How do I find out if my system is using Mir?

Question

I've just installed Mir and I'm wondering if I'm actually running it or if it fell back to X. How can I tell if Mir is running?

Answer 1

You can also simply check if the system compositor process is running:

 ps afx | grep unity-system-compositor

On my system running Mir it returns something like this:

jorge@jillociraptor:~$ ps afx | grep unity-system-compositor
 4260 pts/0    S+     0:00          |   |               \_ grep --color=auto unity-system-compositor
 1606 ?        S      0:00 /usr/sbin/unity-system-compositor --from-dm-fd 9 --to-dm-fd 13 --vt 7

Machines NOT running Mir will not show unity-system-compositor running.

Reference:

• Running Mir - Olli Reis

Answer 2

ps -e | grep unity-system-co

Will return one response if Mir is running, nothing if it is not. This is because 'ps -e' actually truncates the process names to 15 characters (known upstream bug/limitation). I found the suggestion from minerz029 always returned nothing even if Mir was running.

Answer 3

It's going to depend on what you mean by "I just installed Mir". Mir is really just a set of libraries. There are client libraries and server libraries. There are also several different packages that provide actual Mir server binaries.

There is a demo Mir server, but if you were running it you would know, because you'd have switched to a VT and typed in the command to run it. That server is found in the mir-demos package.

There's the Unity 8 Mir server. It runs as a part of Unity 8 (package unity8). You'd know you were running that because your desktop would look like a Unity 8 desktop.

Finally, there is the unity-system-compositor Mir server, which is generally started by LightDM. Unless you wrote your own LightDM integration scripts, you either need to install the Unity 8 desktop session (package unity8-desktop-session-mir), in which case the only way to run the Mir server is to log in to the Unity 8 desktop, or you installed the ubuntu-desktop-mir package, in which case the other answers are correct: a ps will show the unity-system-compositor running underneath the X server.