (the JVM), the language can be compiled to
+ native code.
Keyword
- In the `awk' language, a keyword is a word that has special
+ In the 'awk' language, a keyword is a word that has special
meaning. Keywords are reserved and may not be used as variable
names.
- `gawk''s keywords are: `BEGIN', `BEGINFILE', `END', `ENDFILE',
- `break', `case', `continue', `default' `delete', `do...while',
- `else', `exit', `for...in', `for', `function', `func', `if',
- `next', `nextfile', `switch', and `while'.
+ 'gawk''s keywords are: 'BEGIN', 'BEGINFILE', 'END', 'ENDFILE',
+ 'break', 'case', 'continue', 'default' 'delete', 'do...while',
+ 'else', 'exit', 'for...in', 'for', 'function', 'func', 'if',
+ 'next', 'nextfile', 'switch', and 'while'.
Korn Shell
- The Korn Shell (`ksh') is a Unix shell which was developed by
- David Korn at Bell Laboratories in the early 1980s. The Korn Shell
- is backward-compatible with the Bourne shell and includes many
+ The Korn Shell ('ksh') is a Unix shell which was developed by David
+ Korn at Bell Laboratories in the early 1980s. The Korn Shell is
+ backward-compatible with the Bourne shell and includes many
features of the C shell. See also "Bourne Shell."
Lesser General Public License
@@ -29984,14 +29869,14 @@ Localization
Logical Expression
An expression using the operators for logic, AND, OR, and NOT,
- written `&&', `||', and `!' in `awk'. Often called Boolean
+ written '&&', '||', and '!' in 'awk'. Often called Boolean
expressions, after the mathematician who pioneered this kind of
mathematical logic.
Lvalue
An expression that can appear on the left side of an assignment
operator. In most languages, lvalues can be variables or array
- elements. In `awk', a field designator can also be used as an
+ elements. In 'awk', a field designator can also be used as an
lvalue.
Matching
@@ -30006,8 +29891,8 @@ Metacharacters
Nesting
Nesting is where information is organized in layers, or where
- objects contain other similar objects. In `gawk' the address@hidden'
- directive can be nested. The "natural" nesting of arithmetic and
+ objects contain other similar objects. In 'gawk' the '@include'
+ directive can be nested. The "natural" nesting of arithmetic and
logical operations can be changed using parentheses (*note
Precedence::).
@@ -30016,38 +29901,38 @@ No-op
Null String
A string with no characters in it. It is represented explicitly in
- `awk' programs by placing two double quote characters next to each
- other (`""'). It can appear in input data by having two successive
+ 'awk' programs by placing two double quote characters next to each
+ other ('""'). It can appear in input data by having two successive
occurrences of the field separator appear next to each other.
Number
- A numeric-valued data object. Modern `awk' implementations use
+ A numeric-valued data object. Modern 'awk' implementations use
double precision floating-point to represent numbers. Ancient
- `awk' implementations used single precision floating-point.
+ 'awk' implementations used single precision floating-point.
Octal
- Base-eight notation, where the digits are `0'-`7'. Octal numbers
- are written in C using a leading `0', to indicate their base.
- Thus, `013' is 11 ((1 x 8) + 3). *Note Nondecimal-numbers::.
+ Base-eight notation, where the digits are '0'-'7'. Octal numbers
+ are written in C using a leading '0', to indicate their base.
+ Thus, '013' is 11 ((1 x 8) + 3). *Note Nondecimal-numbers::.
Output Record
- A single chunk of data that is written out by `awk'. Usually, an
- `awk' output record consists of one or more lines of text. *Note
+ A single chunk of data that is written out by 'awk'. Usually, an
+ 'awk' output record consists of one or more lines of text. *Note
Records::.
Pattern
- Patterns tell `awk' which input records are interesting to which
+ Patterns tell 'awk' which input records are interesting to which
rules.
A pattern is an arbitrary conditional expression against which
input is tested. If the condition is satisfied, the pattern is
said to "match" the input record. A typical pattern might compare
- the input record against a regular expression. (*Note Pattern
+ the input record against a regular expression. (*Note Pattern
Overview::.)
PEBKAC
An acronym describing what is possibly the most frequent source of
- computer usage problems. (Problem Exists Between Keyboard And
+ computer usage problems. (Problem Exists Between Keyboard And
Chair.)
Plug-in
@@ -30056,10 +29941,10 @@ Plug-in
POSIX
The name for a series of standards that specify a Portable
Operating System interface. The "IX" denotes the Unix heritage of
- these standards. The main standard of interest for `awk' users is
- `IEEE Standard for Information Technology, Standard 1003.1-2008'.
+ these standards. The main standard of interest for 'awk' users is
+ 'IEEE Standard for Information Technology, Standard 1003.1-2008'.
The 2008 POSIX standard can be found online at
- `http://www.opengroup.org/onlinepubs/9699919799/'.
+ <http://www.opengroup.org/onlinepubs/9699919799/>.
Precedence
The order in which operations are performed when operators are used
@@ -30067,14 +29952,14 @@ Precedence
Private
Variables and/or functions that are meant for use exclusively by
- library functions and not for the main `awk' program. Special care
+ library functions and not for the main 'awk' program. Special care
must be taken when naming such variables and functions. (*Note
Library Names::.)
Range (of input lines)
A sequence of consecutive lines from the input file(s). A pattern
- can specify ranges of input lines for `awk' to process or it can
- specify single lines. (*Note Pattern Overview::.)
+ can specify ranges of input lines for 'awk' to process or it can
+ specify single lines. (*Note Pattern Overview::.)
Record
See "Input record" and "Output record."
@@ -30086,62 +29971,62 @@ Recursion
Redirection
Redirection means performing input from something other than the
- standard input stream, or performing output to something other
- than the standard output stream.
+ standard input stream, or performing output to something other than
+ the standard output stream.
- You can redirect input to the `getline' statement using the `<',
- `|', and `|&' operators. You can redirect the output of the
- `print' and `printf' statements to a file or a system command,
- using the `>', `>>', `|', and `|&' operators. (*Note Getline::,
+ You can redirect input to the 'getline' statement using the '<',
+ '|', and '|&' operators. You can redirect the output of the
+ 'print' and 'printf' statements to a file or a system command,
+ using the '>', '>>', '|', and '|&' operators. (*Note Getline::,
and *note Redirection::.)
Reference Counts
- An internal mechanism in `gawk' to minimize the amount of memory
- needed to store the value of string variables. If the value
- assumed by a variable is used in more than one place, only one
- copy of the value itself is kept, and the associated reference
- count is increased when the same value is used by an additional
- variable, and decresed when the related variable is no longer in
- use. When the reference count goes to zero, the memory space used
- to store the value of the variable is freed.
+ An internal mechanism in 'gawk' to minimize the amount of memory
+ needed to store the value of string variables. If the value
+ assumed by a variable is used in more than one place, only one copy
+ of the value itself is kept, and the associated reference count is
+ increased when the same value is used by an additional variable,
+ and decresed when the related variable is no longer in use. When
+ the reference count goes to zero, the memory space used to store
+ the value of the variable is freed.
Regexp
See "Regular Expression."
Regular Expression
- A regular expression ("regexp" for short) is a pattern that
- denotes a set of strings, possibly an infinite set. For example,
- the regular expression `R.*xp' matches any string starting with
- the letter `R' and ending with the letters `xp'. In `awk',
- regular expressions are used in patterns and in conditional
- expressions. Regular expressions may contain escape sequences.
- (*Note Regexp::.)
+ A regular expression ("regexp" for short) is a pattern that denotes
+ a set of strings, possibly an infinite set. For example, the
+ regular expression 'R.*xp' matches any string starting with the
+ letter 'R' and ending with the letters 'xp'. In 'awk', regular
+ expressions are used in patterns and in conditional expressions.
+ Regular expressions may contain escape sequences. (*Note
+ Regexp::.)
Regular Expression Constant
A regular expression constant is a regular expression written
- within slashes, such as `/foo/'. This regular expression is chosen
- when you write the `awk' program and cannot be changed during its
- execution. (*Note Regexp Usage::.)
+ within slashes, such as '/foo/'. This regular expression is chosen
+ when you write the 'awk' program and cannot be changed during its
+ execution. (*Note Regexp Usage::.)
Regular Expression Operators
See "Metacharacters."
Rounding
- Rounding the result of an arithmetic operation can be tricky.
- More than one way of rounding exists, and in `gawk' it is possible
- to choose which method should be used in a program. *Note Setting
- the rounding mode::.
+ Rounding the result of an arithmetic operation can be tricky. More
+ than one way of rounding exists, and in 'gawk' it is possible to
+ choose which method should be used in a program. *Note Setting the
+ rounding mode::.
Rule
- A segment of an `awk' program that specifies how to process single
+ A segment of an 'awk' program that specifies how to process single
input records. A rule consists of a "pattern" and an "action".
- `awk' reads an input record; then, for each rule, if the input
- record satisfies the rule's pattern, `awk' executes the rule's
+ 'awk' reads an input record; then, for each rule, if the input
+ record satisfies the rule's pattern, 'awk' executes the rule's
action. Otherwise, the rule does nothing for that input record.
Rvalue
A value that can appear on the right side of an assignment
- operator. In `awk', essentially every expression has a value.
+ operator. In 'awk', essentially every expression has a value.
These values are rvalues.
Scalar
@@ -30149,11 +30034,11 @@ Scalar
scalars; arrays and functions are not.
Search Path
- In `gawk', a list of directories to search for `awk' program
- source files. In the shell, a list of directories to search for
+ In 'gawk', a list of directories to search for 'awk' program source
+ files. In the shell, a list of directories to search for
executable programs.
-`sed'
+'sed'
See "Stream Editor."
Seed
@@ -30166,7 +30051,7 @@ Shell
batch files, or shell scripts.
Short-Circuit
- The nature of the `awk' logical operators `&&' and `||'. If the
+ The nature of the 'awk' logical operators '&&' and '||'. If the
value of the entire expression is determinable from evaluating just
the lefthand side of these operators, the righthand side is not
evaluated. (*Note Boolean Ops::.)
@@ -30179,23 +30064,23 @@ Side Effect
Single Precision
An internal representation of numbers that can have fractional
- parts. Single precision numbers keep track of fewer digits than
- do double precision numbers, but operations on them are sometimes
- less expensive in terms of CPU time. This is the type used by
- some ancient versions of `awk' to store numeric values. It is the
- C type `float'.
+ parts. Single precision numbers keep track of fewer digits than do
+ double precision numbers, but operations on them are sometimes less
+ expensive in terms of CPU time. This is the type used by some
+ ancient versions of 'awk' to store numeric values. It is the C
+ type 'float'.
Space
The character generated by hitting the space bar on the keyboard.
Special File
- A file name interpreted internally by `gawk', instead of being
+ A file name interpreted internally by 'gawk', instead of being
handed directly to the underlying operating system--for example,
- `/dev/stderr'. (*Note Special Files::.)
+ '/dev/stderr'. (*Note Special Files::.)
Statement
- An expression inside an `awk' program in the action part of a
- pattern-action rule, or inside an `awk' function. A statement can
+ An expression inside an 'awk' program in the action part of a
+ pattern-action rule, or inside an 'awk' function. A statement can
be a variable assignment, an array operation, a loop, etc.
Stream Editor
@@ -30206,13 +30091,13 @@ Stream Editor
programs which require input from the user.
String
- A datum consisting of a sequence of characters, such as `I am a
+ A datum consisting of a sequence of characters, such as 'I am a
string'. Constant strings are written with double quotes in the
- `awk' language and may contain escape sequences. (*Note Escape
+ 'awk' language and may contain escape sequences. (*Note Escape
Sequences::.)
Tab
- The character generated by hitting the `TAB' key on the keyboard.
+ The character generated by hitting the 'TAB' key on the keyboard.
It usually expands to up to eight spaces upon output.
Text Domain
@@ -30221,15 +30106,15 @@ Text Domain
Timestamp
A value in the "seconds since the epoch" format used by Unix and
- POSIX systems. Used for the `gawk' functions `mktime()',
- `strftime()', and `systime()'. See also "Epoch," "GMT," and "UTC."
+ POSIX systems. Used for the 'gawk' functions 'mktime()',
+ 'strftime()', and 'systime()'. See also "Epoch," "GMT," and "UTC."
Unix
A computer operating system originally developed in the early
1970's at AT&T Bell Laboratories. It initially became popular in
universities around the world and later moved into commercial
environments as a software development system and network server
- system. There are many commercial versions of Unix, as well as
+ system. There are many commercial versions of Unix, as well as
several work-alike systems whose source code is freely available
(such as GNU/Linux, NetBSD (http://www.netbsd.org), FreeBSD
(http://www.freebsd.org), and OpenBSD (http://www.openbsd.org)).
@@ -30237,17 +30122,16 @@ Unix
UTC
The accepted abbreviation for "Universal Coordinated Time." This
is standard time in Greenwich, England, which is used as a
- reference time for day and date calculations. See also "Epoch"
- and "GMT."
+ reference time for day and date calculations. See also "Epoch" and
+ "GMT."
Variable
- A name for a value. In `awk', variables may be either scalars or
+ A name for a value. In 'awk', variables may be either scalars or
arrays.
Whitespace
- A sequence of space, TAB, or newline characters occurring inside
- an input record or a string.
-
+ A sequence of space, TAB, or newline characters occurring inside an
+ input record or a string.
File: gawk.info, Node: Copying, Next: GNU Free Documentation License, Prev:
Glossary, Up: Top
@@ -30256,7 +30140,8 @@ GNU General Public License
**************************
Version 3, 29 June 2007
- Copyright (C) 2007 Free Software Foundation, Inc. `http://fsf.org/'
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
@@ -30270,11 +30155,11 @@ and other kinds of works.
The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom to
-share and change all versions of a program--to make sure it remains
-free software for all its users. We, the Free Software Foundation, use
-the GNU General Public License for most of our software; it applies
-also to any other work released this way by its authors. You can apply
-it to your programs, too.
+share and change all versions of a program--to make sure it remains free
+software for all its users. We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors. You can apply it to
+your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
@@ -30284,9 +30169,9 @@ want it, that you can change the software or use pieces
of it in new
free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you
-these rights or asking you to surrender the rights. Therefore, you
-have certain responsibilities if you distribute copies of the software,
-or if you modify it: responsibilities to respect the freedom of others.
+these rights or asking you to surrender the rights. Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
@@ -30305,16 +30190,15 @@ changed, so that their problems will not be
attributed erroneously to
authors of previous versions.
Some devices are designed to deny users access to install or run
-modified versions of the software inside them, although the
-manufacturer can do so. This is fundamentally incompatible with the
-aim of protecting users' freedom to change the software. The
-systematic pattern of such abuse occurs in the area of products for
-individuals to use, which is precisely where it is most unacceptable.
-Therefore, we have designed this version of the GPL to prohibit the
-practice for those products. If such problems arise substantially in
-other domains, we stand ready to extend this provision to those domains
-in future versions of the GPL, as needed to protect the freedom of
-users.
+modified versions of the software inside them, although the manufacturer
+can do so. This is fundamentally incompatible with the aim of
+protecting users' freedom to change the software. The systematic
+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable. Therefore, we
+have designed this version of the GPL to prohibit the practice for those
+products. If such problems arise substantially in other domains, we
+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.
Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
@@ -30351,8 +30235,8 @@ TERMS AND CONDITIONS
To "propagate" a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
- infringement under applicable copyright law, except executing it
- on a computer or modifying a private copy. Propagation includes
+ infringement under applicable copyright law, except executing it on
+ a computer or modifying a private copy. Propagation includes
copying, distribution (with or without modification), making
available to the public, and in some countries other activities as
well.
@@ -30366,8 +30250,8 @@ TERMS AND CONDITIONS
to the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to
- the extent that warranties are provided), that licensees may
- convey the work under this License, and how to view a copy of this
+ the extent that warranties are provided), that licensees may convey
+ the work under this License, and how to view a copy of this
License. If the interface presents a list of user commands or
options, such as a menu, a prominent item in the list meets this
criterion.
@@ -30375,8 +30259,8 @@ TERMS AND CONDITIONS
1. Source Code.
The "source code" for a work means the preferred form of the work
- for making modifications to it. "Object code" means any
- non-source form of a work.
+ for making modifications to it. "Object code" means any non-source
+ form of a work.
A "Standard Interface" means an interface that either is an
official standard defined by a recognized standards body, or, in
@@ -30387,10 +30271,10 @@ TERMS AND CONDITIONS
The "System Libraries" of an executable work include anything,
other than the work as a whole, that (a) is included in the normal
form of packaging a Major Component, but which is not part of that
- Major Component, and (b) serves only to enable use of the work
- with that Major Component, or to implement a Standard Interface
- for which an implementation is available to the public in source
- code form. A "Major Component", in this context, means a major
+ Major Component, and (b) serves only to enable use of the work with
+ that Major Component, or to implement a Standard Interface for
+ which an implementation is available to the public in source code
+ form. A "Major Component", in this context, means a major
essential component (kernel, window system, and so on) of the
specific operating system (if any) on which the executable work
runs, or a compiler used to produce the work, or an object code
@@ -30398,15 +30282,15 @@ TERMS AND CONDITIONS
The "Corresponding Source" for a work in object code form means all
the source code needed to generate, install, and (for an executable
- work) run the object code and to modify the work, including
- scripts to control those activities. However, it does not include
- the work's System Libraries, or general-purpose tools or generally
+ work) run the object code and to modify the work, including scripts
+ to control those activities. However, it does not include the
+ work's System Libraries, or general-purpose tools or generally
available free programs which are used unmodified in performing
those activities but which are not part of the work. For example,
- Corresponding Source includes interface definition files
- associated with source files for the work, and the source code for
- shared libraries and dynamically linked subprograms that the work
- is specifically designed to require, such as by intimate data
+ Corresponding Source includes interface definition files associated
+ with source files for the work, and the source code for shared
+ libraries and dynamically linked subprograms that the work is
+ specifically designed to require, such as by intimate data
communication or control flow between those subprograms and other
parts of the work.
@@ -30423,22 +30307,22 @@ TERMS AND CONDITIONS
copyright on the Program, and are irrevocable provided the stated
conditions are met. This License explicitly affirms your unlimited
permission to run the unmodified Program. The output from running
- a covered work is covered by this License only if the output,
- given its content, constitutes a covered work. This License
- acknowledges your rights of fair use or other equivalent, as
- provided by copyright law.
+ a covered work is covered by this License only if the output, given
+ its content, constitutes a covered work. This License acknowledges
+ your rights of fair use or other equivalent, as provided by
+ copyright law.
You may make, run and propagate covered works that you do not
convey, without conditions so long as your license otherwise
remains in force. You may convey covered works to others for the
- sole purpose of having them make modifications exclusively for
- you, or provide you with facilities for running those works,
- provided that you comply with the terms of this License in
- conveying all material for which you do not control copyright.
- Those thus making or running the covered works for you must do so
- exclusively on your behalf, under your direction and control, on
- terms that prohibit them from making any copies of your
- copyrighted material outside their relationship with you.
+ sole purpose of having them make modifications exclusively for you,
+ or provide you with facilities for running those works, provided
+ that you comply with the terms of this License in conveying all
+ material for which you do not control copyright. Those thus making
+ or running the covered works for you must do so exclusively on your
+ behalf, under your direction and control, on terms that prohibit
+ them from making any copies of your copyrighted material outside
+ their relationship with you.
Conveying under any other circumstances is permitted solely under
the conditions stated below. Sublicensing is not allowed; section
@@ -30455,8 +30339,8 @@ TERMS AND CONDITIONS
When you convey a covered work, you waive any legal power to forbid
circumvention of technological measures to the extent such
circumvention is effected by exercising rights under this License
- with respect to the covered work, and you disclaim any intention
- to limit operation or modification of the work as a means of
+ with respect to the covered work, and you disclaim any intention to
+ limit operation or modification of the work as a means of
enforcing, against the work's users, your or third parties' legal
rights to forbid circumvention of technological measures.
@@ -30526,8 +30410,8 @@ TERMS AND CONDITIONS
b. Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by a
- written offer, valid for at least three years and valid for
- as long as you offer spare parts or customer support for that
+ written offer, valid for at least three years and valid for as
+ long as you offer spare parts or customer support for that
product model, to give anyone who possesses the object code
either (1) a copy of the Corresponding Source for all the
software in the product that is covered by this License, on a
@@ -30537,32 +30421,31 @@ TERMS AND CONDITIONS
to copy the Corresponding Source from a network server at no
charge.
- c. Convey individual copies of the object code with a copy of
- the written offer to provide the Corresponding Source. This
+ c. Convey individual copies of the object code with a copy of the
+ written offer to provide the Corresponding Source. This
alternative is allowed only occasionally and noncommercially,
and only if you received the object code with such an offer,
in accord with subsection 6b.
d. Convey the object code by offering access from a designated
- place (gratis or for a charge), and offer equivalent access
- to the Corresponding Source in the same way through the same
+ place (gratis or for a charge), and offer equivalent access to
+ the Corresponding Source in the same way through the same
place at no further charge. You need not require recipients
to copy the Corresponding Source along with the object code.
If the place to copy the object code is a network server, the
- Corresponding Source may be on a different server (operated
- by you or a third party) that supports equivalent copying
- facilities, provided you maintain clear directions next to
- the object code saying where to find the Corresponding Source.
+ Corresponding Source may be on a different server (operated by
+ you or a third party) that supports equivalent copying
+ facilities, provided you maintain clear directions next to the
+ object code saying where to find the Corresponding Source.
Regardless of what server hosts the Corresponding Source, you
- remain obligated to ensure that it is available for as long
- as needed to satisfy these requirements.
+ remain obligated to ensure that it is available for as long as
+ needed to satisfy these requirements.
e. Convey the object code using peer-to-peer transmission,
provided you inform other peers where the object code and
Corresponding Source of the work are being offered to the
general public at no charge under subsection 6d.
-
A separable portion of the object code, whose source code is
excluded from the Corresponding Source as a System Library, need
not be included in conveying the object code work.
@@ -30570,8 +30453,8 @@ TERMS AND CONDITIONS
A "User Product" is either (1) a "consumer product", which means
any tangible personal property which is normally used for personal,
family, or household purposes, or (2) anything designed or sold for
- incorporation into a dwelling. In determining whether a product
- is a consumer product, doubtful cases shall be resolved in favor of
+ incorporation into a dwelling. In determining whether a product is
+ a consumer product, doubtful cases shall be resolved in favor of
coverage. For a particular product received by a particular user,
"normally used" refers to a typical or common use of that class of
product, regardless of the status of the particular user or of the
@@ -30602,11 +30485,11 @@ TERMS AND CONDITIONS
The requirement to provide Installation Information does not
include a requirement to continue to provide support service,
- warranty, or updates for a work that has been modified or
- installed by the recipient, or for the User Product in which it
- has been modified or installed. Access to a network may be denied
- when the modification itself materially and adversely affects the
- operation of the network or violates the rules and protocols for
+ warranty, or updates for a work that has been modified or installed
+ by the recipient, or for the User Product in which it has been
+ modified or installed. Access to a network may be denied when the
+ modification itself materially and adversely affects the operation
+ of the network or violates the rules and protocols for
communication across the network.
Corresponding Source conveyed, and Installation Information
@@ -30636,8 +30519,8 @@ TERMS AND CONDITIONS
Notwithstanding any other provision of this License, for material
you add to a covered work, you may (if authorized by the copyright
- holders of that material) supplement the terms of this License
- with terms:
+ holders of that material) supplement the terms of this License with
+ terms:
a. Disclaiming warranty or limiting liability differently from
the terms of sections 15 and 16 of this License; or
@@ -30647,9 +30530,8 @@ TERMS AND CONDITIONS
Legal Notices displayed by works containing it; or
c. Prohibiting misrepresentation of the origin of that material,
- or requiring that modified versions of such material be
- marked in reasonable ways as different from the original
- version; or
+ or requiring that modified versions of such material be marked
+ in reasonable ways as different from the original version; or
d. Limiting the use for publicity purposes of names of licensors
or authors of the material; or
@@ -30668,11 +30550,10 @@ TERMS AND CONDITIONS
you received it, or any part of it, contains a notice stating that
it is governed by this License along with a term that is a further
restriction, you may remove that term. If a license document
- contains a further restriction but permits relicensing or
- conveying under this License, you may add to a covered work
- material governed by the terms of that license document, provided
- that the further restriction does not survive such relicensing or
- conveying.
+ contains a further restriction but permits relicensing or conveying
+ under this License, you may add to a covered work material governed
+ by the terms of that license document, provided that the further
+ restriction does not survive such relicensing or conveying.
If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
@@ -30688,13 +30569,13 @@ TERMS AND CONDITIONS
You may not propagate or modify a covered work except as expressly
provided under this License. Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights
- under this License (including any patent licenses granted under
- the third paragraph of section 11).
+ under this License (including any patent licenses granted under the
+ third paragraph of section 11).
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
- provisionally, unless and until the copyright holder explicitly
- and finally terminates your license, and (b) permanently, if the
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
@@ -30706,10 +30587,10 @@ TERMS AND CONDITIONS
after your receipt of the notice.
Termination of your rights under this section does not terminate
- the licenses of parties who have received copies or rights from
- you under this License. If your rights have been terminated and
- not permanently reinstated, you do not qualify to receive new
- licenses for the same material under section 10.
+ the licenses of parties who have received copies or rights from you
+ under this License. If your rights have been terminated and not
+ permanently reinstated, you do not qualify to receive new licenses
+ for the same material under section 10.
9. Acceptance Not Required for Having Copies.
@@ -30723,7 +30604,7 @@ TERMS AND CONDITIONS
by modifying or propagating a covered work, you indicate your
acceptance of this License to do so.
- 10. Automatic Licensing of Downstream Recipients.
+ 10. Automatic Licensing of Downstream Recipients.
Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
@@ -30737,21 +30618,21 @@ TERMS AND CONDITIONS
covered work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party's predecessor in interest had or
- could give under the previous paragraph, plus a right to
- possession of the Corresponding Source of the work from the
- predecessor in interest, if the predecessor has it or can get it
- with reasonable efforts.
+ could give under the previous paragraph, plus a right to possession
+ of the Corresponding Source of the work from the predecessor in
+ interest, if the predecessor has it or can get it with reasonable
+ efforts.
You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you
- may not impose a license fee, royalty, or other charge for
- exercise of rights granted under this License, and you may not
- initiate litigation (including a cross-claim or counterclaim in a
- lawsuit) alleging that any patent claim is infringed by making,
- using, selling, offering for sale, or importing the Program or any
- portion of it.
+ may not impose a license fee, royalty, or other charge for exercise
+ of rights granted under this License, and you may not initiate
+ litigation (including a cross-claim or counterclaim in a lawsuit)
+ alleging that any patent claim is infringed by making, using,
+ selling, offering for sale, or importing the Program or any portion
+ of it.
- 11. Patents.
+ 11. Patents.
A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based.
@@ -30771,15 +30652,15 @@ TERMS AND CONDITIONS
Each contributor grants you a non-exclusive, worldwide,
royalty-free patent license under the contributor's essential
patent claims, to make, use, sell, offer for sale, import and
- otherwise run, modify and propagate the contents of its
- contributor version.
+ otherwise run, modify and propagate the contents of its contributor
+ version.
In the following three paragraphs, a "patent license" is any
express agreement or commitment, however denominated, not to
enforce a patent (such as an express permission to practice a
- patent or covenant not to sue for patent infringement). To
- "grant" such a patent license to a party means to make such an
- agreement or commitment not to enforce a patent against the party.
+ patent or covenant not to sue for patent infringement). To "grant"
+ such a patent license to a party means to make such an agreement or
+ commitment not to enforce a patent against the party.
If you convey a covered work, knowingly relying on a patent
license, and the Corresponding Source of the work is not available
@@ -30809,36 +30690,35 @@ TERMS AND CONDITIONS
conditioned on the non-exercise of one or more of the rights that
are specifically granted under this License. You may not convey a
covered work if you are a party to an arrangement with a third
- party that is in the business of distributing software, under
- which you make payment to the third party based on the extent of
- your activity of conveying the work, and under which the third
- party grants, to any of the parties who would receive the covered
- work from you, a discriminatory patent license (a) in connection
- with copies of the covered work conveyed by you (or copies made
- from those copies), or (b) primarily for and in connection with
- specific products or compilations that contain the covered work,
- unless you entered into that arrangement, or that patent license
- was granted, prior to 28 March 2007.
+ party that is in the business of distributing software, under which
+ you make payment to the third party based on the extent of your
+ activity of conveying the work, and under which the third party
+ grants, to any of the parties who would receive the covered work
+ from you, a discriminatory patent license (a) in connection with
+ copies of the covered work conveyed by you (or copies made from
+ those copies), or (b) primarily for and in connection with specific
+ products or compilations that contain the covered work, unless you
+ entered into that arrangement, or that patent license was granted,
+ prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
- 12. No Surrender of Others' Freedom.
+ 12. No Surrender of Others' Freedom.
- If conditions are imposed on you (whether by court order,
- agreement or otherwise) that contradict the conditions of this
- License, they do not excuse you from the conditions of this
- License. If you cannot convey a covered work so as to satisfy
- simultaneously your obligations under this License and any other
- pertinent obligations, then as a consequence you may not convey it
- at all. For example, if you agree to terms that obligate you to
- collect a royalty for further conveying from those to whom you
- convey the Program, the only way you could satisfy both those
- terms and this License would be to refrain entirely from conveying
- the Program.
+ If conditions are imposed on you (whether by court order, agreement
+ or otherwise) that contradict the conditions of this License, they
+ do not excuse you from the conditions of this License. If you
+ cannot convey a covered work so as to satisfy simultaneously your
+ obligations under this License and any other pertinent obligations,
+ then as a consequence you may not convey it at all. For example,
+ if you agree to terms that obligate you to collect a royalty for
+ further conveying from those to whom you convey the Program, the
+ only way you could satisfy both those terms and this License would
+ be to refrain entirely from conveying the Program.
- 13. Use with the GNU Affero General Public License.
+ 13. Use with the GNU Affero General Public License.
Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
@@ -30849,22 +30729,21 @@ TERMS AND CONDITIONS
General Public License, section 13, concerning interaction through
a network will apply to the combination as such.
- 14. Revised Versions of this License.
+ 14. Revised Versions of this License.
The Free Software Foundation may publish revised and/or new
- versions of the GNU General Public License from time to time.
- Such new versions will be similar in spirit to the present
- version, but may differ in detail to address new problems or
- concerns.
+ versions of the GNU General Public License from time to time. Such
+ new versions will be similar in spirit to the present version, but
+ may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies that a certain numbered version of the GNU
General Public License "or any later version" applies to it, you
have the option of following the terms and conditions either of
- that numbered version or of any later version published by the
- Free Software Foundation. If the Program does not specify a
- version number of the GNU General Public License, you may choose
- any version ever published by the Free Software Foundation.
+ that numbered version or of any later version published by the Free
+ Software Foundation. If the Program does not specify a version
+ number of the GNU General Public License, you may choose any
+ version ever published by the Free Software Foundation.
If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that
@@ -30876,24 +30755,24 @@ TERMS AND CONDITIONS
author or copyright holder as a result of your choosing to follow a
later version.
- 15. Disclaimer of Warranty.
+ 15. Disclaimer of Warranty.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
- APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
+ APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
+ MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.
SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR OR CORRECTION.
- 16. Limitation of Liability.
+ 16. Limitation of Liability.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES
- AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU
- FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
+ AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
+ DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
@@ -30901,7 +30780,7 @@ TERMS AND CONDITIONS
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES.
- 17. Interpretation of Sections 15 and 16.
+ 17. Interpretation of Sections 15 and 16.
If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
@@ -30910,7 +30789,6 @@ TERMS AND CONDITIONS
connection with the Program, unless a warranty or assumption of
liability accompanies a copy of the Program in return for a fee.
-
END OF TERMS AND CONDITIONS
===========================
@@ -30941,7 +30819,7 @@ state the exclusion of warranty; and each file should
have at least the
General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program. If not, see `http://www.gnu.org/licenses/'.
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
Also add information on how to contact you by electronic and paper
mail.
@@ -30950,11 +30828,11 @@ mail.
notice like this when it starts in an interactive mode:
PROGRAM Copyright (C) YEAR NAME OF AUTHOR
- This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This program comes with ABSOLUTELY NO WARRANTY; for details type 'show w'.
This is free software, and you are welcome to redistribute it
- under certain conditions; type `show c' for details.
+ under certain conditions; type 'show c' for details.
- The hypothetical commands `show w' and `show c' should show the
+ The hypothetical commands 'show w' and 'show c' should show the
appropriate parts of the General Public License. Of course, your
program's commands might be different; for a GUI interface, you would
use an "about box".
@@ -30962,14 +30840,14 @@ use an "about box".
You should also get your employer (if you work as a programmer) or
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. For more information on this, and how to apply and follow
-the GNU GPL, see `http://www.gnu.org/licenses/'.
+the GNU GPL, see <http://www.gnu.org/licenses/>.
The GNU General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Lesser General Public License instead of this License. But first,
-please read `http://www.gnu.org/philosophy/why-not-lgpl.html'.
+please read <http://www.gnu.org/philosophy/why-not-lgpl.html>.
File: gawk.info, Node: GNU Free Documentation License, Next: Index, Prev:
Copying, Up: Top
@@ -30978,8 +30856,9 @@ GNU Free Documentation License
******************************
Version 1.3, 3 November 2008
+
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
- `http://fsf.org/'
+ <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
@@ -31004,21 +30883,21 @@ GNU Free Documentation License
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
- of subject matter or whether it is published as a printed book.
- We recommend this License principally for works whose purpose is
+ of subject matter or whether it is published as a printed book. We
+ recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
- that contains a notice placed by the copyright holder saying it
- can be distributed under the terms of this License. Such a notice
+ that contains a notice placed by the copyright holder saying it can
+ be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
- of the public is a licensee, and is addressed as "you". You
- accept the license if you copy, modify or distribute the work in a
- way requiring permission under copyright law.
+ of the public is a licensee, and is addressed as "you". You accept
+ the license if you copy, modify or distribute the work in a way
+ requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
@@ -31036,12 +30915,12 @@ GNU Free Documentation License
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
- titles are designated, as being those of Invariant Sections, in
- the notice that says that the Document is released under this
- License. If a section does not fit the above definition of
- Secondary then it is not allowed to be designated as Invariant.
- The Document may contain zero Invariant Sections. If the Document
- does not identify any Invariant Sections then there are none.
+ titles are designated, as being those of Invariant Sections, in the
+ notice that says that the Document is released under this License.
+ If a section does not fit the above definition of Secondary then it
+ is not allowed to be designated as Invariant. The Document may
+ contain zero Invariant Sections. If the Document does not identify
+ any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
@@ -31052,27 +30931,27 @@ GNU Free Documentation License
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
- straightforwardly with generic text editors or (for images
- composed of pixels) generic paint programs or (for drawings) some
- widely available drawing editor, and that is suitable for input to
- text formatters or for automatic translation to a variety of
- formats suitable for input to text formatters. A copy made in an
- otherwise Transparent file format whose markup, or absence of
- markup, has been arranged to thwart or discourage subsequent
- modification by readers is not Transparent. An image format is
- not Transparent if used for any substantial amount of text. A
- copy that is not "Transparent" is called "Opaque".
+ straightforwardly with generic text editors or (for images composed
+ of pixels) generic paint programs or (for drawings) some widely
+ available drawing editor, and that is suitable for input to text
+ formatters or for automatic translation to a variety of formats
+ suitable for input to text formatters. A copy made in an otherwise
+ Transparent file format whose markup, or absence of markup, has
+ been arranged to thwart or discourage subsequent modification by
+ readers is not Transparent. An image format is not Transparent if
+ used for any substantial amount of text. A copy that is not
+ "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
- SGML or XML using a publicly available DTD, and
- standard-conforming simple HTML, PostScript or PDF designed for
- human modification. Examples of transparent image formats include
- PNG, XCF and JPG. Opaque formats include proprietary formats that
- can be read and edited only by proprietary word processors, SGML or
- XML for which the DTD and/or processing tools are not generally
- available, and the machine-generated HTML, PostScript or PDF
- produced by some word processors for output purposes only.
+ SGML or XML using a publicly available DTD, and standard-conforming
+ simple HTML, PostScript or PDF designed for human modification.
+ Examples of transparent image formats include PNG, XCF and JPG.
+ Opaque formats include proprietary formats that can be read and
+ edited only by proprietary word processors, SGML or XML for which
+ the DTD and/or processing tools are not generally available, and
+ the machine-generated HTML, PostScript or PDF produced by some word
+ processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
@@ -31110,8 +30989,8 @@ GNU Free Documentation License
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
- distribute a large enough number of copies you must also follow
- the conditions in section 3.
+ distribute a large enough number of copies you must also follow the
+ conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
@@ -31125,12 +31004,11 @@ GNU Free Documentation License
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
- front cover must present the full title with all words of the
- title equally prominent and visible. You may add other material
- on the covers in addition. Copying with changes limited to the
- covers, as long as they preserve the title of the Document and
- satisfy these conditions, can be treated as verbatim copying in
- other respects.
+ front cover must present the full title with all words of the title
+ equally prominent and visible. You may add other material on the
+ covers in addition. Copying with changes limited to the covers, as
+ long as they preserve the title of the Document and satisfy these
+ conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
@@ -31138,40 +31016,39 @@ GNU Free Documentation License
adjacent pages.
If you publish or distribute Opaque copies of the Document
- numbering more than 100, you must either include a
- machine-readable Transparent copy along with each Opaque copy, or
- state in or with each Opaque copy a computer-network location from
- which the general network-using public has access to download
- using public-standard network protocols a complete Transparent
- copy of the Document, free of added material. If you use the
- latter option, you must take reasonably prudent steps, when you
- begin distribution of Opaque copies in quantity, to ensure that
- this Transparent copy will remain thus accessible at the stated
- location until at least one year after the last time you
- distribute an Opaque copy (directly or through your agents or
- retailers) of that edition to the public.
+ numbering more than 100, you must either include a machine-readable
+ Transparent copy along with each Opaque copy, or state in or with
+ each Opaque copy a computer-network location from which the general
+ network-using public has access to download using public-standard
+ network protocols a complete Transparent copy of the Document, free
+ of added material. If you use the latter option, you must take
+ reasonably prudent steps, when you begin distribution of Opaque
+ copies in quantity, to ensure that this Transparent copy will
+ remain thus accessible at the stated location until at least one
+ year after the last time you distribute an Opaque copy (directly or
+ through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
- the Document well before redistributing any large number of
- copies, to give them a chance to provide you with an updated
- version of the Document.
+ the Document well before redistributing any large number of copies,
+ to give them a chance to provide you with an updated version of the
+ Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
- release the Modified Version under precisely this License, with
- the Modified Version filling the role of the Document, thus
- licensing distribution and modification of the Modified Version to
- whoever possesses a copy of it. In addition, you must do these
- things in the Modified Version:
+ release the Modified Version under precisely this License, with the
+ Modified Version filling the role of the Document, thus licensing
+ distribution and modification of the Modified Version to whoever
+ possesses a copy of it. In addition, you must do these things in
+ the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
- distinct from that of the Document, and from those of
- previous versions (which should, if there were any, be listed
- in the History section of the Document). You may use the
- same title as a previous version if the original publisher of
- that version gives permission.
+ distinct from that of the Document, and from those of previous
+ versions (which should, if there were any, be listed in the
+ History section of the Document). You may use the same title
+ as a previous version if the original publisher of that
+ version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
@@ -31201,31 +31078,30 @@ GNU Free Documentation License
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
- authors, and publisher of the Modified Version as given on
- the Title Page. If there is no section Entitled "History" in
- the Document, create one stating the title, year, authors,
- and publisher of the Document as given on its Title Page,
- then add an item describing the Modified Version as stated in
- the previous sentence.
+ authors, and publisher of the Modified Version as given on the
+ Title Page. If there is no section Entitled "History" in the
+ Document, create one stating the title, year, authors, and
+ publisher of the Document as given on its Title Page, then add
+ an item describing the Modified Version as stated in the
+ previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
- previous versions it was based on. These may be placed in
- the "History" section. You may omit a network location for a
- work that was published at least four years before the
- Document itself, or if the original publisher of the version
- it refers to gives permission.
