Configuring multiple key bindings

Question

I would like to bind M-S-up to C-u 7 S-up to move a timestamp a week forward (and down for back). A modification of this answer resulted in a "Symbol is void" error in Emacs.

I tried modifying the define-keys command, but was not successful, as Emacs then stated that "-up" could not follow after "M-S".

How can I configure a keybinding in my ~/.emacs file to execute C-u 7 S-up?

Update

I placed the following, modified from the answer linked above, in the scratch buffer and evaluated it:

(define-key my-map (kbd "C-u 7 S-up") (kbd "M-S-up"))

Emacs returned Symbol's value as variable is void: my-map.

Answer 1

You can't set a key in a keymap that doesn't exist. In order to use define-key, you need to know the name of the keymap you're trying to modify. To add a keybinding to the global keymap, you can use global-set-key instead:

(global-set-key (kbd "M-S-<up>") (kbd "C-u 7 S-<up>"))

If you want to modify the keybinding only for org-mode, you can use

(eval-after-load "org-mode"
  '(define-key org-mode-map (kbd "M-S-<up>") (kbd "C-u 7 S-<up>")))

or

(defun my-org-hook ()
  (local-set-key (kbd "M-S-<up>") (kbd "C-u 7 S-<up>")))

(add-hook 'org-mode-hook 'my-org-hook)

Answer 2

The typical approach would be to bind the key to a command, rather than another key sequence. In your case you want to call org-shiftup with an argument. For example:

(define-key org-mode-map (kbd "<M-S-up>")
   (lambda () (interactive) (org-shiftup 7)))

Alternatively you can bind one key sequence to another as in the example you cited. This works for me:

(define-key org-mode-map (kbd "<M-S-up>") (kbd "C-u 7 <S-up>"))

As @Tyler pointed out, when defining keys for a specific mode you generally want to use a mode hook or eval-after-load so that the key is not defined until the mode's keymap has been defined.

A few general tips:

• Use C-h k to find that S-up is bound to org-shiftup.
• Use C-h f define-key to read the doc for define-key. It looks like you swapped the arguments and may not be familiar with keymaps.
• As noted in the comments, use C-h k to see the appropriate key syntax -- when using up, you need the <>.
• To really understand key maps and key bindings, refer to the Elisp manual. There is also a great overview on Mastering Emacs.