Notifications in Linux

Question

linux

The bottom line is this: It is
required from the program, by running a bash script, to create notifications in the tray area in Linux, how to do this is known (Gnome - notify-send, KDE - kdialog), so how to determine the user's desktop environment (except how to directly request) to run the valence version of the script?
And the second, less important question - what environments besides KDE \ Gnome should you still focus on?

Answer 1

$DESKTOP_SESSION
This environment variable must contain the title.

Answer 2

Don't forget about XFCE.