I just had some fun as, my work day is over. I was curious if I can send message directly to a logged in Gnome user on Ubuntu / Debian environment.
After quick investigation I’ve found gxmessage which is available as deb package for both Debian and Ubuntu.
I installed it and use in the following way:
root@linux:~# apt-get install gxmessage
hipo@linux:~$ ssh firstname.lastname@example.org
hipo@remote-desktop:~$ DISPLAY=:0; XAUTHORITY=~owner_of:0/.Xauthority; export DISPLAY XAUTHORITY
hipo@remote-desktop:~$ gxmessage 'Heya what's up ;) Wanna have a cake?"
Below you see what pops up on the screen on the remote-desktop Gnome Desktop 😉