[Emacs-diffs] Changes to trouble.texi

[Glenn Morris]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Glenn Morris <gm>       07/09/06 04:48:50

Index: trouble.texi
===================================================================
RCS file: trouble.texi
diff -N trouble.texi
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ trouble.texi        6 Sep 2007 04:48:50 -0000       1.1
@@ -0,0 +1,1066 @@
address@hidden This is part of the Emacs manual.
address@hidden Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2001, 
2002,
address@hidden   2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
address@hidden See file emacs.texi for copying conditions.
address@hidden
address@hidden Dealing with Common Problems
+
+  If you type an Emacs command you did not intend, the results are often
+mysterious.  This chapter tells what you can do to cancel your mistake or
+recover from a mysterious situation.  Emacs bugs and system crashes are
+also considered.
address@hidden iftex
+
address@hidden
address@hidden
address@hidden ifnottex
+
address@hidden Quitting, Lossage, Customization, Top
address@hidden Quitting and Aborting
address@hidden quitting
+
address@hidden @kbd
address@hidden C-g
address@hidden address@hidden @r{(MS-DOS only)}
+Quit: cancel running or partially typed command.
address@hidden C-]
+Abort innermost recursive editing level and cancel the command which
+invoked it (@code{abort-recursive-edit}).
address@hidden @key{ESC} @key{ESC} @key{ESC}
+Either quit or abort, whichever makes sense (@code{keyboard-escape-quit}).
address@hidden M-x top-level
+Abort all recursive editing levels that are currently executing.
address@hidden C-x u
+Cancel a previously made change in the buffer contents (@code{undo}).
address@hidden table
+
+  There are two ways of canceling a command before it has finished:
address@hidden with @kbd{C-g}, and @dfn{aborting} with @kbd{C-]} or
address@hidden top-level}.  Quitting cancels a partially typed command, or
+one which is still running.  Aborting exits a recursive editing level
+and cancels the command that invoked the recursive edit.
+(@xref{Recursive Edit}.)
+
address@hidden quitting
address@hidden C-g
+  Quitting with @kbd{C-g} is the way to get rid of a partially typed
+command, or a numeric argument that you don't want.  It also stops a
+running command in the middle in a relatively safe way, so you can use
+it if you accidentally give a command which takes a long time.  In
+particular, it is safe to quit out of a kill command; either your text
+will @emph{all} still be in the buffer, or it will @emph{all} be in
+the kill ring, or maybe both.  Quitting an incremental search does
+special things, documented under searching; it may take two successive
address@hidden characters to get out of a search (@pxref{Incremental
+Search}).
+
+  On MS-DOS, the character @address@hidden serves as a quit character
+like @kbd{C-g}.  The reason is that it is not feasible, on MS-DOS, to
+recognize @kbd{C-g} while a command is running, between interactions
+with the user.  By contrast, it @emph{is} feasible to recognize
address@hidden@key{BREAK}} at all times.
address@hidden
address@hidden Keyboard,,,emacs-xtra, Specialized Emacs Features}.
address@hidden iftex
address@hidden
address@hidden Keyboard}.
address@hidden ifnottex
+
+
address@hidden keyboard-quit
+  @kbd{C-g} works by setting the variable @code{quit-flag} to @code{t}
+the instant @kbd{C-g} is typed; Emacs Lisp checks this variable
+frequently, and quits if it is address@hidden  @kbd{C-g} is only
+actually executed as a command if you type it while Emacs is waiting for
+input.  In that case, the command it runs is @code{keyboard-quit}.
+
+  On a text terminal, if you quit with @kbd{C-g} a second time before
+the first @kbd{C-g} is recognized, you activate the ``emergency
+escape'' feature and return to the shell.  @xref{Emergency Escape}.
+
address@hidden NFS and quitting
+  There are some situations where you cannot quit.  When Emacs is
+waiting for the operating system to do something, quitting is
+impossible unless special pains are taken for the particular system
+call within Emacs where the waiting occurs.  We have done this for the
+system calls that users are likely to want to quit from, but it's
+possible you will a case not handled.  In one very common
+case---waiting for file input or output using NFS---Emacs itself knows
+how to quit, but many NFS implementations simply do not allow user
+programs to stop waiting for NFS when the NFS server is hung.
+
address@hidden aborting recursive edit
address@hidden abort-recursive-edit
address@hidden C-]
+  Aborting with @kbd{C-]} (@code{abort-recursive-edit}) is used to get
+out of a recursive editing level and cancel the command which invoked
+it.  Quitting with @kbd{C-g} does not do this, and could not do this,
+because it is used to cancel a partially typed command @emph{within} the
+recursive editing level.  Both operations are useful.  For example, if
+you are in a recursive edit and type @kbd{C-u 8} to enter a numeric
+argument, you can cancel that argument with @kbd{C-g} and remain in the
+recursive edit.
+
address@hidden keyboard-escape-quit
address@hidden ESC ESC ESC
+  The sequence @address@hidden @key{ESC} @key{ESC}}
+(@code{keyboard-escape-quit}) can either quit or abort.  (We defined
+it this way because @key{ESC} means ``get out'' in many PC programs.)
+It can cancel a prefix argument, clear a selected region, or get out
+of a Query Replace, like @kbd{C-g}.  It can get out of the minibuffer
+or a recursive edit, like @kbd{C-]}.  It can also get out of splitting
+the frame into multiple windows, as with @kbd{C-x 1}.  One thing it
+cannot do, however, is stop a command that is running.  That's because
+it executes as an ordinary command, and Emacs doesn't notice it until
+it is ready for the next command.
