rbxi is one of the family of smxi scripts. This one however runs on any unixlike system that supports bash, rsync, or rdiff-backup.
You can check out the home page for more information, or download the bz2 file directly.
Check out smxi.org for more complete rbxi installation options.
Most of the setup information is contained in the script readme file: rbxi/rbxi-data/rbxi-values
and in the readme file: rbxi/rbxi-data/readme-rbxi.htm which is also available online at smxi.org
And that's about all I'll post here, see also the script options, rbxi -h for option information, but make sure to read the setup information.
This script does NOT work without manual user configuration of the rbxi-values file, which has a lot of comments explaining how to do it, along with the readme-rbxi.htm file.