+ previous versions it was based on. These may be placed in the
+ "History" section. You may omit a network location for a work
+ that was published at least four years before the Document
+ itself, or if the original publisher of the version it refers
+ to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
- Preserve the Title of the section, and preserve in the
- section all the substance and tone of each of the contributor
+ Preserve the Title of the section, and preserve in the section
+ all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
- L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers
- or the equivalent are not considered part of the section
- titles.
+ L. Preserve all the Invariant Sections of the Document, unaltered
+ in their text and in their titles. Section numbers or the
+ equivalent are not considered part of the section titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
@@ -31238,11 +31114,11 @@ GNU Free Documentation License
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
- material copied from the Document, you may at your option
- designate some or all of these sections as invariant. To do this,
- add their titles to the list of Invariant Sections in the Modified
- Version's license notice. These titles must be distinct from any
- other section titles.
+ material copied from the Document, you may at your option designate
+ some or all of these sections as invariant. To do this, add their
+ titles to the list of Invariant Sections in the Modified Version's
+ license notice. These titles must be distinct from any other
+ section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
@@ -31251,15 +31127,15 @@ GNU Free Documentation License
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
- and a passage of up to 25 words as a Back-Cover Text, to the end
- of the list of Cover Texts in the Modified Version. Only one
- passage of Front-Cover Text and one of Back-Cover Text may be
- added by (or through arrangements made by) any one entity. If the
- Document already includes a cover text for the same cover,
- previously added by you or by arrangement made by the same entity
- you are acting on behalf of, you may not add another; but you may
- replace the old one, on explicit permission from the previous
- publisher that added the old one.
+ and a passage of up to 25 words as a Back-Cover Text, to the end of
+ the list of Cover Texts in the Modified Version. Only one passage
+ of Front-Cover Text and one of Back-Cover Text may be added by (or
+ through arrangements made by) any one entity. If the Document
+ already includes a cover text for the same cover, previously added
+ by you or by arrangement made by the same entity you are acting on
+ behalf of, you may not add another; but you may replace the old
+ one, on explicit permission from the previous publisher that added
+ the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
@@ -31269,8 +31145,8 @@ GNU Free Documentation License
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
- modified versions, provided that you include in the combination
- all of the Invariant Sections of all of the original documents,
+ modified versions, provided that you include in the combination all
+ of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
@@ -31297,20 +31173,20 @@ GNU Free Documentation License
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
- rules of this License for verbatim copying of each of the
- documents in all other respects.
+ rules of this License for verbatim copying of each of the documents
+ in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
- a copy of this License into the extracted document, and follow
- this License in all other respects regarding verbatim copying of
- that document.
+ a copy of this License into the extracted document, and follow this
+ License in all other respects regarding verbatim copying of that
+ document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
- separate and independent documents or works, in or on a volume of
- a storage or distribution medium, is called an "aggregate" if the
+ separate and independent documents or works, in or on a volume of a
+ storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
@@ -31355,8 +31231,8 @@ GNU Free Documentation License
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
- provisionally, unless and until the copyright holder explicitly
- and finally terminates your license, and (b) permanently, if the
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
@@ -31368,33 +31244,33 @@ GNU Free Documentation License
after your receipt of the notice.
Termination of your rights under this section does not terminate
- the licenses of parties who have received copies or rights from
- you under this License. If your rights have been terminated and
- not permanently reinstated, receipt of a copy of some or all of
- the same material does not give you any rights to use it.
+ the licenses of parties who have received copies or rights from you
+ under this License. If your rights have been terminated and not
+ permanently reinstated, receipt of a copy of some or all of the
+ same material does not give you any rights to use it.
- 10. FUTURE REVISIONS OF THIS LICENSE
+ 10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
- `http://www.gnu.org/copyleft/'.
+ <http://www.gnu.org/copyleft/>.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
- published (not as a draft) by the Free Software Foundation. If
- the Document does not specify a version number of this License,
- you may choose any version ever published (not as a draft) by the
- Free Software Foundation. If the Document specifies that a proxy
- can decide which future versions of this License can be used, that
+ published (not as a draft) by the Free Software Foundation. If the
+ Document does not specify a version number of this License, you may
+ choose any version ever published (not as a draft) by the Free
+ Software Foundation. If the Document specifies that a proxy can
+ decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
- 11. RELICENSING
+ 11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
@@ -31424,7 +31300,6 @@ GNU Free Documentation License
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
-
ADDENDUM: How to use this License for your documents
====================================================
@@ -31441,7 +31316,7 @@ notices just after the title page:
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
-Texts, replace the "with...Texts." line with this:
+Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
@@ -31452,9 +31327,9 @@ combination of the three, merge those two alternatives
to suit the
situation.
If your document contains nontrivial examples of program code, we
-recommend releasing these examples in parallel under your choice of
-free software license, such as the GNU General Public License, to
-permit their use in free software.
+recommend releasing these examples in parallel under your choice of free
+software license, such as the GNU General Public License, to permit
+their use in free software.
File: gawk.info, Node: Index, Prev: GNU Free Documentation License, Up: Top
@@ -31465,314 +31340,354 @@ Index
[index ]
* Menu:
-* ! (exclamation point), ! operator: Boolean Ops. (line 69)
-* ! (exclamation point), ! operator <1>: Egrep Program. (line 175)
-* ! (exclamation point), ! operator <2>: Ranges. (line 48)
-* ! (exclamation point), ! operator: Precedence. (line 52)
-* ! (exclamation point), != operator <1>: Precedence. (line 65)
-* ! (exclamation point), != operator: Comparison Operators.
+* '!' (exclamation point), '!' operator: Boolean Ops. (line 69)
+* '!' (exclamation point), '!' operator <1>: Precedence. (line 51)
+* '!' (exclamation point), '!' operator <2>: Ranges. (line 47)
+* '!' (exclamation point), '!' operator <3>: Egrep Program. (line 174)
+* '!' (exclamation point), '!=' operator: Comparison Operators.
(line 11)
-* ! (exclamation point), !~ operator <1>: Expression Patterns.
- (line 24)
-* ! (exclamation point), !~ operator <2>: Precedence. (line 80)
-* ! (exclamation point), !~ operator <3>: Comparison Operators.
+* '!' (exclamation point), '!=' operator <1>: Precedence. (line 64)
+* '!' (exclamation point), '!~' operator: Regexp Usage. (line 19)
+* '!' (exclamation point), '!~' operator <1>: Computed Regexps.
+ (line 6)
+* '!' (exclamation point), '!~' operator <2>: Case-sensitivity.
+ (line 26)
+* '!' (exclamation point), '!~' operator <3>: Regexp Constants.
+ (line 6)
+* '!' (exclamation point), '!~' operator <4>: Comparison Operators.
(line 11)
-* ! (exclamation point), !~ operator <4>: Regexp Constants. (line 6)
-* ! (exclamation point), !~ operator <5>: Case-sensitivity. (line 26)
-* ! (exclamation point), !~ operator <6>: Computed Regexps. (line 6)
-* ! (exclamation point), !~ operator: Regexp Usage. (line 19)
-* " (double quote), in regexp constants: Computed Regexps. (line 30)
-* " (double quote), in shell commands: Quoting. (line 54)
-* # (number sign), #! (executable scripts): Executable Scripts.
+* '!' (exclamation point), '!~' operator <5>: Comparison Operators.
+ (line 98)
+* '!' (exclamation point), '!~' operator <6>: Precedence. (line 79)
+* '!' (exclamation point), '!~' operator <7>: Expression Patterns.
+ (line 24)
+* '"' (double quote), in regexp constants: Computed Regexps. (line 30)
+* '"' (double quote), in shell commands: Quoting. (line 54)
+* '#' (number sign), '#!' (executable scripts): Executable Scripts.
(line 6)
-* # (number sign), commenting: Comments. (line 6)
-* $ (dollar sign), $ field operator <1>: Precedence. (line 43)
-* $ (dollar sign), $ field operator: Fields. (line 19)
-* $ (dollar sign), incrementing fields and arrays: Increment Ops.
+* '#' (number sign), commenting: Comments. (line 6)
+* '$' (dollar sign), '$' field operator: Fields. (line 19)
+* '$' (dollar sign), '$' field operator <1>: Precedence. (line 42)
+* '$' (dollar sign), incrementing fields and arrays: Increment Ops.
(line 30)
-* $ (dollar sign), regexp operator: Regexp Operators. (line 35)
-* % (percent sign), % operator: Precedence. (line 55)
-* % (percent sign), %= operator <1>: Precedence. (line 95)
-* % (percent sign), %= operator: Assignment Ops. (line 130)
-* & (ampersand), && operator <1>: Precedence. (line 86)
-* & (ampersand), && operator: Boolean Ops. (line 59)
-* & (ampersand), gsub()/gensub()/sub() functions and: Gory Details.
+* '$' (dollar sign), regexp operator: Regexp Operators. (line 35)
+* '%' (percent sign), '%' operator: Precedence. (line 54)
+* '%' (percent sign), '%=' operator: Assignment Ops. (line 129)
+* '%' (percent sign), '%=' operator <1>: Precedence. (line 94)
+* '&' (ampersand), '&&' operator: Boolean Ops. (line 59)
+* '&' (ampersand), '&&' operator <1>: Precedence. (line 85)
+* '&' (ampersand), 'gsub()'/'gensub()'/'sub()' functions and: Gory Details.
(line 6)
-* ' (single quote): One-shot. (line 15)
-* ' (single quote) in gawk command lines: Long. (line 35)
-* ' (single quote), in shell commands: Quoting. (line 48)
-* ' (single quote), vs. apostrophe: Comments. (line 27)
-* ' (single quote), with double quotes: Quoting. (line 73)
-* () (parentheses), in a profile: Profiling. (line 146)
-* () (parentheses), regexp operator: Regexp Operators. (line 81)
-* * (asterisk), * operator, as multiplication operator: Precedence.
- (line 55)
-* * (asterisk), * operator, as regexp operator: Regexp Operators.
+* ''' (single quote): One-shot. (line 15)
+* ''' (single quote) in 'gawk' command lines: Long. (line 35)
+* ''' (single quote), in shell commands: Quoting. (line 48)
+* ''' (single quote), vs. apostrophe: Comments. (line 27)
+* ''' (single quote), with double quotes: Quoting. (line 73)
+* '()' (parentheses), in a profile: Profiling. (line 146)
+* '()' (parentheses), regexp operator: Regexp Operators. (line 81)
+* '*' (asterisk), '*' operator, as multiplication operator: Precedence.
+ (line 54)
+* '*' (asterisk), '*' operator, as regexp operator: Regexp Operators.
(line 89)
-* * (asterisk), * operator, null strings, matching: String Functions.
+* '*' (asterisk), '*' operator, null strings, matching: String Functions.
(line 537)
-* * (asterisk), ** operator <1>: Precedence. (line 49)
-* * (asterisk), ** operator: Arithmetic Ops. (line 81)
-* * (asterisk), **= operator <1>: Precedence. (line 95)
-* * (asterisk), **= operator: Assignment Ops. (line 130)
-* * (asterisk), *= operator <1>: Precedence. (line 95)
-* * (asterisk), *= operator: Assignment Ops. (line 130)
-* + (plus sign), + operator: Precedence. (line 52)
-* + (plus sign), ++ operator <1>: Precedence. (line 46)
-* + (plus sign), ++ operator: Increment Ops. (line 11)
-* + (plus sign), += operator <1>: Precedence. (line 95)
-* + (plus sign), += operator: Assignment Ops. (line 82)
-* + (plus sign), regexp operator: Regexp Operators. (line 105)
-* , (comma), in range patterns: Ranges. (line 6)
-* - (hyphen), - operator: Precedence. (line 52)
-* - (hyphen), -- operator <1>: Precedence. (line 46)
-* - (hyphen), -- operator: Increment Ops. (line 48)
-* - (hyphen), -= operator <1>: Precedence. (line 95)
-* - (hyphen), -= operator: Assignment Ops. (line 130)
-* - (hyphen), filenames beginning with: Options. (line 59)
-* - (hyphen), in bracket expressions: Bracket Expressions. (line 17)
-* --assign option: Options. (line 32)
-* --bignum option: Options. (line 205)
-* --characters-as-bytes option: Options. (line 68)
-* --copyright option: Options. (line 88)
-* --debug option: Options. (line 108)
-* --disable-extensions configuration option: Additional Configuration Options.
+* '*' (asterisk), '**' operator: Arithmetic Ops. (line 81)
+* '*' (asterisk), '**' operator <1>: Precedence. (line 48)
+* '*' (asterisk), '**=' operator: Assignment Ops. (line 129)
+* '*' (asterisk), '**=' operator <1>: Precedence. (line 94)
+* '*' (asterisk), '*=' operator: Assignment Ops. (line 129)
+* '*' (asterisk), '*=' operator <1>: Precedence. (line 94)
+* '+' (plus sign), '+' operator: Precedence. (line 51)
+* '+' (plus sign), '+' operator <1>: Precedence. (line 57)
+* '+' (plus sign), '++' operator: Increment Ops. (line 11)
+* '+' (plus sign), '++' operator <1>: Increment Ops. (line 40)
+* '+' (plus sign), '++' operator <2>: Precedence. (line 45)
+* '+' (plus sign), '+=' operator: Assignment Ops. (line 81)
+* '+' (plus sign), '+=' operator <1>: Precedence. (line 94)
+* '+' (plus sign), regexp operator: Regexp Operators. (line 105)
+* ',' (comma), in range patterns: Ranges. (line 6)
+* '-' (hyphen), '-' operator: Precedence. (line 51)
+* '-' (hyphen), '-' operator <1>: Precedence. (line 57)
+* '-' (hyphen), '--' operator: Increment Ops. (line 48)
+* '-' (hyphen), '--' operator <1>: Precedence. (line 45)
+* '-' (hyphen), '-=' operator: Assignment Ops. (line 129)
+* '-' (hyphen), '-=' operator <1>: Precedence. (line 94)
+* '-' (hyphen), filenames beginning with: Options. (line 60)
+* '-' (hyphen), in bracket expressions: Bracket Expressions. (line 17)
+* '--assign' option: Options. (line 32)
+* '--bignum' option: Options. (line 203)
+* '--characters-as-bytes' option: Options. (line 69)
+* '--copyright' option: Options. (line 89)
+* '--debug' option: Options. (line 108)
+* '--disable-extensions' configuration option: Additional Configuration
Options.
(line 9)
-* --disable-lint configuration option: Additional Configuration Options.
+* '--disable-lint' configuration option: Additional Configuration Options.
(line 15)
-* --disable-nls configuration option: Additional Configuration Options.
+* '--disable-nls' configuration option: Additional Configuration Options.
(line 32)
-* --dump-variables option: Options. (line 93)
-* --dump-variables option, using for library functions: Library Names.
+* '--dump-variables' option: Options. (line 94)
+* '--dump-variables' option, using for library functions: Library Names.
(line 45)
-* --exec option: Options. (line 125)
-* --field-separator option: Options. (line 21)
-* --file option: Options. (line 25)
-* --gen-pot option <1>: String Extraction. (line 6)
-* --gen-pot option: Options. (line 147)
-* --help option: Options. (line 154)
-* --include option: Options. (line 159)
-* --lint option <1>: Options. (line 185)
-* --lint option: Command Line. (line 20)
-* --lint-old option: Options. (line 297)
-* --load option: Options. (line 173)
-* --non-decimal-data option <1>: Nondecimal Data. (line 6)
-* --non-decimal-data option: Options. (line 211)
-* --non-decimal-data option, strtonum() function and: Nondecimal Data.
+* '--exec' option: Options. (line 125)
+* '--field-separator' option: Options. (line 21)
+* '--file' option: Options. (line 25)
+* '--gen-pot' option: Options. (line 147)
+* '--gen-pot' option <1>: String Extraction. (line 6)
+* '--gen-pot' option <2>: String Extraction. (line 6)
+* '--help' option: Options. (line 154)
+* '--include' option: Options. (line 159)
+* '--lint' option: Command Line. (line 20)
+* '--lint' option <1>: Options. (line 184)
+* '--lint-old' option: Options. (line 294)
+* '--load' option: Options. (line 172)
+* '--non-decimal-data' option: Options. (line 209)
+* '--non-decimal-data' option <1>: Nondecimal Data. (line 6)
+* '--non-decimal-data' option, 'strtonum()' function and: Nondecimal Data.
(line 35)
-* --optimize option: Options. (line 238)
-* --posix option: Options. (line 256)
-* --posix option, --traditional option and: Options. (line 275)
-* --pretty-print option: Options. (line 225)
-* --profile option <1>: Profiling. (line 12)
-* --profile option: Options. (line 244)
-* --re-interval option: Options. (line 281)
-* --sandbox option: Options. (line 288)
-* --sandbox option, disabling system() function: I/O Functions.
+* '--optimize' option: Options. (line 236)
+* '--posix' option: Options. (line 254)
+* '--posix' option, '--traditional' option and: Options. (line 272)
+* '--pretty-print' option: Options. (line 223)
+* '--profile' option: Options. (line 242)
+* '--profile' option <1>: Profiling. (line 12)
+* '--re-interval' option: Options. (line 278)
+* '--sandbox' option: Options. (line 285)
+* '--sandbox' option, disabling 'system()' function: I/O Functions.
(line 129)
-* --sandbox option, input redirection with getline: Getline. (line 19)
-* --sandbox option, output redirection with print, printf: Redirection.
+* '--sandbox' option, input redirection with 'getline': Getline.
+ (line 19)
+* '--sandbox' option, output redirection with 'print', 'printf': Redirection.
(line 6)
-* --source option: Options. (line 117)
-* --traditional option: Options. (line 81)
-* --traditional option, --posix option and: Options. (line 275)
-* --use-lc-numeric option: Options. (line 220)
-* --version option: Options. (line 302)
-* --with-whiny-user-strftime configuration option: Additional Configuration
Options.
+* '--source' option: Options. (line 117)
+* '--traditional' option: Options. (line 82)
+* '--traditional' option, '--posix' option and: Options. (line 272)
+* '--use-lc-numeric' option: Options. (line 218)
+* '--version' option: Options. (line 299)
+* '--with-whiny-user-strftime' configuration option: Additional Configuration
Options.
(line 37)
-* -b option: Options. (line 68)
-* -C option: Options. (line 88)
-* -c option: Options. (line 81)
-* -D option: Options. (line 108)
-* -d option: Options. (line 93)
-* -e option: Options. (line 338)
-* -E option: Options. (line 125)
-* -e option: Options. (line 117)
-* -f option: Options. (line 25)
-* -F option: Options. (line 21)
-* -f option: Long. (line 12)
-* -F option, -Ft sets FS to TAB: Options. (line 310)
-* -F option, command-line: Command Line Field Separator.
+* '-b' option: Options. (line 69)
+* '-c' option: Options. (line 82)
+* '-C' option: Options. (line 89)
+* '-d' option: Options. (line 94)
+* '-D' option: Options. (line 108)
+* '-e' option: Options. (line 117)
+* '-E' option: Options. (line 125)
+* '-e' option <1>: Options. (line 335)
+* '-f' option: Long. (line 12)
+* '-F' option: Options. (line 21)
+* '-f' option <1>: Options. (line 25)
+* '-F' option, '-Ft' sets 'FS' to TAB: Options. (line 307)
+* '-F' option, command-line: Command Line Field Separator.
(line 6)
-* -f option, multiple uses: Options. (line 315)
-* -g option: Options. (line 147)
-* -h option: Options. (line 154)
-* -i option: Options. (line 159)
-* -L option: Options. (line 297)
-* -l option: Options. (line 173)
-* -M option: Options. (line 205)
-* -N option: Options. (line 220)
-* -n option: Options. (line 211)
-* -O option: Options. (line 238)
-* -o option: Options. (line 225)
-* -P option: Options. (line 256)
-* -p option: Options. (line 244)
-* -r option: Options. (line 281)
-* -S option: Options. (line 288)
-* -v option: Assignment Options. (line 12)
-* -V option: Options. (line 302)
-* -v option: Options. (line 32)
-* -W option: Options. (line 46)
-* . (period), regexp operator: Regexp Operators. (line 44)
-* .gmo files: Explaining gettext. (line 42)
-* .gmo files, specifying directory of <1>: Programmer i18n. (line 48)
-* .gmo files, specifying directory of: Explaining gettext. (line 54)
-* .mo files, converting from .po: I18N Example. (line 64)
-* .po files <1>: Translator i18n. (line 6)
-* .po files: Explaining gettext. (line 37)
-* .po files, converting to .mo: I18N Example. (line 64)
-* .pot files: Explaining gettext. (line 31)
-* / (forward slash) to enclose regular expressions: Regexp. (line 10)
-* / (forward slash), / operator: Precedence. (line 55)
-* / (forward slash), /= operator <1>: Precedence. (line 95)
-* / (forward slash), /= operator: Assignment Ops. (line 130)
-* / (forward slash), /= operator, vs. /=.../ regexp constant: Assignment Ops.
- (line 148)
-* / (forward slash), patterns and: Expression Patterns. (line 24)
-* /= operator vs. /=.../ regexp constant: Assignment Ops. (line 148)
-* /dev/... special files: Special FD. (line 48)
-* /dev/fd/N special files (gawk): Special FD. (line 48)
-* /inet/... special files (gawk): TCP/IP Networking. (line 6)
-* /inet4/... special files (gawk): TCP/IP Networking. (line 6)
-* /inet6/... special files (gawk): TCP/IP Networking. (line 6)
-* ; (semicolon), AWKPATH variable and: PC Using. (line 10)
-* ; (semicolon), separating statements in actions <1>: Statements.
- (line 10)
-* ; (semicolon), separating statements in actions <2>: Action Overview.
+* '-f' option, multiple uses: Options. (line 312)
+* '-g' option: Options. (line 147)
+* '-h' option: Options. (line 154)
+* '-i' option: Options. (line 159)
+* '-l' option: Options. (line 172)
+* '-l' option <1>: Options. (line 184)
+* '-L' option: Options. (line 294)
+* '-M' option: Options. (line 203)
+* '-n' option: Options. (line 209)
+* '-N' option: Options. (line 218)
+* '-o' option: Options. (line 223)
+* '-O' option: Options. (line 236)
+* '-p' option: Options. (line 242)
+* '-P' option: Options. (line 254)
+* '-r' option: Options. (line 278)
+* '-S' option: Options. (line 285)
+* '-v' option: Options. (line 32)
+* '-V' option: Options. (line 299)
+* '-v' option <1>: Assignment Options. (line 12)
+* '-W' option: Options. (line 47)
+* '.' (period), regexp operator: Regexp Operators. (line 44)
+* '.gmo' files: Explaining gettext. (line 42)
+* '.gmo' files, specifying directory of: Explaining gettext. (line 54)
+* '.gmo' files, specifying directory of <1>: Programmer i18n. (line 48)
+* '.mo' files, converting from '.po': I18N Example. (line 66)
+* '.po' files: Explaining gettext. (line 37)
+* '.po' files <1>: Translator i18n. (line 6)
+* '.po' files, converting to '.mo': I18N Example. (line 66)
+* '.pot' files: Explaining gettext. (line 31)
+* '/' (forward slash) to enclose regular expressions: Regexp. (line 10)
+* '/' (forward slash), '/' operator: Precedence. (line 54)
+* '/' (forward slash), '/=' operator: Assignment Ops. (line 129)
+* '/' (forward slash), '/=' operator <1>: Precedence. (line 94)
+* '/' (forward slash), '/=' operator, vs. '/=.../' regexp constant: Assignment
Ops.
+ (line 149)
+* '/' (forward slash), patterns and: Expression Patterns. (line 24)
+* '/=' operator vs. '/=.../' regexp constant: Assignment Ops. (line 149)
+* '/dev/...' special files: Special FD. (line 48)
+* '/dev/fd/N' special files ('gawk'): Special FD. (line 48)
+* '/inet/...' special files ('gawk'): TCP/IP Networking. (line 6)
+* '/inet4/...' special files ('gawk'): TCP/IP Networking. (line 6)
+* '/inet6/...' special files ('gawk'): TCP/IP Networking. (line 6)
+* ';' (semicolon), 'AWKPATH' variable and: PC Using. (line 10)
+* ';' (semicolon), separating statements in actions: Statements/Lines.
+ (line 90)
+* ';' (semicolon), separating statements in actions <1>: Action Overview.
(line 19)
-* ; (semicolon), separating statements in actions: Statements/Lines.
- (line 91)
-* < (left angle bracket), < operator <1>: Precedence. (line 65)
-* < (left angle bracket), < operator: Comparison Operators.
+* ';' (semicolon), separating statements in actions <2>: Statements.
+ (line 10)
+* '<' (left angle bracket), '<' operator: Comparison Operators.
(line 11)
-* < (left angle bracket), < operator (I/O): Getline/File. (line 6)
-* < (left angle bracket), <= operator <1>: Precedence. (line 65)
-* < (left angle bracket), <= operator: Comparison Operators.
+* '<' (left angle bracket), '<' operator <1>: Precedence. (line 64)
+* '<' (left angle bracket), '<' operator (I/O): Getline/File. (line 6)
+* '<' (left angle bracket), '<=' operator: Comparison Operators.
(line 11)
-* = (equals sign), = operator: Assignment Ops. (line 6)
-* = (equals sign), == operator <1>: Precedence. (line 65)
-* = (equals sign), == operator: Comparison Operators.
+* '<' (left angle bracket), '<=' operator <1>: Precedence. (line 64)
+* '=' (equals sign), '=' operator: Assignment Ops. (line 6)
+* '=' (equals sign), '==' operator: Comparison Operators.
(line 11)
-* > (right angle bracket), > operator <1>: Precedence. (line 65)
-* > (right angle bracket), > operator: Comparison Operators.
+* '=' (equals sign), '==' operator <1>: Precedence. (line 64)
+* '>' (right angle bracket), '>' operator: Comparison Operators.
(line 11)
-* > (right angle bracket), > operator (I/O): Redirection. (line 22)
-* > (right angle bracket), >= operator <1>: Precedence. (line 65)
-* > (right angle bracket), >= operator: Comparison Operators.
+* '>' (right angle bracket), '>' operator <1>: Precedence. (line 64)
+* '>' (right angle bracket), '>' operator (I/O): Redirection. (line 22)
+* '>' (right angle bracket), '>=' operator: Comparison Operators.
(line 11)
-* > (right angle bracket), >> operator (I/O) <1>: Precedence. (line 65)
-* > (right angle bracket), >> operator (I/O): Redirection. (line 50)
-* ? (question mark), ?: operator: Precedence. (line 92)
-* ? (question mark), regexp operator <1>: GNU Regexp Operators.
- (line 59)
-* ? (question mark), regexp operator: Regexp Operators. (line 111)
-* @-notation for indirect function calls: Indirect Calls. (line 47)
-* @include directive: Include Files. (line 8)
-* @load directive: Loading Shared Libraries.
+* '>' (right angle bracket), '>=' operator <1>: Precedence. (line 64)
+* '>' (right angle bracket), '>>' operator (I/O): Redirection.
+ (line 50)
+* '>' (right angle bracket), '>>' operator (I/O) <1>: Precedence.
+ (line 64)
+* '?' (question mark), '?:' operator: Precedence. (line 91)
+* '?' (question mark), regexp operator: Regexp Operators. (line 111)
+* '?' (question mark), regexp operator <1>: GNU Regexp Operators.
+ (line 62)
+* '@'-notation for indirect function calls: Indirect Calls. (line 47)
+* '@include' directive: Include Files. (line 8)
+* '@load' directive: Loading Shared Libraries.
(line 8)
-* [] (square brackets), regexp operator: Regexp Operators. (line 56)
-* \ (backslash): Comments. (line 50)
-* \ (backslash), \" escape sequence: Escape Sequences. (line 82)
-* \ (backslash), \' operator (gawk): GNU Regexp Operators.
- (line 56)
-* \ (backslash), \/ escape sequence: Escape Sequences. (line 73)
-* \ (backslash), \< operator (gawk): GNU Regexp Operators.
- (line 30)
-* \ (backslash), \> operator (gawk): GNU Regexp Operators.
- (line 34)
-* \ (backslash), \` operator (gawk): GNU Regexp Operators.
- (line 54)
-* \ (backslash), \a escape sequence: Escape Sequences. (line 34)
-* \ (backslash), \b escape sequence: Escape Sequences. (line 38)
-* \ (backslash), \B operator (gawk): GNU Regexp Operators.
- (line 43)
-* \ (backslash), \f escape sequence: Escape Sequences. (line 41)
-* \ (backslash), \n escape sequence: Escape Sequences. (line 44)
-* \ (backslash), \NNN escape sequence: Escape Sequences. (line 56)
-* \ (backslash), \r escape sequence: Escape Sequences. (line 47)
-* \ (backslash), \S operator (gawk): GNU Regexp Operators.
- (line 17)
-* \ (backslash), \s operator (gawk): GNU Regexp Operators.
- (line 13)
-* \ (backslash), \t escape sequence: Escape Sequences. (line 50)
-* \ (backslash), \v escape sequence: Escape Sequences. (line 53)
-* \ (backslash), \W operator (gawk): GNU Regexp Operators.
- (line 26)
-* \ (backslash), \w operator (gawk): GNU Regexp Operators.
- (line 21)
-* \ (backslash), \x escape sequence: Escape Sequences. (line 61)
-* \ (backslash), \y operator (gawk): GNU Regexp Operators.
- (line 38)
-* \ (backslash), as field separator: Command Line Field Separator.
+* '[]' (square brackets), regexp operator: Regexp Operators. (line 56)
+* '\' (backslash): Comments. (line 50)
+* '\' (backslash), as field separator: Command Line Field Separator.
(line 24)
-* \ (backslash), continuing lines and: Statements/Lines. (line 19)
-* \ (backslash), continuing lines and, comments and: Statements/Lines.
- (line 76)
-* \ (backslash), continuing lines and, in csh: Statements/Lines.
- (line 44)
-* \ (backslash), gsub()/gensub()/sub() functions and: Gory Details.
+* '\' (backslash), continuing lines and: Statements/Lines. (line 19)
+* '\' (backslash), continuing lines and, comments and: Statements/Lines.
+ (line 75)
+* '\' (backslash), continuing lines and, in 'csh': Statements/Lines.
+ (line 43)
+* '\' (backslash), 'gsub()'/'gensub()'/'sub()' functions and: Gory Details.
(line 6)
-* \ (backslash), in bracket expressions: Bracket Expressions. (line 17)
-* \ (backslash), in escape sequences: Escape Sequences. (line 6)
-* \ (backslash), in escape sequences, POSIX and: Escape Sequences.
+* '\' (backslash), in bracket expressions: Bracket Expressions.
+ (line 17)
+* '\' (backslash), in escape sequences: Escape Sequences. (line 6)
+* '\' (backslash), in escape sequences <1>: Escape Sequences. (line 100)
+* '\' (backslash), in escape sequences, POSIX and: Escape Sequences.
(line 105)
-* \ (backslash), in regexp constants: Computed Regexps. (line 30)
-* \ (backslash), in shell commands: Quoting. (line 48)
-* \ (backslash), regexp operator: Regexp Operators. (line 18)
-* ^ (caret), ^ operator: Precedence. (line 49)
-* ^ (caret), ^= operator <1>: Precedence. (line 95)
-* ^ (caret), ^= operator: Assignment Ops. (line 130)
-* ^ (caret), in bracket expressions: Bracket Expressions. (line 17)
-* ^ (caret), in FS: Regexp Field Splitting.
+* '\' (backslash), in regexp constants: Computed Regexps. (line 30)
+* '\' (backslash), in shell commands: Quoting. (line 48)
+* '\' (backslash), regexp operator: Regexp Operators. (line 18)
+* '\' (backslash), '\"' escape sequence: Escape Sequences. (line 82)
+* '\' (backslash), '\'' operator ('gawk'): GNU Regexp Operators.
(line 59)
-* ^ (caret), regexp operator <1>: GNU Regexp Operators.
+* '\' (backslash), '\/' escape sequence: Escape Sequences. (line 73)
+* '\' (backslash), '\<' operator ('gawk'): GNU Regexp Operators.
+ (line 33)
+* '\' (backslash), '\>' operator ('gawk'): GNU Regexp Operators.
+ (line 37)
+* '\' (backslash), '\a' escape sequence: Escape Sequences. (line 34)
+* '\' (backslash), '\b' escape sequence: Escape Sequences. (line 38)
+* '\' (backslash), '\B' operator ('gawk'): GNU Regexp Operators.
+ (line 46)
+* '\' (backslash), '\f' escape sequence: Escape Sequences. (line 41)
+* '\' (backslash), '\n' escape sequence: Escape Sequences. (line 44)
+* '\' (backslash), '\'NNN escape sequence: Escape Sequences. (line 56)
+* '\' (backslash), '\r' escape sequence: Escape Sequences. (line 47)
+* '\' (backslash), '\s' operator ('gawk'): GNU Regexp Operators.
+ (line 13)
+* '\' (backslash), '\S' operator ('gawk'): GNU Regexp Operators.
+ (line 17)
+* '\' (backslash), '\t' escape sequence: Escape Sequences. (line 50)
+* '\' (backslash), '\v' escape sequence: Escape Sequences. (line 53)
+* '\' (backslash), '\w' operator ('gawk'): GNU Regexp Operators.
+ (line 22)
+* '\' (backslash), '\W' operator ('gawk'): GNU Regexp Operators.
+ (line 28)
+* '\' (backslash), '\x' escape sequence: Escape Sequences. (line 61)
+* '\' (backslash), '\y' operator ('gawk'): GNU Regexp Operators.
+ (line 41)
+* '\' (backslash), '\`' operator ('gawk'): GNU Regexp Operators.
+ (line 57)
+* '^' (caret), in bracket expressions: Bracket Expressions. (line 17)
+* '^' (caret), in 'FS': Regexp Field Splitting.
(line 59)
-* ^ (caret), regexp operator: Regexp Operators. (line 22)
-* _ (underscore), C macro: Explaining gettext. (line 71)
-* _ (underscore), in names of private variables: Library Names.
+* '^' (caret), regexp operator: Regexp Operators. (line 22)
+* '^' (caret), regexp operator <1>: GNU Regexp Operators.
+ (line 62)
+* '^' (caret), '^' operator: Precedence. (line 48)
+* '^' (caret), '^=' operator: Assignment Ops. (line 129)
+* '^' (caret), '^=' operator <1>: Precedence. (line 94)
+* '_' (underscore), C macro: Explaining gettext. (line 71)
+* '_' (underscore), in names of private variables: Library Names.
(line 29)
-* _ (underscore), translatable string: Programmer i18n. (line 69)
-* _gr_init() user-defined function: Group Functions. (line 83)
-* _ord_init() user-defined function: Ordinal Functions. (line 16)
-* _pw_init() user-defined function: Passwd Functions. (line 105)
+* '_' (underscore), translatable string: Programmer i18n. (line 69)
+* '_gr_init()' user-defined function: Group Functions. (line 83)
+* '_ord_init()' user-defined function: Ordinal Functions. (line 16)
+* '_pw_init()' user-defined function: Passwd Functions. (line 105)
+* '{}' (braces): Profiling. (line 142)
+* '{}' (braces), actions and: Action Overview. (line 19)
+* '{}' (braces), statements, grouping: Statements. (line 10)
+* '|' (vertical bar): Regexp Operators. (line 70)
+* '|' (vertical bar), '|' operator (I/O): Getline/Pipe. (line 10)
+* '|' (vertical bar), '|' operator (I/O) <1>: Redirection. (line 57)
+* '|' (vertical bar), '|' operator (I/O) <2>: Precedence. (line 64)
+* '|' (vertical bar), '|&' operator (I/O): Getline/Coprocess. (line 6)
+* '|' (vertical bar), '|&' operator (I/O) <1>: Redirection. (line 96)
+* '|' (vertical bar), '|&' operator (I/O) <2>: Precedence. (line 64)
+* '|' (vertical bar), '|&' operator (I/O) <3>: Two-way I/O. (line 27)
+* '|' (vertical bar), '|&' operator (I/O), pipes, closing: Close Files And
Pipes.
+ (line 120)
+* '|' (vertical bar), '||' operator: Boolean Ops. (line 59)
+* '|' (vertical bar), '||' operator <1>: Precedence. (line 88)
+* '~' (tilde), '~' operator: Regexp Usage. (line 19)
+* '~' (tilde), '~' operator <1>: Computed Regexps. (line 6)
+* '~' (tilde), '~' operator <2>: Case-sensitivity. (line 26)
+* '~' (tilde), '~' operator <3>: Regexp Constants. (line 6)
+* '~' (tilde), '~' operator <4>: Comparison Operators.
+ (line 11)
+* '~' (tilde), '~' operator <5>: Comparison Operators.
+ (line 98)
+* '~' (tilde), '~' operator <6>: Precedence. (line 79)
+* '~' (tilde), '~' operator <7>: Expression Patterns. (line 24)
* accessing fields: Fields. (line 6)
* accessing global variables from extensions: Symbol Table Access.
(line 6)
-* account information <1>: Group Functions. (line 6)
* account information: Passwd Functions. (line 16)
+* account information <1>: Group Functions. (line 6)
* actions: Action Overview. (line 6)
* actions, control statements in: Statements. (line 6)
* actions, default: Very Simple. (line 34)
* actions, empty: Very Simple. (line 39)
* Ada programming language: Glossary. (line 11)
-* adding, features to gawk: Adding Code. (line 6)
+* adding, features to 'gawk': Adding Code. (line 6)
* adding, fields: Changing Fields. (line 53)
* advanced features, fixed-width data: Constant Size. (line 6)
-* advanced features, gawk: Advanced Features. (line 6)
+* advanced features, 'gawk': Advanced Features. (line 6)
* advanced features, network programming: TCP/IP Networking. (line 6)
* advanced features, nondecimal input data: Nondecimal Data. (line 6)
* advanced features, processes, communicating with: Two-way I/O.
(line 6)
* advanced features, specifying field content: Splitting By Content.
(line 9)
-* Aho, Alfred <1>: Contributors. (line 11)
* Aho, Alfred: History. (line 17)
+* Aho, Alfred <1>: Contributors. (line 12)
* alarm clock example program: Alarm Program. (line 11)
-* alarm.awk program: Alarm Program. (line 31)
-* algorithms: Basic High Level. (line 68)
+* 'alarm.awk' program: Alarm Program. (line 31)
+* algorithms: Basic High Level. (line 57)
* allocating memory for extensions: Memory Allocation Functions.
(line 6)
-* amazing awk assembler (aaa): Glossary. (line 16)
-* amazingly workable formatter (awf): Glossary. (line 24)
-* ambiguity, syntactic: /= operator vs. /=.../ regexp constant: Assignment Ops.
- (line 148)
-* ampersand (&), && operator <1>: Precedence. (line 86)
-* ampersand (&), && operator: Boolean Ops. (line 59)
-* ampersand (&), gsub()/gensub()/sub() functions and: Gory Details.
+* amazing 'awk' assembler ('aaa'): Glossary. (line 16)
+* amazingly workable formatter ('awf'): Glossary. (line 24)
+* ambiguity, syntactic: '/=' operator vs. '/=.../' regexp constant: Assignment
Ops.
+ (line 149)
+* ampersand ('&'), '&&' operator: Boolean Ops. (line 59)
+* ampersand ('&'), '&&' operator <1>: Precedence. (line 85)
+* ampersand ('&'), 'gsub()'/'gensub()'/'sub()' functions and: Gory Details.
(line 6)
-* anagram.awk program: Anagram Program. (line 21)
+* 'anagram.awk' program: Anagram Program. (line 21)
* anagrams, finding: Anagram Program. (line 6)
-* and: Bitwise Functions. (line 40)
+* 'and': Bitwise Functions. (line 40)
* AND bitwise operation: Bitwise Functions. (line 6)
* and Boolean-logic operator: Boolean Ops. (line 6)
* ANSI: Glossary. (line 34)
@@ -31785,46 +31700,47 @@ Index
* arbitrary precision integers: Arbitrary Precision Integers.
(line 6)
* archaeologists: Bugs. (line 6)
-* arctangent: Numeric Functions. (line 11)
-* ARGC/ARGV variables: Auto-set. (line 15)
-* ARGC/ARGV variables, command-line arguments: Other Arguments.
+* arctangent: Numeric Functions. (line 10)
+* 'ARGC'/'ARGV' variables: Auto-set. (line 15)
+* 'ARGC'/'ARGV' variables, command-line arguments: Other Arguments.
