What am I doing wrong here? f1 = open('Drum.d', 'r') lines = f1.readlines() f1.close() f2 = open('Drum.w', 'w') for line in lines: #~ print(patt.sub(replacer, line)) # This replaces the parens correctly f2.write(patt.sub(replacer, line)) # But the file ends up being the same.. f2.close()