function for cleaning org-attach directories

[Eric Abrahamsen <eric@ericabrahamsen.net>]

I use org-attach a lot, and if you're not careful you can get a "data/"
directory of many gigabytes. Not a problem, until you want to rsync it
and it takes all day...

I wrote this to clean my attach directories. I'm not sure how portable
it is (and I'm really not pleased with the (concat attach-dir "/" d "/"
d+)), but I'm posting it to see if it's useful to anyone.

Comments/improvements welcome! If the final product is desirable, I can
work it up as a patch.

Eric

(defun org-attach-clean-dirs (&optional attach-dir clean-archived)
  (interactive)
  (let ((attach-dir
	 (if attach-dir
	     (file-name-as-directory attach-dir)
	   (concat (file-name-as-directory org-directory)
		   org-attach-directory)))
	(valid-dir-re "\\`[0-9a-z-]+\\'")
	(org-id-search-archives (if clean-archived nil org-id-search-archives)))
    (dolist (d (directory-files attach-dir nil valid-dir-re))
      (dolist (d+ (directory-files
		   (concat attach-dir d) nil valid-dir-re))
	(let ((id (format "%s%s" d d+))
	      (full-path (concat attach-dir "/" d "/" d+)))
	  (unless (org-id-find id)
	    (shell-command (format "rm -fr %s" full-path))))))))