Send "C-(" to Emacs in VT100/xterm terminal (Mac OS X's Terminal)?

Question

Is it possible in any way to send the key "C-(" to Emacs over a VT100/xterm terminal (Mac OS X Terminal)? Is there an escape sequence that could be sent to achieve the equivalent?

I suspect the fundamental problem is that the concept of combining control with the character "(" (and other such characters that are produced using shift) does not exist.

Note: Using Cocoa Emacs is not an option. And the reason for needing "C-(" is that paredit.el uses it amongst other key combinations, and it would be preferable to not remap it (because it makes sense to have it on "C-(").

Flog

Answer 1

A VT100 terminal couldn't do that, because there is no ^( control character corresponding to (. However, xterm has the so-called "modifyOtherKeys" mode, which does allow to send unique keycodes for combinations like that.

To enable it, set the modifyOtherKeys resource, e.g. in ~/.Xdefaults:

XTerm*vt100.modifyOtherKeys: 1

With that, Ctrl+( will send the following keycode:

^[[27;6;40~

That's rather long though, so another format for keycodes like that was introduced, which can be enabled by setting the formatOtherKeys resource:

XTerm*vt100.formatOtherKeys: 1

With that, Ctrl+( sends:

^[[40;6u

In both of these keycodes, the 40 is the decimal ASCII code for (, and the 6 represents the Ctrl.

See man xterm and http://invisible-island.net/xterm/ctlseqs/ctlseqs.html for further details. No idea whether Terminal.app supports any of it.

Dextrality

Thank you, this is almost spot on. Part of the puzzle was finding the escape code which would generate "C-(", which you provided -- I managed to verify it also works in MacOS X's Terminal. Now however I noticed that MacOS X's Terminal unfortunately does not provide for mapping arbitrary keys (in this case, Ctrl + parenthesis) to escape sequences -- only function, arrow and a few other keys can be mapped. – Flog

iTerm2 will allow you to remap arbitrary keys to escape sequences. – Yorktown

Over 4 years old and still saving peoples behinds. Good guy @Dextrality :) – Grate