Time Machine style backup with rsync. Should work on Linux, OS X and Windows with Cygwin. The main advantage over Time Machine is the flexibility as it can backup from/to any filesystem and works on any platform. You can also backup, for example, to a Truecrypt drive without any problem.
On OS X, it has a few disadvantages compared to Time Machine - in particular it doesn't auto-start when the backup drive is plugged (though it can be achieved using a launch agent), it requires some knowledge of the command line, and no specific GUI is provided to restore files. Instead files can be restored by using any file explorer, including Finder, or the command line.
An optional exclude file can be provided as a third parameter. It should be compatible with the `--exclude-from` parameter of rsync. See [this tutorial] (https://sites.google.com/site/rsync2u/home/rsync-tutorial/the-exclude-from-option) for more information.
* Automatically purge old backups - within 24 hours, all backups are kept. Within one month, the most recent backup for each day is kept. For all previous backups, the most recent of each month is kept.
