Question

I am trying to write my function for line duplcation. I have to maintain the cursor position. This is the code in the .emacs file :

(defun line-duplicate
  "line duplication."
  (setq position (point))       ;Store the original position of cursor               
  (global-set-key "\C-d" "\C-a\C-k\C-k\C-y\C-y")
  (goto-char position)            ;move the cursor to original position
)

(line-duplicate)

However, some error is arising. What is the mistake?

EDIT

Just discovered the command-execute function:

(defun line-duplicate ()
  (interactive)
  (setq position (point))
  (command-execute (kbd "C-a C-k C-k C-y C-y"))
  (goto-char position)
)

(global-set-key (kbd "C-d") 'line-duplicate)

And this worked.

Answer 1

global-set-key takes two arguments, KEY and COMMAND. COMMAND is not a key sequence, it is a function (usually it is a symbol naming an interactively-callable function, says the documentation). You probably do not want to change the behaviour of C-d when the function is called, you want to bind the function to the key.