(line 15)
-* ARGC/ARGV variables, how to use: ARGC and ARGV. (line 6)
-* ARGC/ARGV variables, portability and: Executable Scripts. (line 59)
-* ARGIND variable: Auto-set. (line 44)
-* ARGIND variable, command-line arguments: Other Arguments. (line 15)
-* arguments, command-line <1>: ARGC and ARGV. (line 6)
-* arguments, command-line <2>: Auto-set. (line 15)
+* 'ARGC'/'ARGV' variables, how to use: ARGC and ARGV. (line 6)
+* 'ARGC'/'ARGV' variables, portability and: Executable Scripts.
+ (line 59)
+* 'ARGIND' variable: Auto-set. (line 44)
+* 'ARGIND' variable, command-line arguments: Other Arguments. (line 15)
* arguments, command-line: Other Arguments. (line 6)
-* arguments, command-line, invoking awk: Command Line. (line 6)
+* arguments, command-line <1>: Auto-set. (line 15)
+* arguments, command-line <2>: ARGC and ARGV. (line 6)
+* arguments, command-line, invoking 'awk': Command Line. (line 6)
* arguments, in function calls: Function Calls. (line 18)
* arguments, processing: Getopt Function. (line 6)
-* ARGV array, indexing into: Other Arguments. (line 15)
+* 'ARGV' array, indexing into: Other Arguments. (line 15)
* arithmetic operators: Arithmetic Ops. (line 6)
* array manipulation in extensions: Array Manipulation. (line 6)
* array members: Reference to Elements.
(line 6)
* array scanning order, controlling: Controlling Scanning.
(line 14)
-* array, number of elements: String Functions. (line 201)
+* array, number of elements: String Functions. (line 200)
* arrays: Arrays. (line 6)
* arrays of arrays: Arrays of Arrays. (line 6)
* arrays, an example of using: Array Example. (line 6)
-* arrays, and IGNORECASE variable: Array Intro. (line 100)
+* arrays, and 'IGNORECASE' variable: Array Intro. (line 100)
* arrays, as parameters to functions: Pass By Value/Reference.
(line 44)
-* arrays, associative: Array Intro. (line 50)
+* arrays, associative: Array Intro. (line 48)
* arrays, associative, library functions and: Library Names. (line 58)
* arrays, deleting entire contents: Delete. (line 39)
* arrays, elements that don't exist: Reference to Elements.
(line 23)
* arrays, elements, assigning values: Assigning Elements. (line 6)
* arrays, elements, deleting: Delete. (line 6)
-* arrays, elements, order of access by in operator: Scanning an Array.
+* arrays, elements, order of access by 'in' operator: Scanning an Array.
(line 48)
* arrays, elements, retrieving number of: String Functions. (line 42)
-* arrays, for statement and: Scanning an Array. (line 20)
-* arrays, indexing: Array Intro. (line 50)
+* arrays, 'for' statement and: Scanning an Array. (line 20)
+* arrays, indexing: Array Intro. (line 48)
* arrays, merging into strings: Join Function. (line 6)
* arrays, multidimensional: Multidimensional. (line 10)
* arrays, multidimensional, scanning: Multiscanning. (line 11)
@@ -31835,205 +31751,215 @@ Index
* arrays, scanning: Scanning an Array. (line 6)
* arrays, sorting: Array Sorting Functions.
(line 6)
-* arrays, sorting, and IGNORECASE variable: Array Sorting Functions.
+* arrays, sorting, and 'IGNORECASE' variable: Array Sorting Functions.
(line 83)
* arrays, sparse: Array Intro. (line 76)
* arrays, subscripts, uninitialized variables as: Uninitialized Subscripts.
(line 6)
* arrays, unassigned elements: Reference to Elements.
(line 18)
-* artificial intelligence, gawk and: Distribution contents.
+* artificial intelligence, 'gawk' and: Distribution contents.
(line 52)
-* ASCII <1>: Glossary. (line 197)
* ASCII: Ordinal Functions. (line 45)
-* asort <1>: Array Sorting Functions.
+* ASCII <1>: Glossary. (line 196)
+* 'asort': String Functions. (line 42)
+* 'asort' <1>: Array Sorting Functions.
(line 6)
-* asort: String Functions. (line 42)
-* asort() function (gawk), arrays, sorting: Array Sorting Functions.
+* 'asort()' function ('gawk'), arrays, sorting: Array Sorting Functions.
(line 6)
-* asorti <1>: Array Sorting Functions.
+* 'asorti': String Functions. (line 42)
+* 'asorti' <1>: Array Sorting Functions.
(line 6)
-* asorti: String Functions. (line 42)
-* asorti() function (gawk), arrays, sorting: Array Sorting Functions.
+* 'asorti()' function ('gawk'), arrays, sorting: Array Sorting Functions.
(line 6)
-* assert() function (C library): Assert Function. (line 6)
-* assert() user-defined function: Assert Function. (line 28)
+* 'assert()' function (C library): Assert Function. (line 6)
+* 'assert()' user-defined function: Assert Function. (line 28)
* assertions: Assert Function. (line 6)
* assign values to variables, in debugger: Viewing And Changing Data.
- (line 59)
+ (line 58)
* assignment operators: Assignment Ops. (line 6)
-* assignment operators, evaluation order: Assignment Ops. (line 111)
-* assignment operators, lvalues/rvalues: Assignment Ops. (line 32)
+* assignment operators, evaluation order: Assignment Ops. (line 110)
+* assignment operators, lvalues/rvalues: Assignment Ops. (line 31)
* assignments as filenames: Ignoring Assigns. (line 6)
-* associative arrays: Array Intro. (line 50)
-* asterisk (*), * operator, as multiplication operator: Precedence.
- (line 55)
-* asterisk (*), * operator, as regexp operator: Regexp Operators.
+* associative arrays: Array Intro. (line 48)
+* asterisk ('*'), '*' operator, as multiplication operator: Precedence.
+ (line 54)
+* asterisk ('*'), '*' operator, as regexp operator: Regexp Operators.
(line 89)
-* asterisk (*), * operator, null strings, matching: String Functions.
+* asterisk ('*'), '*' operator, null strings, matching: String Functions.
(line 537)
-* asterisk (*), ** operator <1>: Precedence. (line 49)
-* asterisk (*), ** operator: Arithmetic Ops. (line 81)
-* asterisk (*), **= operator <1>: Precedence. (line 95)
-* asterisk (*), **= operator: Assignment Ops. (line 130)
-* asterisk (*), *= operator <1>: Precedence. (line 95)
-* asterisk (*), *= operator: Assignment Ops. (line 130)
-* atan2: Numeric Functions. (line 11)
+* asterisk ('*'), '**' operator: Arithmetic Ops. (line 81)
+* asterisk ('*'), '**' operator <1>: Precedence. (line 48)
+* asterisk ('*'), '**=' operator: Assignment Ops. (line 129)
+* asterisk ('*'), '**=' operator <1>: Precedence. (line 94)
+* asterisk ('*'), '*=' operator: Assignment Ops. (line 129)
+* asterisk ('*'), '*=' operator <1>: Precedence. (line 94)
+* 'atan2': Numeric Functions. (line 10)
* automatic displays, in debugger: Debugger Info. (line 24)
-* awf (amazingly workable formatter) program: Glossary. (line 24)
-* awk debugging, enabling: Options. (line 108)
-* awk language, POSIX version: Assignment Ops. (line 137)
-* awk profiling, enabling: Options. (line 244)
-* awk programs <1>: Two Rules. (line 6)
-* awk programs <2>: Executable Scripts. (line 6)
-* awk programs: Getting Started. (line 12)
-* awk programs, complex: When. (line 27)
-* awk programs, documenting <1>: Library Names. (line 6)
-* awk programs, documenting: Comments. (line 6)
-* awk programs, examples of: Sample Programs. (line 6)
-* awk programs, execution of: Next Statement. (line 16)
-* awk programs, internationalizing <1>: Programmer i18n. (line 6)
-* awk programs, internationalizing: I18N Functions. (line 6)
-* awk programs, lengthy: Long. (line 6)
-* awk programs, lengthy, assertions: Assert Function. (line 6)
-* awk programs, location of: Options. (line 25)
-* awk programs, one-line examples: Very Simple. (line 45)
-* awk programs, profiling: Profiling. (line 6)
-* awk programs, running <1>: Long. (line 6)
-* awk programs, running: Running gawk. (line 6)
-* awk programs, running, from shell scripts: One-shot. (line 22)
-* awk programs, running, without input files: Read Terminal. (line 17)
-* awk programs, shell variables in: Using Shell Variables.
+* 'awf' (amazingly workable formatter) program: Glossary. (line 24)
+* 'awk' debugging, enabling: Options. (line 108)
+* 'awk' language, POSIX version: Assignment Ops. (line 138)
+* 'awk' profiling, enabling: Options. (line 242)
+* 'awk' programs: Getting Started. (line 12)
+* 'awk' programs <1>: Executable Scripts. (line 6)
+* 'awk' programs <2>: Two Rules. (line 6)
+* 'awk' programs, complex: When. (line 27)
+* 'awk' programs, documenting: Comments. (line 6)
+* 'awk' programs, documenting <1>: Library Names. (line 6)
+* 'awk' programs, examples of: Sample Programs. (line 6)
+* 'awk' programs, execution of: Next Statement. (line 16)
+* 'awk' programs, internationalizing: I18N Functions. (line 6)
+* 'awk' programs, internationalizing <1>: Programmer i18n. (line 6)
+* 'awk' programs, lengthy: Long. (line 6)
+* 'awk' programs, lengthy, assertions: Assert Function. (line 6)
+* 'awk' programs, location of: Options. (line 25)
+* 'awk' programs, location of <1>: Options. (line 125)
+* 'awk' programs, location of <2>: Options. (line 159)
+* 'awk' programs, one-line examples: Very Simple. (line 45)
+* 'awk' programs, profiling: Profiling. (line 6)
+* 'awk' programs, running: Running gawk. (line 6)
+* 'awk' programs, running <1>: Long. (line 6)
+* 'awk' programs, running, from shell scripts: One-shot. (line 22)
+* 'awk' programs, running, without input files: Read Terminal.
+ (line 17)
+* 'awk' programs, shell variables in: Using Shell Variables.
(line 6)
-* awk, function of: Getting Started. (line 6)
-* awk, gawk and <1>: This Manual. (line 14)
-* awk, gawk and: Preface. (line 21)
-* awk, history of: History. (line 17)
-* awk, implementation issues, pipes: Redirection. (line 129)
-* awk, implementations: Other Versions. (line 6)
-* awk, implementations, limits: Getline Notes. (line 14)
-* awk, invoking: Command Line. (line 6)
-* awk, new vs. old: Names. (line 6)
-* awk, new vs. old, OFMT variable: Strings And Numbers. (line 57)
-* awk, POSIX and: Preface. (line 21)
-* awk, POSIX and, See Also POSIX awk: Preface. (line 21)
-* awk, regexp constants and: Comparison Operators.
+* 'awk', function of: Getting Started. (line 6)
+* 'awk', 'gawk' and: Preface. (line 21)
+* 'awk', 'gawk' and <1>: This Manual. (line 14)
+* 'awk', history of: History. (line 17)
+* 'awk', implementation issues, pipes: Redirection. (line 129)
+* 'awk', implementations: Other Versions. (line 6)
+* 'awk', implementations, limits: Getline Notes. (line 14)
+* 'awk', invoking: Command Line. (line 6)
+* 'awk', new vs. old: Names. (line 6)
+* 'awk', new vs. old, 'OFMT' variable: Strings And Numbers. (line 56)
+* 'awk', POSIX and: Preface. (line 21)
+* 'awk', POSIX and, See Also POSIX 'awk': Preface. (line 21)
+* 'awk', regexp constants and: Comparison Operators.
(line 103)
-* awk, See Also gawk: Preface. (line 34)
-* awk, terms describing: This Manual. (line 6)
-* awk, uses for <1>: When. (line 6)
-* awk, uses for <2>: Getting Started. (line 12)
-* awk, uses for: Preface. (line 21)
-* awk, versions of: V7/SVR3.1. (line 6)
-* awk, versions of, changes between SVR3.1 and SVR4: SVR4. (line 6)
-* awk, versions of, changes between SVR4 and POSIX awk: POSIX.
+* 'awk', See Also 'gawk': Preface. (line 34)
+* 'awk', terms describing: This Manual. (line 6)
+* 'awk', uses for: Preface. (line 21)
+* 'awk', uses for <1>: Getting Started. (line 12)
+* 'awk', uses for <2>: When. (line 6)
+* 'awk', versions of: V7/SVR3.1. (line 6)
+* 'awk', versions of, changes between SVR3.1 and SVR4: SVR4. (line 6)
+* 'awk', versions of, changes between SVR4 and POSIX 'awk': POSIX.
(line 6)
-* awk, versions of, changes between V7 and SVR3.1: V7/SVR3.1. (line 6)
-* awk, versions of, See Also Brian Kernighan's awk <1>: Other Versions.
- (line 13)
-* awk, versions of, See Also Brian Kernighan's awk: BTL. (line 6)
-* awka compiler for awk: Other Versions. (line 68)
-* AWKLIBPATH environment variable: AWKLIBPATH Variable. (line 6)
-* AWKPATH environment variable <1>: PC Using. (line 10)
-* AWKPATH environment variable: AWKPATH Variable. (line 6)
-* awkprof.out file: Profiling. (line 6)
-* awksed.awk program: Simple Sed. (line 25)
-* awkvars.out file: Options. (line 93)
-* b debugger command (alias for break): Breakpoint Control. (line 11)
-* backslash (\): Comments. (line 50)
-* backslash (\), \" escape sequence: Escape Sequences. (line 82)
-* backslash (\), \' operator (gawk): GNU Regexp Operators.
- (line 56)
-* backslash (\), \/ escape sequence: Escape Sequences. (line 73)
-* backslash (\), \< operator (gawk): GNU Regexp Operators.
- (line 30)
-* backslash (\), \> operator (gawk): GNU Regexp Operators.
- (line 34)
-* backslash (\), \` operator (gawk): GNU Regexp Operators.
- (line 54)
-* backslash (\), \a escape sequence: Escape Sequences. (line 34)
-* backslash (\), \b escape sequence: Escape Sequences. (line 38)
-* backslash (\), \B operator (gawk): GNU Regexp Operators.
- (line 43)
-* backslash (\), \f escape sequence: Escape Sequences. (line 41)
-* backslash (\), \n escape sequence: Escape Sequences. (line 44)
-* backslash (\), \NNN escape sequence: Escape Sequences. (line 56)
-* backslash (\), \r escape sequence: Escape Sequences. (line 47)
-* backslash (\), \S operator (gawk): GNU Regexp Operators.
- (line 17)
-* backslash (\), \s operator (gawk): GNU Regexp Operators.
+* 'awk', versions of, changes between V7 and SVR3.1: V7/SVR3.1.
+ (line 6)
+* 'awk', versions of, See Also Brian Kernighan's 'awk': BTL. (line 6)
+* 'awk', versions of, See Also Brian Kernighan's 'awk' <1>: Other Versions.
(line 13)
-* backslash (\), \t escape sequence: Escape Sequences. (line 50)
-* backslash (\), \v escape sequence: Escape Sequences. (line 53)
-* backslash (\), \W operator (gawk): GNU Regexp Operators.
- (line 26)
-* backslash (\), \w operator (gawk): GNU Regexp Operators.
- (line 21)
-* backslash (\), \x escape sequence: Escape Sequences. (line 61)
-* backslash (\), \y operator (gawk): GNU Regexp Operators.
- (line 38)
-* backslash (\), as field separator: Command Line Field Separator.
+* 'awka' compiler for 'awk': Other Versions. (line 68)
+* 'AWKLIBPATH' environment variable: AWKLIBPATH Variable. (line 6)
+* 'AWKPATH' environment variable: AWKPATH Variable. (line 6)
+* 'AWKPATH' environment variable <1>: PC Using. (line 10)
+* 'awkprof.out' file: Profiling. (line 6)
+* 'awksed.awk' program: Simple Sed. (line 25)
+* 'awkvars.out' file: Options. (line 94)
+* 'b' debugger command (alias for 'break'): Breakpoint Control.
+ (line 11)
+* backslash ('\'): Comments. (line 50)
+* backslash ('\'), as field separator: Command Line Field Separator.
(line 24)
-* backslash (\), continuing lines and: Statements/Lines. (line 19)
-* backslash (\), continuing lines and, comments and: Statements/Lines.
- (line 76)
-* backslash (\), continuing lines and, in csh: Statements/Lines.
- (line 44)
-* backslash (\), gsub()/gensub()/sub() functions and: Gory Details.
+* backslash ('\'), continuing lines and: Statements/Lines. (line 19)
+* backslash ('\'), continuing lines and, comments and: Statements/Lines.
+ (line 75)
+* backslash ('\'), continuing lines and, in 'csh': Statements/Lines.
+ (line 43)
+* backslash ('\'), 'gsub()'/'gensub()'/'sub()' functions and: Gory Details.
(line 6)
-* backslash (\), in bracket expressions: Bracket Expressions. (line 17)
-* backslash (\), in escape sequences: Escape Sequences. (line 6)
-* backslash (\), in escape sequences, POSIX and: Escape Sequences.
+* backslash ('\'), in bracket expressions: Bracket Expressions.
+ (line 17)
+* backslash ('\'), in escape sequences: Escape Sequences. (line 6)
+* backslash ('\'), in escape sequences <1>: Escape Sequences. (line 100)
+* backslash ('\'), in escape sequences, POSIX and: Escape Sequences.
(line 105)
-* backslash (\), in regexp constants: Computed Regexps. (line 30)
-* backslash (\), in shell commands: Quoting. (line 48)
-* backslash (\), regexp operator: Regexp Operators. (line 18)
-* backtrace debugger command: Execution Stack. (line 13)
-* Beebe, Nelson H.F. <1>: Other Versions. (line 82)
+* backslash ('\'), in regexp constants: Computed Regexps. (line 30)
+* backslash ('\'), in shell commands: Quoting. (line 48)
+* backslash ('\'), regexp operator: Regexp Operators. (line 18)
+* backslash ('\'), '\"' escape sequence: Escape Sequences. (line 82)
+* backslash ('\'), '\'' operator ('gawk'): GNU Regexp Operators.
+ (line 59)
+* backslash ('\'), '\/' escape sequence: Escape Sequences. (line 73)
+* backslash ('\'), '\<' operator ('gawk'): GNU Regexp Operators.
+ (line 33)
+* backslash ('\'), '\>' operator ('gawk'): GNU Regexp Operators.
+ (line 37)
+* backslash ('\'), '\a' escape sequence: Escape Sequences. (line 34)
+* backslash ('\'), '\b' escape sequence: Escape Sequences. (line 38)
+* backslash ('\'), '\B' operator ('gawk'): GNU Regexp Operators.
+ (line 46)
+* backslash ('\'), '\f' escape sequence: Escape Sequences. (line 41)
+* backslash ('\'), '\n' escape sequence: Escape Sequences. (line 44)
+* backslash ('\'), '\'NNN escape sequence: Escape Sequences. (line 56)
+* backslash ('\'), '\r' escape sequence: Escape Sequences. (line 47)
+* backslash ('\'), '\s' operator ('gawk'): GNU Regexp Operators.
+ (line 13)
+* backslash ('\'), '\S' operator ('gawk'): GNU Regexp Operators.
+ (line 17)
+* backslash ('\'), '\t' escape sequence: Escape Sequences. (line 50)
+* backslash ('\'), '\v' escape sequence: Escape Sequences. (line 53)
+* backslash ('\'), '\w' operator ('gawk'): GNU Regexp Operators.
+ (line 22)
+* backslash ('\'), '\W' operator ('gawk'): GNU Regexp Operators.
+ (line 28)
+* backslash ('\'), '\x' escape sequence: Escape Sequences. (line 61)
+* backslash ('\'), '\y' operator ('gawk'): GNU Regexp Operators.
+ (line 41)
+* backslash ('\'), '\`' operator ('gawk'): GNU Regexp Operators.
+ (line 57)
+* 'backtrace' debugger command: Execution Stack. (line 13)
* Beebe, Nelson H.F.: Acknowledgments. (line 60)
-* BEGIN pattern <1>: Using BEGIN/END. (line 6)
-* BEGIN pattern <2>: BEGIN/END. (line 6)
-* BEGIN pattern: Field Separators. (line 45)
-* BEGIN pattern, and profiling: Profiling. (line 62)
-* BEGIN pattern, assert() user-defined function and: Assert Function.
+* Beebe, Nelson H.F. <1>: Other Versions. (line 82)
+* 'BEGIN' pattern: Field Separators. (line 44)
+* 'BEGIN' pattern <1>: BEGIN/END. (line 6)
+* 'BEGIN' pattern <2>: Using BEGIN/END. (line 6)
+* 'BEGIN' pattern, and profiling: Profiling. (line 62)
+* 'BEGIN' pattern, 'assert()' user-defined function and: Assert Function.
(line 83)
-* BEGIN pattern, Boolean patterns and: Expression Patterns. (line 70)
-* BEGIN pattern, exit statement and: Exit Statement. (line 12)
-* BEGIN pattern, getline and: Getline Notes. (line 19)
-* BEGIN pattern, headings, adding: Print Examples. (line 43)
-* BEGIN pattern, next/nextfile statements and <1>: Next Statement.
+* 'BEGIN' pattern, Boolean patterns and: Expression Patterns. (line 70)
+* 'BEGIN' pattern, 'exit' statement and: Exit Statement. (line 12)
+* 'BEGIN' pattern, 'getline' and: Getline Notes. (line 19)
+* 'BEGIN' pattern, headings, adding: Print Examples. (line 42)
+* 'BEGIN' pattern, 'next'/'nextfile' statements and: I/O And BEGIN/END.
+ (line 36)
+* 'BEGIN' pattern, 'next'/'nextfile' statements and <1>: Next Statement.
(line 44)
-* BEGIN pattern, next/nextfile statements and: I/O And BEGIN/END.
- (line 37)
-* BEGIN pattern, OFS/ORS variables, assigning values to: Output Separators.
- (line 21)
-* BEGIN pattern, operators and: Using BEGIN/END. (line 17)
-* BEGIN pattern, print statement and: I/O And BEGIN/END. (line 16)
-* BEGIN pattern, pwcat program: Passwd Functions. (line 143)
-* BEGIN pattern, running awk programs and: Cut Program. (line 63)
-* BEGIN pattern, TEXTDOMAIN variable and: Programmer i18n. (line 60)
-* BEGINFILE pattern: BEGINFILE/ENDFILE. (line 6)
-* BEGINFILE pattern, Boolean patterns and: Expression Patterns.
+* 'BEGIN' pattern, 'OFS'/'ORS' variables, assigning values to: Output
Separators.
+ (line 20)
+* 'BEGIN' pattern, operators and: Using BEGIN/END. (line 17)
+* 'BEGIN' pattern, 'print' statement and: I/O And BEGIN/END. (line 15)
+* 'BEGIN' pattern, 'pwcat' program: Passwd Functions. (line 143)
+* 'BEGIN' pattern, running 'awk' programs and: Cut Program. (line 63)
+* 'BEGIN' pattern, 'TEXTDOMAIN' variable and: Programmer i18n.
+ (line 60)
+* 'BEGINFILE' pattern: BEGINFILE/ENDFILE. (line 6)
+* 'BEGINFILE' pattern, Boolean patterns and: Expression Patterns.
(line 70)
-* beginfile() user-defined function: Filetrans Function. (line 62)
-* Bentley, Jon: Glossary. (line 207)
-* Benzinger, Michael: Contributors. (line 97)
-* Berry, Karl <1>: Ranges and Locales. (line 74)
+* 'beginfile()' user-defined function: Filetrans Function. (line 62)
+* Bentley, Jon: Glossary. (line 206)
+* Benzinger, Michael: Contributors. (line 98)
* Berry, Karl: Acknowledgments. (line 33)
+* Berry, Karl <1>: Acknowledgments. (line 74)
+* Berry, Karl <2>: Ranges and Locales. (line 74)
* binary input/output: User-modified. (line 15)
-* bindtextdomain <1>: Programmer i18n. (line 48)
-* bindtextdomain: I18N Functions. (line 12)
-* bindtextdomain() function (C library): Explaining gettext. (line 50)
-* bindtextdomain() function (gawk), portability and: I18N Portability.
+* 'bindtextdomain': I18N Functions. (line 11)
+* 'bindtextdomain' <1>: Programmer i18n. (line 48)
+* 'bindtextdomain()' function (C library): Explaining gettext.
+ (line 50)
+* 'bindtextdomain()' function ('gawk'), portability and: I18N Portability.
(line 33)
-* BINMODE variable <1>: PC Using. (line 33)
-* BINMODE variable: User-modified. (line 15)
+* 'BINMODE' variable: User-modified. (line 15)
+* 'BINMODE' variable <1>: PC Using. (line 33)
* bit-manipulation functions: Bitwise Functions. (line 6)
-* bits2str() user-defined function: Bitwise Functions. (line 71)
+* 'bits2str()' user-defined function: Bitwise Functions. (line 72)
* bitwise AND: Bitwise Functions. (line 40)
* bitwise complement: Bitwise Functions. (line 44)
* bitwise OR: Bitwise Functions. (line 50)
-* bitwise XOR: Bitwise Functions. (line 56)
+* bitwise XOR: Bitwise Functions. (line 57)
* bitwise, complement: Bitwise Functions. (line 25)
* bitwise, operations: Bitwise Functions. (line 6)
* bitwise, shift: Bitwise Functions. (line 32)
@@ -32043,25 +31969,25 @@ Index
* Boolean expressions, as patterns: Expression Patterns. (line 39)
* Boolean operators, See Boolean expressions: Boolean Ops. (line 6)
* Bourne shell, quoting rules for: Quoting. (line 18)
-* braces ({}): Profiling. (line 142)
-* braces ({}), actions and: Action Overview. (line 19)
-* braces ({}), statements, grouping: Statements. (line 10)
-* bracket expressions <1>: Bracket Expressions. (line 6)
+* braces ('{}'): Profiling. (line 142)
+* braces ('{}'), actions and: Action Overview. (line 19)
+* braces ('{}'), statements, grouping: Statements. (line 10)
* bracket expressions: Regexp Operators. (line 56)
+* bracket expressions <1>: Bracket Expressions. (line 6)
* bracket expressions, character classes: Bracket Expressions.
(line 32)
* bracket expressions, collating elements: Bracket Expressions.
- (line 79)
+ (line 78)
* bracket expressions, collating symbols: Bracket Expressions.
- (line 86)
+ (line 85)
* bracket expressions, complemented: Regexp Operators. (line 64)
* bracket expressions, equivalence classes: Bracket Expressions.
- (line 92)
-* bracket expressions, non-ASCII: Bracket Expressions. (line 79)
+ (line 91)
+* bracket expressions, non-ASCII: Bracket Expressions. (line 78)
* bracket expressions, range expressions: Bracket Expressions.
(line 6)
-* break debugger command: Breakpoint Control. (line 11)
-* break statement: Break Statement. (line 6)
+* 'break' debugger command: Breakpoint Control. (line 11)
+* 'break' statement: Break Statement. (line 6)
* breakpoint: Debugging Terms. (line 33)
* breakpoint at location, how to delete: Breakpoint Control. (line 36)
* breakpoint commands: Debugger Execution Control.
@@ -32070,47 +31996,50 @@ Index
* breakpoint, delete by number: Breakpoint Control. (line 64)
* breakpoint, how to disable or enable: Breakpoint Control. (line 69)
* breakpoint, setting: Breakpoint Control. (line 11)
-* Brennan, Michael <1>: Other Versions. (line 6)
-* Brennan, Michael <2>: Simple Sed. (line 25)
-* Brennan, Michael <3>: Delete. (line 56)
-* Brennan, Michael <4>: Acknowledgments. (line 78)
-* Brennan, Michael <5>: Foreword4. (line 33)
* Brennan, Michael: Foreword3. (line 84)
-* Brian Kernighan's awk <1>: I/O Functions. (line 43)
-* Brian Kernighan's awk <2>: Gory Details. (line 19)
-* Brian Kernighan's awk <3>: String Functions. (line 493)
-* Brian Kernighan's awk <4>: Delete. (line 51)
-* Brian Kernighan's awk <5>: Nextfile Statement. (line 47)
-* Brian Kernighan's awk <6>: Continue Statement. (line 44)
-* Brian Kernighan's awk <7>: Break Statement. (line 51)
-* Brian Kernighan's awk <8>: I/O And BEGIN/END. (line 16)
-* Brian Kernighan's awk <9>: Concatenation. (line 36)
-* Brian Kernighan's awk <10>: Getline/Pipe. (line 62)
-* Brian Kernighan's awk <11>: Regexp Field Splitting.
+* Brennan, Michael <1>: Foreword4. (line 33)
+* Brennan, Michael <2>: Acknowledgments. (line 78)
+* Brennan, Michael <3>: Delete. (line 56)
+* Brennan, Michael <4>: Simple Sed. (line 25)
+* Brennan, Michael <5>: Other Versions. (line 6)
+* Brennan, Michael <6>: Other Versions. (line 48)
+* Brian Kernighan's 'awk': When. (line 21)
+* Brian Kernighan's 'awk' <1>: Escape Sequences. (line 109)
+* Brian Kernighan's 'awk' <2>: GNU Regexp Operators.
+ (line 85)
+* Brian Kernighan's 'awk' <3>: Regexp Field Splitting.
(line 67)
-* Brian Kernighan's awk <12>: GNU Regexp Operators.
- (line 82)
-* Brian Kernighan's awk <13>: Escape Sequences. (line 109)
-* Brian Kernighan's awk: When. (line 21)
-* Brian Kernighan's awk, extensions: BTL. (line 6)
-* Brian Kernighan's awk, source code: Other Versions. (line 13)
+* Brian Kernighan's 'awk' <4>: Getline/Pipe. (line 62)
+* Brian Kernighan's 'awk' <5>: Concatenation. (line 36)
+* Brian Kernighan's 'awk' <6>: I/O And BEGIN/END. (line 15)
+* Brian Kernighan's 'awk' <7>: Break Statement. (line 51)
+* Brian Kernighan's 'awk' <8>: Continue Statement. (line 44)
+* Brian Kernighan's 'awk' <9>: Nextfile Statement. (line 47)
+* Brian Kernighan's 'awk' <10>: Delete. (line 51)
+* Brian Kernighan's 'awk' <11>: String Functions. (line 493)
+* Brian Kernighan's 'awk' <12>: Gory Details. (line 19)
+* Brian Kernighan's 'awk' <13>: I/O Functions. (line 43)
+* Brian Kernighan's 'awk', extensions: BTL. (line 6)
+* Brian Kernighan's 'awk', source code: Other Versions. (line 13)
* Brini, Davide: Signature Program. (line 6)
* Brink, Jeroen: DOS Quoting. (line 10)
-* Broder, Alan J.: Contributors. (line 88)
-* Brown, Martin: Contributors. (line 82)
-* BSD-based operating systems: Glossary. (line 753)
-* bt debugger command (alias for backtrace): Execution Stack. (line 13)
-* Buening, Andreas <1>: Bugs. (line 71)
-* Buening, Andreas <2>: Contributors. (line 92)
+* Broder, Alan J.: Contributors. (line 89)
+* Brown, Martin: Contributors. (line 83)
+* BSD-based operating systems: Glossary. (line 748)
+* 'bt' debugger command (alias for 'backtrace'): Execution Stack.
+ (line 13)
* Buening, Andreas: Acknowledgments. (line 60)
-* buffering, input/output <1>: Two-way I/O. (line 52)
-* buffering, input/output: I/O Functions. (line 141)
+* Buening, Andreas <1>: Contributors. (line 93)
+* Buening, Andreas <2>: Bugs. (line 73)
+* buffering, input/output: I/O Functions. (line 139)
+* buffering, input/output <1>: Two-way I/O. (line 53)
* buffering, interactive vs. noninteractive: I/O Functions. (line 76)
* buffers, flushing: I/O Functions. (line 32)
+* buffers, flushing <1>: I/O Functions. (line 139)
* buffers, operators for: GNU Regexp Operators.
- (line 48)
-* bug reports, email address, address@hidden: Bugs. (line 30)
-* address@hidden bug reporting address: Bugs. (line 30)
+ (line 51)
+* bug reports, email address, 'address@hidden': Bugs. (line 30)
+* 'address@hidden' bug reporting address: Bugs. (line 30)
* built-in functions: Functions. (line 6)
* built-in functions, evaluation order: Calling Built-in. (line 30)
* BusyBox Awk: Other Versions. (line 92)
@@ -32120,135 +32049,136 @@ Index
* call by value: Pass By Value/Reference.
(line 15)
* call stack, display in debugger: Execution Stack. (line 13)
-* caret (^), ^ operator: Precedence. (line 49)
-* caret (^), ^= operator <1>: Precedence. (line 95)
-* caret (^), ^= operator: Assignment Ops. (line 130)
-* caret (^), in bracket expressions: Bracket Expressions. (line 17)
-* caret (^), regexp operator <1>: GNU Regexp Operators.
- (line 59)
-* caret (^), regexp operator: Regexp Operators. (line 22)
-* case keyword: Switch Statement. (line 6)
+* caret ('^'), in bracket expressions: Bracket Expressions. (line 17)
+* caret ('^'), regexp operator: Regexp Operators. (line 22)
+* caret ('^'), regexp operator <1>: GNU Regexp Operators.
+ (line 62)
+* caret ('^'), '^' operator: Precedence. (line 48)
+* caret ('^'), '^=' operator: Assignment Ops. (line 129)
+* caret ('^'), '^=' operator <1>: Precedence. (line 94)
+* 'case' keyword: Switch Statement. (line 6)
* case sensitivity, and regexps: User-modified. (line 76)
* case sensitivity, and string comparisons: User-modified. (line 76)
* case sensitivity, array indices and: Array Intro. (line 100)
* case sensitivity, converting case: String Functions. (line 523)
* case sensitivity, example programs: Library Functions. (line 53)
-* case sensitivity, gawk: Case-sensitivity. (line 26)
+* case sensitivity, 'gawk': Case-sensitivity. (line 26)
* case sensitivity, regexps and: Case-sensitivity. (line 6)
-* CGI, awk scripts for: Options. (line 125)
+* CGI, 'awk' scripts for: Options. (line 125)
* character classes, See bracket expressions: Regexp Operators.
(line 56)
* character lists in regular expression: Bracket Expressions. (line 6)
* character lists, See bracket expressions: Regexp Operators. (line 56)
-* character sets (machine character encodings) <1>: Glossary. (line 197)
* character sets (machine character encodings): Ordinal Functions.
(line 45)
+* character sets (machine character encodings) <1>: Glossary. (line 196)
* character sets, See Also bracket expressions: Regexp Operators.
(line 56)
* characters, counting: Wc Program. (line 6)
* characters, transliterating: Translate Program. (line 6)
* characters, values of as numbers: Ordinal Functions. (line 6)
* Chassell, Robert J.: Acknowledgments. (line 33)
-* chdir() extension function: Extension Sample File Functions.
+* 'chdir()' extension function: Extension Sample File Functions.
(line 12)
-* chem utility: Glossary. (line 207)
-* chr() extension function: Extension Sample Ord.
+* 'chem' utility: Glossary. (line 206)
+* 'chr()' extension function: Extension Sample Ord.
(line 15)
-* chr() user-defined function: Ordinal Functions. (line 16)
-* clear debugger command: Breakpoint Control. (line 36)
+* 'chr()' user-defined function: Ordinal Functions. (line 16)
+* 'clear' debugger command: Breakpoint Control. (line 36)
* Cliff random numbers: Cliff Random Function.
(line 6)
-* cliff_rand() user-defined function: Cliff Random Function.
+* 'cliff_rand()' user-defined function: Cliff Random Function.
(line 12)
-* close <1>: I/O Functions. (line 10)
-* close: Close Files And Pipes.
+* 'close': Close Files And Pipes.
(line 18)
+* 'close' <1>: I/O Functions. (line 10)
* close file or coprocess: I/O Functions. (line 10)
-* close() function, portability: Close Files And Pipes.
+* 'close()' function, portability: Close Files And Pipes.
(line 81)
-* close() function, return value: Close Files And Pipes.
- (line 133)
-* close() function, two-way pipes and: Two-way I/O. (line 59)
-* Close, Diane <1>: Contributors. (line 20)
+* 'close()' function, return value: Close Files And Pipes.
+ (line 132)
+* 'close()' function, two-way pipes and: Two-way I/O. (line 60)
* Close, Diane: Manual History. (line 34)
+* Close, Diane <1>: Contributors. (line 21)
* Collado, Manuel: Acknowledgments. (line 60)
-* collating elements: Bracket Expressions. (line 79)
-* collating symbols: Bracket Expressions. (line 86)
-* Colombo, Antonio <1>: Contributors. (line 140)
+* collating elements: Bracket Expressions. (line 78)
+* collating symbols: Bracket Expressions. (line 85)
* Colombo, Antonio: Acknowledgments. (line 60)
-* columns, aligning: Print Examples. (line 70)
+* Colombo, Antonio <1>: Contributors. (line 141)
+* columns, aligning: Print Examples. (line 69)
* columns, cutting: Cut Program. (line 6)
-* comma (,), in range patterns: Ranges. (line 6)
+* comma (','), in range patterns: Ranges. (line 6)
* command completion, in debugger: Readline Support. (line 6)
-* command line, arguments <1>: ARGC and ARGV. (line 6)
-* command line, arguments <2>: Auto-set. (line 15)
* command line, arguments: Other Arguments. (line 6)
+* command line, arguments <1>: Auto-set. (line 15)
+* command line, arguments <2>: ARGC and ARGV. (line 6)
* command line, directories on: Command-line directories.
(line 6)
* command line, formats: Running gawk. (line 12)
-* command line, FS on, setting: Command Line Field Separator.
+* command line, 'FS' on, setting: Command Line Field Separator.
(line 6)
-* command line, invoking awk from: Command Line. (line 6)
-* command line, option -f: Long. (line 12)
+* command line, invoking 'awk' from: Command Line. (line 6)
+* command line, option '-f': Long. (line 12)
* command line, options: Options. (line 6)
-* command line, options, end of: Options. (line 54)
+* command line, options, end of: Options. (line 55)
* command line, variables, assigning on: Assignment Options. (line 6)
* command-line options, processing: Getopt Function. (line 6)
* command-line options, string extraction: String Extraction. (line 6)
-* commands debugger command: Debugger Execution Control.
+* 'commands' debugger command: Debugger Execution Control.
(line 10)
* commands to execute at breakpoint: Debugger Execution Control.
(line 10)
* commenting: Comments. (line 6)
-* commenting, backslash continuation and: Statements/Lines. (line 76)
-* common extensions, ** operator: Arithmetic Ops. (line 30)
-* common extensions, **= operator: Assignment Ops. (line 137)
-* common extensions, /dev/stderr special file: Special FD. (line 48)
-* common extensions, /dev/stdin special file: Special FD. (line 48)
-* common extensions, /dev/stdout special file: Special FD. (line 48)
-* common extensions, \x escape sequence: Escape Sequences. (line 61)
-* common extensions, BINMODE variable: PC Using. (line 33)
-* common extensions, delete to delete entire arrays: Delete. (line 39)
-* common extensions, func keyword: Definition Syntax. (line 98)
-* common extensions, length() applied to an array: String Functions.
- (line 201)
-* common extensions, RS as a regexp: gawk split records. (line 6)
+* commenting, backslash continuation and: Statements/Lines. (line 75)
+* common extensions, '**' operator: Arithmetic Ops. (line 30)
+* common extensions, '**=' operator: Assignment Ops. (line 138)
+* common extensions, '/dev/stderr' special file: Special FD. (line 48)
+* common extensions, '/dev/stdin' special file: Special FD. (line 48)
+* common extensions, '/dev/stdout' special file: Special FD. (line 48)
+* common extensions, 'BINMODE' variable: PC Using. (line 33)
+* common extensions, 'delete' to delete entire arrays: Delete.
+ (line 39)
+* common extensions, 'func' keyword: Definition Syntax. (line 99)
+* common extensions, 'length()' applied to an array: String Functions.
+ (line 200)
+* common extensions, 'RS' as a regexp: gawk split records. (line 6)
* common extensions, single character fields: Single Character Fields.
(line 6)
-* comp.lang.awk newsgroup: Bugs. (line 39)
+* common extensions, '\x' escape sequence: Escape Sequences. (line 61)
+* 'comp.lang.awk' newsgroup: Bugs. (line 41)
* comparison expressions: Typing and Comparison.
