How can I check if a current buffer exists in Emacs?

Solution 1:

From the documentation:

(get-buffer name)

Return the buffer named name (a string).
If there is no live buffer named name, return nil.
name may also be a buffer; if so, the value is that buffer.

(get-buffer-create name)

Return the buffer named name, or create such a buffer and return it.
A new buffer is created if there is no live buffer named name.
If name starts with a space, the new buffer does not keep undo information.
If name is a buffer instead of a string, then it is the value returned.
The value is never nil.

Solution 2:

This is what I did:

(when (get-buffer "*scratch*")
  (kill-buffer "*scratch*"))

This checks for the buffer scratch. If there's such a thing, kill it. If not, do nothing at all.

Solution 3:

not sure about version this predicate appeared, but now Emacs has buffer-live-p:

buffer-live-p is a built-in function in `buffer.c'.

(buffer-live-p OBJECT)

Return non-nil if OBJECT is a buffer which has not been killed.
Value is nil if OBJECT is not a buffer or if it has been killed.

Solution 4:

If you'd like to define your hypothetical function as above, this works:

(defun buffer-exists (bufname)   (not (eq nil (get-buffer bufname))))

I use this to automatically close the *scratch* buffer on startup, so I don't have to cycle through it in my list of buffers, as follows:

(defun buffer-exists (bufname) (not (eq nil (get-buffer bufname))))
(if (buffer-exists "*scratch*")  (kill-buffer "*scratch*"))