Question

Suppose I’m entering a bunch of text in a buffer that’s not visiting a file (it could be a new org2blog post, or just some scratch buffer). Is it possible to autosave it somewhere in case disaster strikes and Emacs dies?

Answer 1

auto-save-mode actually works with non-file buffers. It just doesn’t get enabled by default — that usually happens in (after-find-file).

So: M-x auto-save-mode RET

By default the auto-save file will be written to the default-directory of the buffer (or /var/tmp or ~/, depending on write permissions; see C-hv buffer-auto-save-file-name RET) which may be a little awkward to figure out after a crash, so setting that to something standard is probably a good idea.

The following would ensure that these auto-save files are written to your home directory (or M-x customize-variable RET my-non-file-buffer-auto-save-dir RET), if auto-save-mode is invoked interactively. That will hopefully avoid this conflicting with any other uses of auto-save-mode with non-file buffers (the code mentions Mail mode, for instance).

(defcustom my-non-file-buffer-auto-save-dir (expand-file-name "~/")
  "Directory in which to store auto-save files for non-file buffers,
when `auto-save-mode' is invoked manually.")

(defadvice auto-save-mode (around use-my-non-file-buffer-auto-save-dir)
  "Use a standard location for auto-save files for non-file buffers"
  (if (and (not buffer-file-name)
           (called-interactively-p 'any))
      (let ((default-directory my-non-file-buffer-auto-save-dir))
        ad-do-it)
    ad-do-it))
(ad-activate 'auto-save-mode)