I am using Fedora 20 with a MATE desktop and the Z shell.
Is there a way to display a message on the screen somewhere, sent from a shell program, when the terminal window is not visible?
You can use zenity
(GTK+ dialog display):
zenity --warning --text="Warning text" --title="Warning title"
Change --warning
to --error
or --info
for different window versions. And as always: man zenity
is your friend.