Ok, I'm making a full cPanel backup of my site via cron, and I want to set another cron job to "prune" the backup files on the server.
For example, the backup files are named: backup-6.12.2007_14-00-02_static.tar.gz, with 12 being the date. Is there a way to write a php script to take this file name , move date back 7 days and use a wildcard for the rest of the file?

eg, backup-6.[current date - 7].*_static.tar.gz?

I will be grateful for any help @ static [at] staticanime [dot] net. Thanks!

EDIT: I'm a n00b at php, BTW.