public static function parseFile($file)
    {
        if (!file_exists($file) || !is_readable($file)) {
            $message = "crontab config file is not exists or not readable";
            throw new \RuntimeException($message);
        }

        $tasks = array();
        $lines = file($file);
        foreach ($lines as $line) {
            $job = new JobParse($line);
            $tasks[] = $job->getTask();
        }

        return $tasks;
    }