Crontab provide a php 5.3 lib to create crontab file.

use Crontab\Crontab;
use Crontab\Job;

$job = new Job();
$job
	->setMinute('*/5')
	->setHour('*')
	->setDayOfMonth('*')
	->setMonth('1,6')
	->setDayOfWeek('*')
	->setCommand('myAmazingCommandToRunPeriodically')
;

$crontab = new Crontab();
$crontab->addJob($job);
$crontab->write();

You can render what you have created:

echo $crontab->render();

And then you can delete a job you don't want anymore:

$crontab->removeJob($theJobYouWantToDelete);

When you create a Crontab, it will automatically parse your current crontab file and add all present job into your new object.

You can run the unit tests with the following command. You need to be in the crontab directory and have phpunit installed on your computer:

phpunit -v