+
address@hidden top-level
+  The command @kbd{M-x top-level} is equivalent to ``enough'' @kbd{C-]}
+commands to get you out of all the levels of recursive edits that you
+are in.  @kbd{C-]} gets you out one level at a time, but @kbd{M-x
+top-level} goes out all levels at once.  Both @kbd{C-]} and @kbd{M-x
+top-level} are like all other commands, and unlike @kbd{C-g}, in that
+they take effect only when Emacs is ready for a command.  @kbd{C-]} is
+an ordinary key and has its meaning only because of its binding in the
+keymap.  @xref{Recursive Edit}.
+
+  @kbd{C-x u} (@code{undo}) is not strictly speaking a way of canceling
+a command, but you can think of it as canceling a command that already
+finished executing.  @xref{Undo}, for more information
+about the undo facility.
+
address@hidden Lossage, Bugs, Quitting, Top
address@hidden Dealing with Emacs Trouble
+
+  This section describes various conditions in which Emacs fails to work
+normally, and how to recognize them and correct them.  For a list of
+additional problems you might encounter, see @ref{Bugs and problems, ,
+Bugs and problems, efaq, GNU Emacs FAQ}, and the file @file{etc/PROBLEMS}
+in the Emacs distribution.  Type @kbd{C-h C-f} to read the FAQ; type
address@hidden C-e} to read the @file{PROBLEMS} file.
+
address@hidden
+* DEL Does Not Delete::   What to do if @key{DEL} doesn't delete.
+* Stuck Recursive::       `[...]' in mode line around the parentheses.
+* Screen Garbled::        Garbage on the screen.
+* Text Garbled::          Garbage in the text.
+* Memory Full::           How to cope when you run out of memory.
+* After a Crash::         Recovering editing in an Emacs session that crashed.
+* Emergency Escape::      Emergency escape---
+                            What to do if Emacs stops responding.
+* Total Frustration::     When you are at your wits' end.
address@hidden menu
+
address@hidden DEL Does Not Delete
address@hidden If @key{DEL} Fails to Delete
address@hidden @key{DEL} vs @key{BACKSPACE}
address@hidden @key{BACKSPACE} vs @key{DEL}
address@hidden usual erasure key
+
+  Every keyboard has a large key, a little ways above the @key{RET} or
address@hidden key, which you normally use outside Emacs to erase the
+last character that you typed.  We call this key @dfn{the usual
+erasure key}.  In Emacs, it is supposed to be equivalent to @key{DEL},
+and when Emacs is properly configured for your terminal, it translates
+that key into the character @key{DEL}.
+
+  When Emacs starts up on a graphical display, it determines
+automatically which key should be @key{DEL}.  In some unusual cases
+Emacs gets the wrong information from the system.  If the usual
+erasure key deletes forwards instead of backwards, that is probably
+what happened---Emacs ought to be treating the @key{DELETE} key as
address@hidden, but it isn't.
+
+  On a graphical display, if the usual erasure key is labeled
address@hidden and there is a @key{DELETE} key elsewhere, but the
address@hidden key deletes backward instead of forward, that too
+suggests Emacs got the wrong information---but in the opposite sense.
+It ought to be treating the @key{BACKSPACE} key as @key{DEL}, and
+treating @key{DELETE} differently, but it isn't.
+
+  On a text-only terminal, if you find the usual erasure key prompts
+for a Help command, like @kbd{Control-h}, instead of deleting a
+character, it means that key is actually sending the @key{BS}
+character.  Emacs ought to be treating @key{BS} as @key{DEL}, but it
+isn't.
+
+  In all of those cases, the immediate remedy is the same: use the
+command @kbd{M-x normal-erase-is-backspace-mode}.  This toggles
+between the two modes that Emacs supports for handling @key{DEL}, so
+if Emacs starts in the wrong mode, this should switch to the right
+mode.  On a text-only terminal, if you want to ask for help when
address@hidden is treated as @key{DEL}, use @key{F1}; @kbd{C-?} may also
+work, if it sends character code 127.
+
address@hidden normal-erase-is-backspace-mode
+  To fix the problem automatically for every Emacs session, you can
+put one of the following lines into your @file{.emacs} file
+(@pxref{Init File}).  For the first case above, where @key{DELETE}
+deletes forwards instead of backwards, use this line to make
address@hidden act as @key{DEL} (resulting in behavior compatible
+with Emacs 20 and previous versions):
+
address@hidden
+(normal-erase-is-backspace-mode 0)
address@hidden lisp
+
address@hidden
+For the other two cases, where @key{BACKSPACE} ought to act as
address@hidden, use this line:
+
address@hidden
+(normal-erase-is-backspace-mode 1)
address@hidden lisp
+
address@hidden normal-erase-is-backspace
+  Another way to fix the problem for every Emacs session is to
+customize the variable @code{normal-erase-is-backspace}: the value
address@hidden specifies the mode where @key{BS} or @key{BACKSPACE} is
address@hidden, and @code{nil} specifies the other mode.  @xref{Easy
+Customization}.
+
+  On a graphical display, it can also happen that the usual erasure key
+is labeled @key{BACKSPACE}, there is a @key{DELETE} key elsewhere, and
+both keys delete forward.  This probably means that someone has
+redefined your @key{BACKSPACE} key as a @key{DELETE} key.  With X,
+this is typically done with a command to the @code{xmodmap} program
+when you start the server or log in.  The most likely motive for this
+customization was to support old versions of Emacs, so we recommend
+you simply remove it now.
+
address@hidden Stuck Recursive
address@hidden Recursive Editing Levels
+
+  Recursive editing levels are important and useful features of Emacs, but
+they can seem like malfunctions if you do not understand them.