(line 9)
* comparison expressions, as patterns: Expression Patterns. (line 14)
* comparison expressions, string vs. regexp: Comparison Operators.
(line 79)
-* compatibility mode (gawk), extensions: POSIX/GNU. (line 6)
-* compatibility mode (gawk), file names: Special Caveats. (line 9)
-* compatibility mode (gawk), hexadecimal numbers: Nondecimal-numbers.
- (line 60)
-* compatibility mode (gawk), octal numbers: Nondecimal-numbers.
- (line 60)
-* compatibility mode (gawk), specifying: Options. (line 81)
-* compiled programs <1>: Glossary. (line 219)
-* compiled programs: Basic High Level. (line 15)
-* compiling gawk for Cygwin: Cygwin. (line 6)
-* compiling gawk for MS-DOS and MS-Windows: PC Compiling. (line 13)
-* compiling gawk for VMS: VMS Compilation. (line 6)
-* compiling gawk with EMX for OS/2: PC Compiling. (line 28)
-* compl: Bitwise Functions. (line 44)
+* compatibility mode ('gawk'), extensions: POSIX/GNU. (line 6)
+* compatibility mode ('gawk'), file names: Special Caveats. (line 9)
+* compatibility mode ('gawk'), hexadecimal numbers: Nondecimal-numbers.
+ (line 59)
+* compatibility mode ('gawk'), octal numbers: Nondecimal-numbers.
+ (line 59)
+* compatibility mode ('gawk'), specifying: Options. (line 82)
+* compiled programs: Basic High Level. (line 13)
+* compiled programs <1>: Glossary. (line 218)
+* compiling 'gawk' for Cygwin: Cygwin. (line 6)
+* compiling 'gawk' for MS-DOS and MS-Windows: PC Compiling. (line 13)
+* compiling 'gawk' for VMS: VMS Compilation. (line 6)
+* compiling 'gawk' with EMX for OS/2: PC Compiling. (line 28)
+* 'compl': Bitwise Functions. (line 44)
* complement, bitwise: Bitwise Functions. (line 25)
* compound statements, control statements and: Statements. (line 10)
-* concatenating: Concatenation. (line 8)
-* condition debugger command: Breakpoint Control. (line 54)
+* concatenating: Concatenation. (line 9)
+* 'condition' debugger command: Breakpoint Control. (line 54)
* conditional expressions: Conditional Exp. (line 6)
-* configuration option, --disable-extensions: Additional Configuration Options.
+* configuration option, '--disable-extensions': Additional Configuration
Options.
(line 9)
-* configuration option, --disable-lint: Additional Configuration Options.
+* configuration option, '--disable-lint': Additional Configuration Options.
(line 15)
-* configuration option, --disable-nls: Additional Configuration Options.
+* configuration option, '--disable-nls': Additional Configuration Options.
(line 32)
-* configuration option, --with-whiny-user-strftime: Additional Configuration
Options.
+* configuration option, '--with-whiny-user-strftime': Additional Configuration
Options.
(line 37)
-* configuration options, gawk: Additional Configuration Options.
+* configuration options, 'gawk': Additional Configuration Options.
(line 6)
* constant regexps: Regexp Usage. (line 57)
* constants, nondecimal: Nondecimal Data. (line 6)
@@ -32256,7 +32186,7 @@ Index
* constants, types of: Constants. (line 6)
* continue program, in debugger: Debugger Execution Control.
(line 33)
-* continue statement: Continue Statement. (line 6)
+* 'continue' statement: Continue Statement. (line 6)
* control statements: Statements. (line 6)
* controlling array scanning order: Controlling Scanning.
(line 14)
@@ -32265,202 +32195,207 @@ Index
* convert string to upper case: String Functions. (line 530)
* converting integer array subscripts: Numeric Array Subscripts.
(line 31)
-* converting, dates to timestamps: Time Functions. (line 76)
-* converting, numbers to strings <1>: Bitwise Functions. (line 110)
+* converting, dates to timestamps: Time Functions. (line 75)
* converting, numbers to strings: Strings And Numbers. (line 6)
-* converting, strings to numbers <1>: Bitwise Functions. (line 110)
+* converting, numbers to strings <1>: Bitwise Functions. (line 111)
* converting, strings to numbers: Strings And Numbers. (line 6)
-* CONVFMT variable <1>: User-modified. (line 30)
-* CONVFMT variable: Strings And Numbers. (line 29)
-* CONVFMT variable, and array subscripts: Numeric Array Subscripts.
+* converting, strings to numbers <1>: Bitwise Functions. (line 111)
+* 'CONVFMT' variable: Strings And Numbers. (line 29)
+* 'CONVFMT' variable <1>: User-modified. (line 30)
+* 'CONVFMT' variable, and array subscripts: Numeric Array Subscripts.
(line 6)
-* cookie: Glossary. (line 258)
-* coprocesses <1>: Two-way I/O. (line 25)
+* cookie: Glossary. (line 257)
* coprocesses: Redirection. (line 96)
+* coprocesses <1>: Two-way I/O. (line 27)
* coprocesses, closing: Close Files And Pipes.
(line 6)
-* coprocesses, getline from: Getline/Coprocess. (line 6)
-* cos: Numeric Functions. (line 15)
-* cosine: Numeric Functions. (line 15)
+* coprocesses, 'getline' from: Getline/Coprocess. (line 6)
+* 'cos': Numeric Functions. (line 14)
+* cosine: Numeric Functions. (line 14)
* counting: Wc Program. (line 6)
-* csh utility: Statements/Lines. (line 44)
-* csh utility, POSIXLY_CORRECT environment variable: Options. (line 356)
-* csh utility, |& operator, comparison with: Two-way I/O. (line 25)
-* ctime() user-defined function: Function Example. (line 74)
+* 'csh' utility: Statements/Lines. (line 43)
+* 'csh' utility, 'POSIXLY_CORRECT' environment variable: Options.
+ (line 353)
+* 'csh' utility, '|&' operator, comparison with: Two-way I/O. (line 27)
+* 'ctime()' user-defined function: Function Example. (line 74)
* currency symbols, localization: Explaining gettext. (line 104)
-* current system time: Time Functions. (line 66)
-* custom.h file: Configuration Philosophy.
+* current system time: Time Functions. (line 65)
+* 'custom.h' file: Configuration Philosophy.
(line 30)
* customized input parser: Input Parsers. (line 6)
* customized output wrapper: Output Wrappers. (line 6)
* customized two-way processor: Two-way processors. (line 6)
-* cut utility: Cut Program. (line 6)
-* cut.awk program: Cut Program. (line 45)
-* d debugger command (alias for delete): Breakpoint Control. (line 64)
+* 'cut' utility: Cut Program. (line 6)
+* 'cut' utility <1>: Cut Program. (line 6)
+* 'cut.awk' program: Cut Program. (line 45)
+* 'd' debugger command (alias for 'delete'): Breakpoint Control.
+ (line 64)
* d.c., See dark corner: Conventions. (line 42)
-* dark corner <1>: Glossary. (line 269)
* dark corner: Conventions. (line 42)
-* dark corner, "0" is actually true: Truth Values. (line 24)
-* dark corner, /= operator vs. /=.../ regexp constant: Assignment Ops.
- (line 148)
-* dark corner, ^, in FS: Regexp Field Splitting.
- (line 59)
+* dark corner <1>: Glossary. (line 268)
+* dark corner, '"0"' is actually true: Truth Values. (line 24)
+* dark corner, '/=' operator vs. '/=.../' regexp constant: Assignment Ops.
+ (line 149)
* dark corner, array subscripts: Uninitialized Subscripts.
(line 43)
-* dark corner, break statement: Break Statement. (line 51)
-* dark corner, close() function: Close Files And Pipes.
- (line 133)
+* dark corner, 'break' statement: Break Statement. (line 51)
+* dark corner, 'close()' function: Close Files And Pipes.
+ (line 132)
* dark corner, command-line arguments: Assignment Options. (line 43)
-* dark corner, continue statement: Continue Statement. (line 44)
-* dark corner, CONVFMT variable: Strings And Numbers. (line 40)
+* dark corner, 'continue' statement: Continue Statement. (line 44)
+* dark corner, 'CONVFMT' variable: Strings And Numbers. (line 39)
* dark corner, escape sequences: Other Arguments. (line 38)
* dark corner, escape sequences, for metacharacters: Escape Sequences.
(line 140)
-* dark corner, exit statement: Exit Statement. (line 30)
+* dark corner, 'exit' statement: Exit Statement. (line 30)
* dark corner, field separators: Full Line Fields. (line 22)
-* dark corner, FILENAME variable <1>: Auto-set. (line 90)
-* dark corner, FILENAME variable: Getline Notes. (line 19)
-* dark corner, FNR/NR variables: Auto-set. (line 314)
+* dark corner, 'FILENAME' variable: Getline Notes. (line 19)
+* dark corner, 'FILENAME' variable <1>: Auto-set. (line 90)
+* dark corner, 'FNR'/'NR' variables: Auto-set. (line 313)
* dark corner, format-control characters: Control Letters. (line 18)
-* dark corner, FS as null string: Single Character Fields.
+* dark corner, format-control characters <1>: Control Letters.
+ (line 93)
+* dark corner, 'FS' as null string: Single Character Fields.
(line 20)
-* dark corner, input files: awk split records. (line 111)
-* dark corner, invoking awk: Command Line. (line 16)
-* dark corner, length() function: String Functions. (line 187)
+* dark corner, input files: awk split records. (line 110)
+* dark corner, invoking 'awk': Command Line. (line 16)
+* dark corner, 'length()' function: String Functions. (line 186)
* dark corner, locale's decimal point character: Locale influences conversions.
(line 17)
* dark corner, multiline records: Multiple Line. (line 35)
-* dark corner, NF variable, decrementing: Changing Fields. (line 107)
-* dark corner, OFMT variable: OFMT. (line 27)
-* dark corner, regexp as second argument to index(): String Functions.
- (line 165)
+* dark corner, 'NF' variable, decrementing: Changing Fields. (line 107)
+* dark corner, 'OFMT' variable: OFMT. (line 27)
+* dark corner, regexp as second argument to 'index()': String Functions.
+ (line 164)
* dark corner, regexp constants: Using Constant Regexps.
(line 6)
-* dark corner, regexp constants, /= operator and: Assignment Ops.
- (line 148)
+* dark corner, regexp constants, '/=' operator and: Assignment Ops.
+ (line 149)
* dark corner, regexp constants, as arguments to user-defined functions: Using
Constant Regexps.
(line 43)
-* dark corner, split() function: String Functions. (line 362)
-* dark corner, strings, storing: gawk split records. (line 83)
-* dark corner, value of ARGV[0]: Auto-set. (line 39)
+* dark corner, 'split()' function: String Functions. (line 361)
+* dark corner, strings, storing: gawk split records. (line 82)
+* dark corner, value of 'ARGV[0]': Auto-set. (line 39)
+* dark corner, '^', in 'FS': Regexp Field Splitting.
+ (line 59)
* data, fixed-width: Constant Size. (line 6)
-* data-driven languages: Basic High Level. (line 85)
+* data-driven languages: Basic High Level. (line 74)
* database, group, reading: Group Functions. (line 6)
* database, users, reading: Passwd Functions. (line 6)
-* date utility, GNU: Time Functions. (line 17)
-* date utility, POSIX: Time Functions. (line 254)
-* dates, converting to timestamps: Time Functions. (line 76)
+* 'date' utility, GNU: Time Functions. (line 17)
+* 'date' utility, POSIX: Time Functions. (line 252)
+* dates, converting to timestamps: Time Functions. (line 75)
* dates, information related to, localization: Explaining gettext.
(line 112)
-* Davies, Stephen <1>: Contributors. (line 74)
* Davies, Stephen: Acknowledgments. (line 60)
+* Davies, Stephen <1>: Contributors. (line 75)
* Day, Robert P.J.: Acknowledgments. (line 78)
-* dcgettext <1>: Programmer i18n. (line 20)
-* dcgettext: I18N Functions. (line 22)
-* dcgettext() function (gawk), portability and: I18N Portability.
+* 'dcgettext': I18N Functions. (line 21)
+* 'dcgettext' <1>: Programmer i18n. (line 20)
+* 'dcgettext()' function ('gawk'), portability and: I18N Portability.
(line 33)
-* dcngettext <1>: Programmer i18n. (line 37)
-* dcngettext: I18N Functions. (line 28)
-* dcngettext() function (gawk), portability and: I18N Portability.
+* 'dcngettext': I18N Functions. (line 27)
+* 'dcngettext' <1>: Programmer i18n. (line 37)
+* 'dcngettext()' function ('gawk'), portability and: I18N Portability.
(line 33)
-* deadlocks: Two-way I/O. (line 52)
-* debugger commands, b (break): Breakpoint Control. (line 11)
-* debugger commands, backtrace: Execution Stack. (line 13)
-* debugger commands, break: Breakpoint Control. (line 11)
-* debugger commands, bt (backtrace): Execution Stack. (line 13)
-* debugger commands, c (continue): Debugger Execution Control.
+* deadlocks: Two-way I/O. (line 53)
+* debugger commands, 'b' ('break'): Breakpoint Control. (line 11)
+* debugger commands, 'backtrace': Execution Stack. (line 13)
+* debugger commands, 'break': Breakpoint Control. (line 11)
+* debugger commands, 'bt' ('backtrace'): Execution Stack. (line 13)
+* debugger commands, 'c' ('continue'): Debugger Execution Control.
(line 33)
-* debugger commands, clear: Breakpoint Control. (line 36)
-* debugger commands, commands: Debugger Execution Control.
+* debugger commands, 'clear': Breakpoint Control. (line 36)
+* debugger commands, 'commands': Debugger Execution Control.
(line 10)
-* debugger commands, condition: Breakpoint Control. (line 54)
-* debugger commands, continue: Debugger Execution Control.
+* debugger commands, 'condition': Breakpoint Control. (line 54)
+* debugger commands, 'continue': Debugger Execution Control.
(line 33)
-* debugger commands, d (delete): Breakpoint Control. (line 64)
-* debugger commands, delete: Breakpoint Control. (line 64)
-* debugger commands, disable: Breakpoint Control. (line 69)
-* debugger commands, display: Viewing And Changing Data.
+* debugger commands, 'd' ('delete'): Breakpoint Control. (line 64)
+* debugger commands, 'delete': Breakpoint Control. (line 64)
+* debugger commands, 'disable': Breakpoint Control. (line 69)
+* debugger commands, 'display': Viewing And Changing Data.
(line 8)
-* debugger commands, down: Execution Stack. (line 23)
-* debugger commands, dump: Miscellaneous Debugger Commands.
+* debugger commands, 'down': Execution Stack. (line 23)
+* debugger commands, 'dump': Miscellaneous Debugger Commands.
(line 9)
-* debugger commands, e (enable): Breakpoint Control. (line 73)
-* debugger commands, enable: Breakpoint Control. (line 73)
-* debugger commands, end: Debugger Execution Control.
+* debugger commands, 'e' ('enable'): Breakpoint Control. (line 73)
+* debugger commands, 'enable': Breakpoint Control. (line 73)
+* debugger commands, 'end': Debugger Execution Control.
(line 10)
-* debugger commands, eval: Viewing And Changing Data.
+* debugger commands, 'eval': Viewing And Changing Data.
(line 23)
-* debugger commands, f (frame): Execution Stack. (line 27)
-* debugger commands, finish: Debugger Execution Control.
+* debugger commands, 'f' ('frame'): Execution Stack. (line 27)
+* debugger commands, 'finish': Debugger Execution Control.
(line 39)
-* debugger commands, frame: Execution Stack. (line 27)
-* debugger commands, h (help): Miscellaneous Debugger Commands.
+* debugger commands, 'frame': Execution Stack. (line 27)
+* debugger commands, 'h' ('help'): Miscellaneous Debugger Commands.
(line 66)
-* debugger commands, help: Miscellaneous Debugger Commands.
+* debugger commands, 'help': Miscellaneous Debugger Commands.
(line 66)
-* debugger commands, i (info): Debugger Info. (line 13)
-* debugger commands, ignore: Breakpoint Control. (line 87)
-* debugger commands, info: Debugger Info. (line 13)
-* debugger commands, l (list): Miscellaneous Debugger Commands.
+* debugger commands, 'i' ('info'): Debugger Info. (line 13)
+* debugger commands, 'ignore': Breakpoint Control. (line 87)
+* debugger commands, 'info': Debugger Info. (line 13)
+* debugger commands, 'l' ('list'): Miscellaneous Debugger Commands.
(line 72)
-* debugger commands, list: Miscellaneous Debugger Commands.
+* debugger commands, 'list': Miscellaneous Debugger Commands.
(line 72)
-* debugger commands, n (next): Debugger Execution Control.
+* debugger commands, 'n' ('next'): Debugger Execution Control.
(line 43)
-* debugger commands, next: Debugger Execution Control.
+* debugger commands, 'next': Debugger Execution Control.
(line 43)
-* debugger commands, nexti: Debugger Execution Control.
+* debugger commands, 'nexti': Debugger Execution Control.
(line 49)
-* debugger commands, ni (nexti): Debugger Execution Control.
+* debugger commands, 'ni' ('nexti'): Debugger Execution Control.
(line 49)
-* debugger commands, o (option): Debugger Info. (line 57)
-* debugger commands, option: Debugger Info. (line 57)
-* debugger commands, p (print): Viewing And Changing Data.
- (line 36)
-* debugger commands, print: Viewing And Changing Data.
- (line 36)
-* debugger commands, printf: Viewing And Changing Data.
- (line 54)
-* debugger commands, q (quit): Miscellaneous Debugger Commands.
+* debugger commands, 'o' ('option'): Debugger Info. (line 57)
+* debugger commands, 'option': Debugger Info. (line 57)
+* debugger commands, 'p' ('print'): Viewing And Changing Data.
+ (line 35)
+* debugger commands, 'print': Viewing And Changing Data.
+ (line 35)
+* debugger commands, 'printf': Viewing And Changing Data.
+ (line 53)
+* debugger commands, 'q' ('quit'): Miscellaneous Debugger Commands.
(line 99)
-* debugger commands, quit: Miscellaneous Debugger Commands.
+* debugger commands, 'quit': Miscellaneous Debugger Commands.
(line 99)
-* debugger commands, r (run): Debugger Execution Control.
+* debugger commands, 'r' ('run'): Debugger Execution Control.
(line 62)
-* debugger commands, return: Debugger Execution Control.
+* debugger commands, 'return': Debugger Execution Control.
(line 54)
-* debugger commands, run: Debugger Execution Control.
+* debugger commands, 'run': Debugger Execution Control.
(line 62)
-* debugger commands, s (step): Debugger Execution Control.
+* debugger commands, 's' ('step'): Debugger Execution Control.
(line 68)
-* debugger commands, set: Viewing And Changing Data.
- (line 59)
-* debugger commands, si (stepi): Debugger Execution Control.
- (line 76)
-* debugger commands, silent: Debugger Execution Control.
+* debugger commands, 'set': Viewing And Changing Data.
+ (line 58)
+* debugger commands, 'si' ('stepi'): Debugger Execution Control.
+ (line 75)
+* debugger commands, 'silent': Debugger Execution Control.
(line 10)
-* debugger commands, step: Debugger Execution Control.
+* debugger commands, 'step': Debugger Execution Control.
(line 68)
-* debugger commands, stepi: Debugger Execution Control.
- (line 76)
-* debugger commands, t (tbreak): Breakpoint Control. (line 90)
-* debugger commands, tbreak: Breakpoint Control. (line 90)
-* debugger commands, trace: Miscellaneous Debugger Commands.
+* debugger commands, 'stepi': Debugger Execution Control.
+ (line 75)
+* debugger commands, 't' ('tbreak'): Breakpoint Control. (line 90)
+* debugger commands, 'tbreak': Breakpoint Control. (line 90)
+* debugger commands, 'trace': Miscellaneous Debugger Commands.
(line 107)
-* debugger commands, u (until): Debugger Execution Control.
- (line 83)
-* debugger commands, undisplay: Viewing And Changing Data.
- (line 80)
-* debugger commands, until: Debugger Execution Control.
+* debugger commands, 'u' ('until'): Debugger Execution Control.
+ (line 82)
+* debugger commands, 'undisplay': Viewing And Changing Data.
+ (line 79)
+* debugger commands, 'until': Debugger Execution Control.
+ (line 82)
+* debugger commands, 'unwatch': Viewing And Changing Data.
(line 83)
-* debugger commands, unwatch: Viewing And Changing Data.
- (line 84)
-* debugger commands, up: Execution Stack. (line 36)
-* debugger commands, w (watch): Viewing And Changing Data.
- (line 67)
-* debugger commands, watch: Viewing And Changing Data.
- (line 67)
-* debugger commands, where (backtrace): Execution Stack. (line 13)
+* debugger commands, 'up': Execution Stack. (line 36)
+* debugger commands, 'w' ('watch'): Viewing And Changing Data.
+ (line 66)
+* debugger commands, 'watch': Viewing And Changing Data.
+ (line 66)
+* debugger commands, 'where' ('backtrace'): Execution Stack. (line 13)
* debugger default list amount: Debugger Info. (line 69)
* debugger history file: Debugger Info. (line 81)
* debugger history size: Debugger Info. (line 65)
@@ -32468,97 +32403,109 @@ Index
* debugger prompt: Debugger Info. (line 78)
* debugger, how to start: Debugger Invocation. (line 6)
* debugger, read commands from a file: Debugger Info. (line 97)
-* debugging awk programs: Debugger. (line 6)
-* debugging gawk, bug reports: Bugs. (line 9)
-* decimal point character, locale specific: Options. (line 272)
+* debugging 'awk' programs: Debugger. (line 6)
+* debugging 'gawk', bug reports: Bugs. (line 9)
+* decimal point character, locale specific: Options. (line 269)
* decrement operators: Increment Ops. (line 35)
-* default keyword: Switch Statement. (line 6)
-* Deifik, Scott <1>: Bugs. (line 71)
-* Deifik, Scott <2>: Contributors. (line 53)
+* 'default' keyword: Switch Statement. (line 6)
* Deifik, Scott: Acknowledgments. (line 60)
-* delete ARRAY: Delete. (line 39)
+* Deifik, Scott <1>: Contributors. (line 54)
+* Deifik, Scott <2>: Bugs. (line 73)
+* 'delete' ARRAY: Delete. (line 39)
* delete breakpoint at location: Breakpoint Control. (line 36)
* delete breakpoint by number: Breakpoint Control. (line 64)
-* delete debugger command: Breakpoint Control. (line 64)
-* delete statement: Delete. (line 6)
+* 'delete' debugger command: Breakpoint Control. (line 64)
+* 'delete' statement: Delete. (line 6)
* delete watchpoint: Viewing And Changing Data.
- (line 84)
+ (line 83)
* deleting elements in arrays: Delete. (line 6)
* deleting entire arrays: Delete. (line 39)
* Demaille, Akim: Acknowledgments. (line 60)
* describe call stack frame, in debugger: Debugger Info. (line 27)
-* differences between gawk and awk: String Functions. (line 201)
-* differences in awk and gawk, ARGC/ARGV variables: ARGC and ARGV.
+* differences between 'gawk' and 'awk': String Functions. (line 200)
+* differences in 'awk' and 'gawk', 'ARGC'/'ARGV' variables: ARGC and ARGV.
(line 90)
-* differences in awk and gawk, ARGIND variable: Auto-set. (line 44)
-* differences in awk and gawk, array elements, deleting: Delete.
+* differences in 'awk' and 'gawk', 'ARGIND' variable: Auto-set.
+ (line 44)
+* differences in 'awk' and 'gawk', array elements, deleting: Delete.
(line 39)
-* differences in awk and gawk, AWKLIBPATH environment variable: AWKLIBPATH
Variable.
+* differences in 'awk' and 'gawk', 'AWKLIBPATH' environment variable:
AWKLIBPATH Variable.
(line 6)
-* differences in awk and gawk, AWKPATH environment variable: AWKPATH Variable.
+* differences in 'awk' and 'gawk', 'AWKPATH' environment variable: AWKPATH
Variable.
(line 6)
-* differences in awk and gawk, BEGIN/END patterns: I/O And BEGIN/END.
- (line 16)
-* differences in awk and gawk, BEGINFILE/ENDFILE patterns: BEGINFILE/ENDFILE.
+* differences in 'awk' and 'gawk', 'BEGIN'/'END' patterns: I/O And BEGIN/END.
+ (line 15)
+* differences in 'awk' and 'gawk', 'BEGINFILE'/'ENDFILE' patterns:
BEGINFILE/ENDFILE.
(line 6)
-* differences in awk and gawk, BINMODE variable <1>: PC Using.
- (line 33)
-* differences in awk and gawk, BINMODE variable: User-modified.
+* differences in 'awk' and 'gawk', 'BINMODE' variable: User-modified.
(line 15)
-* differences in awk and gawk, close() function: Close Files And Pipes.
+* differences in 'awk' and 'gawk', 'BINMODE' variable <1>: PC Using.
+ (line 33)
+* differences in 'awk' and 'gawk', 'close()' function: Close Files And Pipes.
(line 81)
-* differences in awk and gawk, command-line directories: Command-line
directories.
+* differences in 'awk' and 'gawk', 'close()' function <1>: Close Files And
Pipes.
+ (line 132)
+* differences in 'awk' and 'gawk', command-line directories: Command-line
directories.
(line 6)
-* differences in awk and gawk, ERRNO variable: Auto-set. (line 74)
-* differences in awk and gawk, error messages: Special FD. (line 19)
-* differences in awk and gawk, FIELDWIDTHS variable: User-modified.
+* differences in 'awk' and 'gawk', 'ERRNO' variable: Auto-set.
+ (line 74)
+* differences in 'awk' and 'gawk', error messages: Special FD.
+ (line 19)
+* differences in 'awk' and 'gawk', 'FIELDWIDTHS' variable: User-modified.
(line 37)
-* differences in awk and gawk, FPAT variable: User-modified. (line 43)
-* differences in awk and gawk, FUNCTAB variable: Auto-set. (line 116)
-* differences in awk and gawk, function arguments (gawk): Calling Built-in.
+* differences in 'awk' and 'gawk', 'FPAT' variable: User-modified.
+ (line 43)
+* differences in 'awk' and 'gawk', 'FUNCTAB' variable: Auto-set.
+ (line 116)
+* differences in 'awk' and 'gawk', function arguments ('gawk'): Calling
Built-in.
(line 16)
-* differences in awk and gawk, getline command: Getline. (line 19)
-* differences in awk and gawk, IGNORECASE variable: User-modified.
+* differences in 'awk' and 'gawk', 'getline' command: Getline.
+ (line 19)
+* differences in 'awk' and 'gawk', 'IGNORECASE' variable: User-modified.
(line 76)
-* differences in awk and gawk, implementation limitations <1>: Redirection.
- (line 129)
-* differences in awk and gawk, implementation limitations: Getline Notes.
+* differences in 'awk' and 'gawk', implementation limitations: Getline Notes.
(line 14)
-* differences in awk and gawk, indirect function calls: Indirect Calls.
+* differences in 'awk' and 'gawk', implementation limitations <1>: Redirection.
+ (line 129)
+* differences in 'awk' and 'gawk', indirect function calls: Indirect Calls.
(line 6)
-* differences in awk and gawk, input/output operators <1>: Redirection.
- (line 96)
-* differences in awk and gawk, input/output operators: Getline/Coprocess.
+* differences in 'awk' and 'gawk', input/output operators: Getline/Coprocess.
(line 6)
-* differences in awk and gawk, line continuations: Conditional Exp.
+* differences in 'awk' and 'gawk', input/output operators <1>: Redirection.
+ (line 96)
+* differences in 'awk' and 'gawk', line continuations: Conditional Exp.
(line 34)
-* differences in awk and gawk, LINT variable: User-modified. (line 87)
-* differences in awk and gawk, match() function: String Functions.
- (line 263)
-* differences in awk and gawk, print/printf statements: Format Modifiers.
+* differences in 'awk' and 'gawk', 'LINT' variable: User-modified.
+ (line 87)
+* differences in 'awk' and 'gawk', 'match()' function: String Functions.
+ (line 262)
+* differences in 'awk' and 'gawk', 'print'/'printf' statements: Format
Modifiers.
(line 13)
-* differences in awk and gawk, PROCINFO array: Auto-set. (line 130)
-* differences in awk and gawk, read timeouts: Read Timeout. (line 6)
-* differences in awk and gawk, record separators: awk split records.
- (line 125)
-* differences in awk and gawk, regexp constants: Using Constant Regexps.
+* differences in 'awk' and 'gawk', 'PROCINFO' array: Auto-set.
+ (line 130)
+* differences in 'awk' and 'gawk', read timeouts: Read Timeout.
+ (line 6)
+* differences in 'awk' and 'gawk', record separators: awk split records.
+ (line 124)
+* differences in 'awk' and 'gawk', regexp constants: Using Constant Regexps.
(line 43)
-* differences in awk and gawk, regular expressions: Case-sensitivity.
+* differences in 'awk' and 'gawk', regular expressions: Case-sensitivity.
(line 26)
-* differences in awk and gawk, RS/RT variables: gawk split records.
+* differences in 'awk' and 'gawk', 'RS'/'RT' variables: gawk split records.
(line 58)
-* differences in awk and gawk, RT variable: Auto-set. (line 265)
-* differences in awk and gawk, single-character fields: Single Character
Fields.
+* differences in 'awk' and 'gawk', 'RT' variable: Auto-set. (line 264)
+* differences in 'awk' and 'gawk', single-character fields: Single Character
Fields.
(line 6)
-* differences in awk and gawk, split() function: String Functions.
- (line 349)
-* differences in awk and gawk, strings: Scalar Constants. (line 20)
-* differences in awk and gawk, strings, storing: gawk split records.
- (line 77)
-* differences in awk and gawk, SYMTAB variable: Auto-set. (line 269)
-* differences in awk and gawk, TEXTDOMAIN variable: User-modified.
- (line 151)
-* differences in awk and gawk, trunc-mod operation: Arithmetic Ops.
+* differences in 'awk' and 'gawk', 'split()' function: String Functions.
+ (line 348)
+* differences in 'awk' and 'gawk', strings: Scalar Constants. (line 20)
+* differences in 'awk' and 'gawk', strings, storing: gawk split records.
+ (line 76)
+* differences in 'awk' and 'gawk', 'SYMTAB' variable: Auto-set.
+ (line 268)
+* differences in 'awk' and 'gawk', 'TEXTDOMAIN' variable: User-modified.
+ (line 152)
+* differences in 'awk' and 'gawk', trunc-mod operation: Arithmetic Ops.
(line 66)
* directories, command-line: Command-line directories.
(line 6)
@@ -32567,102 +32514,105 @@ Index
(line 6)
* directories, searching for source files: AWKPATH Variable. (line 6)
* disable breakpoint: Breakpoint Control. (line 69)
-* disable debugger command: Breakpoint Control. (line 69)
-* display debugger command: Viewing And Changing Data.
+* 'disable' debugger command: Breakpoint Control. (line 69)
+* 'display' debugger command: Viewing And Changing Data.
(line 8)
* display debugger options: Debugger Info. (line 57)
* division: Arithmetic Ops. (line 44)
-* do-while statement: Do Statement. (line 6)
-* do-while statement, use of regexps in: Regexp Usage. (line 19)
-* documentation, of awk programs: Library Names. (line 6)
+* 'do'-'while' statement: Do Statement. (line 6)
+* 'do'-'while' statement, use of regexps in: Regexp Usage. (line 19)
+* documentation, of 'awk' programs: Library Names. (line 6)
* documentation, online: Manual History. (line 11)
* documents, searching: Dupword Program. (line 6)
-* dollar sign ($), $ field operator <1>: Precedence. (line 43)
-* dollar sign ($), $ field operator: Fields. (line 19)
-* dollar sign ($), incrementing fields and arrays: Increment Ops.
+* dollar sign ('$'), '$' field operator: Fields. (line 19)
+* dollar sign ('$'), '$' field operator <1>: Precedence. (line 42)
+* dollar sign ('$'), incrementing fields and arrays: Increment Ops.
(line 30)
-* dollar sign ($), regexp operator: Regexp Operators. (line 35)
-* double quote ("), in regexp constants: Computed Regexps. (line 30)
-* double quote ("), in shell commands: Quoting. (line 54)
-* down debugger command: Execution Stack. (line 23)
+* dollar sign ('$'), regexp operator: Regexp Operators. (line 35)
+* double quote ('"'), in regexp constants: Computed Regexps. (line 30)
+* double quote ('"'), in shell commands: Quoting. (line 54)
+* 'down' debugger command: Execution Stack. (line 23)
* Drepper, Ulrich: Acknowledgments. (line 52)
* Duman, Patrice: Acknowledgments. (line 74)
-* dump all variables of a program: Options. (line 93)
-* dump debugger command: Miscellaneous Debugger Commands.
+* dump all variables of a program: Options. (line 94)
+* 'dump' debugger command: Miscellaneous Debugger Commands.
(line 9)
-* dupword.awk program: Dupword Program. (line 31)
-* dynamic profiling: Profiling. (line 179)
+* 'dupword.awk' program: Dupword Program. (line 31)
+* dynamic profiling: Profiling. (line 178)
* dynamically loaded extensions: Dynamic Extensions. (line 6)
-* e debugger command (alias for enable): Breakpoint Control. (line 73)
+* 'e' debugger command (alias for 'enable'): Breakpoint Control.
+ (line 73)
* EBCDIC: Ordinal Functions. (line 45)
-* effective group ID of gawk user: Auto-set. (line 135)
-* effective user ID of gawk user: Auto-set. (line 139)
-* egrep utility <1>: Egrep Program. (line 6)
-* egrep utility: Bracket Expressions. (line 26)
-* egrep.awk program: Egrep Program. (line 54)
+* effective group ID of 'gawk' user: Auto-set. (line 135)
+* effective user ID of 'gawk' user: Auto-set. (line 139)
+* 'egrep' utility: Bracket Expressions. (line 26)
+* 'egrep' utility <1>: Egrep Program. (line 6)
+* 'egrep.awk' program: Egrep Program. (line 53)
* elements in arrays, assigning values: Assigning Elements. (line 6)
* elements in arrays, deleting: Delete. (line 6)
-* elements in arrays, order of access by in operator: Scanning an Array.
+* elements in arrays, order of access by 'in' operator: Scanning an Array.
(line 48)
* elements in arrays, scanning: Scanning an Array. (line 6)
* elements of arrays: Reference to Elements.
(line 6)
-* email address for bug reports, address@hidden: Bugs. (line 30)
-* EMISTERED: TCP/IP Networking. (line 6)
+* email address for bug reports, 'address@hidden': Bugs. (line 30)
+* 'EMISTERED': TCP/IP Networking. (line 6)
* empty array elements: Reference to Elements.
(line 18)
* empty pattern: Empty. (line 6)
-* empty strings: awk split records. (line 115)
+* empty strings: awk split records. (line 114)
* empty strings, See null strings: Regexp Field Splitting.
(line 43)
* enable breakpoint: Breakpoint Control. (line 73)
-* enable debugger command: Breakpoint Control. (line 73)
-* end debugger command: Debugger Execution Control.
+* 'enable' debugger command: Breakpoint Control. (line 73)
+* 'end' debugger command: Debugger Execution Control.
(line 10)
-* END pattern <1>: Using BEGIN/END. (line 6)
-* END pattern: BEGIN/END. (line 6)
-* END pattern, and profiling: Profiling. (line 62)
-* END pattern, assert() user-defined function and: Assert Function.
+* 'END' pattern: BEGIN/END. (line 6)
+* 'END' pattern <1>: Using BEGIN/END. (line 6)
+* 'END' pattern, and profiling: Profiling. (line 62)
+* 'END' pattern, 'assert()' user-defined function and: Assert Function.
(line 75)
-* END pattern, Boolean patterns and: Expression Patterns. (line 70)
-* END pattern, exit statement and: Exit Statement. (line 12)
-* END pattern, next/nextfile statements and <1>: Next Statement.
+* 'END' pattern, Boolean patterns and: Expression Patterns. (line 70)
+* 'END' pattern, 'exit' statement and: Exit Statement. (line 12)
+* 'END' pattern, 'next'/'nextfile' statements and: I/O And BEGIN/END.
+ (line 36)
+* 'END' pattern, 'next'/'nextfile' statements and <1>: Next Statement.
(line 44)
-* END pattern, next/nextfile statements and: I/O And BEGIN/END.
- (line 37)
-* END pattern, operators and: Using BEGIN/END. (line 17)
-* END pattern, print statement and: I/O And BEGIN/END. (line 16)
-* ENDFILE pattern: BEGINFILE/ENDFILE. (line 6)
-* ENDFILE pattern, Boolean patterns and: Expression Patterns. (line 70)
-* endfile() user-defined function: Filetrans Function. (line 62)
-* endgrent() function (C library): Group Functions. (line 212)
-* endgrent() user-defined function: Group Functions. (line 215)
-* endpwent() function (C library): Passwd Functions. (line 207)
-* endpwent() user-defined function: Passwd Functions. (line 210)
+* 'END' pattern, operators and: Using BEGIN/END. (line 17)
+* 'END' pattern, 'print' statement and: I/O And BEGIN/END. (line 15)
+* 'ENDFILE' pattern: BEGINFILE/ENDFILE. (line 6)
+* 'ENDFILE' pattern, Boolean patterns and: Expression Patterns.
+ (line 70)
+* 'endfile()' user-defined function: Filetrans Function. (line 62)
+* 'endgrent()' function (C library): Group Functions. (line 211)
+* 'endgrent()' user-defined function: Group Functions. (line 214)
+* 'endpwent()' function (C library): Passwd Functions. (line 207)
+* 'endpwent()' user-defined function: Passwd Functions. (line 210)
* English, Steve: Advanced Features. (line 6)
-* ENVIRON array: Auto-set. (line 60)
-* environment variables used by gawk: Environment Variables.
+* 'ENVIRON' array: Auto-set. (line 59)
+* environment variables used by 'gawk': Environment Variables.
(line 6)
-* environment variables, in ENVIRON array: Auto-set. (line 60)
-* epoch, definition of: Glossary. (line 315)
-* equals sign (=), = operator: Assignment Ops. (line 6)
-* equals sign (=), == operator <1>: Precedence. (line 65)
-* equals sign (=), == operator: Comparison Operators.
+* environment variables, in 'ENVIRON' array: Auto-set. (line 59)
+* epoch, definition of: Glossary. (line 312)
+* equals sign ('='), '=' operator: Assignment Ops. (line 6)
+* equals sign ('='), '==' operator: Comparison Operators.
(line 11)
+* equals sign ('='), '==' operator <1>: Precedence. (line 64)
* EREs (Extended Regular Expressions): Bracket Expressions. (line 26)
-* ERRNO variable <1>: TCP/IP Networking. (line 54)
-* ERRNO variable: Auto-set. (line 74)
-* ERRNO variable, with BEGINFILE pattern: BEGINFILE/ENDFILE. (line 26)
-* ERRNO variable, with close() function: Close Files And Pipes.
- (line 141)
-* ERRNO variable, with getline command: Getline. (line 19)
+* 'ERRNO' variable: Auto-set. (line 74)
+* 'ERRNO' variable <1>: TCP/IP Networking. (line 54)
+* 'ERRNO' variable, with 'BEGINFILE' pattern: BEGINFILE/ENDFILE.
+ (line 26)
+* 'ERRNO' variable, with 'close()' function: Close Files And Pipes.
+ (line 140)
+* 'ERRNO' variable, with 'getline' command: Getline. (line 19)
* error handling: Special FD. (line 19)
-* error handling, ERRNO variable and: Auto-set. (line 74)
+* error handling, 'ERRNO' variable and: Auto-set. (line 74)
* error output: Special FD. (line 6)
-* escape processing, gsub()/gensub()/sub() functions: Gory Details.
+* escape processing, 'gsub()'/'gensub()'/'sub()' functions: Gory Details.
(line 6)
* escape sequences, in strings: Escape Sequences. (line 6)
-* eval debugger command: Viewing And Changing Data.
+* 'eval' debugger command: Viewing And Changing Data.
(line 23)
* evaluate expressions, in debugger: Viewing And Changing Data.
