I just wanted a script to rename my JPEG files that my camera created, so it would look better when I upload to flickr.

quick_rename.py

#!/usr/bin/env python
from os import rename, listdir

badprefix = "IMG"
fnames = listdir('.')
print(fnames)
for fname in fnames:
    if fname.startswith(badprefix):
        rename(fname, fname.replace(badprefix, 'long_exposure', 1))