I have a large library of PDF documents (papers, lectures, handouts) that I want to be able to quickly navigate through. For that I need thumbnails.

At the same time however, I see that the ~/.thumbnails folder is piling up with thumbs I don't really need. Deleting thumbnail junk without removing the important thumbs is impossible. If I were to delete them, I'd have to go to each and every folder with important PDF documents and let the thumbnail cache regenerate.

I would love to able to automate this process. Is there any way I can tell nautilus to pre-cache the thumbs for a set of given directories?

Note: I did find a set of bash scripts that appear to do this for pictures and videos, but not for any other documents. Maybe someone more experienced with scripting might be able to adjust these for PDF documents or at least point me in the right direction on what I'd have to modify for this to work with PDF documents as well.

Edit: Unfortunately neither of the answers provided below work. See my comments below for more information. Is there anyone who can solve this?