(line 23)
@@ -32670,30 +32620,35 @@ Index
* evaluation order, concatenation: Concatenation. (line 41)
* evaluation order, functions: Calling Built-in. (line 30)
* examining fields: Fields. (line 6)
-* exclamation point (!), ! operator <1>: Egrep Program. (line 175)
-* exclamation point (!), ! operator <2>: Precedence. (line 52)
-* exclamation point (!), ! operator: Boolean Ops. (line 69)
-* exclamation point (!), != operator <1>: Precedence. (line 65)
-* exclamation point (!), != operator: Comparison Operators.
+* exclamation point ('!'), '!' operator: Boolean Ops. (line 69)
+* exclamation point ('!'), '!' operator <1>: Precedence. (line 51)
+* exclamation point ('!'), '!' operator <2>: Egrep Program. (line 174)
+* exclamation point ('!'), '!=' operator: Comparison Operators.
(line 11)
-* exclamation point (!), !~ operator <1>: Expression Patterns.
- (line 24)
-* exclamation point (!), !~ operator <2>: Precedence. (line 80)
-* exclamation point (!), !~ operator <3>: Comparison Operators.
+* exclamation point ('!'), '!=' operator <1>: Precedence. (line 64)
+* exclamation point ('!'), '!~' operator: Regexp Usage. (line 19)
+* exclamation point ('!'), '!~' operator <1>: Computed Regexps.
+ (line 6)
+* exclamation point ('!'), '!~' operator <2>: Case-sensitivity.
+ (line 26)
+* exclamation point ('!'), '!~' operator <3>: Regexp Constants.
+ (line 6)
+* exclamation point ('!'), '!~' operator <4>: Comparison Operators.
(line 11)
-* exclamation point (!), !~ operator <4>: Regexp Constants. (line 6)
-* exclamation point (!), !~ operator <5>: Case-sensitivity. (line 26)
-* exclamation point (!), !~ operator <6>: Computed Regexps. (line 6)
-* exclamation point (!), !~ operator: Regexp Usage. (line 19)
-* exit statement: Exit Statement. (line 6)
-* exit status, of gawk: Exit Status. (line 6)
+* exclamation point ('!'), '!~' operator <5>: Comparison Operators.
+ (line 98)
+* exclamation point ('!'), '!~' operator <6>: Precedence. (line 79)
+* exclamation point ('!'), '!~' operator <7>: Expression Patterns.
+ (line 24)
+* 'exit' statement: Exit Statement. (line 6)
+* exit status, of 'gawk': Exit Status. (line 6)
* exit status, of VMS: VMS Running. (line 28)
* exit the debugger: Miscellaneous Debugger Commands.
(line 99)
-* exp: Numeric Functions. (line 18)
-* expand utility: Very Simple. (line 73)
+* 'exp': Numeric Functions. (line 17)
+* 'expand' utility: Very Simple. (line 72)
* Expat XML parser library: gawkextlib. (line 35)
-* exponent: Numeric Functions. (line 18)
+* exponent: Numeric Functions. (line 17)
* expressions: Expressions. (line 6)
* expressions, as patterns: Expression Patterns. (line 6)
* expressions, assignment: Assignment Ops. (line 6)
@@ -32711,106 +32666,112 @@ Index
(line 6)
* extension API version: Extension Versioning.
(line 6)
-* extension API, version number: Auto-set. (line 232)
+* extension API, version number: Auto-set. (line 231)
* extension example: Extension Example. (line 6)
* extension registration: Registration Functions.
(line 6)
* extension search path: Finding Extensions. (line 6)
-* extensions distributed with gawk: Extension Samples. (line 6)
+* extensions distributed with 'gawk': Extension Samples. (line 6)
* extensions, allocating memory: Memory Allocation Functions.
(line 6)
-* extensions, Brian Kernighan's awk <1>: Common Extensions. (line 6)
-* extensions, Brian Kernighan's awk: BTL. (line 6)
-* extensions, common, ** operator: Arithmetic Ops. (line 30)
-* extensions, common, **= operator: Assignment Ops. (line 137)
-* extensions, common, /dev/stderr special file: Special FD. (line 48)
-* extensions, common, /dev/stdin special file: Special FD. (line 48)
-* extensions, common, /dev/stdout special file: Special FD. (line 48)
-* extensions, common, \x escape sequence: Escape Sequences. (line 61)
-* extensions, common, BINMODE variable: PC Using. (line 33)
-* extensions, common, delete to delete entire arrays: Delete. (line 39)
-* extensions, common, fflush() function: I/O Functions. (line 43)
-* extensions, common, func keyword: Definition Syntax. (line 98)
-* extensions, common, length() applied to an array: String Functions.
- (line 201)
-* extensions, common, RS as a regexp: gawk split records. (line 6)
+* extensions, Brian Kernighan's 'awk': BTL. (line 6)
+* extensions, Brian Kernighan's 'awk' <1>: Common Extensions. (line 6)
+* extensions, common, '**' operator: Arithmetic Ops. (line 30)
+* extensions, common, '**=' operator: Assignment Ops. (line 138)
+* extensions, common, '/dev/stderr' special file: Special FD. (line 48)
+* extensions, common, '/dev/stdin' special file: Special FD. (line 48)
+* extensions, common, '/dev/stdout' special file: Special FD. (line 48)
+* extensions, common, 'BINMODE' variable: PC Using. (line 33)
+* extensions, common, 'delete' to delete entire arrays: Delete.
+ (line 39)
+* extensions, common, 'fflush()' function: I/O Functions. (line 43)
+* extensions, common, 'func' keyword: Definition Syntax. (line 99)
+* extensions, common, 'length()' applied to an array: String Functions.
+ (line 200)
+* extensions, common, 'RS' as a regexp: gawk split records. (line 6)
* extensions, common, single character fields: Single Character Fields.
(line 6)
-* extensions, in gawk, not in POSIX awk: POSIX/GNU. (line 6)
-* extensions, loading, @load directive: Loading Shared Libraries.
+* extensions, common, '\x' escape sequence: Escape Sequences. (line 61)
+* extensions, in 'gawk', not in POSIX 'awk': POSIX/GNU. (line 6)
+* extensions, loading, '@load' directive: Loading Shared Libraries.
(line 8)
-* extensions, mawk: Common Extensions. (line 6)
+* extensions, 'mawk': Common Extensions. (line 6)
* extensions, where to find: gawkextlib. (line 6)
-* extract.awk program: Extract Program. (line 79)
+* 'extract.awk' program: Extract Program. (line 79)
* extraction, of marked strings (internationalization): String Extraction.
(line 6)
-* f debugger command (alias for frame): Execution Stack. (line 27)
+* 'f' debugger command (alias for 'frame'): Execution Stack. (line 27)
* false, logical: Truth Values. (line 6)
* FDL (Free Documentation License): GNU Free Documentation License.
- (line 7)
-* features, adding to gawk: Adding Code. (line 6)
+ (line 8)
+* features, adding to 'gawk': Adding Code. (line 6)
* features, deprecated: Obsolete. (line 6)
* features, undocumented: Undocumented. (line 6)
-* Fenlason, Jay <1>: Contributors. (line 18)
* Fenlason, Jay: History. (line 30)
-* fflush: I/O Functions. (line 28)
+* Fenlason, Jay <1>: Contributors. (line 19)
+* 'fflush': I/O Functions. (line 28)
* field numbers: Nonconstant Fields. (line 6)
-* field operator $: Fields. (line 19)
+* field operator '$': Fields. (line 19)
* field operators, dollar sign as: Fields. (line 19)
* field separator, in multiline records: Multiple Line. (line 41)
* field separator, on command line: Command Line Field Separator.
(line 6)
* field separator, POSIX and: Full Line Fields. (line 16)
-* field separators <1>: User-modified. (line 50)
* field separators: Field Separators. (line 15)
-* field separators, choice of: Field Separators. (line 51)
-* field separators, FIELDWIDTHS variable and: User-modified. (line 37)
-* field separators, FPAT variable and: User-modified. (line 43)
+* field separators <1>: User-modified. (line 50)
+* field separators <2>: User-modified. (line 113)
+* field separators, choice of: Field Separators. (line 50)
+* field separators, 'FIELDWIDTHS' variable and: User-modified.
+ (line 37)
+* field separators, 'FPAT' variable and: User-modified. (line 43)
* field separators, POSIX and: Fields. (line 6)
+* field separators, regular expressions as: Field Separators. (line 50)
* field separators, regular expressions as <1>: Regexp Field Splitting.
(line 6)
-* field separators, regular expressions as: Field Separators. (line 51)
-* field separators, See Also OFS: Changing Fields. (line 64)
+* field separators, See Also 'OFS': Changing Fields. (line 64)
* field separators, spaces as: Cut Program. (line 103)
-* fields <1>: Basic High Level. (line 73)
-* fields <2>: Fields. (line 6)
* fields: Reading Files. (line 14)
+* fields <1>: Fields. (line 6)
+* fields <2>: Basic High Level. (line 62)
* fields, adding: Changing Fields. (line 53)
* fields, changing contents of: Changing Fields. (line 6)
* fields, cutting: Cut Program. (line 6)
* fields, examining: Fields. (line 6)
* fields, number of: Fields. (line 33)
* fields, numbers: Nonconstant Fields. (line 6)
-* fields, printing: Print Examples. (line 21)
+* fields, printing: Print Examples. (line 20)
* fields, separating: Field Separators. (line 15)
+* fields, separating <1>: Field Separators. (line 15)
* fields, single-character: Single Character Fields.
(line 6)
-* FIELDWIDTHS variable <1>: User-modified. (line 37)
-* FIELDWIDTHS variable: Constant Size. (line 22)
+* 'FIELDWIDTHS' variable: Constant Size. (line 22)
+* 'FIELDWIDTHS' variable <1>: User-modified. (line 37)
* file descriptors: Special FD. (line 6)
-* file inclusion, @include directive: Include Files. (line 8)
-* file names, distinguishing: Auto-set. (line 56)
+* file inclusion, '@include' directive: Include Files. (line 8)
+* file names, distinguishing: Auto-set. (line 55)
* file names, in compatibility mode: Special Caveats. (line 9)
-* file names, standard streams in gawk: Special FD. (line 48)
-* FILENAME variable <1>: Auto-set. (line 90)
-* FILENAME variable: Reading Files. (line 6)
-* FILENAME variable, getline, setting with: Getline Notes. (line 19)
+* file names, standard streams in 'gawk': Special FD. (line 48)
+* 'FILENAME' variable: Reading Files. (line 6)
+* 'FILENAME' variable <1>: Auto-set. (line 90)
+* 'FILENAME' variable, 'getline', setting with: Getline Notes.
+ (line 19)
* filenames, assignments as: Ignoring Assigns. (line 6)
-* files, .gmo: Explaining gettext. (line 42)
-* files, .gmo, specifying directory of <1>: Programmer i18n. (line 48)
-* files, .gmo, specifying directory of: Explaining gettext. (line 54)
-* files, .mo, converting from .po: I18N Example. (line 64)
-* files, .po <1>: Translator i18n. (line 6)
-* files, .po: Explaining gettext. (line 37)
-* files, .po, converting to .mo: I18N Example. (line 64)
-* files, .pot: Explaining gettext. (line 31)
-* files, /dev/... special files: Special FD. (line 48)
-* files, /inet/... (gawk): TCP/IP Networking. (line 6)
-* files, /inet4/... (gawk): TCP/IP Networking. (line 6)
-* files, /inet6/... (gawk): TCP/IP Networking. (line 6)
-* files, awk programs in: Long. (line 6)
-* files, awkprof.out: Profiling. (line 6)
-* files, awkvars.out: Options. (line 93)
+* files, '.gmo': Explaining gettext. (line 42)
+* files, '.gmo', specifying directory of: Explaining gettext. (line 54)
+* files, '.gmo', specifying directory of <1>: Programmer i18n.
+ (line 48)
+* files, '.mo', converting from '.po': I18N Example. (line 66)
+* files, '.po': Explaining gettext. (line 37)
+* files, '.po' <1>: Translator i18n. (line 6)
+* files, '.po', converting to '.mo': I18N Example. (line 66)
+* files, '.pot': Explaining gettext. (line 31)
+* files, '/dev/...' special files: Special FD. (line 48)
+* files, '/inet/...' ('gawk'): TCP/IP Networking. (line 6)
+* files, '/inet4/...' ('gawk'): TCP/IP Networking. (line 6)
+* files, '/inet6/...' ('gawk'): TCP/IP Networking. (line 6)
+* files, 'awk' programs in: Long. (line 6)
+* files, 'awkprof.out': Profiling. (line 6)
+* files, 'awkvars.out': Options. (line 94)
* files, closing: I/O Functions. (line 10)
* files, descriptors, See file descriptors: Special FD. (line 6)
* files, group: Group Functions. (line 6)
@@ -32822,23 +32783,23 @@ Index
* files, managing, data file boundaries: Filetrans Function. (line 6)
* files, message object: Explaining gettext. (line 42)
* files, message object, converting from portable object files: I18N Example.
- (line 64)
-* files, message object, specifying directory of <1>: Programmer i18n.
- (line 48)
+ (line 66)
* files, message object, specifying directory of: Explaining gettext.
(line 54)
+* files, message object, specifying directory of <1>: Programmer i18n.
+ (line 48)
* files, multiple passes over: Other Arguments. (line 56)
* files, multiple, duplicating output into: Tee Program. (line 6)
* files, output, See output files: Close Files And Pipes.
(line 6)
* files, password: Passwd Functions. (line 16)
-* files, portable object <1>: Translator i18n. (line 6)
* files, portable object: Explaining gettext. (line 37)
+* files, portable object <1>: Translator i18n. (line 6)
* files, portable object template: Explaining gettext. (line 31)
* files, portable object, converting to message object files: I18N Example.
- (line 64)
+ (line 66)
* files, portable object, generating: Options. (line 147)
-* files, processing, ARGIND variable and: Auto-set. (line 51)
+* files, processing, 'ARGIND' variable and: Auto-set. (line 50)
* files, reading: Rewind Function. (line 6)
* files, reading, multiline records: Multiple Line. (line 6)
* files, searching for regular expressions: Egrep Program. (line 6)
@@ -32846,84 +32807,86 @@ Index
* files, source, search path for: Programs Exercises. (line 70)
* files, splitting: Split Program. (line 6)
* files, Texinfo, extracting programs from: Extract Program. (line 6)
-* find substring in string: String Functions. (line 156)
+* find substring in string: String Functions. (line 155)
* finding extensions: Finding Extensions. (line 6)
-* finish debugger command: Debugger Execution Control.
+* 'finish' debugger command: Debugger Execution Control.
(line 39)
-* Fish, Fred: Contributors. (line 50)
+* Fish, Fred: Contributors. (line 51)
* fixed-width data: Constant Size. (line 6)
-* flag variables <1>: Tee Program. (line 20)
* flag variables: Boolean Ops. (line 69)
+* flag variables <1>: Tee Program. (line 20)
* floating-point, numbers, arbitrary precision: Arbitrary Precision Arithmetic.
(line 6)
* floating-point, VAX/VMS: VMS Running. (line 50)
* flush buffered output: I/O Functions. (line 28)
-* fnmatch() extension function: Extension Sample Fnmatch.
+* 'fnmatch()' extension function: Extension Sample Fnmatch.
(line 12)
-* FNR variable <1>: Auto-set. (line 100)
-* FNR variable: Records. (line 6)
-* FNR variable, changing: Auto-set. (line 314)
-* for statement: For Statement. (line 6)
-* for statement, looping over arrays: Scanning an Array. (line 20)
-* fork() extension function: Extension Sample Fork.
+* 'FNR' variable: Records. (line 6)
+* 'FNR' variable <1>: Auto-set. (line 100)
+* 'FNR' variable, changing: Auto-set. (line 313)
+* 'for' statement: For Statement. (line 6)
+* 'for' statement, looping over arrays: Scanning an Array. (line 20)
+* 'fork()' extension function: Extension Sample Fork.
(line 11)
* format specifiers: Basic Printf. (line 15)
* format specifiers, mixing regular with positional specifiers: Printf
Ordering.
(line 57)
-* format specifiers, printf statement: Control Letters. (line 6)
-* format specifiers, strftime() function (gawk): Time Functions.
- (line 89)
+* format specifiers, 'printf' statement: Control Letters. (line 6)
+* format specifiers, 'strftime()' function ('gawk'): Time Functions.
+ (line 88)
* format time string: Time Functions. (line 48)
* formats, numeric output: OFMT. (line 6)
* formatting output: Printf. (line 6)
* formatting strings: String Functions. (line 384)
-* forward slash (/) to enclose regular expressions: Regexp. (line 10)
-* forward slash (/), / operator: Precedence. (line 55)
-* forward slash (/), /= operator <1>: Precedence. (line 95)
-* forward slash (/), /= operator: Assignment Ops. (line 130)
-* forward slash (/), /= operator, vs. /=.../ regexp constant: Assignment Ops.
- (line 148)
-* forward slash (/), patterns and: Expression Patterns. (line 24)
-* FPAT variable <1>: User-modified. (line 43)
-* FPAT variable: Splitting By Content.
+* forward slash ('/') to enclose regular expressions: Regexp. (line 10)
+* forward slash ('/'), '/' operator: Precedence. (line 54)
+* forward slash ('/'), '/=' operator: Assignment Ops. (line 129)
+* forward slash ('/'), '/=' operator <1>: Precedence. (line 94)
+* forward slash ('/'), '/=' operator, vs. '/=.../' regexp constant: Assignment
Ops.
+ (line 149)
+* forward slash ('/'), patterns and: Expression Patterns. (line 24)
+* 'FPAT' variable: Splitting By Content.
(line 25)
-* frame debugger command: Execution Stack. (line 27)
+* 'FPAT' variable <1>: User-modified. (line 43)
+* 'frame' debugger command: Execution Stack. (line 27)
* Free Documentation License (FDL): GNU Free Documentation License.
- (line 7)
-* Free Software Foundation (FSF) <1>: Glossary. (line 375)
-* Free Software Foundation (FSF) <2>: Getting. (line 10)
+ (line 8)
* Free Software Foundation (FSF): Manual History. (line 6)
-* FreeBSD: Glossary. (line 753)
-* FS variable <1>: User-modified. (line 50)
-* FS variable: Field Separators. (line 15)
-* FS variable, --field-separator option and: Options. (line 21)
-* FS variable, as null string: Single Character Fields.
+* Free Software Foundation (FSF) <1>: Getting. (line 10)
+* Free Software Foundation (FSF) <2>: Glossary. (line 372)
+* Free Software Foundation (FSF) <3>: Glossary. (line 405)
+* FreeBSD: Glossary. (line 748)
+* 'FS' variable: Field Separators. (line 15)
+* 'FS' variable <1>: User-modified. (line 50)
+* 'FS' variable, '--field-separator' option and: Options. (line 21)
+* 'FS' variable, as null string: Single Character Fields.
(line 20)
-* FS variable, as TAB character: Options. (line 268)
-* FS variable, changing value of: Field Separators. (line 35)
-* FS variable, running awk programs and: Cut Program. (line 63)
-* FS variable, setting from command line: Command Line Field Separator.
+* 'FS' variable, as TAB character: Options. (line 266)
+* 'FS' variable, changing value of: Field Separators. (line 34)
+* 'FS' variable, running 'awk' programs and: Cut Program. (line 63)
+* 'FS' variable, setting from command line: Command Line Field Separator.
(line 6)
-* FS, containing ^: Regexp Field Splitting.
+* 'FS', containing '^': Regexp Field Splitting.
(line 59)
-* FS, in multiline records: Multiple Line. (line 41)
-* FSF (Free Software Foundation) <1>: Glossary. (line 375)
-* FSF (Free Software Foundation) <2>: Getting. (line 10)
+* 'FS', in multiline records: Multiple Line. (line 41)
* FSF (Free Software Foundation): Manual History. (line 6)
-* fts() extension function: Extension Sample File Functions.
- (line 61)
-* FUNCTAB array: Auto-set. (line 116)
+* FSF (Free Software Foundation) <1>: Getting. (line 10)
+* FSF (Free Software Foundation) <2>: Glossary. (line 372)
+* FSF (Free Software Foundation) <3>: Glossary. (line 405)
+* 'fts()' extension function: Extension Sample File Functions.
+ (line 60)
+* 'FUNCTAB' array: Auto-set. (line 116)
* function calls: Function Calls. (line 6)
* function calls, indirect: Indirect Calls. (line 6)
-* function calls, indirect, @-notation for: Indirect Calls. (line 47)
+* function calls, indirect, '@'-notation for: Indirect Calls. (line 47)
* function definition example: Function Example. (line 6)
* function pointers: Indirect Calls. (line 6)
* functions, arrays as parameters to: Pass By Value/Reference.
(line 44)
-* functions, built-in <1>: Functions. (line 6)
* functions, built-in: Function Calls. (line 10)
+* functions, built-in <1>: Functions. (line 6)
* functions, built-in, evaluation order: Calling Built-in. (line 30)
-* functions, defining: Definition Syntax. (line 9)
+* functions, defining: Definition Syntax. (line 10)
* functions, library: Library Functions. (line 6)
* functions, library, assertions: Assert Function. (line 6)
* functions, library, associative arrays and: Library Names. (line 58)
@@ -32946,8 +32909,8 @@ Index
* functions, library, rounding numbers: Round Function. (line 6)
* functions, library, user database, reading: Passwd Functions.
(line 6)
-* functions, names of: Definition Syntax. (line 23)
-* functions, recursive: Definition Syntax. (line 88)
+* functions, names of: Definition Syntax. (line 24)
+* functions, recursive: Definition Syntax. (line 89)
* functions, string-translation: I18N Functions. (line 6)
* functions, undefined: Pass By Value/Reference.
(line 68)
@@ -32955,255 +32918,266 @@ Index
* functions, user-defined, calling: Function Caveats. (line 6)
* functions, user-defined, counts, in a profile: Profiling. (line 137)
* functions, user-defined, library of: Library Functions. (line 6)
-* functions, user-defined, next/nextfile statements and <1>: Nextfile
Statement.
- (line 47)
-* functions, user-defined, next/nextfile statements and: Next Statement.
+* functions, user-defined, 'next'/'nextfile' statements and: Next Statement.
(line 44)
-* G-d: Acknowledgments. (line 94)
-* Garfinkle, Scott: Contributors. (line 34)
-* gawk program, dynamic profiling: Profiling. (line 179)
-* gawk version: Auto-set. (line 207)
-* gawk, ARGIND variable in: Other Arguments. (line 15)
-* gawk, awk and <1>: This Manual. (line 14)
-* gawk, awk and: Preface. (line 21)
-* gawk, bitwise operations in: Bitwise Functions. (line 40)
-* gawk, break statement in: Break Statement. (line 51)
-* gawk, character classes and: Bracket Expressions. (line 101)
-* gawk, coding style in: Adding Code. (line 38)
-* gawk, command-line options, and regular expressions: GNU Regexp Operators.
- (line 70)
-* gawk, configuring: Configuration Philosophy.
+* functions, user-defined, 'next'/'nextfile' statements and <1>: Nextfile
Statement.
+ (line 47)
+* G-d: Acknowledgments. (line 93)
+* Garfinkle, Scott: Contributors. (line 35)
+* 'gawk' program, dynamic profiling: Profiling. (line 178)
+* 'gawk' version: Auto-set. (line 206)
+* 'gawk', 'ARGIND' variable in: Other Arguments. (line 15)
+* 'gawk', 'awk' and: Preface. (line 21)
+* 'gawk', 'awk' and <1>: This Manual. (line 14)
+* 'gawk', bitwise operations in: Bitwise Functions. (line 40)
+* 'gawk', 'break' statement in: Break Statement. (line 51)
+* 'gawk', character classes and: Bracket Expressions. (line 100)
+* 'gawk', coding style in: Adding Code. (line 37)
+* 'gawk', command-line options, and regular expressions: GNU Regexp Operators.
+ (line 73)
+* 'gawk', configuring: Configuration Philosophy.
(line 6)
-* gawk, configuring, options: Additional Configuration Options.
+* 'gawk', configuring, options: Additional Configuration Options.
(line 6)
-* gawk, continue statement in: Continue Statement. (line 44)
-* gawk, distribution: Distribution contents.
+* 'gawk', 'continue' statement in: Continue Statement. (line 44)
+* 'gawk', distribution: Distribution contents.
(line 6)
-* gawk, ERRNO variable in <1>: TCP/IP Networking. (line 54)
-* gawk, ERRNO variable in <2>: Auto-set. (line 74)
-* gawk, ERRNO variable in <3>: BEGINFILE/ENDFILE. (line 26)
-* gawk, ERRNO variable in <4>: Close Files And Pipes.
- (line 141)
-* gawk, ERRNO variable in: Getline. (line 19)
-* gawk, escape sequences: Escape Sequences. (line 117)
-* gawk, extensions, disabling: Options. (line 256)
-* gawk, features, adding: Adding Code. (line 6)
-* gawk, features, advanced: Advanced Features. (line 6)
-* gawk, field separators and: User-modified. (line 71)
-* gawk, FIELDWIDTHS variable in <1>: User-modified. (line 37)
-* gawk, FIELDWIDTHS variable in: Constant Size. (line 22)
-* gawk, file names in: Special Files. (line 6)
-* gawk, format-control characters: Control Letters. (line 18)
-* gawk, FPAT variable in <1>: User-modified. (line 43)
-* gawk, FPAT variable in: Splitting By Content.
+* 'gawk', 'ERRNO' variable in: Getline. (line 19)
+* 'gawk', 'ERRNO' variable in <1>: Close Files And Pipes.
+ (line 140)
+* 'gawk', 'ERRNO' variable in <2>: BEGINFILE/ENDFILE. (line 26)
+* 'gawk', 'ERRNO' variable in <3>: Auto-set. (line 74)
+* 'gawk', 'ERRNO' variable in <4>: TCP/IP Networking. (line 54)
+* 'gawk', escape sequences: Escape Sequences. (line 117)
+* 'gawk', extensions, disabling: Options. (line 254)
+* 'gawk', features, adding: Adding Code. (line 6)
+* 'gawk', features, advanced: Advanced Features. (line 6)
+* 'gawk', field separators and: User-modified. (line 71)
+* 'gawk', 'FIELDWIDTHS' variable in: Constant Size. (line 22)
+* 'gawk', 'FIELDWIDTHS' variable in <1>: User-modified. (line 37)
+* 'gawk', file names in: Special Files. (line 6)
+* 'gawk', format-control characters: Control Letters. (line 18)
+* 'gawk', format-control characters <1>: Control Letters. (line 93)
+* 'gawk', 'FPAT' variable in: Splitting By Content.
(line 25)
-* gawk, FUNCTAB array in: Auto-set. (line 116)
-* gawk, function arguments and: Calling Built-in. (line 16)
-* gawk, hexadecimal numbers and: Nondecimal-numbers. (line 42)
-* gawk, IGNORECASE variable in <1>: Array Sorting Functions.
+* 'gawk', 'FPAT' variable in <1>: User-modified. (line 43)
+* 'gawk', 'FUNCTAB' array in: Auto-set. (line 116)
+* 'gawk', function arguments and: Calling Built-in. (line 16)
+* 'gawk', hexadecimal numbers and: Nondecimal-numbers. (line 41)
+* 'gawk', 'IGNORECASE' variable in: Case-sensitivity. (line 26)
+* 'gawk', 'IGNORECASE' variable in <1>: User-modified. (line 76)
+* 'gawk', 'IGNORECASE' variable in <2>: Array Intro. (line 100)
+* 'gawk', 'IGNORECASE' variable in <3>: String Functions. (line 58)
+* 'gawk', 'IGNORECASE' variable in <4>: Array Sorting Functions.
(line 83)
-* gawk, IGNORECASE variable in <2>: String Functions. (line 58)
-* gawk, IGNORECASE variable in <3>: Array Intro. (line 100)
-* gawk, IGNORECASE variable in <4>: User-modified. (line 76)
-* gawk, IGNORECASE variable in: Case-sensitivity. (line 26)
-* gawk, implementation issues: Notes. (line 6)
-* gawk, implementation issues, debugging: Compatibility Mode. (line 6)
-* gawk, implementation issues, downward compatibility: Compatibility Mode.
+* 'gawk', implementation issues: Notes. (line 6)
+* 'gawk', implementation issues, debugging: Compatibility Mode.
+ (line 6)
+* 'gawk', implementation issues, downward compatibility: Compatibility Mode.
(line 6)
-* gawk, implementation issues, limits: Getline Notes. (line 14)
-* gawk, implementation issues, pipes: Redirection. (line 129)
-* gawk, installing: Installation. (line 6)
-* gawk, internationalization and, See internationalization:
Internationalization.
+* 'gawk', implementation issues, limits: Getline Notes. (line 14)
+* 'gawk', implementation issues, pipes: Redirection. (line 129)
+* 'gawk', installing: Installation. (line 6)
+* 'gawk', internationalization and, See internationalization:
Internationalization.
(line 13)
-* gawk, interpreter, adding code to: Using Internal File Ops.
+* 'gawk', interpreter, adding code to: Using Internal File Ops.
(line 6)
-* gawk, interval expressions and: Regexp Operators. (line 139)
-* gawk, line continuation in: Conditional Exp. (line 34)
-* gawk, LINT variable in: User-modified. (line 87)
-* gawk, list of contributors to: Contributors. (line 6)
-* gawk, MS-DOS version of: PC Using. (line 10)
-* gawk, MS-Windows version of: PC Using. (line 10)
-* gawk, newlines in: Statements/Lines. (line 12)
-* gawk, octal numbers and: Nondecimal-numbers. (line 42)
-* gawk, OS/2 version of: PC Using. (line 16)
-* gawk, predefined variables and: Built-in Variables. (line 14)
-* gawk, PROCINFO array in <1>: Two-way I/O. (line 99)
-* gawk, PROCINFO array in <2>: Time Functions. (line 47)
-* gawk, PROCINFO array in: Auto-set. (line 130)
-* gawk, regexp constants and: Using Constant Regexps.
+* 'gawk', interval expressions and: Regexp Operators. (line 139)
+* 'gawk', line continuation in: Conditional Exp. (line 34)
+* 'gawk', 'LINT' variable in: User-modified. (line 87)
+* 'gawk', list of contributors to: Contributors. (line 6)
+* 'gawk', MS-DOS version of: PC Using. (line 10)
+* 'gawk', MS-Windows version of: PC Using. (line 10)
+* 'gawk', newlines in: Statements/Lines. (line 12)
+* 'gawk', octal numbers and: Nondecimal-numbers. (line 41)
+* 'gawk', OS/2 version of: PC Using. (line 16)
+* 'gawk', predefined variables and: Built-in Variables. (line 14)
+* 'gawk', 'PROCINFO' array in: Auto-set. (line 130)
+* 'gawk', 'PROCINFO' array in <1>: Auto-set. (line 241)
+* 'gawk', 'PROCINFO' array in <2>: Time Functions. (line 47)
+* 'gawk', 'PROCINFO' array in <3>: Two-way I/O. (line 99)
+* 'gawk', regexp constants and: Using Constant Regexps.
(line 28)
-* gawk, regular expressions, case sensitivity: Case-sensitivity.
+* 'gawk', regular expressions, case sensitivity: Case-sensitivity.
(line 26)
-* gawk, regular expressions, operators: GNU Regexp Operators.
+* 'gawk', regular expressions, operators: GNU Regexp Operators.
(line 6)
-* gawk, regular expressions, precedence: Regexp Operators. (line 161)
-* gawk, RT variable in <1>: Auto-set. (line 265)
-* gawk, RT variable in <2>: Multiple Line. (line 129)
-* gawk, RT variable in: awk split records. (line 125)
-* gawk, See Also awk: Preface. (line 34)
-* gawk, source code, obtaining: Getting. (line 6)
-* gawk, splitting fields and: Constant Size. (line 87)
-* gawk, string-translation functions: I18N Functions. (line 6)
-* gawk, SYMTAB array in: Auto-set. (line 269)
-* gawk, TEXTDOMAIN variable in: User-modified. (line 151)
-* gawk, timestamps: Time Functions. (line 6)
-* gawk, uses for: Preface. (line 34)
-* gawk, versions of, information about, printing: Options. (line 302)
-* gawk, VMS version of: VMS Installation. (line 6)
-* gawk, word-boundary operator: GNU Regexp Operators.
- (line 63)
-* gawkextlib: gawkextlib. (line 6)
-* gawkextlib project: gawkextlib. (line 6)
-* General Public License (GPL): Glossary. (line 399)
+* 'gawk', regular expressions, precedence: Regexp Operators. (line 161)
+* 'gawk', 'RT' variable in: awk split records. (line 124)
+* 'gawk', 'RT' variable in <1>: Multiple Line. (line 129)
+* 'gawk', 'RT' variable in <2>: Auto-set. (line 264)
+* 'gawk', See Also 'awk': Preface. (line 34)
+* 'gawk', source code, obtaining: Getting. (line 6)
+* 'gawk', splitting fields and: Constant Size. (line 86)
+* 'gawk', string-translation functions: I18N Functions. (line 6)
+* 'gawk', 'SYMTAB' array in: Auto-set. (line 268)
+* 'gawk', 'TEXTDOMAIN' variable in: User-modified. (line 152)
+* 'gawk', timestamps: Time Functions. (line 6)
+* 'gawk', uses for: Preface. (line 34)
+* 'gawk', versions of, information about, printing: Options. (line 299)
+* 'gawk', VMS version of: VMS Installation. (line 6)
+* 'gawk', word-boundary operator: GNU Regexp Operators.
+ (line 66)
+* 'gawkextlib': gawkextlib. (line 6)
+* 'gawkextlib' project: gawkextlib. (line 6)
+* General Public License (GPL): Glossary. (line 396)
* General Public License, See GPL: Manual History. (line 11)
* generate time values: Time Functions. (line 25)
-* gensub <1>: String Functions. (line 90)
-* gensub: Using Constant Regexps.
+* 'gensub': Using Constant Regexps.
(line 43)
-* gensub() function (gawk), escape processing: Gory Details. (line 6)
-* getaddrinfo() function (C library): TCP/IP Networking. (line 38)
-* getgrent() function (C library): Group Functions. (line 6)
-* getgrent() user-defined function: Group Functions. (line 6)
-* getgrgid() function (C library): Group Functions. (line 183)
-* getgrgid() user-defined function: Group Functions. (line 186)
-* getgrnam() function (C library): Group Functions. (line 172)
-* getgrnam() user-defined function: Group Functions. (line 177)
-* getgruser() function (C library): Group Functions. (line 192)
-* getgruser() function, user-defined: Group Functions. (line 195)
-* getline command: Reading Files. (line 20)
-* getline command, _gr_init() user-defined function: Group Functions.
- (line 83)
-* getline command, _pw_init() function: Passwd Functions. (line 154)
-* getline command, coprocesses, using from <1>: Close Files And Pipes.
+* 'gensub' <1>: String Functions. (line 89)
+* 'gensub()' function ('gawk'), escape processing: Gory Details.
+ (line 6)
+* 'getaddrinfo()' function (C library): TCP/IP Networking. (line 39)
+* 'getgrent()' function (C library): Group Functions. (line 6)
+* 'getgrent()' function (C library) <1>: Group Functions. (line 200)
+* 'getgrent()' user-defined function: Group Functions. (line 6)
+* 'getgrent()' user-defined function <1>: Group Functions. (line 203)
+* 'getgrgid()' function (C library): Group Functions. (line 182)
+* 'getgrgid()' user-defined function: Group Functions. (line 185)
+* 'getgrnam()' function (C library): Group Functions. (line 171)
+* 'getgrnam()' user-defined function: Group Functions. (line 176)
+* 'getgruser()' function (C library): Group Functions. (line 191)
+* 'getgruser()' function, user-defined: Group Functions. (line 194)
+* 'getline' command: Reading Files. (line 20)
+* 'getline' command, coprocesses, using from: Getline/Coprocess.
(line 6)
-* getline command, coprocesses, using from: Getline/Coprocess.
+* 'getline' command, coprocesses, using from <1>: Close Files And Pipes.
(line 6)
-* getline command, deadlock and: Two-way I/O. (line 52)
-* getline command, explicit input with: Getline. (line 6)
-* getline command, FILENAME variable and: Getline Notes. (line 19)
-* getline command, return values: Getline. (line 19)
-* getline command, variants: Getline Summary. (line 6)
-* getline from a file: Getline/File. (line 6)
-* getline into a variable: Getline/Variable. (line 6)
-* getline statement, BEGINFILE/ENDFILE patterns and: BEGINFILE/ENDFILE.
+* 'getline' command, deadlock and: Two-way I/O. (line 53)
+* 'getline' command, explicit input with: Getline. (line 6)
+* 'getline' command, 'FILENAME' variable and: Getline Notes. (line 19)
+* 'getline' command, return values: Getline. (line 19)
+* 'getline' command, variants: Getline Summary. (line 6)
+* 'getline' command, '_gr_init()' user-defined function: Group Functions.
+ (line 83)
+* 'getline' command, '_pw_init()' function: Passwd Functions. (line 154)
+* 'getline' from a file: Getline/File. (line 6)
+* 'getline' into a variable: Getline/Variable. (line 6)
+* 'getline' statement, 'BEGINFILE'/'ENDFILE' patterns and: BEGINFILE/ENDFILE.
(line 53)
-* getlocaltime() user-defined function: Getlocaltime Function.
+* 'getlocaltime()' user-defined function: Getlocaltime Function.
(line 16)
-* getopt() function (C library): Getopt Function. (line 15)
-* getopt() user-defined function: Getopt Function. (line 108)
-* getpwent() function (C library): Passwd Functions. (line 16)
-* getpwent() user-defined function: Passwd Functions. (line 16)
-* getpwnam() function (C library): Passwd Functions. (line 174)
-* getpwnam() user-defined function: Passwd Functions. (line 179)
-* getpwuid() function (C library): Passwd Functions. (line 185)
-* getpwuid() user-defined function: Passwd Functions. (line 189)
-* gettext library: Explaining gettext. (line 6)
-* gettext library, locale categories: Explaining gettext. (line 81)
-* gettext() function (C library): Explaining gettext. (line 63)
-* gettimeofday() extension function: Extension Sample Time.
+* 'getopt()' function (C library): Getopt Function. (line 15)
+* 'getopt()' user-defined function: Getopt Function. (line 108)
+* 'getopt()' user-defined function <1>: Getopt Function. (line 134)
+* 'getpwent()' function (C library): Passwd Functions. (line 16)
+* 'getpwent()' function (C library) <1>: Passwd Functions. (line 195)
+* 'getpwent()' user-defined function: Passwd Functions. (line 16)
+* 'getpwent()' user-defined function <1>: Passwd Functions. (line 199)
+* 'getpwnam()' function (C library): Passwd Functions. (line 174)
+* 'getpwnam()' user-defined function: Passwd Functions. (line 179)
+* 'getpwuid()' function (C library): Passwd Functions. (line 185)
+* 'getpwuid()' user-defined function: Passwd Functions. (line 189)
+* 'gettext' library: Explaining gettext. (line 6)
+* 'gettext' library, locale categories: Explaining gettext. (line 81)
+* 'gettext()' function (C library): Explaining gettext. (line 63)
+* 'gettimeofday()' extension function: Extension Sample Time.
(line 12)
-* git utility <1>: Adding Code. (line 111)
-* git utility <2>: Accessing The Source.
+* 'git' utility: gawkextlib. (line 29)
+* 'git' utility <1>: Other Versions. (line 29)
+* 'git' utility <2>: Accessing The Source.
(line 10)
-* git utility <3>: Other Versions. (line 29)
-* git utility: gawkextlib. (line 29)
-* Git, use of for gawk source code: Derived Files. (line 6)
+* 'git' utility <3>: Adding Code. (line 110)
+* Git, use of for 'gawk' source code: Derived Files. (line 6)
* GNITS mailing list: Acknowledgments. (line 52)
-* GNU awk, See gawk: Preface. (line 51)
+* GNU 'awk', See 'gawk': Preface. (line 51)
* GNU Free Documentation License: GNU Free Documentation License.
