Emacs: Turn Off Backup

disable emacs's automatic backup~ file

Put this code in your emacs init file:

(setq make-backup-files nil)

disable emacs's #autosave#

Emacs: Auto Save

set emacs so that all backups are placed into one backup folder

Put the following in your emacs init:

;; backup in one place. flat, no tree structure
(setq backup-directory-alist '(("" . "~/.emacs.d/backup")))

This will create backup files flat in the given dir, and the backup file names will have “!” characters in place of the directory separator.

For example:

• file /A/B/web/xyz/myfile.txt
• backup root dir /A/B/.emacs.d/backup
• backup at /A/B/.emacs.d/backup/A!B!web!emacs!myfile.txt~

If you use long file names or many nested dirs, this scheme will reach file name length limit quickly. (Mac and Windows allow 255 chars for file name.)

set emacs backups in one dir with tree structure

Put the following in your emacs init file:

;; make backup to a designated dir, mirroring the full path

(defun my-backup-file-name (fpath)
  "Return a new file path of a given file path.
If the new path's directories does not exist, create them."
  (let* (
        (backupRootDir "~/.emacs.d/backup/")
        (filePath (replace-regexp-in-string "[A-Za-z]:" "" fpath )) ; remove Windows driver letter in path, for example, “C:”
        (backupFilePath (replace-regexp-in-string "//" "/" (concat backupRootDir filePath "~") ))
        )
    (make-directory (file-name-directory backupFilePath) (file-name-directory backupFilePath))
    backupFilePath
  )
)

(setq make-backup-file-name-function 'my-backup-file-name)

The above will mirror tree structure to the backup dir.

For example:

• file /A/B/web/xyz/myfile.txt
• backup root dir /A/B/.emacs.d/backup/
• backup at /A/B/.emacs.d/backup/A/B/web/xyz/myfile.txt~

stop emacs's backup changing the file's creation date of the original file

Put this code in your emacs init file:

(setq backup-by-copying t)

Explanation: when emacs does a backup, by default it renames the original file into the backup file name, then create a new file and insert new file content into it. This effectively destroys the creation date of your file. (If a file is created in 2001, and you modified it today, the file's creation date will become today. Note: unixes (including Linux and BSD) do not record file creation date, so this doesn't matter. (ctime is not creation date.) Microsoft Windows and Mac OS X do record file creation date.).