Ubuntu – How to return to the shell/terminal

Ah, you're hitting the wrong key. It's Control + C. This is the command to force the current running application in the terminal to end. If you end the command it will also end the corresponding open application. So if you want to execute more commands in the same terminal, you have to press Control + C to exit the program, which will also exit geany. So it's best to simply run programs through the GUI, therefore saving you a lot of terminal windows. Or you can also use Ubuntu's run command function by pressing Alt + F2 and typing the command you want to run, no terminal required.

The typical way to close application gracefully is to use kill -TERM 1234 , where 1234 is the PID of the window. Problem, however, is that graphical applications are designed to listen for a specific signal from X server itself , not listening for the TERM signal.

That means you would need some kind of agent in between you and the X server to communicate that you want to send appropriate signal. You can of course write a C program, however there aready exists wmctrl program ( not-surprisingly written in C ) that does exactly that.

Usage of wmctrl is simple:

wmctrl -c :SELECT: # close window that will be selected with pointer
wmctrl -c :ACTIVE: # close currently active window
wmctrl -ic <numeric id> # close window with specific id in hex

It's not installed by default, so get it with sudo apt-get install wmctrl

There's many uses for wmctrl is far beyond just closing windows, so please see more of my answers and Jacob Vlijm's for examples of scripts where it's been used