rdup is a utility inspired by rsync and the Plan9 way of doing backups.

rdup itself does not backup anything; it only prints a list of the names of
files that have changed since the last backup. It also handles files that are
removed, allowing for correct incremental backups.

Example scripts named rdup-simple and rdup-ln are included to show how to 
implement a simple snapshot-style backup strategy.  These bash scripts require 
GNU date and cp, which are not installed by this FreeBSD port. If you want to 
use the scripts, you should also install the sysutils/coreutils port.

WWW: http://miek.nl/projects/rdup