findall and multiline mode makes it even easier, at the cost of loading whole file into memory though, for that reason your alternaive is probably better i

findall and multiline mode makes it even easier, at the cost of loading whole file into memory though, for that reason your alternaive is probably better import re wordlist = open("/usr/share/dict/words").read() for word in re.findall(r"^[a-foi]{6}$", wordlist, re.IGNORECASE | re.MULTILINE): hexword = word.upper().replace("O", "0").replace("I", "1") print(f"#{hexword}")