Emacs: Backup Current File 🚀

By Xah Lee. Date: . Last updated: .

Here's a command to backup the current file. It creates a copy of the file in the current dir, with file name ending in ~. 

(defun xah-make-backup ()
  "Make a backup copy of current file or dired marked files.
If in dired, backup current file or marked files.
The backup file name is in this format
 x.html~2018-05-15_133429~
 The last part is hour, minutes, seconds.
in the same dir. If such a file already exist, it's overwritten.
If the current buffer is not associated with a file, nothing's done.

URL `http://xahlee.info/emacs/emacs/elisp_make-backup.html'
Version 2018-05-15"
  (interactive)
  (let (($fname (buffer-file-name))
        ($date-time-format "%Y-%m-%d_%H%M%S"))
    (if $fname
        (let (($backup-name
               (concat $fname "~" (format-time-string $date-time-format) "~")))
          (copy-file $fname $backup-name t)
          (message (concat "Backup saved at: " $backup-name)))
      (if (string-equal major-mode "dired-mode")
          (progn
            (mapc (lambda ($x)
                    (let (($backup-name
                           (concat $x "~" (format-time-string $date-time-format) "~")))
                      (copy-file $x $backup-name t)))
                  (dired-get-marked-files))
            (message "marked files backed up"))
        (user-error "buffer not file nor dired")))))
(defun xah-make-backup-and-save ()
  "Backup of current file and save, or backup dired marked files.
For detail, see `xah-make-backup'.
If the current buffer is not associated with a file nor dired, nothing's done.
URL `http://xahlee.info/emacs/emacs/elisp_make-backup.html'
Version 2015-10-14"
  (interactive)
  (if (buffer-file-name)
      (progn
        (xah-make-backup)
        (when (buffer-modified-p)
          (save-buffer)))
    (progn
      (xah-make-backup))))

Emacs: auto save, backup