问题
I'm trying to put in a feature that I miss from Eclipse, where Alt+[Up/Down] transposes the lines up or down, but can not for the life of me figure out how to assign to these keys properly. I am using it in -nw mode (so just in a shell window), and typically run in a screen session.
Using a global key binding, I can get it to work with letter combinations, like (kbd "M-m"), but every combination I have tried for the arrow keys just gives me a message that doesn't make sense, I always get:
"ESC <up> is undefined"
What I have tried:
(global-set-key (kbd "M-<up>") 'transpose-line-up)
(global-set-key (kbd "<escape>-<up>") 'transpose-line-up)
(global-set-key [M-up] 'transpose-line-up)
(global-set-key [\e \M-O A] 'transpose-line-up)
And C-h c just returns:
ESC <up> (translated from ESC M-O A) is undefined
None of these work, either using ESC or Alt.
Any idea how I can make this work? I would prefer to have these as Alt+[Up/Down] just because that is what I am used to.
Edit
From the comments:
C-q Up prints
^[OA.C-q M-Up prints
^[and moves the cursor up a line.C-h k (Alt+Up) prints
ESC <up> (translated from ESC M-O A) is undefined.
Thanks for the suggestions, but they all turned out the same.
回答1:
Emacs has a complex mechanism to handle the vicissitudes of function key and modifier encodings on various terminal types. It doesn't work out of the box in all cases. The following settings should work on your terminal:
(define-key input-decode-map "\e\eOA" [(meta up)])
(define-key input-decode-map "\e\eOB" [(meta down)])
(global-set-key [(meta up)] 'transpose-line-up)
(global-set-key [(meta down)] 'transpose-line-down)
You should be able to use (kbd "<M-up>") and (kbd "<M-down>") in place of [(meta up)] and [(meta down)], as long as you've done the step of telling Emacs (via input-decode-map) about the escape sequences that your terminal uses to encode these key combinations.
回答2:
I always use C-h k (key) (i.e. describe-key) to find out how Emacs refers to (key), and then use (kbd) with that same string to utilise it.
In this case, describe-key returns <M-up>, so I would use (global-set-key (kbd "<M-up>") 'transpose-line-up) (exactly as J.F. Sebastian has done).
Edit:
Running emacs -nw (but not through screen), describe-key reports ESC <up> (translated from ESC M-[ A), and (kbd "ESC <up>") is successful for binding it.
Running screen emacs -nw, describe-key reports ESC <up> (translated from ESC M-O A), which seems to match what you see, and the binding for (kbd "ESC <up>") still works for me.
(n.b. Tested under Cygwin with screen 4.00.03, and Emacs 23.2.1.)
回答3:
(global-set-key [M-up] 'beginning-of-buffer)
(global-set-key [M-down] 'end-of-buffer)
In my OSX, I have this definition to perform Alt-up/down to jump to top/bottom of buffer.
回答4:
ugly workaround:
I've typed C-q <M-up> it produced ^[[1;3A on the terminal inside screen inside emacs.
(global-set-key (kbd "<M-up>") 'transpose-line-up)
(global-set-key (kbd "^[[1;3A") 'transpose-line-up)
I've got Lisp error: (void-function transpose-line-up) so the key bindings work.
Note: C-q runs the command quoted-insert.
回答5:
The following lines work for me on macOS 10.11.6 and GNU Emacs 25.2.1:
(global-set-key (kbd "ESC <down>") 'end-of-buffer)
(global-set-key (kbd "ESC <up>") 'beginning-of-buffer)
回答6:
Assuming you have the functions transpose-line-up and transpose-line-down already defined (as it seems to be from the example code in your original question):
(global-set-key [(meta up)] 'transpose-line-up)
(global-set-key [(meta down)] 'transpose-line-down)
来源：https://stackoverflow.com/questions/4351044/binding-m-up-m-down-in-emacs-23-1-1