Re: How to do a massive unfill paragraph operation over several hundred files?

[Noam Postavsky]

On Tue, 2 Oct 2018 at 08:11, Gerald Wildgruber <wildgruber@tu-berlin.de> wrote:

> (dolist (f argv)
>   (find-file f)
>   (mark-whole-buffer)
>   (unfill-paragraph t)
>   (org-forward-paragraph)
>   (save-buffer))
>
> ------------------------------------------------------------
>
> I call this from a terminal like so:
>
> emacs -Q --batch --script unfill.el FILE.org
>
> Unfortunately, nothing happens; I get two "Mark set" messages in the 
> terminal, but the file itself remains untouched. It isn't edited at all, same 
> timestamp etc.

I think the problem is that find-file only makes sense for interactive
functions, because it switches the displayed buffer (which takes
effect after the current command finishes), but doesn't actually set
the current buffer (i.e., no immediate change).

So you should have

    (with-current-buffer (find-file-noselect f)
      (mark-whole-buffer)
      ...)

By the way, I don't see the benefit of invoking Emacs in batch mode
here, especially since this sounds like a one-off transformation. Just
put the expression which does the work into *scratch* and evaluate.
Something like this:

    (let ((fill-column most-positive-fixnum))
      (dolist (f (directory-files-recursively
                  "dir/with/my/files/" (rx (or ".tex" ".org") eos)))
        (with-current-buffer (find-file-noselect f)
          (fill-region (point-min) (point-max)) ; Unfill, per `fill-column'
          (save-buffer))))

(of course replace the (directory-files-recursively...) thing with
(list "test-file.org") first to make sure it works right.)