symfony如何从外部脚本运行任务？

Need to run symfony task from external script (e.g. cron or etc).

Try to run:

<?php

require_once(dirname(__FILE__).'/libs/symfony/config/ProjectConfiguration.class.php');

$configuration = ProjectConfiguration::getApplicationConfiguration('frontend', 'dev', true);

$task = new parseTask($configuration->getEventDispatcher(), new sfFormatter());
$argumentsArray = array();
$optionsArray = array();
$task->run($argumentsArray, $optionsArray);

But its return

Fatal error: Uncaught exception 'sfException' with message 'You must be in a symfony project directory.' in /public_html/libs/symfony/lib/task/sfBaseTask.class.php:116

Need to change directory to symfony, e.g.:

$symfony_dir = $_SERVER['DOCUMENT_ROOT'].'/libs/symfony/';
chdir($symfony_dir);