Reassigning Ctrl+x ?

[fiso64]

I'm wondering if it's possible to reassign Ctrl-x to another action (like cua-cut). I've tried adding a line with "\C-X" to my inputrc, but it doesn't seem to work because it waits for the next key press as there are some default shortcuts like Ctrl-x,Ctrl-u.

[chrisant996]

You will need to undefine all of the Ctrl-X chords, i.e. all of the multi-key bindings that start with Ctrl-X.

[chrisant996]

Ah ... right, I just tested this.

This is a known limitation in Readline (and bash and all programs that use Readline).

Once a multi-key sequence has been defined, there is no way to undefine the multi-ness and go back to a single key.

Readline itself defines Ctrl-XCtrl-F and other combinations starting with Ctrl-X.

This was discussed in issue in the Clink repo in the past, and I'm looking for the issue number to link it here.
UPDATE: I found it. This unbind issue was discussed in #248 (comment), in the context of a different kind of situation. See the final section of that comment ("Nope, there is a Readline problem"). But for that to make sense, also read the earlier section of that comment, "Sidebar: What is a shadowed key?".

[chrisant996]

I can't find the issue with the previous discussion.
UPDATE: I found it. This unbind issue was discussed in #248 (comment), in the context of a different kind of situation. See the final section of that comment ("Nope, there is a Readline problem"). But for that to make sense, also read the earlier section of that comment, "Sidebar: What is a shadowed key?".

But what happens is that Ctrl-X will do the cua-cut command ... but not until you press another key -- because Readline is stuck on believing that Ctrl-X is the beginning of a multi-key binding, since it doesn't know how to undo that once it's been done.

Ctrl-X is the only key that suffers that from that by default. I can't remove all the Ctrl-X key bindings by default, as that would create an even worse problem.

I'll explore whether it might be reasonable to try to patch how Readline handles that situation, though.

[fiso64]

I see, thanks for answering

[chrisant996]

@fiso64 I've debugged through it, and now I see what's going on...

Readline has code that tries to revert the shadow key issue when unbinding keys.

But there are four caveats:

1. The code can only revert the shadow key issue when keys are bound to commands; not when they're bound to macros. That doesn't appear to be relevant in your case.
2. The code can only revert one level of the shadow key issue at a time. That isn't relevant in your case, because the longest Ctrl-X key binding is only 2 keys long. But if there were any that were 3 or more long, then it would be a lot more complicated and persnickety about how to successfully fully revert them.
3. The code can only revert the shadow key issue when all sub-keys become unbound. And while it looks to us like all the sub-keys have been unbound ... they actually haven't. More on that in a moment.
4. Readline cheats and has a hard-coded table listing its default Ctrl-X key bindings. So if you successfully unbind all of the Ctrl-X bindings, then Readline should try to free hard-coded non-allocated memory and it should either crash or corrupt memory. But Readline has a bug where it leaks the memory instead of freeing it, when unbinding the last key from a sub-table. So two wrongs cancel each other out and it doesn't crash -- but it does leak a small amount of memory.

Ok, so caveats 1, 2, and 4 end up working out in your case.

But not caveat 3. Because Readline has a hard-coded table of key bindings for Ctrl-X, and all of the uppercase letters are bound to the command do-lowercase-version (i.e. Ctrl-XA .. Ctrl-XZ). And that command doesn't get listed as being a key binding when retrieving key bindings, because the whole point is for it to silently do whatever is bound to the same lowercase letter instead.

So to successfully fully revert the Ctrl-X key bindings, you have to also list all the upper case letter combinations.

I confirmed that once they're all unbound as well, then it finally does what you wanted.

What an ordeal, eh?!

# Unbind the keys that were explicitly bound.
"\C-x(":
"\C-x)":
"\C-x*":
"\C-x\C-?":
"\C-x\C-e":
"\C-x\C-g":
"\C-x\C-r":
"\C-x\C-u":
"\C-x\C-x":
"\C-x\C-z":
"\C-xe":
"\C-xg":

# Unbind the keys that were implicitly bound.
"\C-xA":
"\C-xB":
"\C-xC":
"\C-xD":
"\C-xE":
"\C-xF":
"\C-xG":
"\C-xH":
"\C-xI":
"\C-xJ":
"\C-xK":
"\C-xL":
"\C-xM":
"\C-xN":
"\C-xO":
"\C-xP":
"\C-xQ":
"\C-xR":
"\C-xS":
"\C-xT":
"\C-xU":
"\C-xV":
"\C-xW":
"\C-xX":
"\C-xY":
"\C-xZ":

# Finally, bind Ctrl-X.
"\C-x":			cua-cut

[fiso64]

Yep, it works! Thanks a lot for the effort

[chrisant996]

Note: what you're trying to do is some relatively advanced configuration. This is not a common thing.