And here is another nice little script for a problem I have.
I use awesome as window manager, and in my rc.lua file i've setup some nice tweaks so that my wallpaper changes every 5 minutes to a new one randomly chosen from /usr/share/wallpapers/.
(done by: awsetbg -r '/usr/share/wallpapers' on a crontab.)
But I have a lot of wallpapers, now my collection has over 1500. But awsetbg/feh has some problems with filenames and so once in a while I got this annoying message from feh, and I hate annoying messages.
So I fixed it. With a nice little bash script. It renames all the jpg files to a number. Instead of having Beach.jpg, Clouds.jpg and Tux.jpeg you will then have 1.jpg, 2.jpg and 3.jpg.
Much easier for feh :P. So enough talking, here is the script:

If you get an error like: mv: cannot stat `*.jpeg': No such file or directory then it means that there are no jpeg files to rename.

And remember, all on your own risk ;).