+
+  If the mode line has square brackets @address@hidden around the parentheses
+that contain the names of the major and minor modes, you have entered a
+recursive editing level.  If you did not do this on purpose, or if you
+don't understand what that means, you should just get out of the recursive
+editing level.  To do so, type @kbd{M-x top-level}.  This is called getting
+back to top level.  @xref{Recursive Edit}.
+
address@hidden Screen Garbled
address@hidden Garbage on the Screen
+
+  If the text on a text terminal looks wrong, the first thing to do is
+see whether it is wrong in the buffer.  Type @kbd{C-l} to redisplay
+the entire screen.  If the screen appears correct after this, the
+problem was entirely in the previous screen update.  (Otherwise, see
+the following section.)
+
+  Display updating problems often result from an incorrect terminfo
+entry for the terminal you are using.  The file @file{etc/TERMS} in
+the Emacs distribution gives the fixes for known problems of this
+sort.  @file{INSTALL} contains general advice for these problems in
+one of its sections.  To investigate the possibility that you have
+this sort of problem, try Emacs on another terminal made by a
+different manufacturer.  If problems happen frequently on one kind of
+terminal but not another kind, it is likely to be a bad terminfo entry,
+though it could also be due to a bug in Emacs that appears for
+terminals that have or that lack specific features.
+
address@hidden Text Garbled
address@hidden Garbage in the Text
+
+  If @kbd{C-l} shows that the text is wrong, first type @kbd{C-h l} to
+see what commands you typed to produce the observed results.  Then try
+undoing the changes step by step using @kbd{C-x u}, until it gets back
+to a state you consider correct.
+
+  If a large portion of text appears to be missing at the beginning or
+end of the buffer, check for the word @samp{Narrow} in the mode line.
+If it appears, the text you don't see is probably still present, but
+temporarily off-limits.  To make it accessible again, type @kbd{C-x n
+w}.  @xref{Narrowing}.
+
address@hidden Memory Full
address@hidden Running out of Memory
address@hidden memory full
address@hidden out of memory
+
+  If you get the error message @samp{Virtual memory exceeded}, save
+your modified buffers with @kbd{C-x s}.  This method of saving them
+has the smallest need for additional memory.  Emacs keeps a reserve of
+memory which it makes available when this error happens; that should
+be enough to enable @kbd{C-x s} to complete its work.  When the
+reserve has been used, @samp{!MEM FULL!} appears at the beginning of
+the mode line, indicating there is no more reserve.
+
+  Once you have saved your modified buffers, you can exit this Emacs
+session and start another, or you can use @kbd{M-x kill-some-buffers}
+to free space in the current Emacs job.  If this frees up sufficient
+space, Emacs will refill its memory reserve, and @samp{!MEM FULL!}
+will disappear from the mode line.  That means you can safely go on
+editing in the same Emacs session.
+
+  Do not use @kbd{M-x buffer-menu} to save or kill buffers when you run
+out of memory, because the buffer menu needs a fair amount of memory
+itself, and the reserve supply may not be enough.
+
address@hidden After a Crash
address@hidden Recovery After a Crash
+
+  If Emacs or the computer crashes, you can recover the files you were
+editing at the time of the crash from their auto-save files.  To do
+this, start Emacs again and type the command @kbd{M-x recover-session}.
+
+  This command initially displays a buffer which lists interrupted
+session files, each with its date.  You must choose which session to
+recover from.  Typically the one you want is the most recent one.  Move
+point to the one you choose, and type @kbd{C-c C-c}.
+
+  Then @code{recover-session} considers each of the files that you
+were editing during that session; for each such file, it asks whether
+to recover that file.  If you answer @kbd{y} for a file, it shows the
+dates of that file and its auto-save file, then asks once again
+whether to recover that file.  For the second question, you must
+confirm with @kbd{yes}.  If you do, Emacs visits the file but gets the
+text from the auto-save file.
+
+  When @code{recover-session} is done, the files you've chosen to
+recover are present in Emacs buffers.  You should then save them.  Only
+this---saving them---updates the files themselves.
+
+  As a last resort, if you had buffers with content which were not
+associated with any files, or if the autosave was not recent enough to
+have recorded important changes, you can use the
address@hidden/emacs-buffer.gdb} script with GDB (the GNU Debugger) to
+retrieve them from a core dump--provided that a core dump was saved,
+and that the Emacs executable was not stripped of its debugging
+symbols.
+
+  As soon as you get the core dump, rename it to another name such as
address@hidden, so that another crash won't overwrite it.
+
+  To use this script, run @code{gdb} with the file name of your Emacs
+executable and the file name of the core dump, e.g. @samp{gdb
+/usr/bin/emacs core.emacs}.  At the @code{(gdb)} prompt, load the
+recovery script: @samp{source /usr/src/emacs/etc/emacs-buffer.gdb}.
+Then type the command @code{ybuffer-list} to see which buffers are
+available.  For each buffer, it lists a buffer number.  To save a
+buffer, use @code{ysave-buffer}; you specify the buffer number, and
+the file name to write that buffer into.  You should use a file name
+which does not already exist; if the file does exist, the script does
+not make a backup of its old contents.
+
address@hidden Emergency Escape
address@hidden Emergency Escape
+
+  On text-only terminals, the @dfn{emergency escape} feature suspends
+Emacs immediately if you type @kbd{C-g} a second time before Emacs can
+actually respond to the first one by quitting.  This is so you can
+always get out of GNU Emacs no matter how badly it might be hung.
+When things are working properly, Emacs recognizes and handles the
+first @kbd{C-g} so fast that the second one won't trigger emergency
+escape.  However, if some problem prevents Emacs from handling the
+first @kbd{C-g} properly, then the second one will get you back to the
+shell.
