How to auto-save buffers when Emacs loses focus?

Question

I recently had a Sublime Text user try out Emacs for a while, and he was interested in getting the same auto-save behavior in Emacs.

Basically, he wanted all buffers to be saved whenever the frame lost focus (really saved, not just backed-up). This includes when switching windows to a completely different application.

I could not find any event that was triggered when switching to a different application. Is there such an event or is there another way to achieve the same behavior?

Note a time based solution was not satisfactory, and neither was the default auto backup behavior. He specifically wanted the buffers to be saved (as in save-buffer) for all files.

score 33 · Accepted Answer · edited Jun 15 '15 at 15:17

33

Unfortunately, this exact behavior isn't possible in Emacs <= 24.3, but you can save on window/buffer change using defadvice (as detailed on bbatsov's blog):

(defadvice switch-to-buffer (before save-buffer-now activate)
  (when (and buffer-file-name (buffer-modified-p)) (save-buffer)))
(defadvice other-window (before other-window-now activate)
  (when (and buffer-file-name (buffer-modified-p)) (save-buffer)))

In Emacs 24.4, you will also be able to save on frame focus loss thanks to the new focus hooks: (add-hook 'focus-out-hook 'save-buffer) (to save the active buffer) or (add-hook 'focus-out-hook (lambda () (save-some-buffers t))) (to save all open buffers).

edited Jun 15 '15 at 15:17

skrat

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6

answered Sep 25 '14 at 18:34

shosti

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Could you expand a bit on the `defadvice` version, in case the blog post goes down or something? Thanks! – Tikhon Jelvis Sep 25 '14 at 18:35
Unfortunately, that solution on saves the currently visible buffer, not *all* buffers. – b4hand Sep 25 '14 at 18:45
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@b4hand: Sorry, didn't realize that's what you wanted. Answer updated. – shosti Sep 25 '14 at 18:47
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@shosti By the way, thanks for finding that link to bbatsov's blog for me. I had actually found that solution before, but couldn't find it again. I was going to include that as one of the non-working solutions in my question. – b4hand Sep 25 '14 at 20:24
3

I like doing it this way to avoid trashing the minibuffer (pardon the formatting): ```(add-hook 'focus-out-hook (lambda () (flet ((message (format &rest args) nil)) (save-some-buffers t)))) ``` – Andreas Oct 16 '14 at 06:19

score 6 · Answer 2 · answered Jul 18 '15 at 10:01

6

There is focus-autosave-mode now. It's available via MELPA. Why not give it a chance to do the hacking for you‽

answered Jul 18 '15 at 10:01

Mark Karpov

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Hi, How it work? I've install it but it don't seems to work. – Asme Just Apr 08 '17 at 02:46
@AsmeJust, I don't use right now, try to ask on its issue tracker here: https://github.com/vifon/focus-autosave-mode.el/issues – Mark Karpov Apr 08 '17 at 21:50
Do you currently use an alternative or somethng like that? – Asme Just Apr 10 '17 at 07:10
No, I don't use anything like that right now. – Mark Karpov Apr 10 '17 at 12:03
But you still use Emacs, right? – Asme Just Apr 10 '17 at 19:03
Yes, but I save manually ;-) – Mark Karpov Apr 11 '17 at 16:01
See [this issue](https://github.com/Vifon/focus-autosave-mode.el/issues/4); you must use `M-x focus-autosave-mode` for now. – Jesse Glick Jun 22 '19 at 00:53

score 4 · Answer 3 · answered Nov 01 '14 at 13:48

4

(add-to-list 'focus-out-hook (lambda () (save-some-buffers t nil)))

This will save all unsaved buffers visiting file, on emacs 24.4

answered Nov 01 '14 at 13:48

Łukasz Gruner

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Don't use `add-to-list` on a hook, use `add-hook`. shosti's answer already contains the correct form of this snippet. – Gilles 'SO- stop being evil' Nov 10 '14 at 23:17

score 1 · Answer 4 · answered Jan 17 '15 at 01:06

For wanderers who stumble on this, I use this form:

(eval-when-compile (require 'cl-lib))
;; [...]
(add-hook 'focus-out-hook
  (lambda ()
    (cl-letf (((symbol-function 'message) #'format))
      (save-some-buffers t))))

The use of cl-letf keeps the annoying (No files need saving) messages from clogging your echo area.

How to auto-save buffers when Emacs loses focus?

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