import re blacklist = open("/home/mroz/workspace/coin-hoster/blacklist.txt",'r') domains = set() wildcards = set() domain_matcher = re.compile("[^/]+//(\*\.)?(?P[^/]+)") for line in blacklist: try: domains.add(domain_matcher.match(line).groupdict()['domain']) except: pass print(domains) hosts_file = map(lambda d: "0.0.0.0 " + d, domains) hosts_file = "\n".join(hosts_file) print(hosts_file)