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Execing perl?


From: Paul D. Smith
Subject: Execing perl?
Date: 11 Jul 2001 14:50:19 -0400
User-agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7

OK, this isn't a bug, and it's also something that you'd _think_ would
be so obvious it'd be right at the top of all the FAQs, etc... but I
can't find it, nor can I figure it out.

The Perl docs (perlrun) say you can use this stanza to write a perl
script when you don't know where the perl runtime will be; something
like:

  #!/bin/sh -- # -*- perl -*-
  eval 'exec perl -wS $0 ${1+"$@"}'
    if $running_under_some_shell;

This doesn't work if bash is /bin/sh; I get this error:

  /bin/sh: -- # -*-perl-*-: unrecognized option

(ditto if I use /bin/bash instead).  This does work with other Bourne
shells, though, such as Solaris' /bin/sh.

If I leave out the -- and just use the comment, I get this error:

  # -*-perl-*-: # -*-perl-*-: No such file or directory

(it doesn't ignore the comment).  Even moving this past the "normal"
32-char boundary doesn't help.

However, if I remove the extra stuff from the first line, then _Perl_
screws up, due to this little gem (from perlrun):

       If the #! line does not contain the word "perl", the pro-
       gram named after the #! is executed instead of the Perl
       interpreter.  This is slightly bizarre, but it helps peo-
       ple on machines that don't do #!, because they can tell a
       program that their SHELL is /usr/bin/perl, and Perl will
       then dispatch the program to the correct interpreter for
       them.

As a result, /bin/sh runs Perl, which turns right around and tries to
run /bin/sh, I guess with the options it got (-wS etc. etc.) and I get
this:

  /bin/sh: -w: unrecognized option


_Surely_ someone has solved this problem!

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <address@hidden>    HASMAT--HA Software Methods & Tools
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist
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   These are my opinions---Nortel Networks takes no responsibility for them.



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