#!/usr/bin/perl

use warnings;
use strict;

my $fn;
my $cmd_out;

$fn = "/tilde/lyadmin/user_list.txt";

open FILE, "<", $fn or die "could not open $fn";

$cmd_out = `ls /home`;
chomp $cmd_out;

while(<FILE>){
    chomp;
    `userdel $_` unless($cmd_out =~ /$_/);
}
close FILE;