- (line 7)
-* GNU General Public License: Glossary. (line 399)
-* GNU Lesser General Public License: Glossary. (line 496)
-* GNU long options <1>: Options. (line 6)
+ (line 8)
+* GNU General Public License: Glossary. (line 396)
+* GNU Lesser General Public License: Glossary. (line 491)
* GNU long options: Command Line. (line 13)
+* GNU long options <1>: Options. (line 6)
* GNU long options, printing list of: Options. (line 154)
-* GNU Project <1>: Glossary. (line 408)
* GNU Project: Manual History. (line 11)
-* GNU/Linux <1>: Glossary. (line 753)
-* GNU/Linux <2>: I18N Example. (line 55)
+* GNU Project <1>: Glossary. (line 405)
* GNU/Linux: Manual History. (line 28)
-* Gordon, Assaf: Contributors. (line 105)
-* GPL (General Public License) <1>: Glossary. (line 399)
+* GNU/Linux <1>: I18N Example. (line 57)
+* GNU/Linux <2>: Glossary. (line 748)
+* Gordon, Assaf: Contributors. (line 106)
* GPL (General Public License): Manual History. (line 11)
-* GPL (General Public License), printing: Options. (line 88)
-* grcat program: Group Functions. (line 16)
-* Grigera, Juan: Contributors. (line 57)
+* GPL (General Public License) <1>: Glossary. (line 396)
+* GPL (General Public License), printing: Options. (line 89)
+* 'grcat' program: Group Functions. (line 16)
+* Grigera, Juan: Contributors. (line 58)
* group database, reading: Group Functions. (line 6)
* group file: Group Functions. (line 6)
-* group ID of gawk user: Auto-set. (line 180)
+* group ID of 'gawk' user: Auto-set. (line 179)
* groups, information about: Group Functions. (line 6)
-* gsub <1>: String Functions. (line 140)
-* gsub: Using Constant Regexps.
+* 'gsub': Using Constant Regexps.
(line 43)
-* gsub() function, arguments of: String Functions. (line 463)
-* gsub() function, escape processing: Gory Details. (line 6)
-* h debugger command (alias for help): Miscellaneous Debugger Commands.
+* 'gsub' <1>: String Functions. (line 139)
+* 'gsub()' function, arguments of: String Functions. (line 463)
+* 'gsub()' function, escape processing: Gory Details. (line 6)
+* 'h' debugger command (alias for 'help'): Miscellaneous Debugger Commands.
(line 66)
-* Hankerson, Darrel <1>: Contributors. (line 60)
* Hankerson, Darrel: Acknowledgments. (line 60)
-* Haque, John: Contributors. (line 108)
+* Hankerson, Darrel <1>: Contributors. (line 61)
+* Haque, John: Contributors. (line 109)
* Hartholz, Elaine: Acknowledgments. (line 38)
* Hartholz, Marshall: Acknowledgments. (line 38)
-* Hasegawa, Isamu: Contributors. (line 94)
-* help debugger command: Miscellaneous Debugger Commands.
+* Hasegawa, Isamu: Contributors. (line 95)
+* 'help' debugger command: Miscellaneous Debugger Commands.
(line 66)
* hexadecimal numbers: Nondecimal-numbers. (line 6)
-* hexadecimal values, enabling interpretation of: Options. (line 211)
+* hexadecimal values, enabling interpretation of: Options. (line 209)
* history expansion, in debugger: Readline Support. (line 6)
-* histsort.awk program: History Sorting. (line 25)
+* 'histsort.awk' program: History Sorting. (line 25)
* Hughes, Phil: Acknowledgments. (line 43)
-* HUP signal, for dynamic profiling: Profiling. (line 211)
-* hyphen (-), - operator: Precedence. (line 52)
-* hyphen (-), -- operator <1>: Precedence. (line 46)
-* hyphen (-), -- operator: Increment Ops. (line 48)
-* hyphen (-), -= operator <1>: Precedence. (line 95)
-* hyphen (-), -= operator: Assignment Ops. (line 130)
-* hyphen (-), filenames beginning with: Options. (line 59)
-* hyphen (-), in bracket expressions: Bracket Expressions. (line 17)
-* i debugger command (alias for info): Debugger Info. (line 13)
-* id utility: Id Program. (line 6)
-* id.awk program: Id Program. (line 31)
-* if statement: If Statement. (line 6)
-* if statement, actions, changing: Ranges. (line 25)
-* if statement, use of regexps in: Regexp Usage. (line 19)
-* igawk.sh program: Igawk Program. (line 124)
+* 'HUP' signal, for dynamic profiling: Profiling. (line 210)
+* hyphen ('-'), '-' operator: Precedence. (line 51)
+* hyphen ('-'), '-' operator <1>: Precedence. (line 57)
+* hyphen ('-'), '--' operator: Increment Ops. (line 48)
+* hyphen ('-'), '--' operator <1>: Precedence. (line 45)
+* hyphen ('-'), '-=' operator: Assignment Ops. (line 129)
+* hyphen ('-'), '-=' operator <1>: Precedence. (line 94)
+* hyphen ('-'), filenames beginning with: Options. (line 60)
+* hyphen ('-'), in bracket expressions: Bracket Expressions. (line 17)
+* 'i' debugger command (alias for 'info'): Debugger Info. (line 13)
+* 'id' utility: Id Program. (line 6)
+* 'id.awk' program: Id Program. (line 31)
+* 'if' statement: If Statement. (line 6)
+* 'if' statement, actions, changing: Ranges. (line 25)
+* 'if' statement, use of regexps in: Regexp Usage. (line 19)
+* 'igawk.sh' program: Igawk Program. (line 124)
* ignore breakpoint: Breakpoint Control. (line 87)
-* ignore debugger command: Breakpoint Control. (line 87)
-* IGNORECASE variable: User-modified. (line 76)
-* IGNORECASE variable, and array indices: Array Intro. (line 100)
-* IGNORECASE variable, and array sorting functions: Array Sorting Functions.
+* 'ignore' debugger command: Breakpoint Control. (line 87)
+* 'IGNORECASE' variable: User-modified. (line 76)
+* 'IGNORECASE' variable, and array indices: Array Intro. (line 100)
+* 'IGNORECASE' variable, and array sorting functions: Array Sorting Functions.
(line 83)
-* IGNORECASE variable, in example programs: Library Functions.
+* 'IGNORECASE' variable, in example programs: Library Functions.
(line 53)
-* IGNORECASE variable, with ~ and !~ operators: Case-sensitivity.
+* 'IGNORECASE' variable, with '~' and '!~' operators: Case-sensitivity.
(line 26)
* Illumos: Other Versions. (line 109)
-* Illumos, POSIX-compliant awk: Other Versions. (line 109)
-* implementation issues, gawk: Notes. (line 6)
-* implementation issues, gawk, debugging: Compatibility Mode. (line 6)
-* implementation issues, gawk, limits <1>: Redirection. (line 129)
-* implementation issues, gawk, limits: Getline Notes. (line 14)
-* in operator <1>: For Statement. (line 76)
-* in operator <2>: Precedence. (line 83)
-* in operator: Comparison Operators.
+* Illumos, POSIX-compliant 'awk': Other Versions. (line 109)
+* implementation issues, 'gawk': Notes. (line 6)
+* implementation issues, 'gawk', debugging: Compatibility Mode.
+ (line 6)
+* implementation issues, 'gawk', limits: Getline Notes. (line 14)
+* implementation issues, 'gawk', limits <1>: Redirection. (line 129)
+* 'in' operator: Comparison Operators.
(line 11)
-* in operator, index existence in multidimensional arrays: Multidimensional.
- (line 43)
-* in operator, order of array access: Scanning an Array. (line 48)
-* in operator, testing if array element exists: Reference to Elements.
+* 'in' operator <1>: Precedence. (line 82)
+* 'in' operator <2>: For Statement. (line 76)
+* 'in' operator, index existence in multidimensional arrays: Multidimensional.
+ (line 41)
+* 'in' operator, order of array access: Scanning an Array. (line 48)
+* 'in' operator, testing if array element exists: Reference to Elements.
(line 38)
-* in operator, use in loops: Scanning an Array. (line 17)
-* including files, @include directive: Include Files. (line 8)
+* 'in' operator, use in loops: Scanning an Array. (line 17)
+* including files, '@include' directive: Include Files. (line 8)
* increment operators: Increment Ops. (line 6)
-* index: String Functions. (line 156)
-* indexing arrays: Array Intro. (line 50)
+* 'index': String Functions. (line 155)
+* indexing arrays: Array Intro. (line 48)
* indirect function calls: Indirect Calls. (line 6)
-* indirect function calls, @-notation: Indirect Calls. (line 47)
+* indirect function calls, '@'-notation: Indirect Calls. (line 47)
* infinite precision: Arbitrary Precision Arithmetic.
(line 6)
-* info debugger command: Debugger Info. (line 13)
-* initialization, automatic: More Complex. (line 38)
-* inplace extension: Extension Sample Inplace.
+* 'info' debugger command: Debugger Info. (line 13)
+* initialization, automatic: More Complex. (line 39)
+* 'inplace' extension: Extension Sample Inplace.
(line 6)
* input files: Reading Files. (line 6)
* input files, closing: Close Files And Pipes.
@@ -33211,42 +33185,43 @@ Index
* input files, counting elements in: Wc Program. (line 6)
* input files, examples: Sample Data Files. (line 6)
* input files, reading: Reading Files. (line 6)
-* input files, running awk without: Read Terminal. (line 6)
+* input files, running 'awk' without: Read Terminal. (line 6)
+* input files, running 'awk' without <1>: Read Terminal. (line 17)
* input files, variable assignments and: Other Arguments. (line 26)
-* input pipeline: Getline/Pipe. (line 9)
-* input record, length of: String Functions. (line 178)
+* input pipeline: Getline/Pipe. (line 10)
+* input record, length of: String Functions. (line 177)
* input redirection: Getline/File. (line 6)
* input, data, nondecimal: Nondecimal Data. (line 6)
* input, explicit: Getline. (line 6)
* input, files, See input files: Multiple Line. (line 6)
* input, multiline records: Multiple Line. (line 6)
* input, splitting into records: Records. (line 6)
-* input, standard <1>: Special FD. (line 6)
* input, standard: Read Terminal. (line 6)
+* input, standard <1>: Special FD. (line 6)
* input/output functions: I/O Functions. (line 6)
* input/output, binary: User-modified. (line 15)
-* input/output, from BEGIN and END: I/O And BEGIN/END. (line 6)
-* input/output, two-way: Two-way I/O. (line 25)
+* input/output, from 'BEGIN' and 'END': I/O And BEGIN/END. (line 6)
+* input/output, two-way: Two-way I/O. (line 27)
* insomnia, cure for: Alarm Program. (line 6)
* installation, VMS: VMS Installation. (line 6)
-* installing gawk: Installation. (line 6)
+* installing 'gawk': Installation. (line 6)
* instruction tracing, in debugger: Debugger Info. (line 90)
-* int: Numeric Functions. (line 23)
-* INT signal (MS-Windows): Profiling. (line 214)
+* 'int': Numeric Functions. (line 22)
+* 'INT' signal (MS-Windows): Profiling. (line 213)
* integer array indices: Numeric Array Subscripts.
(line 31)
* integers, arbitrary precision: Arbitrary Precision Integers.
(line 6)
* integers, unsigned: Computer Arithmetic. (line 41)
* interacting with other programs: I/O Functions. (line 107)
-* internationalization <1>: I18N and L10N. (line 6)
* internationalization: I18N Functions. (line 6)
+* internationalization <1>: I18N and L10N. (line 6)
+* internationalization, localization: User-modified. (line 152)
* internationalization, localization <1>: Internationalization.
(line 13)
-* internationalization, localization: User-modified. (line 151)
* internationalization, localization, character classes: Bracket Expressions.
- (line 101)
-* internationalization, localization, gawk and: Internationalization.
+ (line 100)
+* internationalization, localization, 'gawk' and: Internationalization.
(line 13)
* internationalization, localization, locale categories: Explaining gettext.
(line 81)
@@ -33255,99 +33230,99 @@ Index
* internationalization, localization, portability and: I18N Portability.
(line 6)
* internationalizing a program: Explaining gettext. (line 6)
-* interpreted programs <1>: Glossary. (line 450)
-* interpreted programs: Basic High Level. (line 15)
+* interpreted programs: Basic High Level. (line 13)
+* interpreted programs <1>: Glossary. (line 445)
* interval expressions, regexp operator: Regexp Operators. (line 116)
-* inventory-shipped file: Sample Data Files. (line 32)
+* 'inventory-shipped' file: Sample Data Files. (line 32)
* invoke shell command: I/O Functions. (line 107)
-* isarray: Type Functions. (line 11)
-* ISO: Glossary. (line 461)
-* ISO 8859-1: Glossary. (line 197)
-* ISO Latin-1: Glossary. (line 197)
+* 'isarray': Type Functions. (line 11)
+* ISO: Glossary. (line 456)
+* ISO 8859-1: Glossary. (line 196)
+* ISO Latin-1: Glossary. (line 196)
* Jacobs, Andrew: Passwd Functions. (line 90)
-* Jaegermann, Michal <1>: Contributors. (line 45)
* Jaegermann, Michal: Acknowledgments. (line 60)
-* Java implementation of awk: Other Versions. (line 117)
-* Java programming language: Glossary. (line 473)
-* jawk: Other Versions. (line 117)
+* Jaegermann, Michal <1>: Contributors. (line 46)
+* Java implementation of 'awk': Other Versions. (line 117)
+* Java programming language: Glossary. (line 468)
+* 'jawk': Other Versions. (line 117)
* Jedi knights: Undocumented. (line 6)
* Johansen, Chris: Signature Program. (line 25)
-* join() user-defined function: Join Function. (line 18)
-* Kahrs, Ju"rgen <1>: Contributors. (line 70)
+* 'join()' user-defined function: Join Function. (line 18)
* Kahrs, Ju"rgen: Acknowledgments. (line 60)
+* Kahrs, Ju"rgen <1>: Contributors. (line 71)
* Kasal, Stepan: Acknowledgments. (line 60)
* Kenobi, Obi-Wan: Undocumented. (line 6)
-* Kernighan, Brian <1>: Glossary. (line 207)
-* Kernighan, Brian <2>: Basic Data Typing. (line 54)
-* Kernighan, Brian <3>: Other Versions. (line 13)
-* Kernighan, Brian <4>: Contributors. (line 11)
-* Kernighan, Brian <5>: BTL. (line 6)
-* Kernighan, Brian <6>: Library Functions. (line 12)
-* Kernighan, Brian <7>: Concatenation. (line 6)
-* Kernighan, Brian <8>: Getline/Pipe. (line 6)
-* Kernighan, Brian <9>: Acknowledgments. (line 78)
-* Kernighan, Brian <10>: Conventions. (line 38)
* Kernighan, Brian: History. (line 17)
-* kill command, dynamic profiling: Profiling. (line 188)
+* Kernighan, Brian <1>: Conventions. (line 38)
+* Kernighan, Brian <2>: Acknowledgments. (line 78)
+* Kernighan, Brian <3>: Getline/Pipe. (line 6)
+* Kernighan, Brian <4>: Concatenation. (line 6)
+* Kernighan, Brian <5>: Library Functions. (line 12)
+* Kernighan, Brian <6>: BTL. (line 6)
+* Kernighan, Brian <7>: Contributors. (line 12)
+* Kernighan, Brian <8>: Other Versions. (line 13)
+* Kernighan, Brian <9>: Basic Data Typing. (line 54)
+* Kernighan, Brian <10>: Glossary. (line 206)
+* 'kill' command, dynamic profiling: Profiling. (line 187)
* Knights, jedi: Undocumented. (line 6)
-* Kwok, Conrad: Contributors. (line 34)
-* l debugger command (alias for list): Miscellaneous Debugger Commands.
+* Kwok, Conrad: Contributors. (line 35)
+* 'l' debugger command (alias for 'list'): Miscellaneous Debugger Commands.
(line 72)
-* labels.awk program: Labels Program. (line 51)
+* 'labels.awk' program: Labels Program. (line 51)
* Langston, Peter: Advanced Features. (line 6)
-* languages, data-driven: Basic High Level. (line 85)
-* LC_ALL locale category: Explaining gettext. (line 117)
-* LC_COLLATE locale category: Explaining gettext. (line 94)
-* LC_CTYPE locale category: Explaining gettext. (line 98)
-* LC_MESSAGES locale category: Explaining gettext. (line 88)
-* LC_MESSAGES locale category, bindtextdomain() function (gawk): Programmer
i18n.
+* languages, data-driven: Basic High Level. (line 74)
+* 'LC_ALL' locale category: Explaining gettext. (line 117)
+* 'LC_COLLATE' locale category: Explaining gettext. (line 94)
+* 'LC_CTYPE' locale category: Explaining gettext. (line 98)
+* 'LC_MESSAGES' locale category: Explaining gettext. (line 88)
+* 'LC_MESSAGES' locale category, 'bindtextdomain()' function ('gawk'):
Programmer i18n.
(line 101)
-* LC_MONETARY locale category: Explaining gettext. (line 104)
-* LC_NUMERIC locale category: Explaining gettext. (line 108)
-* LC_TIME locale category: Explaining gettext. (line 112)
-* left angle bracket (<), < operator <1>: Precedence. (line 65)
-* left angle bracket (<), < operator: Comparison Operators.
+* 'LC_MONETARY' locale category: Explaining gettext. (line 104)
+* 'LC_NUMERIC' locale category: Explaining gettext. (line 108)
+* 'LC_TIME' locale category: Explaining gettext. (line 112)
+* left angle bracket ('<'), '<' operator: Comparison Operators.
(line 11)
-* left angle bracket (<), < operator (I/O): Getline/File. (line 6)
-* left angle bracket (<), <= operator <1>: Precedence. (line 65)
-* left angle bracket (<), <= operator: Comparison Operators.
+* left angle bracket ('<'), '<' operator <1>: Precedence. (line 64)
+* left angle bracket ('<'), '<' operator (I/O): Getline/File. (line 6)
+* left angle bracket ('<'), '<=' operator: Comparison Operators.
(line 11)
+* left angle bracket ('<'), '<=' operator <1>: Precedence. (line 64)
* left shift: Bitwise Functions. (line 47)
* left shift, bitwise: Bitwise Functions. (line 32)
* leftmost longest match: Multiple Line. (line 26)
-* length: String Functions. (line 171)
-* length of input record: String Functions. (line 178)
-* length of string: String Functions. (line 171)
-* Lesser General Public License (LGPL): Glossary. (line 496)
-* LGPL (Lesser General Public License): Glossary. (line 496)
+* 'length': String Functions. (line 170)
+* length of input record: String Functions. (line 177)
+* length of string: String Functions. (line 170)
+* Lesser General Public License (LGPL): Glossary. (line 491)
+* LGPL (Lesser General Public License): Glossary. (line 491)
* libmawk: Other Versions. (line 125)
-* libraries of awk functions: Library Functions. (line 6)
-* libraries of awk functions, assertions: Assert Function. (line 6)
-* libraries of awk functions, associative arrays and: Library Names.
+* libraries of 'awk' functions: Library Functions. (line 6)
+* libraries of 'awk' functions, assertions: Assert Function. (line 6)
+* libraries of 'awk' functions, associative arrays and: Library Names.
(line 58)
-* libraries of awk functions, character values as numbers: Ordinal Functions.
+* libraries of 'awk' functions, character values as numbers: Ordinal Functions.
(line 6)
-* libraries of awk functions, command-line options: Getopt Function.
+* libraries of 'awk' functions, command-line options: Getopt Function.
(line 6)
-* libraries of awk functions, example program for using: Igawk Program.
+* libraries of 'awk' functions, example program for using: Igawk Program.
(line 6)
-* libraries of awk functions, group database, reading: Group Functions.
+* libraries of 'awk' functions, group database, reading: Group Functions.
(line 6)
-* libraries of awk functions, managing, data files: Data File Management.
+* libraries of 'awk' functions, managing, data files: Data File Management.
(line 6)
-* libraries of awk functions, managing, time: Getlocaltime Function.
+* libraries of 'awk' functions, managing, time: Getlocaltime Function.
(line 6)
-* libraries of awk functions, merging arrays into strings: Join Function.
+* libraries of 'awk' functions, merging arrays into strings: Join Function.
(line 6)
-* libraries of awk functions, rounding numbers: Round Function.
+* libraries of 'awk' functions, rounding numbers: Round Function.
(line 6)
-* libraries of awk functions, user database, reading: Passwd Functions.
+* libraries of 'awk' functions, user database, reading: Passwd Functions.
(line 6)
* line breaks: Statements/Lines. (line 6)
* line continuations: Boolean Ops. (line 64)
-* line continuations, gawk: Conditional Exp. (line 34)
-* line continuations, in print statement: Print Examples. (line 76)
-* line continuations, with C shell: More Complex. (line 30)
+* line continuations, 'gawk': Conditional Exp. (line 34)
+* line continuations, in 'print' statement: Print Examples. (line 75)
+* line continuations, with C shell: More Complex. (line 31)
* lines, blank, printing: Print. (line 22)
* lines, counting: Wc Program. (line 6)
* lines, duplicate, removing: History Sorting. (line 6)
@@ -33358,172 +33333,175 @@ Index
* lint checking, array subscripts: Uninitialized Subscripts.
(line 43)
* lint checking, empty programs: Command Line. (line 16)
-* lint checking, issuing warnings: Options. (line 185)
-* lint checking, POSIXLY_CORRECT environment variable: Options.
- (line 341)
+* lint checking, issuing warnings: Options. (line 184)
+* lint checking, 'POSIXLY_CORRECT' environment variable: Options.
+ (line 338)
* lint checking, undefined functions: Pass By Value/Reference.
(line 85)
-* LINT variable: User-modified. (line 87)
-* Linux <1>: Glossary. (line 753)
-* Linux <2>: I18N Example. (line 55)
+* 'LINT' variable: User-modified. (line 87)
* Linux: Manual History. (line 28)
+* Linux <1>: I18N Example. (line 57)
+* Linux <2>: Glossary. (line 748)
* list all global variables, in debugger: Debugger Info. (line 48)
-* list debugger command: Miscellaneous Debugger Commands.
+* 'list' debugger command: Miscellaneous Debugger Commands.
(line 72)
* list function definitions, in debugger: Debugger Info. (line 30)
-* loading extensions, @load directive: Loading Shared Libraries.
+* loading extensions, '@load' directive: Loading Shared Libraries.
(line 8)
-* loading, extensions: Options. (line 173)
+* loading, extensions: Options. (line 172)
* local variables, in a function: Variable Scope. (line 6)
* locale categories: Explaining gettext. (line 81)
-* locale decimal point character: Options. (line 272)
+* locale decimal point character: Options. (line 269)
* locale, definition of: Locales. (line 6)
* localization: I18N and L10N. (line 6)
* localization, See internationalization, localization: I18N and L10N.
(line 6)
-* log: Numeric Functions. (line 28)
+* 'log': Numeric Functions. (line 27)
* log files, timestamps in: Time Functions. (line 6)
-* logarithm: Numeric Functions. (line 28)
+* logarithm: Numeric Functions. (line 27)
* logical false/true: Truth Values. (line 6)
* logical operators, See Boolean expressions: Boolean Ops. (line 6)
* login information: Passwd Functions. (line 16)
* long options: Command Line. (line 13)
* loops: While Statement. (line 6)
-* loops, break statement and: Break Statement. (line 6)
-* loops, continue statements and: For Statement. (line 65)
+* loops, 'break' statement and: Break Statement. (line 6)
+* loops, 'continue' statements and: For Statement. (line 65)
* loops, count for header, in a profile: Profiling. (line 131)
-* loops, do-while: Do Statement. (line 6)
+* loops, 'do'-'while': Do Statement. (line 6)
* loops, exiting: Break Statement. (line 6)
-* loops, for, array scanning: Scanning an Array. (line 6)
-* loops, for, iterative: For Statement. (line 6)
-* loops, See Also while statement: While Statement. (line 6)
-* loops, while: While Statement. (line 6)
-* ls utility: More Complex. (line 15)
-* lshift: Bitwise Functions. (line 47)
-* lvalues/rvalues: Assignment Ops. (line 32)
-* mail-list file: Sample Data Files. (line 6)
+* loops, 'for', array scanning: Scanning an Array. (line 6)
+* loops, 'for', iterative: For Statement. (line 6)
+* loops, See Also 'while' statement: While Statement. (line 6)
+* loops, 'while': While Statement. (line 6)
+* 'ls' utility: More Complex. (line 15)
+* 'lshift': Bitwise Functions. (line 47)
+* lvalues/rvalues: Assignment Ops. (line 31)
+* 'mail-list' file: Sample Data Files. (line 6)
* mailing labels, printing: Labels Program. (line 6)
* mailing list, GNITS: Acknowledgments. (line 52)
-* Malmberg, John <1>: Bugs. (line 71)
* Malmberg, John: Acknowledgments. (line 60)
-* Malmberg, John E.: Contributors. (line 137)
+* Malmberg, John <1>: Bugs. (line 73)
+* Malmberg, John E.: Contributors. (line 138)
* mark parity: Ordinal Functions. (line 45)
* marked string extraction (internationalization): String Extraction.
(line 6)
* marked strings, extracting: String Extraction. (line 6)
* Marx, Groucho: Increment Ops. (line 60)
-* match: String Functions. (line 211)
-* match regexp in string: String Functions. (line 211)
-* match() function, RSTART/RLENGTH variables: String Functions.
- (line 228)
+* 'match': String Functions. (line 210)
+* match regexp in string: String Functions. (line 210)
+* 'match()' function, 'RSTART'/'RLENGTH' variables: String Functions.
+ (line 227)
* matching, expressions, See comparison expressions: Typing and Comparison.
(line 9)
* matching, leftmost longest: Multiple Line. (line 26)
* matching, null strings: String Functions. (line 537)
-* mawk utility <1>: Other Versions. (line 48)
-* mawk utility <2>: Nextfile Statement. (line 47)
-* mawk utility <3>: Concatenation. (line 36)
-* mawk utility <4>: Getline/Pipe. (line 62)
-* mawk utility: Escape Sequences. (line 117)
-* maximum precision supported by MPFR library: Auto-set. (line 221)
-* McIlroy, Doug: Glossary. (line 258)
-* McPhee, Patrick: Contributors. (line 100)
+* 'mawk' utility: Escape Sequences. (line 117)
+* 'mawk' utility <1>: Getline/Pipe. (line 62)
+* 'mawk' utility <2>: Concatenation. (line 36)
+* 'mawk' utility <3>: Nextfile Statement. (line 47)
+* 'mawk' utility <4>: Other Versions. (line 48)
+* maximum precision supported by MPFR library: Auto-set. (line 220)
+* McIlroy, Doug: Glossary. (line 257)
+* McPhee, Patrick: Contributors. (line 101)
* message object files: Explaining gettext. (line 42)
* message object files, converting from portable object files: I18N Example.
- (line 64)
-* message object files, specifying directory of <1>: Programmer i18n.
- (line 48)
+ (line 66)
* message object files, specifying directory of: Explaining gettext.
(line 54)
+* message object files, specifying directory of <1>: Programmer i18n.
+ (line 48)
* messages from extensions: Printing Messages. (line 6)
* metacharacters in regular expressions: Regexp Operators. (line 6)
* metacharacters, escape sequences for: Escape Sequences. (line 136)
-* minimum precision required by MPFR library: Auto-set. (line 224)
-* mktime: Time Functions. (line 25)
+* minimum precision required by MPFR library: Auto-set. (line 223)
+* 'mktime': Time Functions. (line 25)
* modifiers, in format specifiers: Format Modifiers. (line 6)
* monetary information, localization: Explaining gettext. (line 104)
* Moore, Duncan: Getline Notes. (line 40)
-* msgfmt utility: I18N Example. (line 64)
+* 'msgfmt' utility: I18N Example. (line 66)
* multiple precision: Arbitrary Precision Arithmetic.
(line 6)
* multiple-line records: Multiple Line. (line 6)
-* n debugger command (alias for next): Debugger Execution Control.
+* 'n' debugger command (alias for 'next'): Debugger Execution Control.
(line 43)
* names, arrays/variables: Library Names. (line 6)
+* names, functions: Definition Syntax. (line 24)
* names, functions <1>: Library Names. (line 6)
-* names, functions: Definition Syntax. (line 23)
* namespace issues: Library Names. (line 6)
-* namespace issues, functions: Definition Syntax. (line 23)
-* NetBSD: Glossary. (line 753)
+* namespace issues, functions: Definition Syntax. (line 24)
+* NetBSD: Glossary. (line 748)
* networks, programming: TCP/IP Networking. (line 6)
* networks, support for: Special Network. (line 6)
-* newlines <1>: Boolean Ops. (line 69)
-* newlines <2>: Options. (line 262)
* newlines: Statements/Lines. (line 6)
+* newlines <1>: Options. (line 260)
+* newlines <2>: Boolean Ops. (line 69)
* newlines, as field separators: Default Field Splitting.
(line 6)
* newlines, as record separators: awk split records. (line 12)
* newlines, in dynamic regexps: Computed Regexps. (line 60)
* newlines, in regexp constants: Computed Regexps. (line 70)
-* newlines, printing: Print Examples. (line 12)
-* newlines, separating statements in actions <1>: Statements. (line 10)
+* newlines, printing: Print Examples. (line 11)
* newlines, separating statements in actions: Action Overview.
(line 19)
-* next debugger command: Debugger Execution Control.
+* newlines, separating statements in actions <1>: Statements. (line 10)
+* 'next' debugger command: Debugger Execution Control.
(line 43)
-* next file statement: Feature History. (line 169)
-* next statement <1>: Next Statement. (line 6)
-* next statement: Boolean Ops. (line 95)
-* next statement, BEGIN/END patterns and: I/O And BEGIN/END. (line 37)
-* next statement, BEGINFILE/ENDFILE patterns and: BEGINFILE/ENDFILE.
+* 'next file' statement: Feature History. (line 168)
+* 'next' statement: Boolean Ops. (line 95)
+* 'next' statement <1>: Next Statement. (line 6)
+* 'next' statement, 'BEGIN'/'END' patterns and: I/O And BEGIN/END.
+ (line 36)
+* 'next' statement, 'BEGINFILE'/'ENDFILE' patterns and: BEGINFILE/ENDFILE.
(line 49)
-* next statement, user-defined functions and: Next Statement. (line 44)
-* nextfile statement: Nextfile Statement. (line 6)
-* nextfile statement, BEGIN/END patterns and: I/O And BEGIN/END.
- (line 37)
-* nextfile statement, BEGINFILE/ENDFILE patterns and: BEGINFILE/ENDFILE.
+* 'next' statement, user-defined functions and: Next Statement.
+ (line 44)
+* 'nextfile' statement: Nextfile Statement. (line 6)
+* 'nextfile' statement, 'BEGIN'/'END' patterns and: I/O And BEGIN/END.
+ (line 36)
+* 'nextfile' statement, 'BEGINFILE'/'ENDFILE' patterns and: BEGINFILE/ENDFILE.
(line 26)
-* nextfile statement, user-defined functions and: Nextfile Statement.
+* 'nextfile' statement, user-defined functions and: Nextfile Statement.
(line 47)
-* nexti debugger command: Debugger Execution Control.
+* 'nexti' debugger command: Debugger Execution Control.
(line 49)
-* NF variable <1>: Auto-set. (line 105)
-* NF variable: Fields. (line 33)
-* NF variable, decrementing: Changing Fields. (line 107)
-* ni debugger command (alias for nexti): Debugger Execution Control.
+* 'NF' variable: Fields. (line 33)
+* 'NF' variable <1>: Auto-set. (line 105)
+* 'NF' variable, decrementing: Changing Fields. (line 107)
+* 'ni' debugger command (alias for 'nexti'): Debugger Execution Control.
(line 49)
-* noassign.awk program: Ignoring Assigns. (line 15)
+* 'noassign.awk' program: Ignoring Assigns. (line 15)
* non-existent array elements: Reference to Elements.
(line 23)
* not Boolean-logic operator: Boolean Ops. (line 6)
-* NR variable <1>: Auto-set. (line 125)
-* NR variable: Records. (line 6)
-* NR variable, changing: Auto-set. (line 314)
-* null strings <1>: Basic Data Typing. (line 26)
-* null strings <2>: Truth Values. (line 6)
-* null strings <3>: Regexp Field Splitting.
+* 'NR' variable: Records. (line 6)
+* 'NR' variable <1>: Auto-set. (line 125)
+* 'NR' variable, changing: Auto-set. (line 313)
+* null strings: awk split records. (line 114)
+* null strings <1>: Regexp Field Splitting.
(line 43)
-* null strings: awk split records. (line 115)
-* null strings in gawk arguments, quoting and: Quoting. (line 82)
+* null strings <2>: Truth Values. (line 6)
+* null strings <3>: Basic Data Typing. (line 26)
+* null strings in 'gawk' arguments, quoting and: Quoting. (line 82)
* null strings, and deleting array elements: Delete. (line 27)
* null strings, as array subscripts: Uninitialized Subscripts.
(line 43)
* null strings, converting numbers to strings: Strings And Numbers.
(line 21)
* null strings, matching: String Functions. (line 537)
-* number as string of bits: Bitwise Functions. (line 110)
-* number of array elements: String Functions. (line 201)
-* number sign (#), #! (executable scripts): Executable Scripts.
+* number as string of bits: Bitwise Functions. (line 111)
+* number of array elements: String Functions. (line 200)
+* number sign ('#'), '#!' (executable scripts): Executable Scripts.
(line 6)
-* number sign (#), commenting: Comments. (line 6)
+* number sign ('#'), commenting: Comments. (line 6)
* numbers, as array subscripts: Numeric Array Subscripts.
(line 6)
* numbers, as values of characters: Ordinal Functions. (line 6)
* numbers, Cliff random: Cliff Random Function.
(line 6)
-* numbers, converting <1>: Bitwise Functions. (line 110)
* numbers, converting: Strings And Numbers. (line 6)
+* numbers, converting <1>: Bitwise Functions. (line 111)
* numbers, converting, to strings: User-modified. (line 30)
+* numbers, converting, to strings <1>: User-modified. (line 104)
* numbers, hexadecimal: Nondecimal-numbers. (line 6)
* numbers, octal: Nondecimal-numbers. (line 6)
* numbers, rounding: Round Function. (line 6)
@@ -33531,92 +33509,98 @@ Index
* numeric functions: Numeric Functions. (line 6)
* numeric, output format: OFMT. (line 6)
* numeric, strings: Variable Typing. (line 6)
-* o debugger command (alias for option): Debugger Info. (line 57)
+* 'o' debugger command (alias for 'option'): Debugger Info. (line 57)
* obsolete features: Obsolete. (line 6)
* octal numbers: Nondecimal-numbers. (line 6)
-* octal values, enabling interpretation of: Options. (line 211)
-* OFMT variable <1>: User-modified. (line 104)
-* OFMT variable <2>: Strings And Numbers. (line 57)
-* OFMT variable: OFMT. (line 15)
-* OFMT variable, POSIX awk and: OFMT. (line 27)
-* OFS variable <1>: User-modified. (line 113)
-* OFS variable <2>: Output Separators. (line 6)
-* OFS variable: Changing Fields. (line 64)
-* OpenBSD: Glossary. (line 753)
+* octal values, enabling interpretation of: Options. (line 209)
+* 'OFMT' variable: OFMT. (line 15)
+* 'OFMT' variable <1>: Strings And Numbers. (line 56)
+* 'OFMT' variable <2>: User-modified. (line 104)
+* 'OFMT' variable, POSIX 'awk' and: OFMT. (line 27)
+* 'OFS' variable: Changing Fields. (line 64)
+* 'OFS' variable <1>: Output Separators. (line 6)
+* 'OFS' variable <2>: User-modified. (line 113)
+* OpenBSD: Glossary. (line 748)
* OpenSolaris: Other Versions. (line 100)
* operating systems, BSD-based: Manual History. (line 28)
-* operating systems, PC, gawk on: PC Using. (line 6)
-* operating systems, PC, gawk on, installing: PC Installation.
+* operating systems, PC, 'gawk' on: PC Using. (line 6)
+* operating systems, PC, 'gawk' on, installing: PC Installation.
(line 6)
-* operating systems, porting gawk to: New Ports. (line 6)
+* operating systems, porting 'gawk' to: New Ports. (line 6)
* operating systems, See Also GNU/Linux, PC operating systems, Unix:
Installation.
(line 6)
* operations, bitwise: Bitwise Functions. (line 6)
* operators, arithmetic: Arithmetic Ops. (line 6)
* operators, assignment: Assignment Ops. (line 6)
-* operators, assignment, evaluation order: Assignment Ops. (line 111)
+* operators, assignment <1>: Assignment Ops. (line 31)
+* operators, assignment, evaluation order: Assignment Ops. (line 110)
* operators, Boolean, See Boolean expressions: Boolean Ops. (line 6)
* operators, decrement/increment: Increment Ops. (line 6)
* operators, GNU-specific: GNU Regexp Operators.
(line 6)
-* operators, input/output <1>: Precedence. (line 65)
-* operators, input/output <2>: Redirection. (line 22)
-* operators, input/output <3>: Getline/Coprocess. (line 6)
-* operators, input/output <4>: Getline/Pipe. (line 9)
* operators, input/output: Getline/File. (line 6)
+* operators, input/output <1>: Getline/Pipe. (line 10)
+* operators, input/output <2>: Getline/Coprocess. (line 6)
+* operators, input/output <3>: Redirection. (line 22)
+* operators, input/output <4>: Redirection. (line 96)
+* operators, input/output <5>: Precedence. (line 64)
+* operators, input/output <6>: Precedence. (line 64)
+* operators, input/output <7>: Precedence. (line 64)
* operators, logical, See Boolean expressions: Boolean Ops. (line 6)
-* operators, precedence <1>: Precedence. (line 6)
* operators, precedence: Increment Ops. (line 60)
+* operators, precedence <1>: Precedence. (line 6)
* operators, relational, See operators, comparison: Typing and Comparison.
(line 9)
* operators, short-circuit: Boolean Ops. (line 59)
-* operators, string: Concatenation. (line 8)
+* operators, string: Concatenation. (line 9)
* operators, string-matching: Regexp Usage. (line 19)
* operators, string-matching, for buffers: GNU Regexp Operators.
- (line 48)
-* operators, word-boundary (gawk): GNU Regexp Operators.
- (line 63)
-* option debugger command: Debugger Info. (line 57)
+ (line 51)
+* operators, word-boundary ('gawk'): GNU Regexp Operators.
+ (line 66)
+* 'option' debugger command: Debugger Info. (line 57)
* options, command-line: Options. (line 6)
-* options, command-line, end of: Options. (line 54)
-* options, command-line, invoking awk: Command Line. (line 6)
+* options, command-line, end of: Options. (line 55)
+* options, command-line, invoking 'awk': Command Line. (line 6)
* options, command-line, processing: Getopt Function. (line 6)
* options, deprecated: Obsolete. (line 6)
-* options, long <1>: Options. (line 6)
* options, long: Command Line. (line 13)
+* options, long <1>: Options. (line 6)
* options, printing list of: Options. (line 154)
-* or: Bitwise Functions. (line 50)
+* 'or': Bitwise Functions. (line 50)
* OR bitwise operation: Bitwise Functions. (line 6)
* or Boolean-logic operator: Boolean Ops. (line 6)
-* ord() extension function: Extension Sample Ord.
+* 'ord()' extension function: Extension Sample Ord.
(line 12)
-* ord() user-defined function: Ordinal Functions. (line 16)
+* 'ord()' user-defined function: Ordinal Functions. (line 16)
* order of evaluation, concatenation: Concatenation. (line 41)
-* ORS variable <1>: User-modified. (line 118)
-* ORS variable: Output Separators. (line 21)
-* output field separator, See OFS variable: Changing Fields. (line 64)
-* output record separator, See ORS variable: Output Separators.
- (line 21)
+* 'ORS' variable: Output Separators. (line 20)
+* 'ORS' variable <1>: User-modified. (line 119)
+* output field separator, See 'OFS' variable: Changing Fields.
+ (line 64)
+* output record separator, See 'ORS' variable: Output Separators.
+ (line 20)
* output redirection: Redirection. (line 6)
* output wrapper: Output Wrappers. (line 6)
* output, buffering: I/O Functions. (line 32)
+* output, buffering <1>: I/O Functions. (line 139)
* output, duplicating into files: Tee Program. (line 6)
* output, files, closing: Close Files And Pipes.
(line 6)
-* output, format specifier, OFMT: OFMT. (line 15)
+* output, format specifier, 'OFMT': OFMT. (line 15)
* output, formatted: Printf. (line 6)
* output, pipes: Redirection. (line 57)
* output, printing, See printing: Printing. (line 6)
-* output, records: Output Separators. (line 21)
+* output, records: Output Separators. (line 20)
* output, standard: Special FD. (line 6)
-* p debugger command (alias for print): Viewing And Changing Data.
