I have two servers.. One has websites running and other have backup of those websites.. I need to synchronize the servers every week such that the files that were updated or changed after the previous backup schedule should only be updated the next time the backup runs.. The backups are kept in tar format(eg. hellowebsite-12-03-2011.tar.gz) in the backup server. How can I check whether the files were updated or not if the files are in tar format?
Instead of re-inventing the wheel, you should use one of the various solutions for incremental backups.
My favorite for this purpose is rsnapshot.