+
+  When you resume Emacs after a suspension caused by emergency escape,
+it asks two questions before going back to what it had been doing:
+
address@hidden
+Auto-save? (y or n)
+Abort (and dump core)? (y or n)
address@hidden example
+
address@hidden
+Answer each one with @kbd{y} or @kbd{n} followed by @key{RET}.
+
+  Saying @kbd{y} to @samp{Auto-save?} causes immediate auto-saving of
+all modified buffers in which auto-saving is enabled.  Saying @kbd{n}
+skips this.
+
+  Saying @kbd{y} to @samp{Abort (and dump core)?} causes Emacs to
+crash, dumping core.  This is to enable a wizard to figure out why
+Emacs was failing to quit in the first place.  Execution does not
+continue after a core dump.
+
+  If you answer this question @kbd{n}, Emacs execution resumes.  With
+luck, Emacs will ultimately do the requested quit.  If not, each
+subsequent @kbd{C-g} invokes emergency escape again.
+
+  If Emacs is not really hung, just slow, you may invoke the double
address@hidden feature without really meaning to.  Then just resume and
+answer @kbd{n} to both questions, and you will get back to the former
+state.  The quit you requested will happen by and by.
+
+  Emergency escape is active only for text terminals.  On graphical
+displays, you can use the mouse to kill Emacs or switch to another
+program.
+
+  On MS-DOS, you must type @address@hidden (twice) to cause
+emergency escape---but there are cases where it won't work, when
+system call hangs or when Emacs is stuck in a tight loop in C code.
+
address@hidden Total Frustration
address@hidden Help for Total Frustration
address@hidden Eliza
address@hidden doctor
+
+  If using Emacs (or something else) becomes terribly frustrating and none
+of the techniques described above solve the problem, Emacs can still help
+you.
+
+  First, if the Emacs you are using is not responding to commands, type
address@hidden C-g} to get out of it and then start a new one.
+
address@hidden doctor
+  Second, type @kbd{M-x doctor @key{RET}}.
+
+  The Emacs psychotherapist will help you feel better.  Each time you
+say something to the psychotherapist, you must end it by typing
address@hidden @key{RET}.  This indicates you are finished typing.
+
address@hidden Bugs, Contributing, Lossage, Top
address@hidden Reporting Bugs
+
address@hidden bugs
+  Sometimes you will encounter a bug in Emacs.  Although we cannot
+promise we can or will fix the bug, and we might not even agree that it
+is a bug, we want to hear about problems you encounter.  Often we agree
+they are bugs and want to fix them.
+
+  To make it possible for us to fix a bug, you must report it.  In order
+to do so effectively, you must know when and how to do it.
+
+  Before reporting a bug, it is a good idea to see if it is already
+known.  You can find the list of known problems in the file
address@hidden/PROBLEMS} in the Emacs distribution; type @kbd{C-h C-e} to read
+it.  Some additional user-level problems can be found in @ref{Bugs and
+problems, , Bugs and problems, efaq, GNU Emacs FAQ}.  Looking up your
+problem in these two documents might provide you with a solution or a
+work-around, or give you additional information about related issues.
+
address@hidden
+* Criteria:  Bug Criteria.      Have you really found a bug?
+* Understanding Bug Reporting::         How to report a bug effectively.
+* Checklist::                   Steps to follow for a good bug report.
+* Sending Patches::             How to send a patch for GNU Emacs.
address@hidden menu
+
address@hidden Bug Criteria
address@hidden When Is There a Bug
+
+  If Emacs accesses an invalid memory location (``segmentation
+fault''), or exits with an operating system error message that
+indicates a problem in the program (as opposed to something like
+``disk full''), then it is certainly a bug.
+
+  If Emacs updates the display in a way that does not correspond to what is
+in the buffer, then it is certainly a bug.  If a command seems to do the
+wrong thing but the problem corrects itself if you type @kbd{C-l}, it is a
+case of incorrect display updating.
+
+  Taking forever to complete a command can be a bug, but you must make
+certain that it was really Emacs's fault.  Some commands simply take a
+long time.  Type @kbd{C-g} (@address@hidden on MS-DOS) and then @kbd{C-h l}
+to see whether the input Emacs received was what you intended to type;
+if the input was such that you @emph{know} it should have been processed
+quickly, report a bug.  If you don't know whether the command should
+take a long time, find out by looking in the manual or by asking for
+assistance.
+
+  If a command you are familiar with causes an Emacs error message in a
+case where its usual definition ought to be reasonable, it is probably a
+bug.
+
+  If a command does the wrong thing, that is a bug.  But be sure you know
+for certain what it ought to have done.  If you aren't familiar with the
+command, or don't know for certain how the command is supposed to work,
+then it might actually be working right.  Rather than jumping to
+conclusions, show the problem to someone who knows for certain.
+
+  Finally, a command's intended definition may not be the best
+possible definition for editing with.  This is a very important sort
+of problem, but it is also a matter of judgment.  Also, it is easy to
+come to such a conclusion out of ignorance of some of the existing
+features.  It is probably best not to complain about such a problem
+until you have checked the documentation in the usual ways, feel
+confident that you understand it, and know for certain that what you
+want is not available.  Ask other Emacs users, too.  If you are not
+sure what the command is supposed to do after a careful reading of the
+manual, check the index and glossary for any terms that may be
+unclear.
+
+  If after careful rereading of the manual you still do not understand
+what the command should do, that indicates a bug in the manual, which
+you should report.  The manual's job is to make everything clear to
+people who are not Emacs experts---including you.  It is just as
+important to report documentation bugs as program bugs.
