[Techtalk] Comments in bash scripts

[MMP - Barb Fox]

Many shell scripting environments are written to read the very first line 
of a shell script.

Example:  IF shellscript begins with a  #!/bin/sh, then the script will be 
run under a Bourne shell environment.  If the line is #!/usr/sbin/perl, 
then the script will be interpreted with the perl program located in 
/usr/sbin, etc.   If the #! is NOT the first line of a shell script, then 
the #! simply becomes a normal comment.

When is this important?  When you write a program using bash constructs, 
you should put #!/bin/bash as the first line, then other users who are 
running in cshells, for example, would still be able to run your program 
without knowing it was a bash shell script.  Otherwise they would get 
syntax errors and have to manually execute a bash shell to make the script 
work.

Hope that helps!
Barb Fox
mmp_fox at bellsouth.net


At 06:06 PM 2/15/2004, you wrote:
>Someone told me recently that you mustn't put comments before the
>hash bang line in a bash script because it's bad practice.  Why is
>that?
>
>Thanks
>Berenice