How to know on which virtual console X11 is running?

Question

I want to know on which virtual console the X11 is runnning. Of course, I can know it by invoking the ps command and watching the process tree. Or, I can know it by pressing ctrl+alt+F1, ctrl+alt+F2, ... But it is nice if there is an easier way.

When the system is in CUI mode, I can know it by the tty command. But under X11, the tty command tells me such as /dev/pts/0 and it doesn't seem to be a clue to the virtual console. Is there is any connection between tty* and pst/*?

In my environment, X11 is usually running on tty1. But in some rare case, it runs on another console. If I can know the console easily, it helps me a lot.

P.S.

Recently I knew the following fact:

On machies using systemd, the environment variable $XDG_VTNR is set to the number of the virtual console.

What is the environment variable XDG_VTNR?

Answer 1

You can use the fgconsole command. In Debian it's included in the package kbd.

For example:

$ fgconsole
7

Answer 2

You could always run grep "using VT number " /var/log/Xorg.0.log. I'll leave it to you on how to extract the number.