PHP script that executes lpr program

direct_print.php

<?php
function print_labels($files)
{
        $cmd = '/usr/bin/lpr -PDYMO_LabelWriter_450_Turbo -o PageSize=w102h252.1 -o PageRegion=w102h252.1 -o landscape -o page-left=10 -o page-top=10 -o page-right=0 -o page-bottom=0 -o Resolution=300dpi -o cupsDarkness=Normal -o scaling=100 '.$files;
        $output = system($cmd, $ret);

        if($ret!=0 || $output!='')
        {
                return 'ERR ['.$ret.']: '.$output;
        }

        $cmd = '/usr/bin/lpq -PDYMO_LabelWriter_450_Turbo | head -n1 | grep -q "is ready$"';
        $idx=0;
        while(TRUE)
        {
                $output = system($cmd, $ret);
                if($idx > 120 && $ret!=0)
                        return $output;
                if($ret==0)
                        return TRUE;
                sleep(1);
                $idx++;
        }
        return TRUE;
}
?>