php判断进程是否存在

    //计划任务定时检测master进程是否存在，不存在则启动，以root用户运行
    public function checkMaster()
    {
        $cmd = 'ps axu|grep "UctDataWorker masterRun"|grep -v "grep"|wc -l';
        $ret = shell_exec("$cmd");

        $ret = rtrim($ret, "
");

        if($ret === "0") {
            $path = dirname(__FILE__) . '/index.php';
            $php_path = Config::$php_path;
            $start_master_cmd = "nohup ".$php_path." ".$path." UctDataWorker masterRun >> /data/log/uctWorker.log 2>&1 &";
            $ret = shell_exec("$start_master_cmd");
        }
    }