Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!elroy!devvax!lwall
From: lwall@devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.sources.d
Subject: Re: Perl: Hacking The !# Simulation
Message-ID: <1950@devvax.JPL.NASA.GOV>
Date: 3 May 88 20:23:54 GMT
References: <67@uvaarpa.virginia.edu> <394@dsinc.UUCP> <75@uvaarpa.virginia.edu>
Reply-To: lwall@devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA.
Lines: 42

In article <75@uvaarpa.virginia.edu> mer6g@uvaarpa.Virginia.EDU (Marc E. Rouleau) writes:
: >>eval "exec /bin/perl `/usr/local/ksh -c \"whence $0\"` $*"
: >>	if $running_via_sh;
: >>
: >>The only folks still left in the cold are those who have only the Bourne
: >>shell (sh(1)).
: >
: >Even those are not left out in the cold, they can use the type internal
: >command which finds the executable.
: 
: But "type" prints its output in "whence -v" format, so further processing with
: something like expr(1) would be necessary.

I know, let's have a contest to see how many processes we can use up before
actually executing the script...

: >Now we need a way to have it automatically determine the shell type and use
: >the appropriate command if needed.
: 
: I think this is all becoming much too complicated.  The original idea is
: relatively elegant and simple, and, in the absence of #! for System V, it
: seems like the next best thing; _however_, I really think the path-searching
: complexity oughta be implemented within perl.
: 
: What if we could do something like this:
: 
: eval "exec /bin/perl -S $0 $*"
: 	if $running_via_sh;
: 
: The -S switch would cause the script file to be searched for either using an
: algorithm implemented within perl (best case) or else by running a program
: (ksh, csh, sh) the path to which is configurable and compiled in (acceptable
: case).

Let's go with the best case.

I've hacked -S into version 2.0, so you guys can stop squabbling now.  The -S
switch will cause a path search if the filename doesn't begin with '/'.

Takes about 20 lines of code to do it right.  Hacking #! into the kernel
wouldn't have been that much harder...    :-)

Larry