How to bind a key combination to null in .inputrc?

Question

You can bind keys like Ctrl-Left and Ctrl-Right in .inputrc like this:

# Ctrl-Left
"\033[1;5D": backward-word
# Ctrl-Right
"\033[1;5C": forward-word

How would I bind Ctrl-Up and Ctrl-Down to nothing?

# Ctrl-Up
"\033[1;5A": null
# Ctrl-Down
"\033[1;5B": null

This obviously does not work.

I use these keys for doing stuff in tmux (nested configuration), but often ;3~ gets output into the terminal when I use either of the keys.

I'm hoping that I will be able to bind them to nothing while still having the keys work for tmux.

Of course the root cause of the problem is that GNU Readline does not have a proper ECMA-48 parser (c.f. https://unix.stackexchange.com/a/523308/5132 and its further reading). But how to do a no-op in Readline is a valid question in its own right. — JdeBP, Dec 11 '19 at 14:23

score 2 · Accepted Answer · answered Dec 11 '19 at 17:46

2

Bind them to redraw-current-line.

answered Dec 11 '19 at 17:46

of course, in bash you can use bind -x with an empty script (bind -x '"\033[1;5D":'), but I assume that the Q is about readline in general. – Dec 11 '19 at 17:54
There is nop. But unbinding is the correct thing to do, see @paradroid's answer. – kkm -still wary of SE promises Apr 12 '20 at 07:30
Where is nop? – Apr 12 '20 at 08:35
1

I always thought it was a thing, but it appears that binding to any undefined function name has the same effect. "\e=": is bound to possible-completions by default. Putting any of the lines "\e=":,"\e=": nop, "\e=": foobar results in bind -p | fgrep '"\e=' printing nothing (And M-= does not do anything). It appears either RL or bash is permissive: no diagnostics, no nothing. Sorry I was misleading you. In fact, "\e=": w/o arguments unbinds the key just fine. – kkm -still wary of SE promises Apr 14 '20 at 06:44
@kkm-stillwaryofSEpromises It seems this works for simple key sequences involving 1 Ctrl or escape. For sequences with both, running e.g. bind '"\e\C-f":' on the command line reliably unbinds the sequence from shell-forward-word, but does not work in inputrc. It seems like a bug. – SpinUp __ A Davis Dec 07 '23 at 04:28
@SpinUp__ADavis Thanks, interesting. I'll try to figure out. – kkm -still wary of SE promises Dec 09 '23 at 06:25

score 1 · Answer 2 · answered Mar 08 '20 at 17:21

1

I found that another option is to use double quotation marks.

# Ctrl-Up
"\033[1;5A": ""
# Ctrl-Down
"\033[1;5B": ""

answered Mar 08 '20 at 17:21

paradroid

This is the correct answer. This difference is important when the bound key is also prefix to a multi-key sequence: if the head key is not bound, readline waits for the second key indefinitely; if it's bound, only for a short timeout. – kkm -still wary of SE promises Apr 12 '20 at 07:33
This is not quite the same as unbinding the key -- this actually binds it to an empty macro, which may or may not work for a particular application. You can see the macros using bind -s. – SpinUp __ A Davis Dec 07 '23 at 02:46

2 Answers2