- (line 36)
-* Papadopoulos, Panos: Contributors. (line 128)
-* parent process ID of gawk process: Auto-set. (line 189)
-* parentheses (), in a profile: Profiling. (line 146)
-* parentheses (), regexp operator: Regexp Operators. (line 81)
+* 'p' debugger command (alias for 'print'): Viewing And Changing Data.
+ (line 35)
+* Papadopoulos, Panos: Contributors. (line 129)
+* parent process ID of 'gawk' process: Auto-set. (line 188)
+* parentheses '()', in a profile: Profiling. (line 146)
+* parentheses '()', regexp operator: Regexp Operators. (line 81)
* password file: Passwd Functions. (line 16)
-* patsplit: String Functions. (line 297)
+* 'patsplit': String Functions. (line 296)
* patterns: Patterns and Actions.
(line 6)
* patterns, comparison expressions as: Expression Patterns. (line 14)
@@ -33627,150 +33611,163 @@ Index
* patterns, ranges in: Ranges. (line 6)
* patterns, regexp constants as: Expression Patterns. (line 34)
* patterns, types of: Pattern Overview. (line 15)
-* pawk (profiling version of Brian Kernighan's awk): Other Versions.
+* 'pawk' (profiling version of Brian Kernighan's 'awk'): Other Versions.
(line 82)
-* pawk, awk-like facilities for Python: Other Versions. (line 129)
-* PC operating systems, gawk on: PC Using. (line 6)
-* PC operating systems, gawk on, installing: PC Installation. (line 6)
-* percent sign (%), % operator: Precedence. (line 55)
-* percent sign (%), %= operator <1>: Precedence. (line 95)
-* percent sign (%), %= operator: Assignment Ops. (line 130)
-* period (.), regexp operator: Regexp Operators. (line 44)
+* 'pawk', 'awk'-like facilities for Python: Other Versions. (line 129)
+* PC operating systems, 'gawk' on: PC Using. (line 6)
+* PC operating systems, 'gawk' on, installing: PC Installation.
+ (line 6)
+* percent sign ('%'), '%' operator: Precedence. (line 54)
+* percent sign ('%'), '%=' operator: Assignment Ops. (line 129)
+* percent sign ('%'), '%=' operator <1>: Precedence. (line 94)
+* period ('.'), regexp operator: Regexp Operators. (line 44)
* Perl: Future Extensions. (line 6)
-* Peters, Arno: Contributors. (line 85)
-* Peterson, Hal: Contributors. (line 39)
+* Peters, Arno: Contributors. (line 86)
+* Peterson, Hal: Contributors. (line 40)
* pipe, closing: Close Files And Pipes.
(line 6)
-* pipe, input: Getline/Pipe. (line 9)
+* pipe, input: Getline/Pipe. (line 10)
* pipe, output: Redirection. (line 57)
-* Pitts, Dave <1>: Bugs. (line 71)
* Pitts, Dave: Acknowledgments. (line 60)
+* Pitts, Dave <1>: Bugs. (line 73)
* Plauger, P.J.: Library Functions. (line 12)
* plug-in: Extension Intro. (line 6)
-* plus sign (+), + operator: Precedence. (line 52)
-* plus sign (+), ++ operator <1>: Precedence. (line 46)
-* plus sign (+), ++ operator: Increment Ops. (line 11)
-* plus sign (+), += operator <1>: Precedence. (line 95)
-* plus sign (+), += operator: Assignment Ops. (line 82)
-* plus sign (+), regexp operator: Regexp Operators. (line 105)
+* plus sign ('+'), '+' operator: Precedence. (line 51)
+* plus sign ('+'), '+' operator <1>: Precedence. (line 57)
+* plus sign ('+'), '++' operator: Increment Ops. (line 11)
+* plus sign ('+'), '++' operator <1>: Increment Ops. (line 40)
+* plus sign ('+'), '++' operator <2>: Precedence. (line 45)
+* plus sign ('+'), '+=' operator: Assignment Ops. (line 81)
+* plus sign ('+'), '+=' operator <1>: Precedence. (line 94)
+* plus sign ('+'), regexp operator: Regexp Operators. (line 105)
* pointers to functions: Indirect Calls. (line 6)
* portability: Escape Sequences. (line 100)
-* portability, #! (executable scripts): Executable Scripts. (line 33)
-* portability, ** operator and: Arithmetic Ops. (line 81)
-* portability, **= operator and: Assignment Ops. (line 143)
-* portability, ARGV variable: Executable Scripts. (line 59)
+* portability, '#!' (executable scripts): Executable Scripts. (line 33)
+* portability, '**' operator and: Arithmetic Ops. (line 81)
+* portability, '**=' operator and: Assignment Ops. (line 144)
+* portability, 'ARGV' variable: Executable Scripts. (line 59)
* portability, backslash continuation and: Statements/Lines. (line 30)
* portability, backslash in escape sequences: Escape Sequences.
(line 105)
-* portability, close() function and: Close Files And Pipes.
+* portability, 'close()' function and: Close Files And Pipes.
(line 81)
* portability, data files as single record: gawk split records.
(line 65)
* portability, deleting array elements: Delete. (line 56)
* portability, example programs: Library Functions. (line 42)
* portability, functions, defining: Definition Syntax. (line 114)
-* portability, gawk: New Ports. (line 6)
-* portability, gettext library and: Explaining gettext. (line 11)
+* portability, 'gawk': New Ports. (line 6)
+* portability, 'gettext' library and: Explaining gettext. (line 11)
* portability, internationalization and: I18N Portability. (line 6)
-* portability, length() function: String Functions. (line 180)
-* portability, new awk vs. old awk: Strings And Numbers. (line 57)
-* portability, next statement in user-defined functions: Pass By
Value/Reference.
+* portability, 'length()' function: String Functions. (line 179)
+* portability, new 'awk' vs. old 'awk': Strings And Numbers. (line 56)
+* portability, 'next' statement in user-defined functions: Pass By
Value/Reference.
(line 88)
-* portability, NF variable, decrementing: Changing Fields. (line 115)
+* portability, 'NF' variable, decrementing: Changing Fields. (line 115)
* portability, operators: Increment Ops. (line 60)
-* portability, operators, not in POSIX awk: Precedence. (line 98)
-* portability, POSIXLY_CORRECT environment variable: Options. (line 361)
-* portability, substr() function: String Functions. (line 513)
-* portable object files <1>: Translator i18n. (line 6)
+* portability, operators, not in POSIX 'awk': Precedence. (line 97)
+* portability, 'POSIXLY_CORRECT' environment variable: Options.
+ (line 358)
+* portability, 'substr()' function: String Functions. (line 513)
* portable object files: Explaining gettext. (line 37)
+* portable object files <1>: Translator i18n. (line 6)
* portable object files, converting to message object files: I18N Example.
- (line 64)
+ (line 66)
* portable object files, generating: Options. (line 147)
* portable object template files: Explaining gettext. (line 31)
-* porting gawk: New Ports. (line 6)
-* positional specifiers, printf statement <1>: Printf Ordering.
+* porting 'gawk': New Ports. (line 6)
+* positional specifiers, 'printf' statement: Format Modifiers.
+ (line 13)
+* positional specifiers, 'printf' statement <1>: Printf Ordering.
(line 6)
-* positional specifiers, printf statement: Format Modifiers. (line 13)
-* positional specifiers, printf statement, mixing with regular formats: Printf
Ordering.
+* positional specifiers, 'printf' statement, mixing with regular formats:
Printf Ordering.
(line 57)
-* POSIX awk <1>: Assignment Ops. (line 137)
-* POSIX awk: This Manual. (line 14)
-* POSIX awk, ** operator and: Precedence. (line 98)
-* POSIX awk, **= operator and: Assignment Ops. (line 143)
-* POSIX awk, < operator and: Getline/File. (line 26)
-* POSIX awk, arithmetic operators and: Arithmetic Ops. (line 30)
-* POSIX awk, backslashes in string constants: Escape Sequences.
+* POSIX 'awk': This Manual. (line 14)
+* POSIX 'awk' <1>: Assignment Ops. (line 138)
+* POSIX 'awk', '**' operator and: Precedence. (line 97)
+* POSIX 'awk', '**=' operator and: Assignment Ops. (line 144)
+* POSIX 'awk', '<' operator and: Getline/File. (line 26)
+* POSIX 'awk', arithmetic operators and: Arithmetic Ops. (line 30)
+* POSIX 'awk', backslashes in string constants: Escape Sequences.
(line 105)
-* POSIX awk, BEGIN/END patterns: I/O And BEGIN/END. (line 16)
-* POSIX awk, bracket expressions and: Bracket Expressions. (line 26)
-* POSIX awk, bracket expressions and, character classes: Bracket Expressions.
+* POSIX 'awk', 'BEGIN'/'END' patterns: I/O And BEGIN/END. (line 15)
+* POSIX 'awk', bracket expressions and: Bracket Expressions. (line 26)
+* POSIX 'awk', bracket expressions and, character classes: Bracket Expressions.
(line 32)
-* POSIX awk, break statement and: Break Statement. (line 51)
-* POSIX awk, changes in awk versions: POSIX. (line 6)
-* POSIX awk, continue statement and: Continue Statement. (line 44)
-* POSIX awk, CONVFMT variable and: User-modified. (line 30)
-* POSIX awk, date utility and: Time Functions. (line 254)
-* POSIX awk, field separators and <1>: Full Line Fields. (line 16)
-* POSIX awk, field separators and: Fields. (line 6)
-* POSIX awk, FS variable and: User-modified. (line 60)
-* POSIX awk, function keyword in: Definition Syntax. (line 98)
-* POSIX awk, functions and, gsub()/sub(): Gory Details. (line 90)
-* POSIX awk, functions and, length(): String Functions. (line 180)
-* POSIX awk, GNU long options and: Options. (line 15)
-* POSIX awk, interval expressions in: Regexp Operators. (line 135)
-* POSIX awk, next/nextfile statements and: Next Statement. (line 44)
-* POSIX awk, numeric strings and: Variable Typing. (line 6)
-* POSIX awk, OFMT variable and <1>: Strings And Numbers. (line 57)
-* POSIX awk, OFMT variable and: OFMT. (line 27)
-* POSIX awk, period (.), using: Regexp Operators. (line 51)
-* POSIX awk, printf format strings and: Format Modifiers. (line 158)
-* POSIX awk, regular expressions and: Regexp Operators. (line 161)
-* POSIX awk, timestamps and: Time Functions. (line 6)
-* POSIX awk, | I/O operator and: Getline/Pipe. (line 55)
-* POSIX mode: Options. (line 256)
-* POSIX, awk and: Preface. (line 21)
-* POSIX, gawk extensions not included in: POSIX/GNU. (line 6)
-* POSIX, programs, implementing in awk: Clones. (line 6)
-* POSIXLY_CORRECT environment variable: Options. (line 341)
-* PREC variable: User-modified. (line 123)
-* precedence <1>: Precedence. (line 6)
+* POSIX 'awk', bracket expressions and, character classes <1>: Bracket
Expressions.
+ (line 100)
+* POSIX 'awk', 'break' statement and: Break Statement. (line 51)
+* POSIX 'awk', changes in 'awk' versions: POSIX. (line 6)
+* POSIX 'awk', 'continue' statement and: Continue Statement. (line 44)
+* POSIX 'awk', 'CONVFMT' variable and: User-modified. (line 30)
+* POSIX 'awk', 'date' utility and: Time Functions. (line 252)
+* POSIX 'awk', field separators and: Fields. (line 6)
+* POSIX 'awk', field separators and <1>: Full Line Fields. (line 16)
+* POSIX 'awk', 'FS' variable and: User-modified. (line 60)
+* POSIX 'awk', 'function' keyword in: Definition Syntax. (line 99)
+* POSIX 'awk', functions and, 'gsub()'/'sub()': Gory Details. (line 90)
+* POSIX 'awk', functions and, 'length()': String Functions. (line 179)
+* POSIX 'awk', GNU long options and: Options. (line 15)
+* POSIX 'awk', interval expressions in: Regexp Operators. (line 135)
+* POSIX 'awk', 'next'/'nextfile' statements and: Next Statement.
+ (line 44)
+* POSIX 'awk', numeric strings and: Variable Typing. (line 6)
+* POSIX 'awk', 'OFMT' variable and: OFMT. (line 27)
+* POSIX 'awk', 'OFMT' variable and <1>: Strings And Numbers. (line 56)
+* POSIX 'awk', period ('.'), using: Regexp Operators. (line 51)
+* POSIX 'awk', 'printf' format strings and: Format Modifiers. (line 157)
+* POSIX 'awk', regular expressions and: Regexp Operators. (line 161)
+* POSIX 'awk', timestamps and: Time Functions. (line 6)
+* POSIX 'awk', '|' I/O operator and: Getline/Pipe. (line 56)
+* POSIX mode: Options. (line 254)
+* POSIX mode <1>: Options. (line 338)
+* POSIX, 'awk' and: Preface. (line 21)
+* POSIX, 'gawk' extensions not included in: POSIX/GNU. (line 6)
+* POSIX, programs, implementing in 'awk': Clones. (line 6)
+* 'POSIXLY_CORRECT' environment variable: Options. (line 338)
+* 'PREC' variable: User-modified. (line 124)
* precedence: Increment Ops. (line 60)
+* precedence <1>: Precedence. (line 6)
* precedence, regexp operators: Regexp Operators. (line 156)
* predefined variables: Built-in Variables. (line 6)
-* predefined variables, -v option, setting with: Options. (line 40)
+* predefined variables, '-v' option, setting with: Options. (line 41)
* predefined variables, conveying information: Auto-set. (line 6)
* predefined variables, user-modifiable: User-modified. (line 6)
-* print debugger command: Viewing And Changing Data.
- (line 36)
-* print statement: Printing. (line 16)
-* print statement, BEGIN/END patterns and: I/O And BEGIN/END. (line 16)
-* print statement, commas, omitting: Print Examples. (line 31)
-* print statement, I/O operators in: Precedence. (line 71)
-* print statement, line continuations and: Print Examples. (line 76)
-* print statement, OFMT variable and: User-modified. (line 113)
-* print statement, See Also redirection, of output: Redirection.
+* 'print' debugger command: Viewing And Changing Data.
+ (line 35)
+* 'print' statement: Printing. (line 16)
+* 'print' statement, 'BEGIN'/'END' patterns and: I/O And BEGIN/END.
+ (line 15)
+* 'print' statement, commas, omitting: Print Examples. (line 30)
+* 'print' statement, I/O operators in: Precedence. (line 70)
+* 'print' statement, line continuations and: Print Examples. (line 75)
+* 'print' statement, 'OFMT' variable and: User-modified. (line 113)
+* 'print' statement, See Also redirection, of output: Redirection.
(line 17)
-* print statement, sprintf() function and: Round Function. (line 6)
+* 'print' statement, 'sprintf()' function and: Round Function.
+ (line 6)
* print variables, in debugger: Viewing And Changing Data.
- (line 36)
-* printf debugger command: Viewing And Changing Data.
- (line 54)
-* printf statement <1>: Printf. (line 6)
-* printf statement: Printing. (line 16)
-* printf statement, columns, aligning: Print Examples. (line 70)
-* printf statement, format-control characters: Control Letters.
+ (line 35)
+* 'printf' debugger command: Viewing And Changing Data.
+ (line 53)
+* 'printf' statement: Printing. (line 16)
+* 'printf' statement <1>: Printf. (line 6)
+* 'printf' statement, columns, aligning: Print Examples. (line 69)
+* 'printf' statement, format-control characters: Control Letters.
(line 6)
-* printf statement, I/O operators in: Precedence. (line 71)
-* printf statement, modifiers: Format Modifiers. (line 6)
-* printf statement, positional specifiers <1>: Printf Ordering.
+* 'printf' statement, I/O operators in: Precedence. (line 70)
+* 'printf' statement, modifiers: Format Modifiers. (line 6)
+* 'printf' statement, positional specifiers: Format Modifiers.
+ (line 13)
+* 'printf' statement, positional specifiers <1>: Printf Ordering.
(line 6)
-* printf statement, positional specifiers: Format Modifiers. (line 13)
-* printf statement, positional specifiers, mixing with regular formats: Printf
Ordering.
+* 'printf' statement, positional specifiers, mixing with regular formats:
Printf Ordering.
(line 57)
-* printf statement, See Also redirection, of output: Redirection.
+* 'printf' statement, See Also redirection, of output: Redirection.
(line 17)
-* printf statement, sprintf() function and: Round Function. (line 6)
-* printf statement, syntax of: Basic Printf. (line 6)
+* 'printf' statement, 'sprintf()' function and: Round Function.
+ (line 6)
+* 'printf' statement, syntax of: Basic Printf. (line 6)
* printing: Printing. (line 6)
* printing messages from extensions: Printing Messages. (line 6)
* printing, list of options: Options. (line 154)
@@ -33778,36 +33775,37 @@ Index
* printing, unduplicated lines of text: Uniq Program. (line 6)
* printing, user information: Id Program. (line 6)
* private variables: Library Names. (line 11)
-* process group ID of gawk process: Auto-set. (line 183)
-* process ID of gawk process: Auto-set. (line 186)
+* process group ID of 'gawk' process: Auto-set. (line 182)
+* process ID of 'gawk' process: Auto-set. (line 185)
* processes, two-way communications with: Two-way I/O. (line 6)
* processing data: Basic High Level. (line 6)
-* PROCINFO array <1>: Passwd Functions. (line 6)
-* PROCINFO array <2>: Time Functions. (line 47)
-* PROCINFO array: Auto-set. (line 130)
-* PROCINFO array, and communications via ptys: Two-way I/O. (line 99)
-* PROCINFO array, and group membership: Group Functions. (line 6)
-* PROCINFO array, and user and group ID numbers: Id Program. (line 15)
-* PROCINFO array, testing the field splitting: Passwd Functions.
+* 'PROCINFO' array: Auto-set. (line 130)
+* 'PROCINFO' array <1>: Time Functions. (line 47)
+* 'PROCINFO' array <2>: Passwd Functions. (line 6)
+* 'PROCINFO' array, and communications via ptys: Two-way I/O. (line 99)
+* 'PROCINFO' array, and group membership: Group Functions. (line 6)
+* 'PROCINFO' array, and user and group ID numbers: Id Program.
+ (line 15)
+* 'PROCINFO' array, testing the field splitting: Passwd Functions.
(line 154)
-* PROCINFO array, uses: Auto-set. (line 242)
-* PROCINFO, values of sorted_in: Controlling Scanning.
+* 'PROCINFO' array, uses: Auto-set. (line 241)
+* 'PROCINFO', values of 'sorted_in': Controlling Scanning.
(line 26)
-* profiling awk programs: Profiling. (line 6)
-* profiling awk programs, dynamically: Profiling. (line 179)
+* profiling 'awk' programs: Profiling. (line 6)
+* profiling 'awk' programs, dynamically: Profiling. (line 178)
* program identifiers: Auto-set. (line 148)
* program, definition of: Getting Started. (line 21)
-* programming conventions, --non-decimal-data option: Nondecimal Data.
+* programming conventions, '--non-decimal-data' option: Nondecimal Data.
(line 35)
-* programming conventions, ARGC/ARGV variables: Auto-set. (line 35)
-* programming conventions, exit statement: Exit Statement. (line 38)
+* programming conventions, 'ARGC'/'ARGV' variables: Auto-set. (line 35)
+* programming conventions, 'exit' statement: Exit Statement. (line 38)
* programming conventions, function parameters: Return Statement.
- (line 45)
+ (line 44)
* programming conventions, functions, calling: Calling Built-in.
(line 10)
* programming conventions, functions, writing: Definition Syntax.
- (line 70)
-* programming conventions, gawk extensions: Internal File Ops.
+ (line 71)
+* programming conventions, 'gawk' extensions: Internal File Ops.
(line 45)
* programming conventions, private variable names: Library Names.
(line 23)
@@ -33815,114 +33813,116 @@ Index
* programming languages, Ada: Glossary. (line 11)
* programming languages, data-driven vs. procedural: Getting Started.
(line 12)
-* programming languages, Java: Glossary. (line 473)
-* programming, basic steps: Basic High Level. (line 20)
+* programming languages, Java: Glossary. (line 468)
+* programming, basic steps: Basic High Level. (line 18)
* programming, concepts: Basic Concepts. (line 6)
-* pwcat program: Passwd Functions. (line 23)
-* q debugger command (alias for quit): Miscellaneous Debugger Commands.
+* programming, concepts <1>: Basic Concepts. (line 6)
+* 'pwcat' program: Passwd Functions. (line 23)
+* 'q' debugger command (alias for 'quit'): Miscellaneous Debugger Commands.
(line 99)
-* QSE awk: Other Versions. (line 135)
+* QSE 'awk': Other Versions. (line 135)
* Quanstrom, Erik: Alarm Program. (line 8)
-* question mark (?), ?: operator: Precedence. (line 92)
-* question mark (?), regexp operator <1>: GNU Regexp Operators.
- (line 59)
-* question mark (?), regexp operator: Regexp Operators. (line 111)
+* question mark ('?'), '?:' operator: Precedence. (line 91)
+* question mark ('?'), regexp operator: Regexp Operators. (line 111)
+* question mark ('?'), regexp operator <1>: GNU Regexp Operators.
+ (line 62)
* QuikTrim Awk: Other Versions. (line 139)
-* quit debugger command: Miscellaneous Debugger Commands.
+* 'quit' debugger command: Miscellaneous Debugger Commands.
(line 99)
-* QUIT signal (MS-Windows): Profiling. (line 214)
-* quoting in gawk command lines: Long. (line 26)
-* quoting in gawk command lines, tricks for: Quoting. (line 91)
+* 'QUIT' signal (MS-Windows): Profiling. (line 213)
+* quoting in 'gawk' command lines: Long. (line 26)
+* quoting in 'gawk' command lines, tricks for: Quoting. (line 91)
* quoting, for small awk programs: Comments. (line 27)
-* r debugger command (alias for run): Debugger Execution Control.
+* 'r' debugger command (alias for 'run'): Debugger Execution Control.
(line 62)
* Rakitzis, Byron: History Sorting. (line 25)
-* Ramey, Chet <1>: General Data Types. (line 6)
* Ramey, Chet: Acknowledgments. (line 60)
-* rand: Numeric Functions. (line 33)
+* Ramey, Chet <1>: General Data Types. (line 6)
+* 'rand': Numeric Functions. (line 32)
* random numbers, Cliff: Cliff Random Function.
(line 6)
-* random numbers, rand()/srand() functions: Numeric Functions.
- (line 33)
-* random numbers, seed of: Numeric Functions. (line 63)
+* random numbers, 'rand()'/'srand()' functions: Numeric Functions.
+ (line 32)
+* random numbers, seed of: Numeric Functions. (line 62)
* range expressions (regexps): Bracket Expressions. (line 6)
* range patterns: Ranges. (line 6)
-* range patterns, line continuation and: Ranges. (line 65)
-* Rankin, Pat <1>: Contributors. (line 37)
-* Rankin, Pat <2>: Assignment Ops. (line 100)
+* range patterns, line continuation and: Ranges. (line 64)
* Rankin, Pat: Acknowledgments. (line 60)
-* reada() extension function: Extension Sample Read write array.
+* Rankin, Pat <1>: Assignment Ops. (line 99)
+* Rankin, Pat <2>: Contributors. (line 38)
+* 'reada()' extension function: Extension Sample Read write array.
(line 18)
* readable data files, checking: File Checking. (line 6)
-* readable.awk program: File Checking. (line 11)
-* readdir extension: Extension Sample Readdir.
+* 'readable.awk' program: File Checking. (line 11)
+* 'readdir' extension: Extension Sample Readdir.
(line 9)
-* readfile() extension function: Extension Sample Readfile.
+* 'readfile()' extension function: Extension Sample Readfile.
(line 12)
-* readfile() user-defined function: Readfile Function. (line 30)
+* 'readfile()' user-defined function: Readfile Function. (line 30)
* reading input files: Reading Files. (line 6)
* recipe for a programming language: History. (line 6)
-* record separators <1>: User-modified. (line 132)
* record separators: awk split records. (line 6)
+* record separators <1>: User-modified. (line 133)
* record separators, changing: awk split records. (line 85)
* record separators, regular expressions as: awk split records.
- (line 125)
+ (line 124)
* record separators, with multiline records: Multiple Line. (line 10)
-* records <1>: Basic High Level. (line 73)
* records: Reading Files. (line 14)
+* records <1>: Basic High Level. (line 62)
* records, multiline: Multiple Line. (line 6)
* records, printing: Print. (line 22)
* records, splitting input into: Records. (line 6)
-* records, terminating: awk split records. (line 125)
-* records, treating files as: gawk split records. (line 93)
-* recursive functions: Definition Syntax. (line 88)
-* redirect gawk output, in debugger: Debugger Info. (line 73)
+* records, terminating: awk split records. (line 124)
+* records, treating files as: gawk split records. (line 92)
+* recursive functions: Definition Syntax. (line 89)
+* redirect 'gawk' output, in debugger: Debugger Info. (line 73)
* redirection of input: Getline/File. (line 6)
* redirection of output: Redirection. (line 6)
* reference counting, sorting arrays: Array Sorting Functions.
(line 77)
* regexp: Regexp. (line 6)
-* regexp constants <1>: Comparison Operators.
- (line 103)
-* regexp constants <2>: Regexp Constants. (line 6)
* regexp constants: Regexp Usage. (line 57)
-* regexp constants, /=.../, /= operator and: Assignment Ops. (line 148)
+* regexp constants <1>: Regexp Constants. (line 6)
+* regexp constants <2>: Comparison Operators.
+ (line 103)
+* regexp constants, '/=.../', '/=' operator and: Assignment Ops.
+ (line 149)
* regexp constants, as patterns: Expression Patterns. (line 34)
-* regexp constants, in gawk: Using Constant Regexps.
+* regexp constants, in 'gawk': Using Constant Regexps.
(line 28)
* regexp constants, slashes vs. quotes: Computed Regexps. (line 30)
* regexp constants, vs. string constants: Computed Regexps. (line 40)
* register extension: Registration Functions.
(line 6)
* regular expressions: Regexp. (line 6)
-* regular expressions as field separators: Field Separators. (line 51)
+* regular expressions as field separators: Field Separators. (line 50)
* regular expressions, anchors in: Regexp Operators. (line 22)
* regular expressions, as field separators: Regexp Field Splitting.
(line 6)
-* regular expressions, as patterns <1>: Regexp Patterns. (line 6)
* regular expressions, as patterns: Regexp Usage. (line 6)
+* regular expressions, as patterns <1>: Regexp Patterns. (line 6)
* regular expressions, as record separators: awk split records.
- (line 125)
-* regular expressions, case sensitivity <1>: User-modified. (line 76)
+ (line 124)
* regular expressions, case sensitivity: Case-sensitivity. (line 6)
+* regular expressions, case sensitivity <1>: User-modified. (line 76)
* regular expressions, computed: Computed Regexps. (line 6)
* regular expressions, constants, See regexp constants: Regexp Usage.
(line 57)
* regular expressions, dynamic: Computed Regexps. (line 6)
* regular expressions, dynamic, with embedded newlines: Computed Regexps.
(line 60)
-* regular expressions, gawk, command-line options: GNU Regexp Operators.
- (line 70)
-* regular expressions, interval expressions and: Options. (line 281)
+* regular expressions, 'gawk', command-line options: GNU Regexp Operators.
+ (line 73)
+* regular expressions, interval expressions and: Options. (line 278)
* regular expressions, leftmost longest match: Leftmost Longest.
(line 6)
-* regular expressions, operators <1>: Regexp Operators. (line 6)
* regular expressions, operators: Regexp Usage. (line 19)
+* regular expressions, operators <1>: Regexp Operators. (line 6)
* regular expressions, operators, for buffers: GNU Regexp Operators.
- (line 48)
+ (line 51)
* regular expressions, operators, for words: GNU Regexp Operators.
(line 6)
-* regular expressions, operators, gawk: GNU Regexp Operators.
+* regular expressions, operators, 'gawk': GNU Regexp Operators.
(line 6)
* regular expressions, operators, precedence of: Regexp Operators.
(line 156)
@@ -33930,128 +33930,136 @@ Index
* relational operators, See comparison operators: Typing and Comparison.
(line 9)
* replace in string: String Functions. (line 409)
-* return debugger command: Debugger Execution Control.
+* 'return' debugger command: Debugger Execution Control.
(line 54)
-* return statement, user-defined functions: Return Statement. (line 6)
-* return value, close() function: Close Files And Pipes.
- (line 133)
-* rev() user-defined function: Function Example. (line 54)
-* revoutput extension: Extension Sample Revout.
+* 'return' statement, user-defined functions: Return Statement.
+ (line 6)
+* return value, 'close()' function: Close Files And Pipes.
+ (line 132)
+* 'rev()' user-defined function: Function Example. (line 54)
+* 'revoutput' extension: Extension Sample Revout.
(line 11)
-* revtwoway extension: Extension Sample Rev2way.
+* 'revtwoway' extension: Extension Sample Rev2way.
(line 12)
-* rewind() user-defined function: Rewind Function. (line 15)
-* right angle bracket (>), > operator <1>: Precedence. (line 65)
-* right angle bracket (>), > operator: Comparison Operators.
+* 'rewind()' user-defined function: Rewind Function. (line 15)
+* right angle bracket ('>'), '>' operator: Comparison Operators.
(line 11)
-* right angle bracket (>), > operator (I/O): Redirection. (line 22)
-* right angle bracket (>), >= operator <1>: Precedence. (line 65)
-* right angle bracket (>), >= operator: Comparison Operators.
+* right angle bracket ('>'), '>' operator <1>: Precedence. (line 64)
+* right angle bracket ('>'), '>' operator (I/O): Redirection. (line 22)
+* right angle bracket ('>'), '>=' operator: Comparison Operators.
(line 11)
-* right angle bracket (>), >> operator (I/O) <1>: Precedence. (line 65)
-* right angle bracket (>), >> operator (I/O): Redirection. (line 50)
-* right shift: Bitwise Functions. (line 53)
+* right angle bracket ('>'), '>=' operator <1>: Precedence. (line 64)
+* right angle bracket ('>'), '>>' operator (I/O): Redirection.
+ (line 50)
+* right angle bracket ('>'), '>>' operator (I/O) <1>: Precedence.
+ (line 64)
+* right shift: Bitwise Functions. (line 54)
* right shift, bitwise: Bitwise Functions. (line 32)
* Ritchie, Dennis: Basic Data Typing. (line 54)
-* RLENGTH variable: Auto-set. (line 252)
-* RLENGTH variable, match() function and: String Functions. (line 228)
-* Robbins, Arnold <1>: Future Extensions. (line 6)
-* Robbins, Arnold <2>: Bugs. (line 71)
-* Robbins, Arnold <3>: Contributors. (line 144)
-* Robbins, Arnold <4>: General Data Types. (line 6)
-* Robbins, Arnold <5>: Alarm Program. (line 6)
-* Robbins, Arnold <6>: Passwd Functions. (line 90)
-* Robbins, Arnold <7>: Getline/Pipe. (line 39)
+* 'RLENGTH' variable: Auto-set. (line 251)
+* 'RLENGTH' variable, 'match()' function and: String Functions.
+ (line 227)
* Robbins, Arnold: Command Line Field Separator.
(line 71)
-* Robbins, Bill: Getline/Pipe. (line 39)
-* Robbins, Harry: Acknowledgments. (line 94)
-* Robbins, Jean: Acknowledgments. (line 94)
-* Robbins, Miriam <1>: Passwd Functions. (line 90)
-* Robbins, Miriam <2>: Getline/Pipe. (line 39)
-* Robbins, Miriam: Acknowledgments. (line 94)
-* Rommel, Kai Uwe: Contributors. (line 42)
-* round to nearest integer: Numeric Functions. (line 23)
-* round() user-defined function: Round Function. (line 16)
+* Robbins, Arnold <1>: Getline/Pipe. (line 40)
+* Robbins, Arnold <2>: Passwd Functions. (line 90)
+* Robbins, Arnold <3>: Alarm Program. (line 6)
+* Robbins, Arnold <4>: General Data Types. (line 6)
+* Robbins, Arnold <5>: Contributors. (line 145)
+* Robbins, Arnold <6>: Bugs. (line 73)
+* Robbins, Arnold <7>: Future Extensions. (line 6)
+* Robbins, Bill: Getline/Pipe. (line 40)
+* Robbins, Harry: Acknowledgments. (line 93)
+* Robbins, Jean: Acknowledgments. (line 93)
+* Robbins, Miriam: Acknowledgments. (line 93)
+* Robbins, Miriam <1>: Getline/Pipe. (line 40)
+* Robbins, Miriam <2>: Passwd Functions. (line 90)
+* Rommel, Kai Uwe: Contributors. (line 43)
+* round to nearest integer: Numeric Functions. (line 22)
+* 'round()' user-defined function: Round Function. (line 16)
* rounding numbers: Round Function. (line 6)
-* ROUNDMODE variable: User-modified. (line 127)
-* RS variable <1>: User-modified. (line 132)
-* RS variable: awk split records. (line 12)
-* RS variable, multiline records and: Multiple Line. (line 17)
-* rshift: Bitwise Functions. (line 53)
-* RSTART variable: Auto-set. (line 258)
-* RSTART variable, match() function and: String Functions. (line 228)
-* RT variable <1>: Auto-set. (line 265)
-* RT variable <2>: Multiple Line. (line 129)
-* RT variable: awk split records. (line 125)
-* Rubin, Paul <1>: Contributors. (line 15)
+* 'ROUNDMODE' variable: User-modified. (line 128)
+* 'RS' variable: awk split records. (line 12)
+* 'RS' variable <1>: User-modified. (line 133)
+* 'RS' variable, multiline records and: Multiple Line. (line 17)
+* 'rshift': Bitwise Functions. (line 54)
+* 'RSTART' variable: Auto-set. (line 257)
+* 'RSTART' variable, 'match()' function and: String Functions.
+ (line 227)
+* 'RT' variable: awk split records. (line 124)
+* 'RT' variable <1>: Multiple Line. (line 129)
+* 'RT' variable <2>: Auto-set. (line 264)
* Rubin, Paul: History. (line 30)
+* Rubin, Paul <1>: Contributors. (line 16)
* rule, definition of: Getting Started. (line 21)
-* run debugger command: Debugger Execution Control.
+* 'run' debugger command: Debugger Execution Control.
(line 62)
-* rvalues/lvalues: Assignment Ops. (line 32)
-* s debugger command (alias for step): Debugger Execution Control.
+* rvalues/lvalues: Assignment Ops. (line 31)
+* 's' debugger command (alias for 'step'): Debugger Execution Control.
(line 68)
* sample debugging session: Sample Debugging Session.
(line 6)
-* sandbox mode: Options. (line 288)
+* sandbox mode: Options. (line 285)
* save debugger options: Debugger Info. (line 85)
* scalar or array: Type Functions. (line 11)
* scalar values: Basic Data Typing. (line 13)
* scanning arrays: Scanning an Array. (line 6)
* scanning multidimensional arrays: Multiscanning. (line 11)
-* Schorr, Andrew <1>: Contributors. (line 133)
-* Schorr, Andrew <2>: Auto-set. (line 297)
* Schorr, Andrew: Acknowledgments. (line 60)
+* Schorr, Andrew <1>: Auto-set. (line 296)
+* Schorr, Andrew <2>: Contributors. (line 134)
* Schreiber, Bert: Acknowledgments. (line 38)
* Schreiber, Rita: Acknowledgments. (line 38)
-* search and replace in strings: String Functions. (line 90)
-* search in string: String Functions. (line 156)
-* search paths <1>: VMS Running. (line 57)
-* search paths <2>: PC Using. (line 10)
+* search and replace in strings: String Functions. (line 89)
+* search in string: String Functions. (line 155)
* search paths: Programs Exercises. (line 70)
+* search paths <1>: PC Using. (line 10)
+* search paths <2>: VMS Running. (line 57)
* search paths, for loadable extensions: AWKLIBPATH Variable. (line 6)
-* search paths, for source files <1>: VMS Running. (line 57)
-* search paths, for source files <2>: PC Using. (line 10)
-* search paths, for source files <3>: Programs Exercises. (line 70)
* search paths, for source files: AWKPATH Variable. (line 6)
+* search paths, for source files <1>: Programs Exercises. (line 70)
+* search paths, for source files <2>: PC Using. (line 10)
+* search paths, for source files <3>: VMS Running. (line 57)
* searching, files for regular expressions: Egrep Program. (line 6)
* searching, for words: Dupword Program. (line 6)
-* sed utility <1>: Glossary. (line 16)
-* sed utility <2>: Simple Sed. (line 6)
-* sed utility: Full Line Fields. (line 22)
-* seeding random number generator: Numeric Functions. (line 63)
-* semicolon (;), AWKPATH variable and: PC Using. (line 10)
-* semicolon (;), separating statements in actions <1>: Statements.
- (line 10)
-* semicolon (;), separating statements in actions <2>: Action Overview.
+* 'sed' utility: Full Line Fields. (line 22)
+* 'sed' utility <1>: Simple Sed. (line 6)
+* 'sed' utility <2>: Glossary. (line 16)
+* seeding random number generator: Numeric Functions. (line 62)
+* semicolon (';'), 'AWKPATH' variable and: PC Using. (line 10)
+* semicolon (';'), separating statements in actions: Statements/Lines.
+ (line 90)
+* semicolon (';'), separating statements in actions <1>: Action Overview.
(line 19)
-* semicolon (;), separating statements in actions: Statements/Lines.
- (line 91)
+* semicolon (';'), separating statements in actions <2>: Statements.
+ (line 10)
* separators, field: User-modified. (line 50)
-* separators, field, FIELDWIDTHS variable and: User-modified. (line 37)
-* separators, field, FPAT variable and: User-modified. (line 43)
+* separators, field <1>: User-modified. (line 113)
+* separators, field, 'FIELDWIDTHS' variable and: User-modified.
+ (line 37)
+* separators, field, 'FPAT' variable and: User-modified. (line 43)
* separators, field, POSIX and: Fields. (line 6)
-* separators, for records <1>: User-modified. (line 132)
* separators, for records: awk split records. (line 6)
+* separators, for records <1>: awk split records. (line 85)
+* separators, for records <2>: User-modified. (line 133)
* separators, for records, regular expressions as: awk split records.
- (line 125)
+ (line 124)
* separators, for statements in actions: Action Overview. (line 19)
-* separators, subscript: User-modified. (line 145)
+* separators, subscript: User-modified. (line 146)
* set breakpoint: Breakpoint Control. (line 11)
-* set debugger command: Viewing And Changing Data.
- (line 59)
-* set directory of message catalogs: I18N Functions. (line 12)
+* 'set' debugger command: Viewing And Changing Data.
+ (line 58)
+* set directory of message catalogs: I18N Functions. (line 11)
* set watchpoint: Viewing And Changing Data.
- (line 67)
-* shadowing of variable values: Definition Syntax. (line 76)
+ (line 66)
+* shadowing of variable values: Definition Syntax. (line 77)
* shell quoting, rules for: Quoting. (line 6)
* shells, piping commands into: Redirection. (line 136)
* shells, quoting: Using Shell Variables.
(line 12)
* shells, quoting, rules for: Quoting. (line 18)
* shells, scripts: One-shot. (line 22)
-* shells, sea: Undocumented. (line 8)
+* shells, sea: Undocumented. (line 9)
* shells, variables: Using Shell Variables.
(line 6)
* shift, bitwise: Bitwise Functions. (line 32)
@@ -34063,159 +34071,161 @@ Index
* show name of current source file, in debugger: Debugger Info.
(line 37)
* show watchpoints: Debugger Info. (line 51)
-* si debugger command (alias for stepi): Debugger Execution Control.
- (line 76)
-* side effects <1>: Increment Ops. (line 11)
+* 'si' debugger command (alias for 'stepi'): Debugger Execution Control.
+ (line 75)
* side effects: Concatenation. (line 41)
+* side effects <1>: Increment Ops. (line 11)
+* side effects <2>: Increment Ops. (line 75)
* side effects, array indexing: Reference to Elements.
(line 43)
-* side effects, asort() function: Array Sorting Functions.
+* side effects, 'asort()' function: Array Sorting Functions.
