Linux系统下后台执行程序

$now_os = PHP_OS;
if ($now_os == 'Linux'){// this is for Fedora 8
$p = "/usr/bin/php";
}
else{
$document_root = $_SERVER['DOCUMENT_ROOT'];
$path_array = explode("/",$document_root);
$path_len = count($path_array);
for($i=0;$i<($path_len-1);$i  ){
$p .= $path_array[$i]."\\";
}
$p .="php5\\php.exe";
}

system("".$p." queue_run_firm.php ".$p." ".$class." ");