Determine if Ubuntu 17.10 (desktop) is using Wayland

[Ralf Mardorf]

On Mon, 4 Dec 2017 22:10:49 -0500, J Doe wrote:
>If I recall correctly, Ubuntu 17.10 (desktop version), uses Wayland if
>the computer’s hardware supports it.  Is there an easy way for me to
>determine on a running 17.10 machine if Wayland is being used or if
>the OS is falling back to X ?

AFAIK from threads on this mailing list, Wayland comes with software
pitfalls, for example the current method to allow users to access GUIs
with root privileges, e.g. for GUIs to install packages, doesn't work
anymore. AFAIK the user could chose by the display manager's greeter, if
starting a user session with X or wayland is wanted. I wonder what's
used by the display manager's greeter itself ;).