+
+  If the on-line documentation string of a function or variable disagrees
+with the manual, one of them must be wrong; that is a bug.
+
address@hidden Understanding Bug Reporting
address@hidden Understanding Bug Reporting
+
address@hidden emacs-version
+  When you decide that there is a bug, it is important to report it and to
+report it in a way which is useful.  What is most useful is an exact
+description of what commands you type, starting with the shell command to
+run Emacs, until the problem happens.
+
+  The most important principle in reporting a bug is to report
address@hidden  Hypotheses and verbal descriptions are no substitute for
+the detailed raw data.  Reporting the facts is straightforward, but many
+people strain to posit explanations and report them instead of the
+facts.  If the explanations are based on guesses about how Emacs is
+implemented, they will be useless; meanwhile, lacking the facts, we will
+have no real information about the bug.
+
+  For example, suppose that you type @kbd{C-x C-f /glorp/baz.ugh
address@hidden, visiting a file which (you know) happens to be rather
+large, and Emacs displays @samp{I feel pretty today}.  The best way to
+report the bug is with a sentence like the preceding one, because it
+gives all the facts.
+
+  A bad way would be to assume that the problem is due to the size of
+the file and say, ``I visited a large file, and Emacs displayed @samp{I
+feel pretty today}.''  This is what we mean by ``guessing
+explanations.''  The problem is just as likely to be due to the fact
+that there is a @samp{z} in the file name.  If this is so, then when we
+got your report, we would try out the problem with some ``large file,''
+probably with no @samp{z} in its name, and not see any problem.  There
+is no way in the world that we could guess that we should try visiting a
+file with a @samp{z} in its name.
+
+  Alternatively, the problem might be due to the fact that the file starts
+with exactly 25 spaces.  For this reason, you should make sure that you
+inform us of the exact contents of any file that is needed to reproduce the
+bug.  What if the problem only occurs when you have typed the @kbd{C-x C-a}
+command previously?  This is why we ask you to give the exact sequence of
+characters you typed since starting the Emacs session.
+
+  You should not even say ``visit a file'' instead of @kbd{C-x C-f} unless
+you @emph{know} that it makes no difference which visiting command is used.
+Similarly, rather than saying ``if I have three characters on the line,''
+say ``after I type @address@hidden A B C @key{RET} C-p},'' if that is
+the way you entered the text.
+
+  So please don't guess any explanations when you report a bug.  If you
+want to actually @emph{debug} the problem, and report explanations that
+are more than guesses, that is useful---but please include the facts as
+well.
+
address@hidden Checklist
address@hidden Checklist for Bug Reports
+
address@hidden reporting bugs
+  The best way to send a bug report is to mail it electronically to the
+Emacs maintainers at @email{bug-gnu-emacs@@gnu.org}, or to
address@hidden@@gnu.org} if you are pretesting an Emacs beta
+release.  (If you want to suggest a change as an improvement, use the
+same address.)
+
+  If you'd like to read the bug reports, you can find them on the
+newsgroup @samp{gnu.emacs.bug}; keep in mind, however, that as a
+spectator you should not criticize anything about what you see there.
+The purpose of bug reports is to give information to the Emacs
+maintainers.  Spectators are welcome only as long as they do not
+interfere with this.  In particular, some bug reports contain fairly
+large amounts of data; spectators should not complain about this.
+
+  Please do not post bug reports using netnews; mail is more reliable
+than netnews about reporting your correct address, which we may need
+in order to ask you for more information.  If your data is more than
+500,000 bytes, please don't include it directly in the bug report;
+instead, offer to send it on request, or make it available by ftp and
+say where.
+
address@hidden report-emacs-bug
+  A convenient way to send a bug report for Emacs is to use the command
address@hidden report-emacs-bug}.  This sets up a mail buffer (@pxref{Sending
+Mail}) and automatically inserts @emph{some} of the essential
+information.  However, it cannot supply all the necessary information;
+you should still read and follow the guidelines below, so you can enter
+the other crucial information by hand before you send the message.
+
+  To enable maintainers to investigate a bug, your report
+should include all these things:
+
address@hidden @bullet
address@hidden
+The version number of Emacs.  Without this, we won't know whether there
+is any point in looking for the bug in the current version of GNU
+Emacs.
+
+You can get the version number by typing @kbd{M-x emacs-version
address@hidden  If that command does not work, you probably have something
+other than GNU Emacs, so you will have to report the bug somewhere
+else.
+
address@hidden
+The type of machine you are using, and the operating system name and
+version number.  @kbd{M-x emacs-version @key{RET}} provides this
+information too.  Copy its output from the @samp{*Messages*} buffer, so
+that you get it all and get it accurately.
+
address@hidden
+The operands given to the @code{configure} command when Emacs was
+installed.
+
address@hidden
+A complete list of any modifications you have made to the Emacs source.
+(We may not have time to investigate the bug unless it happens in an
+unmodified Emacs.  But if you've made modifications and you don't tell
+us, you are sending us on a wild goose chase.)
+
+Be precise about these changes.  A description in English is not
+enough---send a context diff for them.
+
+Adding files of your own, or porting to another machine, is a
+modification of the source.
+
address@hidden
+Details of any other deviations from the standard procedure for installing
+GNU Emacs.
+
address@hidden
+The complete text of any files needed to reproduce the bug.
+
+  If you can tell us a way to cause the problem without visiting any files,
+please do so.  This makes it much easier to debug.  If you do need files,
+make sure you arrange for us to see their exact contents.  For example, it
+can matter whether there are spaces at the ends of lines, or a
+newline after the last line in the buffer (nothing ought to care whether
+the last line is terminated, but try telling the bugs that).
