!sort           <-- this Vim command calls a binary, OK
!myfilter.pl    <-- this Vim command calls a perl script, FAIL

##</code><code>##

#!/usr/local/perl
### myfilter.pl

my  $sTest  = '';
while(<STDIN>){$sTest .= $_;}
print "
    _IT_WORKED_
    $sTest
    _IT_WORKED_
";