rdiffdir: A succinct sync

Forgive me if I jump slightly out of order. I wanted to work with rdiffdir today, and I promise to touch on rdiff-backup tomorrow.

Also please forgive me if I don’t have screenshots this time. I think I can adequately explain what’s happening, and rdiffdir isn’t particularly wordy.

I have practical experience with it, albeit a few years out of date. At a time when I quit lugging an ancient laptop back and forth to work to listen to music, rdiffdir made it easy to synchronize my main music archive at home with the remote one at work … without a network connection.

“What witchcraft is this?!” you might howl. I’ll give you the command sequence, and you work out what’s happening. Office machine first:

rdiffdir signature music/ music.signature

Then at home:

rdiffdir delta music.signature music/ music.delta

Carry that back to the office, and …

rdiffdir patch music/ music.delta

And that’s it (or at least what I remember of it). The signature command creates a distinct impression of what’s available on the office machine. The delta creates a file packed with changed material from the home machine, and the patch command merges it with the destination at the office again.

It’s very clever, really. What you avoid is rsyncing entire folders to USB drives, then USB drives to destination folders — hopefully saving time, and space on your intermediary drive.

I could see where this would also be useful for completely offline backups, where you want to preserve file arrangements and integrity on one machine with another that is completely disconnected. Which, in this day and age, isn’t a bad idea. 😯

rdiffdir is part of duplicity, which is available in Debian and Arch. Tomorrow, rdiffdir’s ugly kid brother. 😉

By the way, I should mention that everything I know about rdiffdir I learned years ago from this page. Credit where credit is due. 😀