+
address@hidden
+The precise commands we need to type to reproduce the bug.
+
address@hidden open-dribble-file
address@hidden dribble file
address@hidden logging keystrokes
+The easy way to record the input to Emacs precisely is to write a
+dribble file.  To start the file, execute the Lisp expression
+
address@hidden
+(open-dribble-file "~/dribble")
address@hidden example
+
address@hidden
+using @kbd{M-:} or from the @samp{*scratch*} buffer just after
+starting Emacs.  From then on, Emacs copies all your input to the
+specified dribble file until the Emacs process is killed.
+
address@hidden
address@hidden open-termscript
address@hidden termscript file
address@hidden @env{TERM} environment variable
+For possible display bugs, the terminal type (the value of environment
+variable @env{TERM}), the complete termcap entry for the terminal from
address@hidden/etc/termcap} (since that file is not identical on all machines),
+and the output that Emacs actually sent to the terminal.
+
+The way to collect the terminal output is to execute the Lisp expression
+
address@hidden
+(open-termscript "~/termscript")
address@hidden example
+
address@hidden
+using @kbd{M-:} or from the @samp{*scratch*} buffer just after
+starting Emacs.  From then on, Emacs copies all terminal output to the
+specified termscript file as well, until the Emacs process is killed.
+If the problem happens when Emacs starts up, put this expression into
+your @file{.emacs} file so that the termscript file will be open when
+Emacs displays the screen for the first time.
+
+Be warned: it is often difficult, and sometimes impossible, to fix a
+terminal-dependent bug without access to a terminal of the type that
+stimulates the bug.
+
address@hidden
+If address@hidden text or internationalization is relevant, the locale that
+was current when you started Emacs.  On GNU/Linux and Unix systems, or
+if you use a Posix-style shell such as Bash, you can use this shell
+command to view the relevant values:
+
address@hidden
+echo LC_ALL=$LC_ALL LC_COLLATE=$LC_COLLATE LC_CTYPE=$LC_CTYPE \
+  LC_MESSAGES=$LC_MESSAGES LC_TIME=$LC_TIME LANG=$LANG
address@hidden smallexample
+
+Alternatively, use the @command{locale} command, if your system has it,
+to display your locale settings.
+
+You can use the @kbd{M-!} command to execute these commands from
+Emacs, and then copy the output from the @samp{*Messages*} buffer into
+the bug report.  Alternatively, @kbd{M-x getenv @key{RET} LC_ALL
address@hidden will display the value of @code{LC_ALL} in the echo area, and
+you can copy its output from the @samp{*Messages*} buffer.
+
address@hidden
+A description of what behavior you observe that you believe is
+incorrect.  For example, ``The Emacs process gets a fatal signal,'' or,
+``The resulting text is as follows, which I think is wrong.''
+
+Of course, if the bug is that Emacs gets a fatal signal, then one can't
+miss it.  But if the bug is incorrect text, the maintainer might fail to
+notice what is wrong.  Why leave it to chance?
+
+Even if the problem you experience is a fatal signal, you should still
+say so explicitly.  Suppose something strange is going on, such as, your
+copy of the source is out of sync, or you have encountered a bug in the
+C library on your system.  (This has happened!)  Your copy might crash
+and the copy here might not.  If you @emph{said} to expect a crash, then
+when Emacs here fails to crash, we would know that the bug was not
+happening.  If you don't say to expect a crash, then we would not know
+whether the bug was happening---we would not be able to draw any
+conclusion from our observations.
+
address@hidden
+If the bug is that the Emacs Manual or the Emacs Lisp Reference Manual
+fails to describe the actual behavior of Emacs, or that the text is
+confusing, copy in the text from the online manual which you think is
+at fault.  If the section is small, just the section name is enough.
+
address@hidden
+If the manifestation of the bug is an Emacs error message, it is
+important to report the precise text of the error message, and a
+backtrace showing how the Lisp program in Emacs arrived at the error.
+
+To get the error message text accurately, copy it from the
address@hidden buffer into the bug report.  Copy all of it, not just
+part.
+
address@hidden toggle-debug-on-error
address@hidden Edebug
+To make a backtrace for the error, use @kbd{M-x toggle-debug-on-error}
+before the error happens (that is to say, you must give that command
+and then make the bug happen).  This causes the error to start the Lisp
+debugger, which shows you a backtrace.  Copy the text of the
+debugger's backtrace into the bug report.  @xref{Debugger,, The Lisp
+Debugger, elisp, the Emacs Lisp Reference Manual}, for information on
+debugging Emacs Lisp programs with the Edebug package.
+
+This use of the debugger is possible only if you know how to make the
+bug happen again.  If you can't make it happen again, at least copy
+the whole error message.
+
address@hidden
+Check whether any programs you have loaded into the Lisp world,
+including your @file{.emacs} file, set any variables that may affect the
+functioning of Emacs.  Also, see whether the problem happens in a
+freshly started Emacs without loading your @file{.emacs} file (start
+Emacs with the @code{-q} switch to prevent loading the init file).  If
+the problem does @emph{not} occur then, you must report the precise
+contents of any programs that you must load into the Lisp world in order
+to cause the problem to occur.
+
address@hidden
+If the problem does depend on an init file or other Lisp programs that
+are not part of the standard Emacs system, then you should make sure it
+is not a bug in those programs by complaining to their maintainers
+first.  After they verify that they are using Emacs in a way that is
+supposed to work, they should report the bug.
+
address@hidden
+If you wish to mention something in the GNU Emacs source, show the line
+of code with a few lines of context.  Don't just give a line number.
