Why is CTRL + = shortcut blocked? When I'm e.g. in the Terminal and press CTRL^= I get the "invalid key sound". I need to bind this shortcut to a Terminal app, but it doesn't work. Just get this sound and it's not evaluated. 

What's blocking it?
That's because &lt;CTRL-=&gt; is an invalid key combination in a terminal interface.

(Hint:  There's no such corresponding ASCII character.)