Get all files in a directory with a specific file extension

file_list.py

import os

def list_files(source, extension):
    matches = []
    for root, dirnames, filenames in os.walk(source):
        for filename in filenames:
            if filename.endswith((extension)):
                print filename

# Ex: Get all files in the directory docs with the extension PDF
# Can be easily written to a text file by running at the command line: python file_list.py > file_list.txt
list_files('docs', '.pdf')