+
+The line numbers in the development sources don't match those in your
+sources.  It would take extra work for the maintainers to determine what
+code is in your version at a given line number, and we could not be
+certain.
+
address@hidden
+Additional information from a C debugger such as GDB might enable
+someone to find a problem on a machine which he does not have available.
+If you don't know how to use GDB, please read the GDB manual---it is not
+very long, and using GDB is easy.  You can find the GDB distribution,
+including the GDB manual in online form, in most of the same places you
+can find the Emacs distribution.  To run Emacs under GDB, you should
+switch to the @file{src} subdirectory in which Emacs was compiled, then
+do @samp{gdb emacs}.  It is important for the directory @file{src} to be
+current so that GDB will read the @file{.gdbinit} file in this
+directory.
+
+However, you need to think when you collect the additional information
+if you want it to show what causes the bug.
+
address@hidden backtrace for bug reports
+For example, many people send just a backtrace, but that is not very
+useful by itself.  A simple backtrace with arguments often conveys
+little about what is happening inside GNU Emacs, because most of the
+arguments listed in the backtrace are pointers to Lisp objects.  The
+numeric values of these pointers have no significance whatever; all that
+matters is the contents of the objects they point to (and most of the
+contents are themselves pointers).
+
address@hidden debug_print
+To provide useful information, you need to show the values of Lisp
+objects in Lisp notation.  Do this for each variable which is a Lisp
+object, in several stack frames near the bottom of the stack.  Look at
+the source to see which variables are Lisp objects, because the debugger
+thinks of them as integers.
+
+To show a variable's value in Lisp syntax, first print its value, then
+use the user-defined GDB command @code{pr} to print the Lisp object in
+Lisp syntax.  (If you must use another debugger, call the function
address@hidden with the object as an argument.)  The @code{pr}
+command is defined by the file @file{.gdbinit}, and it works only if you
+are debugging a running process (not with a core dump).
+
+To make Lisp errors stop Emacs and return to GDB, put a breakpoint at
address@hidden
+
+For a short listing of Lisp functions running, type the GDB
+command @code{xbacktrace}.
+
+The file @file{.gdbinit} defines several other commands that are useful
+for examining the data types and contents of Lisp objects.  Their names
+begin with @samp{x}.  These commands work at a lower level than
address@hidden, and are less convenient, but they may work even when
address@hidden does not, such as when debugging a core dump or when Emacs has
+had a fatal signal.
+
address@hidden debugging Emacs, tricks and techniques
+More detailed advice and other useful techniques for debugging Emacs
+are available in the file @file{etc/DEBUG} in the Emacs distribution.
+That file also includes instructions for investigating problems
+whereby Emacs stops responding (many people assume that Emacs is
+``hung,'' whereas in fact it might be in an infinite loop).
+
+To find the file @file{etc/DEBUG} in your Emacs installation, use the
+directory name stored in the variable @code{data-directory}.
address@hidden itemize
+
+Here are some things that are not necessary in a bug report:
+
address@hidden @bullet
address@hidden
+A description of the envelope of the bug---this is not necessary for a
+reproducible bug.
+
+Often people who encounter a bug spend a lot of time investigating
+which changes to the input file will make the bug go away and which
+changes will not affect it.
+
+This is often time-consuming and not very useful, because the way we
+will find the bug is by running a single example under the debugger
+with breakpoints, not by pure deduction from a series of examples.
+You might as well save time by not searching for additional examples.
+It is better to send the bug report right away, go back to editing,
+and find another bug to report.
+
+Of course, if you can find a simpler example to report @emph{instead} of
+the original one, that is a convenience.  Errors in the output will be
+easier to spot, running under the debugger will take less time, etc.
+
+However, simplification is not vital; if you can't do this or don't have
+time to try, please report the bug with your original test case.
+
address@hidden
+A core dump file.
+
+Debugging the core dump might be useful, but it can only be done on
+your machine, with your Emacs executable.  Therefore, sending the core
+dump file to the Emacs maintainers won't be useful.  Above all, don't
+include the core file in an email bug report!  Such a large message
+can be extremely inconvenient.
+
address@hidden
+A system-call trace of Emacs execution.
+
+System-call traces are very useful for certain special kinds of
+debugging, but in most cases they give little useful information.  It is
+therefore strange that many people seem to think that @emph{the} way to
+report information about a crash is to send a system-call trace.  Perhaps
+this is a habit formed from experience debugging programs that don't
+have source code or debugging symbols.
+
+In most programs, a backtrace is normally far, far more informative than
+a system-call trace.  Even in Emacs, a simple backtrace is generally
+more informative, though to give full information you should supplement
+the backtrace by displaying variable values and printing them as Lisp
+objects with @code{pr} (see above).
+
address@hidden
+A patch for the bug.
+
+A patch for the bug is useful if it is a good one.  But don't omit the
+other information that a bug report needs, such as the test case, on the
+assumption that a patch is sufficient.  We might see problems with your
+patch and decide to fix the problem another way, or we might not
+understand it at all.  And if we can't understand what bug you are
+trying to fix, or why your patch should be an improvement, we mustn't
+install it.
+
address@hidden
address@hidden Patches}, for guidelines on how to make it easy for us to
+understand and install your patches.
address@hidden ifnottex
+
address@hidden
+A guess about what the bug is or what it depends on.
+
+Such guesses are usually wrong.  Even experts can't guess right about
+such things without first using the debugger to find the facts.
address@hidden itemize
+
address@hidden Sending Patches
address@hidden Sending Patches for GNU Emacs
+
address@hidden sending patches for GNU Emacs
address@hidden patches, sending
+  If you would like to write bug fixes or improvements for GNU Emacs,
+that is very helpful.  When you send your changes, please follow these
+guidelines to make it easy for the maintainers to use them.  If you
+don't follow these guidelines, your information might still be useful,
+but using it will take extra work.  Maintaining GNU Emacs is a lot of
+work in the best of circumstances, and we can't keep up unless you do
+your best to help.
