Python case insensitive file name?

I need to load a file given it's name, but the name I get is case insensitive. "A.txt" could actually be "a.txt". How to do this the fast way (not generate all possible names and try each)?

You could list the directory the file's in (os.listdir), and see if there are matches for your filename. The matching can be done by lower-casing both filenames and comparing.