Syndicator is a python script providing a "synchronization indicator" for the file synchronzation software Unison on Ubuntu, i.e. a dynamic icon in the Unity panel that indicates the current synchronization state.
Each time you log in, Syndicator will run Back In Time (or some other command that you can specify) once and then try to start Unison. If running Unison fails (for example because there is no connection to the server), Syndicator keeps trying at intervals of 1, 2, 4 .... 300 seconds. The current status is displayed in the indicator panel as follows:
| icon | status |
|---|---|
  |
creating backups |
  |
syncing |
 |
repositories are fully synchronized |
 |
error (will restart automatically in x seconds) |
Additional information is provided via a menu: the current output of Back In Time/Unison, a list of recently synchronized files, and a list of errors.
Clicking on the first menu entry brings up a window displaying the last few (rather than just the last one) line of output from Back In Time/Unison.
- Linux operating system on your client machine (tested only on Ubuntu, see above)
- AppIndicator developer libraries for Python
- ssh access to a server, preferably via public key authentication
- a working installation of Unison on both client and server (version 2.48.3 or later)
- (optional) a working installation of Back In Time, or of some other command line backup tool
Brief details on how to set up 2-4 are included further below.
Syndicator comes in three versions:
| Name | Language | System | Desktop | Unison | Back in Time | |
|---|---|---|---|---|---|---|
| Syndicator 2 | Python 2 | tested with: | Ubuntu 14.04 | Unity | 2.48 | 1.0.34 |
| Syndicator 3.0 | Python 3 | tested with: | Ubuntu 18.04 | GNOME | 2.48 | 1.1.24 |
| Syndicator 3.1 | Python 3 | tested with: | Ubuntu 20.04 | GNOME | 2.48 | 1.2.1 |
! Due to an error in Back in Time versions 1.1.x, Syndicator 3.0 might synchronize files even when backing up failed. This is not usually a problem in practice, but if you are very sceptical of Unison you might prefer to use Syndicator 2 until this bug has been fixed. See issue #3 for details.
Once you’ve decided on a version, download either the folder syndicator2 or the folder syndicator3.
Open config.pyand adapt the following lines:
backup_command = "backintime --profile-id 2 -b"
sync_command = "unison XPS12-reh -repeat watch"
That is, replace the 2 in the first line with the id of the Back In Time profile that you would like Syndicator to use, and replace XPS12-reh by the name of the relevant Unison profile. The Unison profile should include the following options:
batch = true
prefer = newer
copyonconflict = true
Alternatively, you can include these flags as command line arguments in the value of the sync_command, of course.
Finally, make main.py executable (if necessary) with chmod +x main.py.
You should now be able to start Syndicator with one of the following commands:
Syndicator 2: call python main.py from within the folder syndicator2.
Syndicator 3: call python -m syndicator3.main from the parent folder of the folder syndicator3.
The icons used by Syndicator are essentially the UbuntuOne icons delivered with Ubuntu 14.04. You can change these either by replacing the relevant files in the icons folder or by editing config.py. For [at least some of the] icons in /usr/share/icons/ you only need to supply the file name, not the full path.
Generate a public-private-keypair on your client with:
$ ssh-keygen -t rsa -b 4096
You will be promted for a passphrase. Choose it carefully. Empty passphrases work, but then whoever manages to hack into your computer will automatically gain access to your server.
There should now be one private key (id_rsa) and one public key (id_rsa.pub) in ~/.ssh.
Copy the public key to the server:
$ scp .ssh/id_rsa.pub [email protected]:/user-directory/.ssh/otherkeys
Append this public key to the file .ssh/authorized_keys on the server:
$ ssh [email protected]
$ cd ~/.ssh
$ cat otherkeys/id_rsa.pub >> authorized_keys
If the server is correctly configured, future calls of ssh [email protected] should no longer ask for a password.
The scripts rely on a Python library called AppIndicator3: one of the first lines in Indicator.py is from gi.repository import AppIndicator3. Which packages precisely you need in order for this Python library to be available I do not know how to tell. On Ubuntu 14.04 with Unity desktop, it seems the necessary Python 2 library is usually installed by default, but some users reported that they needed to install it manually with:
$ sudo apt-get install gir1.2-appindicator3-0.1
On Ubuntu 18.04, I managed to install the corresponding Python 3 library with:
$ sudo apt install libappindicator3-dev
Binaries for Unison 2.48.3 built for 64-bit versions of Ubuntu 14.04 are included in the unison-binaries folder in this repository, and these binaries also seem to run fine on Ubuntu 16.10 and Ubuntu 18.04. So if you are running any of these versions of Ubuntu on your client and server, you can simply copy these binaries to any folder in which the system would usually look for them, e.g. usr/bin/ or ~/bin/. Then read the manual to find out how to configure your profile.
Unison is also available through the official Ubuntu channels and other distributions. Note however that continuous synchronization of 'watched' folders only works with Unison versions ≥ 2.48. If the above binaries don't work for you, and if no sufficiently young versions of Unison are available through your system repositories, you might need to compile your own Unison binaries. For this, you will need an OCaml compiler.
- Install Ocaml from the software center (4.01.0-3ubuntu3).
- Download Unison from http://www.cis.upenn.edu/~bcpierce/unison/ and unpack, e.g. to
~/Downloads/unison-2.48.3. - Switch to this folder and run make:
$ cd ~/Downloads/unison-2.48.3
$ sudo make UISTYLE=text
Test success with $ ./unison -- this should display a usage message.
- Copy the binaries to
~/binor whereever you want them, and create a link so that you can start Unison simply by typingunisonin the command line:
$ mkdir ~/bin
$ cp ~/Downloads/unison ~/bin/unison-2.48.3
$ cp ~/Downloads/unison-fsmonitor ~/bin/unison-fsmonitor
$ ln -s unison-2.48.3 unison
Calling unison should now display the same usage message as before.
This should work exactly as above. However, you need to make sure you have the same version of Unison on both client on server, and they should be compiled with the same version of OCaml. Unison 2.48 compiled with OCaml < 4.02 conflicts with Unison 2.48 compiled with OCaml 4.02! If you're lucky and the server uses the same architecture as your client you can of course simply copy the binaries.
If there are several versions of Unison on the server, you need to start Unison with the flag --add-version-no. More precisely, starting unison-2.48.3 on the client with --add-version-no will call unison-2.48 (without subversion number) on the server, so in addition to setting this flag you will need to create a soft link unison-2.48 on the server pointing to unison-2.48.3.
For Unison to actually do anything, you will need to create a profile myprofile.prf in ~/.unison/ -- see the manual.