+
address@hidden @bullet
address@hidden
+Send an explanation with your changes of what problem they fix or what
+improvement they bring about.  For a bug fix, just include a copy of the
+bug report, and explain why the change fixes the bug.
+
+(Referring to a bug report is not as good as including it, because then
+we will have to look it up, and we have probably already deleted it if
+we've already fixed the bug.)
+
address@hidden
+Always include a proper bug report for the problem you think you have
+fixed.  We need to convince ourselves that the change is right before
+installing it.  Even if it is correct, we might have trouble
+understanding it if we don't have a way to reproduce the problem.
+
address@hidden
+Include all the comments that are appropriate to help people reading the
+source in the future understand why this change was needed.
+
address@hidden
+Don't mix together changes made for different reasons.
+Send them @emph{individually}.
+
+If you make two changes for separate reasons, then we might not want to
+install them both.  We might want to install just one.  If you send them
+all jumbled together in a single set of diffs, we have to do extra work
+to disentangle them---to figure out which parts of the change serve
+which purpose.  If we don't have time for this, we might have to ignore
+your changes entirely.
+
+If you send each change as soon as you have written it, with its own
+explanation, then two changes never get tangled up, and we can consider
+each one properly without any extra work to disentangle them.
+
address@hidden
+Send each change as soon as that change is finished.  Sometimes people
+think they are helping us by accumulating many changes to send them all
+together.  As explained above, this is absolutely the worst thing you
+could do.
+
+Since you should send each change separately, you might as well send it
+right away.  That gives us the option of installing it immediately if it
+is important.
+
address@hidden
+Use @samp{diff -c} to make your diffs.  Diffs without context are hard
+to install reliably.  More than that, they are hard to study; we must
+always study a patch to decide whether we want to install it.  Unidiff
+format is better than contextless diffs, but not as easy to read as
address@hidden format.
+
+If you have GNU diff, use @samp{diff -c -F'^[_a-zA-Z0-9$]+ *('} when
+making diffs of C code.  This shows the name of the function that each
+change occurs in.
+
address@hidden
+Avoid any ambiguity as to which is the old version and which is the new.
+Please make the old version the first argument to diff, and the new
+version the second argument.  And please give one version or the other a
+name that indicates whether it is the old version or your new changed
+one.
+
address@hidden
+Write the change log entries for your changes.  This is both to save us
+the extra work of writing them, and to help explain your changes so we
+can understand them.
+
+The purpose of the change log is to show people where to find what was
+changed.  So you need to be specific about what functions you changed;
+in large functions, it's often helpful to indicate where within the
+function the change was.
+
+On the other hand, once you have shown people where to find the change,
+you need not explain its purpose in the change log.  Thus, if you add a
+new function, all you need to say about it is that it is new.  If you
+feel that the purpose needs explaining, it probably does---but put the
+explanation in comments in the code.  It will be more useful there.
+
+Please read the @file{ChangeLog} files in the @file{src} and
address@hidden directories to see what sorts of information to put in,
+and to learn the style that we use.  @xref{Change Log}.
+
address@hidden
+When you write the fix, keep in mind that we can't install a change that
+would break other systems.  Please think about what effect your change
+will have if compiled on another type of system.
+
+Sometimes people send fixes that @emph{might} be an improvement in
+general---but it is hard to be sure of this.  It's hard to install
+such changes because we have to study them very carefully.  Of course,
+a good explanation of the reasoning by which you concluded the change
+was correct can help convince us.
+
+The safest changes are changes to the configuration files for a
+particular machine.  These are safe because they can't create new bugs
+on other machines.
+
+Please help us keep up with the workload by designing the patch in a
+form that is clearly safe to install.
address@hidden itemize
+
address@hidden Contributing, Service, Bugs, Top
address@hidden Contributing to Emacs Development
+
+If you would like to help pretest Emacs releases to assure they work
+well, or if you would like to work on improving Emacs, please contact
+the maintainers at @email{emacs-devel@@gnu.org}.  A pretester
+should be prepared to investigate bugs as well as report them.  If you'd
+like to work on improving Emacs, please ask for suggested projects or
+suggest your own ideas.
+
+If you have already written an improvement, please tell us about it.  If
+you have not yet started work, it is useful to contact
address@hidden@@gnu.org} before you start; it might be
+possible to suggest ways to make your extension fit in better with the
+rest of Emacs.
+
+The development version of Emacs can be downloaded from the CVS
+repository where it is actively maintained by a group of developers.
+See the Emacs project page
address@hidden://savannah.gnu.org/projects/emacs/} for details.
+
address@hidden Service, Copying, Contributing, Top
address@hidden How To Get Help with GNU Emacs
+
+If you need help installing, using or changing GNU Emacs, there are two
+ways to find it:
+
address@hidden @bullet
address@hidden
+Send a message to the mailing list
address@hidden@@gnu.org}, or post your request on
+newsgroup @code{gnu.emacs.help}.  (This mailing list and newsgroup
+interconnect, so it does not matter which one you use.)
+
address@hidden
+Look in the service directory for someone who might help you for a fee.
+The service directory is found in the file named @file{etc/SERVICE} in the
+Emacs distribution.
address@hidden itemize
+
address@hidden
address@hidden
address@hidden ifnottex
+
address@hidden
+   arch-tag: c9cba76d-b2cb-4e0c-ae3f-19d5ef35817c
address@hidden ignore