#!/bin/sh
perl -lne 'print+(split(/:/))[0]' /etc/passwd

##</code><code>##

#!/usr/bin/perl -ln
BEGIN{ @ARGV = "/etc/passwd"; }
print+(split(/:/))[0]

##</code><code>##

#!/usr/bin/perl -w
@ARGV = "/etc/passwd";
$\ = $/;
while(<>) {
print+(split(/:/))[0];
}