6
You might wanna check out this (freeware) product (script):
http://www.bitesser.de/freeware/script.php?id=1&PHPSESSID=452664cf6998154913f1ce116aa8c13a
They also have an english forum behind the community button on that page. I think you will be able to use this PHP script and call it from your cron job.
(though i never tried it myself ... just something i noted for myself in case i ever needed it)