Simple TimeMachine-like Backup Scripts for Linux. This is works for a mounted volume.

This backup system assumes you are backing up to a file system that supports hard links.

You must modify the linuxbackuprc file to fit your specific circumstances and move it to your $HOME directory. You may rename it with a leading . (dot) to hide it if you like.

Of course, you should review the scripts to see what they do before trying to run them. There are interesting and useful variables you can set there or in the rc file.

The home_backup script prompts you whether or not to actually do the backup, since it may not be a convenient time, depending on the performance of your system while it is backing up. It also checks whether your destination is actually mounted and gives you a chance to mount it.

The script produces a log file in whatever directory you told it was _HOME.

In the _DEST_ROOT directory, a new directory will be created for each backup, and the backup will be named with a timestamp. All files identical between backups (from rsync's perspective) will be hard-linked, so there will actually only be one copy on the disk and any can be deleted without affecting the others. When the backup is completed a symlink called latest will point to the backup directory just created.

NOTE: If you cancel a backup, you should confirm that the latest symlink still points to the previous complete backup, or the hardlinking strategy won't work well.

Since the starting of a backup is interactive, and launching an interactive process from cron is discouraged, we have a sort of daemon that can be started from your "startup" apps that will wait for a signal, and when received, will launch the backup. This "daemon" is called cron_backup_starter. It starts a process that runs in the background, but does not use up CPU while waiting. The PID of the process is stored in /tmp/cron_backup_starter_PID. So the cron task simply sends the expected signal (SIGTRAP/5) to the process, which will then launch the interactive backup.

sudo crontab -u <your-username> -e

Then paste the contents of crontab_contents into the editor and save it.

Much thanks to Michael Jakl's "Time Machine for every Unix out there" blog post, on which the incremental_backup script is based.