How do I control how Emacs makes backup files?

Question

Emacs puts backup files named foo~ everywhere and I don't like having to remember to delete them. Also, if I edit a file that has a hard link somewhere else in the file system, the hard link points to the backup when I'm done editing, and that's confusing and awful. How can I either eliminate these backup files, or have them go somewhere other than the same directory?

Answer 1

If you've ever had your ass saved by an Emacs backup file, you probably want more of them, not less of them. It is annoying that they go in the same directory as the file you're editing, but that is easy to change. You can make all backup files go into a directory by putting something like the following in your .emacs.

(setq backup-directory-alist `(("." . "~/.saves")))

There are a number of arcane details associated with how Emacs might create your backup files. Should it rename the original and write out the edited buffer? What if the original is linked? In general, the safest but slowest bet is to always make backups by copying.

(setq backup-by-copying t)

If that's too slow for some reason you might also have a look at backup-by-copying-when-linked.

Since your backups are all in their own place now, you might want more of them, rather than less of them. Have a look at the Emacs documentation for these variables (with C-h v).

(setq delete-old-versions t
  kept-new-versions 6
  kept-old-versions 2
  version-control t)

Finally, if you absolutely must have no backup files, you can set make-backup-files to nil. It makes me sick to think of it though.

Answer 2

Another way of configuring backup options is via the Customize interface. Enter:

M-x customize-group

And then at the Customize group: prompt enter backup.

If you scroll to the bottom of the buffer you'll see Backup Directory Alist. Click Show Value and set the first entry of the list as follows:

Regexp matching filename: .*
Backup directory name: /path/to/your/backup/dir

Alternatively, you can turn backups off my setting Make Backup Files to off.

If you don't want Emacs to automatically edit your .emacs file you'll want to set up a customisations file.

Answer 3

You can disable them altogether by

(setq make-backup-files nil)