Re-open *scratch* buffer in Emacs?

Question

If I accidentally closed the scratch buffer in Emacs, how do I create a new scratch buffer?

Answer 1

This is what I use - I have this bound to a convenient keystroke. It sends you to the *scratch* buffer, regardless of whether or not it already exists, and sets it to be in lisp-interaction-mode

(defun eme-goto-scratch () 
  "this sends you to the scratch buffer"
  (interactive)
  (let ((eme-scratch-buffer (get-buffer-create "*scratch*")))
    (switch-to-buffer eme-scratch-buffer)
    (lisp-interaction-mode)))

Answer 2

I add following in my .emacs:

;; bury *scratch* buffer instead of kill it
(defadvice kill-buffer (around kill-buffer-around-advice activate)
  (let ((buffer-to-kill (ad-get-arg 0)))
    (if (equal buffer-to-kill "*scratch*")
        (bury-buffer)
      ad-do-it)))

If I don't want to see scratch buffer I press C-x C-k , but it doesn't kill it, just place in the end of buffer list, so then I need it next time I don't have to create new one.

Answer 3

I have combined the solutions posted so far into one function:

(defun --scratch-buffer(&optional reset)
  "Get the *scratch* buffer object.
Make new scratch buffer unless it exists. 
If RESET is non-nil arrange it that it can't be killed."
  (let ((R (get-buffer "*scratch*")))
    (unless R
      (message "Creating new *scratch* buffer")
      (setq R (get-buffer-create "*scratch*") reset t))
        (when reset
          (save-excursion
            (set-buffer R)
            (lisp-interaction-mode)
            (make-local-variable 'kill-buffer-query-functions)
            (add-hook 'kill-buffer-query-functions '(lambda()(bury-buffer) nil)
          )))
    R))

To apply this function in your .emacs use:

(--scratch-buffer t)
(run-with-idle-timer 3 t '--scratch-buffer)

This will make the scratch buffer indestructible in the first place, and if saved it will be recreated. Additionally we can use a shortcut function scratch to bring up the buffer quickly:

(defun scratch()
  "Switch to *scratch*.  With prefix-arg delete its contents."
  (interactive)
  (switch-to-buffer (--scratch-buffer))
  (if current-prefix-arg
      (delete-region (point-min) (point-max))
    (goto-char (point-max))))

In the past it has proven useful to know the original startup-directory from which Emacs was started. This is either the value of desktop-dirname or the default-directory local variable of the scratch-buffer:

(defvar --scratch-directory
  (save-excursion (set-buffer "*scratch*") default-directory)
  "The `default-directory' local variable of the *scratch* buffer.")

(defconst --no-desktop (member "--no-desktop" command-line-args)
  "True when no desktop file is loaded (--no-desktop command-line switch set).")

(defun --startup-directory ()
  "Return directory from which Emacs was started: `desktop-dirname' or the `--scratch-directory'.
Note also `default-minibuffer-frame'."
  (if (and (not --no-desktop) desktop-dirname) 
      desktop-dirname
    --scratch-directory))

So --startup-directory will always return the base directory of your makefile, TODO-file etc. In case there is no desktop (--no-desktop commandline-switch or no desktop-file) the --scratch-directory variable will hold directory Emacs was once started under.

Answer 4

find answer in EmacsWiki: http://www.emacswiki.org/emacs/RecreateScratchBuffer

(defun create-scratch-buffer nil
   "create a scratch buffer"
   (interactive)
   (switch-to-buffer (get-buffer-create "*scratch*"))
   (lisp-interaction-mode))

Answer 5

C-xb and then type *scratch* ↩︎

to create a new buffer which is in lisp interaction mode also.

Answer 6

I prefer to have my scratch buffer be an actual file that is automatically saved, and reopening it is as simple as opening a file. On startup, I kill the default and find my own like this.

(add-hook 'emacs-startup-hook
  (lambda ()
    (kill-buffer "*scratch*")
    (find-file "/Users/HOME/Desktop/.scratch")))

I have a custom kill-buffer function that does essentially the same thing -- reopens my personal scratch saved file and kills the default scratch if I killed the last visible buffer.

I customized a few of the desktop.el functions to load after (kill-buffer "*scratch*") and (find-file "/Users/HOME/Desktop/.scratch") so that the file last visible on exiting Emacs doesn't get buried by the default scratch or buried by my custom scratch when launching Emacs.

I enjoy using auto-save-buffers-enhanced, which automatically saves any file extension that is not specifically excluded:

https://github.com/kentaro/auto-save-buffers-enhanced/blob/master/auto-save-buffers-enhanced.el

(require 'auto-save-buffers-enhanced)
(auto-save-buffers-enhanced t)
(setq auto-save-buffers-enhanced-save-scratch-buffer-to-file-p 1)
(setq auto-save-buffers-enhanced-exclude-regexps '("\\.txt" "\\.el" "\\.tex"))

I use a slight variation of the function by @paprika when I want to create a no-file visiting buffer:

(defun lawlist-new-buffer ()
  "Create a new buffer -- \*lawlist\*"
(interactive)
  (let* (
    (n 0)
    bufname)
  (catch 'done
    (while t
      (setq bufname (concat "*lawlist"
        (if (= n 0) "" (int-to-string n))
          "*"))
      (setq n (1+ n))
      (if (not (get-buffer bufname))
        (throw 'done nil)) ))
  (switch-to-buffer (get-buffer-create bufname))
  (text-mode) ))