Re: bash "while do echo" can't function correctly

[John McKown]

On Wed, Apr 13, 2016 at 6:45 AM, Pierre Gaston <pierre.gaston@gmail.com> wrote:

On Wed, Apr 13, 2016 at 2:34 PM, John McKown <john.archie.mckown@gmail.com> wrote:

On Wed, Apr 13, 2016 at 1:10 AM, Geir Hauge <geir.hauge@gmail.com> wrote:

​...

 

though printf should be preferred over echo:

    while read -r line; do printf '%s\n' "$line"; done < test.txt

​I've never read about using printf in preference to echo. Why is that? ​I have used it myself in special cases, such as wanting leading zeros (i=0;printf '%03d\n' "${i}";)

Posix says:

It is not possible to use echo portably across all POSIX systems unless both -n (as the first argument) and escape sequences are omitted.

The printf utility can be used portably to emulate any of the traditional behaviors of the echo utility as follows (assuming that IFS has its standard value or is unset)

​Ah. Thanks. I only use BASH and the GNU infrastructure, so I have never run into that problem. I think I'll change my habits, just in case I run across a system which doesn't have it (especially in my scripts)

--

How many surrealists does it take to screw in a lightbulb? One to hold the griffon and one to fill the bathtub with brightly colored LEDs.

Maranatha! <><
John McKown