Changes to environment variables are only passed down to child processes in Unix. Therefore, without taking some special steps, any changes your Perl program makes to your environment won't be reflected back to the calling shell program. A typical way to do something like this is to have your program output a bash command on its stdout, and eval that in bash.

For example, your bash line in .profile or .bashrc would be:eval `path_munch.pl`where the basic structure of path_munch.pl (bad name, I know) is:

#! /usr/bin/perl -w
my @newpath;
foreach (split /:/, $ENV{PATH})
{
   push @newpath, ... # however you do this
}
print 'export PATH=', join(':', @newpath), "\n";
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HTH

This is a case where you want to use the shell (VSarkiss++ has told you why). The shell 'source' operator, '.' (dot) will let you read a file of bash statements into the current environment. See 'man bash'.

For instance, to regain much of your startup environment:

$ . ~/.bash_profile
$
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After Compline,
Zaxo

• Put the following in your .profile if you are using sh or bash:

  PATH =`munch.pl $PATH`
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  This is replaced by:

  setenv PATH `munch.pl $PATH`
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  to put in .cshrc if you are using csh or tcsh.
• The munch.pl script (why, VSarkiss, I like that name:)) is something like this:

  #!/usr/bin/perl -w
  use strict;
  my @comp = split /:/,shift;
  my %saw = ();
  @saw{@comp} = ();
  print join ":",keys %saw;
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This gives the following under bash:

$ TEST="a:b:c:a:c:z:a:b:z"
$ echo $TEST 
a:b:c:a:c:z:a:b:z
$ TEST=`tmp/test.pl $TEST`
$ echo $TEST
a:z:b:c
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> setenv TEST "a:b:c:a:c:z:a:b:z"
> echo $TEST
a:b:c:a:c:z:a:b:z
> setenv TEST `tmp/test.pl $TEST`
> echo $TEST
a:z:b:c
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Hope that helps....

Cheers

Argh.... I'm stupid today:) There is a big mistake in my post...

The component order in PATH-like variables is important, sometimes very important, and my munch.pl script mess it up. This version of munch.it don't has this pitfall:

#!/usr/bin/perl -w
use strict;
my @comp = split /:/,shift;
my %saw = ();
my @out = ();
for (@comp) {
  push @out,$_ unless $saw{$_}++;
}
print join ":",@out;
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Now I may gonna hide in the monastery cellar...

---

Leo TheHobbit