In my case I use wall in a script to conveniently get a message to anybody on the machine, including a GUI user. It just worked like magic. I could use notify-send, but that doesn't come with an audible "ping" and it's very cumbersome, as I then have to do something like this: sudo -u <target_user> DISPLAY=:0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/<target_user>/bus notify-send test So I first need to figure out who's logged on ...