#!/usr/bin/perl -w
use strict;
use Shell qw( ls touch );

touch( "dummy" ) or die "touch: $!";
ls( "dummy" ) or die "first ls: $!";
ls( "dummy" ) or die "second ls: $!";

##</code><code>##

$ rm dummy
$ perl shell-test.pl
touch: Illegal seek at shell-test.pl line 6.
$ touch dummy
$ perl shell-test.pl
touch: Illegal seek at shell-test.pl line 6.