Curiously, on many terminal emulators the following work: Ctrl-2 = Ctrl-@ = NUL byte Ctrl-3 = Ctrl-[ = ESC Ctrl-4 = Ctrl-\ = default for SIGQUIT Ctrl-5 = Ct

Curiously, on many terminal emulators the following work: Ctrl-2 = Ctrl-@ = NUL byte Ctrl-3 = Ctrl-[ = ESC Ctrl-4 = Ctrl-\ = default for SIGQUIT Ctrl-5 = Ctrl-] = jump to definition in vim Ctrl-6 = Ctrl-^ = mosh escape key Ctrl-7 = Ctrl-_ = undo in Emacs I think these probably originate in xterm.