get_hostnames.py

#!/usr/bin/env python

import requests
import sys
import re

domain = sys.argv[1]

r = requests.get('https://crt.sh/?q=%.'+domain)
hostnames = re.findall(r'<TD>(\S+\.'+domain+r')',r.text)
uniq_hostnames = set(hostnames)
for host in uniq_hostnames:
    print(host)