Example 3: Executing command with user bin's Environment and
     Permissions

     To execute command with the temporary environment  and  per-
     missions of user bin, type:

     example% su - bin -c "command args"

##</code><code>##

su - myuser -c "/home/myuser/t1.pl"

##</code><code>##

#!/usr/bin/perl -w
use strict;

open(OUT,">su-test.log") or die;
print OUT "user $ENV{'USER'}\n";
close(OUT) or die;
exit;