unison

Install unison on both machines, and on both make the ~/.unison directory.

Make a job called backup:

vim ~/.unison/backup.prf

All jobs must end in .prf.

Here is an example job, which synchronizes the ~/music directory with a remote machine.

auto = true
root=/home/ghost
root=ssh://ghost@192.168.0.10//home/ghost/

path=music

ignore=Name *.flac

The last command means it will ignore any file with a name ending in .flac.

Add a port with this line:

sshargs=-p 4444

Automatic Runs

The first command means this will run but also confirm which files will be deleted, and which will be transferred, us batch = true instead.

Set unison to run with crontab or a systemd unit file to have directories synchronize automatically.

Problem Solving

Unison is extremely sensitive to version changes. Both machines must have exactly the same version of unison installed, as well as the same version of ocaml.

Check with:

unison -version

You will see data files summarizing what has happened in the ~/.unison directory. If something goes wrong, you may be prompted to delete these to start again.