Path: utzoo!mnetor!uunet!husc6!purdue!umd5!uvaarpa!mer6g
From: mer6g@uvaarpa.virginia.edu (Marc E. Rouleau)
Newsgroups: comp.sources.d
Subject: Perl: Hacking The !# Simulation
Message-ID: <67@uvaarpa.virginia.edu>
Date: 28 Apr 88 14:08:29 GMT
Reply-To: mer6g@uvaarpa.Virginia.EDU (Marc E. Rouleau)
Organization: University of Virginia, Charlottesville
Lines: 33
References:


While the simulation of the #! hack is a very clever, useful idea (thanks,
Chip!) for those of us who suffer with the more primitive dialects of UNIX
:-), I'd like to suggest an improvement.  As you may recall, the final notion
was to place the following lines in every perl script immediately below the
#!/bin/perl line:

eval "exec /bin/perl $0 $*"
	if $running_via_sh;

This works great as long as $0 contains an complete path to the perl script;
however, such is frequently not the case.  In particular, the above solution
fails whenever the shell uses the $PATH environment variable to find the perl
script.

With this in mind I'd like to propose that something like the following be
done instead:

eval "exec /bin/perl `/usr/local/ksh -c \"whence $0\"` $*"
	if $running_via_sh;

If ksh(1) isn't available on your system, I think csh(1) has a built-in
called "which" which functions like ksh's "whence".

The only folks still left in the cold are those who have only the Bourne
shell (sh(1)).

I think the only solution for sh-only folks would be an option to perl
(perhaps -S?) which requests that it use $PATH if it exists in the evironment
or else some compiled-in default to determine the location of its script.

Comments?

	-- Marc Rouleau