code: def cmd_extract_hostname(infile, check, verbose, jsonout):
      
  
      if verbose:
          logging.basicConfig(level=logging.INFO, format='%(message)s')
  
      data = infile.read()
  
      result = extract_hostname(data)
  
      if check:
          logging.info('Checking against DNS...')
          for candidate in result:
              try:
                  socket.getaddrinfo(candidate, None)
              except socket.gaierror:
                  result.remove(candidate)
  
      if jsonout:
          print(json.dumps(result, indent=4))
      else:
          print('\n'.join(result))
docs: Extract hostnames from a file or stdin.
  
      Example:
  
      \b
      $ cat /var/log/some.log | habu.extract.hostname
      www.google.com
      ibm.com
      fileserver.redhat.com