(line 24)
-* side effects, assignment expressions: Assignment Ops. (line 23)
+* side effects, assignment expressions: Assignment Ops. (line 22)
* side effects, Boolean operators: Boolean Ops. (line 30)
* side effects, conditional expressions: Conditional Exp. (line 22)
* side effects, decrement/increment operators: Increment Ops. (line 11)
-* side effects, FILENAME variable: Getline Notes. (line 19)
+* side effects, 'FILENAME' variable: Getline Notes. (line 19)
* side effects, function calls: Function Calls. (line 57)
* side effects, statements: Action Overview. (line 32)
* sidebar, A Constant's Base Does Not Affect Its Value: Nondecimal-numbers.
- (line 64)
+ (line 63)
* sidebar, Backslash Before Regular Characters: Escape Sequences.
(line 103)
-* sidebar, Changing FS Does Not Affect the Fields: Full Line Fields.
+* sidebar, Changing 'FS' Does Not Affect the Fields: Full Line Fields.
(line 14)
-* sidebar, Changing NR and FNR: Auto-set. (line 312)
-* sidebar, Controlling Output Buffering with system(): I/O Functions.
- (line 139)
+* sidebar, Changing 'NR' and 'FNR': Auto-set. (line 311)
+* sidebar, Controlling Output Buffering with 'system()': I/O Functions.
+ (line 137)
* sidebar, Escape Sequences for Metacharacters: Escape Sequences.
(line 134)
-* sidebar, FS and IGNORECASE: Field Splitting Summary.
- (line 38)
+* sidebar, 'FS' and 'IGNORECASE': Field Splitting Summary.
+ (line 37)
* sidebar, Interactive Versus Noninteractive Buffering: I/O Functions.
(line 74)
* sidebar, Matching the Null String: String Functions. (line 535)
* sidebar, Operator Evaluation Order: Increment Ops. (line 58)
-* sidebar, Piping into sh: Redirection. (line 134)
-* sidebar, Pre-POSIX awk Used OFMT for String Conversion: Strings And Numbers.
- (line 55)
+* sidebar, Piping into 'sh': Redirection. (line 134)
+* sidebar, Pre-POSIX 'awk' Used 'OFMT' for String Conversion: Strings And
Numbers.
+ (line 54)
* sidebar, Recipe for a Programming Language: History. (line 6)
-* sidebar, RS = "\0" Is Not Portable: gawk split records. (line 63)
-* sidebar, So Why Does gawk Have BEGINFILE and ENDFILE?: Filetrans Function.
+* sidebar, 'RS = "\0"' Is Not Portable: gawk split records. (line 63)
+* sidebar, So Why Does 'gawk' Have 'BEGINFILE' and 'ENDFILE'?: Filetrans
Function.
(line 83)
-* sidebar, Syntactic Ambiguities Between /= and Regular Expressions:
Assignment Ops.
- (line 146)
-* sidebar, Understanding #!: Executable Scripts. (line 31)
-* sidebar, Understanding $0: Changing Fields. (line 134)
-* sidebar, Using \n in Bracket Expressions of Dynamic Regexps: Computed
Regexps.
+* sidebar, Syntactic Ambiguities Between '/=' and Regular Expressions:
Assignment Ops.
+ (line 147)
+* sidebar, Understanding '#!': Executable Scripts. (line 31)
+* sidebar, Understanding '$0': Changing Fields. (line 134)
+* sidebar, Using 'close()''s Return Value: Close Files And Pipes.
+ (line 130)
+* sidebar, Using '\n' in Bracket Expressions of Dynamic Regexps: Computed
Regexps.
(line 58)
-* sidebar, Using close()'s Return Value: Close Files And Pipes.
- (line 131)
-* SIGHUP signal, for dynamic profiling: Profiling. (line 211)
-* SIGINT signal (MS-Windows): Profiling. (line 214)
-* signals, HUP/SIGHUP, for profiling: Profiling. (line 211)
-* signals, INT/SIGINT (MS-Windows): Profiling. (line 214)
-* signals, QUIT/SIGQUIT (MS-Windows): Profiling. (line 214)
-* signals, USR1/SIGUSR1, for profiling: Profiling. (line 188)
+* 'SIGHUP' signal, for dynamic profiling: Profiling. (line 210)
+* 'SIGINT' signal (MS-Windows): Profiling. (line 213)
+* signals, 'HUP'/'SIGHUP', for profiling: Profiling. (line 210)
+* signals, 'INT'/'SIGINT' (MS-Windows): Profiling. (line 213)
+* signals, 'QUIT'/'SIGQUIT' (MS-Windows): Profiling. (line 213)
+* signals, 'USR1'/'SIGUSR1', for profiling: Profiling. (line 187)
* signature program: Signature Program. (line 6)
-* SIGQUIT signal (MS-Windows): Profiling. (line 214)
-* SIGUSR1 signal, for dynamic profiling: Profiling. (line 188)
-* silent debugger command: Debugger Execution Control.
+* 'SIGQUIT' signal (MS-Windows): Profiling. (line 213)
+* 'SIGUSR1' signal, for dynamic profiling: Profiling. (line 187)
+* 'silent' debugger command: Debugger Execution Control.
(line 10)
-* sin: Numeric Functions. (line 74)
-* sine: Numeric Functions. (line 74)
-* single quote ('): One-shot. (line 15)
-* single quote (') in gawk command lines: Long. (line 35)
-* single quote ('), in shell commands: Quoting. (line 48)
-* single quote ('), vs. apostrophe: Comments. (line 27)
-* single quote ('), with double quotes: Quoting. (line 73)
+* 'sin': Numeric Functions. (line 73)
+* sine: Numeric Functions. (line 73)
+* single quote ('''): One-shot. (line 15)
+* single quote (''') in 'gawk' command lines: Long. (line 35)
+* single quote ('''), in shell commands: Quoting. (line 48)
+* single quote ('''), vs. apostrophe: Comments. (line 27)
+* single quote ('''), with double quotes: Quoting. (line 73)
* single-character fields: Single Character Fields.
(line 6)
* single-step execution, in the debugger: Debugger Execution Control.
(line 43)
* Skywalker, Luke: Undocumented. (line 6)
-* sleep utility: Alarm Program. (line 110)
-* sleep() extension function: Extension Sample Time.
+* 'sleep' utility: Alarm Program. (line 109)
+* 'sleep()' extension function: Extension Sample Time.
(line 22)
-* Solaris, POSIX-compliant awk: Other Versions. (line 100)
+* Solaris, POSIX-compliant 'awk': Other Versions. (line 100)
* sort array: String Functions. (line 42)
* sort array indices: String Functions. (line 42)
* sort function, arrays, sorting: Array Sorting Functions.
(line 6)
-* sort utility: Word Sorting. (line 50)
-* sort utility, coprocesses and: Two-way I/O. (line 65)
+* 'sort' utility: Word Sorting. (line 50)
+* 'sort' utility, coprocesses and: Two-way I/O. (line 66)
* sorting characters in different languages: Explaining gettext.
(line 94)
-* source code, awka: Other Versions. (line 68)
-* source code, Brian Kernighan's awk: Other Versions. (line 13)
+* source code, 'awka': Other Versions. (line 68)
+* source code, Brian Kernighan's 'awk': Other Versions. (line 13)
* source code, BusyBox Awk: Other Versions. (line 92)
-* source code, gawk: Gawk Distribution. (line 6)
-* source code, Illumos awk: Other Versions. (line 109)
-* source code, jawk: Other Versions. (line 117)
+* source code, 'gawk': Gawk Distribution. (line 6)
+* source code, Illumos 'awk': Other Versions. (line 109)
+* source code, 'jawk': Other Versions. (line 117)
* source code, libmawk: Other Versions. (line 125)
-* source code, mawk: Other Versions. (line 48)
+* source code, 'mawk': Other Versions. (line 48)
* source code, mixing: Options. (line 117)
-* source code, pawk: Other Versions. (line 82)
-* source code, pawk (Python version): Other Versions. (line 129)
-* source code, QSE awk: Other Versions. (line 135)
+* source code, 'pawk': Other Versions. (line 82)
+* source code, 'pawk' (Python version): Other Versions. (line 129)
+* source code, QSE 'awk': Other Versions. (line 135)
* source code, QuikTrim Awk: Other Versions. (line 139)
-* source code, Solaris awk: Other Versions. (line 100)
+* source code, Solaris 'awk': Other Versions. (line 100)
* source files, search path for: Programs Exercises. (line 70)
* sparse arrays: Array Intro. (line 76)
* Spencer, Henry: Glossary. (line 16)
-* split: String Functions. (line 316)
-* split string into array: String Functions. (line 297)
-* split utility: Split Program. (line 6)
-* split() function, array elements, deleting: Delete. (line 61)
-* split.awk program: Split Program. (line 30)
-* sprintf <1>: String Functions. (line 384)
-* sprintf: OFMT. (line 15)
-* sprintf() function, OFMT variable and: User-modified. (line 113)
-* sprintf() function, print/printf statements and: Round Function.
+* 'split': String Functions. (line 315)
+* split string into array: String Functions. (line 296)
+* 'split' utility: Split Program. (line 6)
+* 'split()' function, array elements, deleting: Delete. (line 61)
+* 'split.awk' program: Split Program. (line 30)
+* 'sprintf': OFMT. (line 15)
+* 'sprintf' <1>: String Functions. (line 384)
+* 'sprintf()' function, 'OFMT' variable and: User-modified. (line 113)
+* 'sprintf()' function, 'print'/'printf' statements and: Round Function.
(line 6)
-* sqrt: Numeric Functions. (line 77)
-* square brackets ([]), regexp operator: Regexp Operators. (line 56)
-* square root: Numeric Functions. (line 77)
-* srand: Numeric Functions. (line 81)
+* 'sqrt': Numeric Functions. (line 76)
+* square brackets ('[]'), regexp operator: Regexp Operators. (line 56)
+* square root: Numeric Functions. (line 76)
+* 'srand': Numeric Functions. (line 80)
* stack frame: Debugging Terms. (line 10)
-* Stallman, Richard <1>: Glossary. (line 375)
-* Stallman, Richard <2>: Contributors. (line 23)
-* Stallman, Richard <3>: Acknowledgments. (line 18)
* Stallman, Richard: Manual History. (line 6)
+* Stallman, Richard <1>: Acknowledgments. (line 18)
+* Stallman, Richard <2>: Contributors. (line 24)
+* Stallman, Richard <3>: Glossary. (line 372)
* standard error: Special FD. (line 6)
-* standard input <1>: Special FD. (line 6)
* standard input: Read Terminal. (line 6)
+* standard input <1>: Special FD. (line 6)
* standard output: Special FD. (line 6)
* starting the debugger: Debugger Invocation. (line 6)
-* stat() extension function: Extension Sample File Functions.
+* 'stat()' extension function: Extension Sample File Functions.
(line 18)
* statements, compound, control statements and: Statements. (line 10)
* statements, control, in actions: Statements. (line 6)
-* statements, multiple: Statements/Lines. (line 91)
-* step debugger command: Debugger Execution Control.
+* statements, multiple: Statements/Lines. (line 90)
+* 'step' debugger command: Debugger Execution Control.
(line 68)
-* stepi debugger command: Debugger Execution Control.
- (line 76)
+* 'stepi' debugger command: Debugger Execution Control.
+ (line 75)
* stop automatic display, in debugger: Viewing And Changing Data.
- (line 80)
-* stream editors <1>: Simple Sed. (line 6)
+ (line 79)
* stream editors: Full Line Fields. (line 22)
-* strftime: Time Functions. (line 48)
+* stream editors <1>: Simple Sed. (line 6)
+* 'strftime': Time Functions. (line 48)
* string constants: Scalar Constants. (line 15)
* string constants, vs. regexp constants: Computed Regexps. (line 40)
* string extraction (internationalization): String Extraction.
(line 6)
-* string length: String Functions. (line 171)
-* string operators: Concatenation. (line 8)
-* string, regular expression match: String Functions. (line 211)
+* string length: String Functions. (line 170)
+* string operators: Concatenation. (line 9)
+* string, regular expression match: String Functions. (line 210)
* string-manipulation functions: String Functions. (line 6)
* string-matching operators: Regexp Usage. (line 19)
* string-translation functions: I18N Functions. (line 6)
-* strings splitting, example: String Functions. (line 335)
-* strings, converting <1>: Bitwise Functions. (line 110)
+* strings splitting, example: String Functions. (line 334)
* strings, converting: Strings And Numbers. (line 6)
+* strings, converting <1>: Bitwise Functions. (line 111)
* strings, converting letter case: String Functions. (line 523)
* strings, converting, numbers to: User-modified. (line 30)
-* strings, empty, See null strings: awk split records. (line 115)
+* strings, converting, numbers to <1>: User-modified. (line 104)
+* strings, empty, See null strings: awk split records. (line 114)
* strings, extracting: String Extraction. (line 6)
* strings, for localization: Programmer i18n. (line 13)
* strings, length limitations: Scalar Constants. (line 20)
@@ -34223,15 +34233,15 @@ Index
* strings, null: Regexp Field Splitting.
(line 43)
* strings, numeric: Variable Typing. (line 6)
-* strtonum: String Functions. (line 391)
-* strtonum() function (gawk), --non-decimal-data option and: Nondecimal Data.
+* 'strtonum': String Functions. (line 391)
+* 'strtonum()' function ('gawk'), '--non-decimal-data' option and: Nondecimal
Data.
(line 35)
-* sub <1>: String Functions. (line 409)
-* sub: Using Constant Regexps.
+* 'sub': Using Constant Regexps.
(line 43)
-* sub() function, arguments of: String Functions. (line 463)
-* sub() function, escape processing: Gory Details. (line 6)
-* subscript separators: User-modified. (line 145)
+* 'sub' <1>: String Functions. (line 409)
+* 'sub()' function, arguments of: String Functions. (line 463)
+* 'sub()' function, escape processing: Gory Details. (line 6)
+* subscript separators: User-modified. (line 146)
* subscripts in arrays, multidimensional: Multidimensional. (line 10)
* subscripts in arrays, multidimensional, scanning: Multiscanning.
(line 11)
@@ -34239,57 +34249,61 @@ Index
(line 6)
* subscripts in arrays, uninitialized variables as: Uninitialized Subscripts.
(line 6)
-* SUBSEP variable: User-modified. (line 145)
-* SUBSEP variable, and multidimensional arrays: Multidimensional.
+* 'SUBSEP' variable: User-modified. (line 146)
+* 'SUBSEP' variable, and multidimensional arrays: Multidimensional.
(line 16)
-* substitute in string: String Functions. (line 90)
-* substr: String Functions. (line 482)
+* substitute in string: String Functions. (line 89)
+* 'substr': String Functions. (line 482)
* substring: String Functions. (line 482)
* Sumner, Andrew: Other Versions. (line 68)
-* supplementary groups of gawk process: Auto-set. (line 237)
-* switch statement: Switch Statement. (line 6)
-* SYMTAB array: Auto-set. (line 269)
-* syntactic ambiguity: /= operator vs. /=.../ regexp constant: Assignment Ops.
- (line 148)
-* system: I/O Functions. (line 107)
-* systime: Time Functions. (line 66)
-* t debugger command (alias for tbreak): Breakpoint Control. (line 90)
-* tbreak debugger command: Breakpoint Control. (line 90)
+* supplementary groups of 'gawk' process: Auto-set. (line 236)
+* 'switch' statement: Switch Statement. (line 6)
+* 'SYMTAB' array: Auto-set. (line 268)
+* syntactic ambiguity: '/=' operator vs. '/=.../' regexp constant: Assignment
Ops.
+ (line 149)
+* 'system': I/O Functions. (line 107)
+* 'systime': Time Functions. (line 65)
+* 't' debugger command (alias for 'tbreak'): Breakpoint Control.
+ (line 90)
+* 'tbreak' debugger command: Breakpoint Control. (line 90)
* Tcl: Library Names. (line 58)
* TCP/IP: TCP/IP Networking. (line 6)
* TCP/IP, support for: Special Network. (line 6)
-* tee utility: Tee Program. (line 6)
-* tee.awk program: Tee Program. (line 26)
+* 'tee' utility: Tee Program. (line 6)
+* 'tee.awk' program: Tee Program. (line 26)
* temporary breakpoint: Breakpoint Control. (line 90)
-* terminating records: awk split records. (line 125)
-* testbits.awk program: Bitwise Functions. (line 71)
-* testext extension: Extension Sample API Tests.
+* terminating records: awk split records. (line 124)
+* 'testbits.awk' program: Bitwise Functions. (line 72)
+* 'testext' extension: Extension Sample API Tests.
(line 6)
-* Texinfo <1>: Adding Code. (line 99)
-* Texinfo <2>: Distribution contents.
- (line 77)
-* Texinfo <3>: Extract Program. (line 12)
-* Texinfo <4>: Dupword Program. (line 17)
-* Texinfo <5>: Library Functions. (line 33)
* Texinfo: Conventions. (line 6)
+* Texinfo <1>: Library Functions. (line 33)
+* Texinfo <2>: Dupword Program. (line 17)
+* Texinfo <3>: Extract Program. (line 12)
+* Texinfo <4>: Distribution contents.
+ (line 77)
+* Texinfo <5>: Adding Code. (line 98)
* Texinfo, chapter beginnings in files: Regexp Operators. (line 22)
* Texinfo, extracting programs from source files: Extract Program.
(line 6)
* text, printing: Print. (line 22)
* text, printing, unduplicated lines of: Uniq Program. (line 6)
-* TEXTDOMAIN variable <1>: Programmer i18n. (line 8)
-* TEXTDOMAIN variable: User-modified. (line 151)
-* TEXTDOMAIN variable, BEGIN pattern and: Programmer i18n. (line 60)
-* TEXTDOMAIN variable, portability and: I18N Portability. (line 20)
-* textdomain() function (C library): Explaining gettext. (line 28)
-* tilde (~), ~ operator <1>: Expression Patterns. (line 24)
-* tilde (~), ~ operator <2>: Precedence. (line 80)
-* tilde (~), ~ operator <3>: Comparison Operators.
+* 'TEXTDOMAIN' variable: User-modified. (line 152)
+* 'TEXTDOMAIN' variable <1>: Programmer i18n. (line 8)
+* 'TEXTDOMAIN' variable, 'BEGIN' pattern and: Programmer i18n.
+ (line 60)
+* 'TEXTDOMAIN' variable, portability and: I18N Portability. (line 20)
+* 'textdomain()' function (C library): Explaining gettext. (line 28)
+* tilde ('~'), '~' operator: Regexp Usage. (line 19)
+* tilde ('~'), '~' operator <1>: Computed Regexps. (line 6)
+* tilde ('~'), '~' operator <2>: Case-sensitivity. (line 26)
+* tilde ('~'), '~' operator <3>: Regexp Constants. (line 6)
+* tilde ('~'), '~' operator <4>: Comparison Operators.
(line 11)
-* tilde (~), ~ operator <4>: Regexp Constants. (line 6)
-* tilde (~), ~ operator <5>: Case-sensitivity. (line 26)
-* tilde (~), ~ operator <6>: Computed Regexps. (line 6)
-* tilde (~), ~ operator: Regexp Usage. (line 19)
+* tilde ('~'), '~' operator <5>: Comparison Operators.
+ (line 98)
+* tilde ('~'), '~' operator <6>: Precedence. (line 79)
+* tilde ('~'), '~' operator <7>: Expression Patterns. (line 24)
* time functions: Time Functions. (line 6)
* time, alarm clock example program: Alarm Program. (line 11)
* time, localization and: Explaining gettext. (line 112)
@@ -34298,92 +34312,95 @@ Index
* time, retrieving: Time Functions. (line 17)
* timeout, reading input: Read Timeout. (line 6)
* timestamps: Time Functions. (line 6)
-* timestamps, converting dates to: Time Functions. (line 76)
+* timestamps <1>: Time Functions. (line 65)
+* timestamps, converting dates to: Time Functions. (line 75)
* timestamps, formatted: Getlocaltime Function.
(line 6)
-* tolower: String Functions. (line 524)
-* toupper: String Functions. (line 530)
-* tr utility: Translate Program. (line 6)
-* trace debugger command: Miscellaneous Debugger Commands.
+* 'tolower': String Functions. (line 524)
+* 'toupper': String Functions. (line 530)
+* 'tr' utility: Translate Program. (line 6)
+* 'trace' debugger command: Miscellaneous Debugger Commands.
(line 107)
* traceback, display in debugger: Execution Stack. (line 13)
-* translate string: I18N Functions. (line 22)
-* translate.awk program: Translate Program. (line 55)
-* treating files, as single records: gawk split records. (line 93)
-* troubleshooting, --non-decimal-data option: Options. (line 211)
-* troubleshooting, == operator: Comparison Operators.
+* translate string: I18N Functions. (line 21)
+* 'translate.awk' program: Translate Program. (line 55)
+* treating files, as single records: gawk split records. (line 92)
+* troubleshooting, '--non-decimal-data' option: Options. (line 209)
+* troubleshooting, '==' operator: Comparison Operators.
(line 37)
-* troubleshooting, awk uses FS not IFS: Field Separators. (line 30)
+* troubleshooting, 'awk' uses 'FS' not 'IFS': Field Separators.
+ (line 29)
* troubleshooting, backslash before nonspecial character: Escape Sequences.
(line 105)
* troubleshooting, division: Arithmetic Ops. (line 44)
* troubleshooting, fatal errors, field widths, specifying: Constant Size.
(line 22)
-* troubleshooting, fatal errors, printf format strings: Format Modifiers.
- (line 158)
-* troubleshooting, fflush() function: I/O Functions. (line 63)
+* troubleshooting, fatal errors, 'printf' format strings: Format Modifiers.
+ (line 157)
+* troubleshooting, 'fflush()' function: I/O Functions. (line 63)
* troubleshooting, function call syntax: Function Calls. (line 30)
-* troubleshooting, gawk: Compatibility Mode. (line 6)
-* troubleshooting, gawk, bug reports: Bugs. (line 9)
-* troubleshooting, gawk, fatal errors, function arguments: Calling Built-in.
+* troubleshooting, 'gawk': Compatibility Mode. (line 6)
+* troubleshooting, 'gawk', bug reports: Bugs. (line 9)
+* troubleshooting, 'gawk', fatal errors, function arguments: Calling Built-in.
(line 16)
-* troubleshooting, getline function: File Checking. (line 25)
-* troubleshooting, gsub()/sub() functions: String Functions. (line 473)
-* troubleshooting, match() function: String Functions. (line 292)
-* troubleshooting, print statement, omitting commas: Print Examples.
- (line 31)
+* troubleshooting, 'getline' function: File Checking. (line 25)
+* troubleshooting, 'gsub()'/'sub()' functions: String Functions.
+ (line 473)
+* troubleshooting, 'match()' function: String Functions. (line 291)
+* troubleshooting, 'print' statement, omitting commas: Print Examples.
+ (line 30)
* troubleshooting, printing: Redirection. (line 112)
* troubleshooting, quotes with file names: Special FD. (line 62)
* troubleshooting, readable data files: File Checking. (line 6)
* troubleshooting, regexp constants vs. string constants: Computed Regexps.
(line 40)
-* troubleshooting, string concatenation: Concatenation. (line 26)
-* troubleshooting, substr() function: String Functions. (line 500)
-* troubleshooting, system() function: I/O Functions. (line 129)
+* troubleshooting, string concatenation: Concatenation. (line 27)
+* troubleshooting, 'substr()' function: String Functions. (line 500)
+* troubleshooting, 'system()' function: I/O Functions. (line 129)
* troubleshooting, typographical errors, global variables: Options.
- (line 98)
+ (line 99)
* true, logical: Truth Values. (line 6)
-* Trueman, David <1>: Contributors. (line 30)
-* Trueman, David <2>: Acknowledgments. (line 47)
* Trueman, David: History. (line 30)
+* Trueman, David <1>: Acknowledgments. (line 47)
+* Trueman, David <2>: Contributors. (line 31)
* trunc-mod operation: Arithmetic Ops. (line 66)
* truth values: Truth Values. (line 6)
* type conversion: Strings And Numbers. (line 21)
-* u debugger command (alias for until): Debugger Execution Control.
- (line 83)
+* 'u' debugger command (alias for 'until'): Debugger Execution Control.
+ (line 82)
* unassigned array elements: Reference to Elements.
(line 18)
* undefined functions: Pass By Value/Reference.
(line 68)
-* underscore (_), C macro: Explaining gettext. (line 71)
-* underscore (_), in names of private variables: Library Names.
+* underscore ('_'), C macro: Explaining gettext. (line 71)
+* underscore ('_'), in names of private variables: Library Names.
(line 29)
-* underscore (_), translatable string: Programmer i18n. (line 69)
-* undisplay debugger command: Viewing And Changing Data.
- (line 80)
+* underscore ('_'), translatable string: Programmer i18n. (line 69)
+* 'undisplay' debugger command: Viewing And Changing Data.
+ (line 79)
* undocumented features: Undocumented. (line 6)
-* Unicode <1>: Glossary. (line 197)
-* Unicode <2>: Ranges and Locales. (line 61)
* Unicode: Ordinal Functions. (line 45)
+* Unicode <1>: Ranges and Locales. (line 61)
+* Unicode <2>: Glossary. (line 196)
* uninitialized variables, as array subscripts: Uninitialized Subscripts.
(line 6)
-* uniq utility: Uniq Program. (line 6)
-* uniq.awk program: Uniq Program. (line 65)
-* Unix: Glossary. (line 753)
-* Unix awk, backslashes in escape sequences: Escape Sequences.
+* 'uniq' utility: Uniq Program. (line 6)
+* 'uniq.awk' program: Uniq Program. (line 65)
+* Unix: Glossary. (line 748)
+* Unix 'awk', backslashes in escape sequences: Escape Sequences.
(line 117)
-* Unix awk, close() function and: Close Files And Pipes.
- (line 133)
-* Unix awk, password files, field separators and: Command Line Field Separator.
+* Unix 'awk', 'close()' function and: Close Files And Pipes.
+ (line 132)
+* Unix 'awk', password files, field separators and: Command Line Field
Separator.
(line 62)
-* Unix, awk scripts and: Executable Scripts. (line 6)
-* UNIXROOT variable, on OS/2 systems: PC Using. (line 16)
+* Unix, 'awk' scripts and: Executable Scripts. (line 6)
+* 'UNIXROOT' variable, on OS/2 systems: PC Using. (line 16)
* unsigned integers: Computer Arithmetic. (line 41)
-* until debugger command: Debugger Execution Control.
+* 'until' debugger command: Debugger Execution Control.
+ (line 82)
+* 'unwatch' debugger command: Viewing And Changing Data.
(line 83)
-* unwatch debugger command: Viewing And Changing Data.
- (line 84)
-* up debugger command: Execution Stack. (line 36)
+* 'up' debugger command: Execution Stack. (line 36)
* user database, reading: Passwd Functions. (line 6)
* user-defined functions: User-defined. (line 6)
* user-defined, functions, counts, in a profile: Profiling. (line 137)
@@ -34391,686 +34408,663 @@ Index
* user-modifiable variables: User-modified. (line 6)
* users, information about, printing: Id Program. (line 6)
* users, information about, retrieving: Passwd Functions. (line 16)
-* USR1 signal, for dynamic profiling: Profiling. (line 188)
+* 'USR1' signal, for dynamic profiling: Profiling. (line 187)
* values, numeric: Basic Data Typing. (line 13)
* values, string: Basic Data Typing. (line 13)
* variable assignments and input files: Other Arguments. (line 26)
* variable typing: Typing and Comparison.
(line 9)
-* variables <1>: Basic Data Typing. (line 6)
* variables: Other Features. (line 6)
+* variables <1>: Basic Data Typing. (line 6)
* variables, assigning on command line: Assignment Options. (line 6)
* variables, built-in: Using Variables. (line 23)
* variables, flag: Boolean Ops. (line 69)
-* variables, getline command into, using <1>: Getline/Variable/Coprocess.
+* variables, 'getline' command into, using: Getline/Variable. (line 6)
+* variables, 'getline' command into, using <1>: Getline/Variable/File.
(line 6)
-* variables, getline command into, using <2>: Getline/Variable/Pipe.
+* variables, 'getline' command into, using <2>: Getline/Variable/Pipe.
(line 6)
-* variables, getline command into, using <3>: Getline/Variable/File.
+* variables, 'getline' command into, using <3>: Getline/Variable/Coprocess.
(line 6)
-* variables, getline command into, using: Getline/Variable. (line 6)
* variables, global, for library functions: Library Names. (line 11)
-* variables, global, printing list of: Options. (line 93)
+* variables, global, printing list of: Options. (line 94)
* variables, initializing: Using Variables. (line 23)
* variables, local to a function: Variable Scope. (line 6)
* variables, predefined: Built-in Variables. (line 6)
-* variables, predefined -v option, setting with: Options. (line 40)
+* variables, predefined '-v' option, setting with: Options. (line 41)
* variables, predefined conveying information: Auto-set. (line 6)
* variables, private: Library Names. (line 11)
* variables, setting: Options. (line 32)
-* variables, shadowing: Definition Syntax. (line 76)
-* variables, types of: Assignment Ops. (line 40)
+* variables, shadowing: Definition Syntax. (line 77)
+* variables, types of: Assignment Ops. (line 39)
* variables, types of, comparison expressions and: Typing and Comparison.
(line 9)
* variables, uninitialized, as array subscripts: Uninitialized Subscripts.
(line 6)
* variables, user-defined: Variables. (line 6)
-* version of gawk: Auto-set. (line 207)
-* version of gawk extension API: Auto-set. (line 232)
-* version of GNU MP library: Auto-set. (line 218)
-* version of GNU MPFR library: Auto-set. (line 214)
-* vertical bar (|): Regexp Operators. (line 70)
-* vertical bar (|), | operator (I/O) <1>: Precedence. (line 65)
-* vertical bar (|), | operator (I/O): Getline/Pipe. (line 9)
-* vertical bar (|), |& operator (I/O) <1>: Two-way I/O. (line 25)
-* vertical bar (|), |& operator (I/O) <2>: Precedence. (line 65)
-* vertical bar (|), |& operator (I/O): Getline/Coprocess. (line 6)
-* vertical bar (|), || operator <1>: Precedence. (line 89)
-* vertical bar (|), || operator: Boolean Ops. (line 59)
+* version of 'gawk': Auto-set. (line 206)
+* version of 'gawk' extension API: Auto-set. (line 231)
+* version of GNU MP library: Auto-set. (line 217)
+* version of GNU MPFR library: Auto-set. (line 213)
+* vertical bar ('|'): Regexp Operators. (line 70)
+* vertical bar ('|'), '|' operator (I/O): Getline/Pipe. (line 10)
+* vertical bar ('|'), '|' operator (I/O) <1>: Precedence. (line 64)
+* vertical bar ('|'), '|&' operator (I/O): Getline/Coprocess. (line 6)
+* vertical bar ('|'), '|&' operator (I/O) <1>: Precedence. (line 64)
+* vertical bar ('|'), '|&' operator (I/O) <2>: Two-way I/O. (line 27)
+* vertical bar ('|'), '||' operator: Boolean Ops. (line 59)
+* vertical bar ('|'), '||' operator <1>: Precedence. (line 88)
* Vinschen, Corinna: Acknowledgments. (line 60)
-* w debugger command (alias for watch): Viewing And Changing Data.
- (line 67)
-* w utility: Constant Size. (line 22)
-* wait() extension function: Extension Sample Fork.
+* 'w' debugger command (alias for 'watch'): Viewing And Changing Data.
+ (line 66)
+* 'w' utility: Constant Size. (line 22)
+* 'wait()' extension function: Extension Sample Fork.
(line 22)
-* waitpid() extension function: Extension Sample Fork.
+* 'waitpid()' extension function: Extension Sample Fork.
(line 18)
-* walk_array() user-defined function: Walking Arrays. (line 14)
-* Wall, Larry <1>: Future Extensions. (line 6)
+* 'walk_array()' user-defined function: Walking Arrays. (line 14)
* Wall, Larry: Array Intro. (line 6)
-* Wallin, Anders: Contributors. (line 103)
-* warnings, issuing: Options. (line 185)
-* watch debugger command: Viewing And Changing Data.
- (line 67)
+* Wall, Larry <1>: Future Extensions. (line 6)
+* Wallin, Anders: Contributors. (line 104)
+* warnings, issuing: Options. (line 184)
+* 'watch' debugger command: Viewing And Changing Data.
+ (line 66)
* watchpoint: Debugging Terms. (line 42)
-* wc utility: Wc Program. (line 6)
-* wc.awk program: Wc Program. (line 46)
-* Weinberger, Peter <1>: Contributors. (line 11)
+* 'wc' utility: Wc Program. (line 6)
+* 'wc.awk' program: Wc Program. (line 46)
* Weinberger, Peter: History. (line 17)
-* where debugger command: Execution Stack. (line 13)
-* where debugger command (alias for backtrace): Execution Stack.
+* Weinberger, Peter <1>: Contributors. (line 12)
+* 'where' debugger command: Execution Stack. (line 13)
+* 'where' debugger command (alias for 'backtrace'): Execution Stack.
(line 13)
-* while statement: While Statement. (line 6)
-* while statement, use of regexps in: Regexp Usage. (line 19)
+* 'while' statement: While Statement. (line 6)
+* 'while' statement, use of regexps in: Regexp Usage. (line 19)
* whitespace, as field separators: Default Field Splitting.
(line 6)
* whitespace, functions, calling: Calling Built-in. (line 10)
-* whitespace, newlines as: Options. (line 262)
-* Williams, Kent: Contributors. (line 34)
-* Woehlke, Matthew: Contributors. (line 79)
-* Woods, John: Contributors. (line 27)
+* whitespace, newlines as: Options. (line 260)
+* Williams, Kent: Contributors. (line 35)
+* Woehlke, Matthew: Contributors. (line 80)
+* Woods, John: Contributors. (line 28)
* word boundaries, matching: GNU Regexp Operators.
- (line 38)
+ (line 41)
* word, regexp definition of: GNU Regexp Operators.
(line 6)
-* word-boundary operator (gawk): GNU Regexp Operators.
- (line 63)
-* wordfreq.awk program: Word Sorting. (line 56)
+* word-boundary operator ('gawk'): GNU Regexp Operators.
+ (line 66)
+* 'wordfreq.awk' program: Word Sorting. (line 56)
* words, counting: Wc Program. (line 6)
* words, duplicate, searching for: Dupword Program. (line 6)
* words, usage counts, generating: Word Sorting. (line 6)
-* writea() extension function: Extension Sample Read write array.
+* 'writea()' extension function: Extension Sample Read write array.
(line 12)
-* xgettext utility: String Extraction. (line 13)
-* xor: Bitwise Functions. (line 56)
+* 'xgettext' utility: String Extraction. (line 13)
+* 'xor': Bitwise Functions. (line 57)
* XOR bitwise operation: Bitwise Functions. (line 6)
-* Yawitz, Efraim: Contributors. (line 131)
-* Zaretskii, Eli <1>: Bugs. (line 71)
-* Zaretskii, Eli <2>: Contributors. (line 55)
+* Yawitz, Efraim: Contributors. (line 132)
* Zaretskii, Eli: Acknowledgments. (line 60)
-* zerofile.awk program: Empty Files. (line 21)
-* Zoulas, Christos: Contributors. (line 66)
-* {} (braces): Profiling. (line 142)
-* {} (braces), actions and: Action Overview. (line 19)
-* {} (braces), statements, grouping: Statements. (line 10)
-* | (vertical bar): Regexp Operators. (line 70)
-* | (vertical bar), | operator (I/O) <1>: Precedence. (line 65)
-* | (vertical bar), | operator (I/O) <2>: Redirection. (line 57)
-* | (vertical bar), | operator (I/O): Getline/Pipe. (line 9)
-* | (vertical bar), |& operator (I/O) <1>: Two-way I/O. (line 25)
-* | (vertical bar), |& operator (I/O) <2>: Precedence. (line 65)
-* | (vertical bar), |& operator (I/O) <3>: Redirection. (line 96)
-* | (vertical bar), |& operator (I/O): Getline/Coprocess. (line 6)
-* | (vertical bar), |& operator (I/O), pipes, closing: Close Files And Pipes.
- (line 121)
-* | (vertical bar), || operator <1>: Precedence. (line 89)
-* | (vertical bar), || operator: Boolean Ops. (line 59)
-* ~ (tilde), ~ operator <1>: Expression Patterns. (line 24)
-* ~ (tilde), ~ operator <2>: Precedence. (line 80)
-* ~ (tilde), ~ operator <3>: Comparison Operators.
- (line 11)
-* ~ (tilde), ~ operator <4>: Regexp Constants. (line 6)
-* ~ (tilde), ~ operator <5>: Case-sensitivity. (line 26)
-* ~ (tilde), ~ operator <6>: Computed Regexps. (line 6)
-* ~ (tilde), ~ operator: Regexp Usage. (line 19)
+* Zaretskii, Eli <1>: Contributors. (line 56)
+* Zaretskii, Eli <2>: Bugs. (line 73)
+* 'zerofile.awk' program: Empty Files. (line 20)
+* Zoulas, Christos: Contributors. (line 67)
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+Node: VMS GNV1131987
+Node: VMS Old Gawk1132722
+Node: Bugs1133193
+Node: Other Versions1137307
+Node: Installation summary1143781
+Node: Notes1144839
+Node: Compatibility Mode1145704
+Node: Additions1146486
+Node: Accessing The Source1147411
+Node: Adding Code1148847
+Node: New Ports1155002
+Node: Derived Files1159490
+Ref: Derived Files-Footnote-11164975
+Ref: Derived Files-Footnote-21165010
+Ref: Derived Files-Footnote-31165608
+Node: Future Extensions1165722
+Node: Implementation Limitations1166380
+Node: Extension Design1167563
+Node: Old Extension Problems1168717
+Ref: Old Extension Problems-Footnote-11170235
+Node: Extension New Mechanism Goals1170292
+Ref: Extension New Mechanism Goals-Footnote-11173656
+Node: Extension Other Design Decisions1173845
+Node: Extension Future Growth1175958
+Node: Old Extension Mechanism1176794
+Node: Notes summary1178557
+Node: Basic Concepts1179739
+Node: Basic High Level1180420
+Ref: figure-general-flow1180702
+Ref: figure-process-flow1181387
+Ref: Basic High Level-Footnote-11184688
+Node: Basic Data Typing1184873
+Node: Glossary1188201
+Node: Copying1220147
+Node: GNU Free Documentation License1257686
+Node: Index1282804
End Tag Table
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=e0a3a3191f80dca16a7ab569fdd9412497ea7f24
commit e0a3a3191f80dca16a7ab569fdd9412497ea7f24
Author: Arnold D. Robbins <address@hidden>
Date: Thu May 14 15:15:24 2015 +0300
Update Bugs section in doc to ask for plain text.
diff --git a/doc/ChangeLog b/doc/ChangeLog
index a5c546e..89bd658 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,8 @@
+2015-05-14 Arnold D. Robbins <address@hidden>
+
+ * gawktexi.in (Bugs): Add that email should be in plain
+ text and not in HTML. Sigh.
+
2015-04-29 Arnold D. Robbins <address@hidden>
* 4.1.2: Release tar ball made.
diff --git a/doc/gawk.texi b/doc/gawk.texi
index f1cef1c..f9fde82 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -38144,6 +38144,8 @@ the bug reporting address is preferred because the
email list is archived at the GNU Project.
@emph{All email must be in English. This is the only language
understood in common by all the maintainers.}
+In addition, please be sure to send all mail in @emph{plain text},
+not (or not exclusively) in HTML.
@cindex @code{comp.lang.awk} newsgroup
@quotation CAUTION
diff --git a/doc/gawktexi.in b/doc/gawktexi.in
index af21c5a..d53fded 100644
--- a/doc/gawktexi.in
+++ b/doc/gawktexi.in
@@ -37235,6 +37235,8 @@ the bug reporting address is preferred because the
email list is archived at the GNU Project.
@emph{All email must be in English. This is the only language
understood in common by all the maintainers.}
+In addition, please be sure to send all mail in @emph{plain text},
+not (or not exclusively) in HTML.
@cindex @code{comp.lang.awk} newsgroup
@quotation CAUTION
-----------------------------------------------------------------------
Summary of changes:
doc/ChangeLog | 5 +
doc/gawk.info |25788 +++++++++++++++++++++++++++----------------------------
doc/gawk.texi | 2 +
doc/gawktexi.in | 2 +
4 files changed, 12900 insertions(+), 12897 deletions(-)
hooks/post-receive
--
gawk
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