get_slac_known_hosts.py

#!/usr/bin/env python
import os
from shutil import copyfileobj
try:
    from urllib.request import urlopen
except ImportError:
    from urllib2 import urlopen

SLAC_KNOWN_HOSTS_URL = 'ftp://ftp.slac.stanford.edu/admin/known_hosts'
KNOWN_HOSTS_PATH = os.path.join(os.getenv('HOME'), '.ssh', 'known_hosts')

my_hosts = []
if os.path.isfile(KNOWN_HOSTS_PATH):
    with open(KNOWN_HOSTS_PATH, 'r') as f:
        for l in f:
            l = l.strip()
            if l and l[0] != '#' and 'slac.stanford.edu' not in l:
                my_hosts.append(l)
    os.rename(KNOWN_HOSTS_PATH, KNOWN_HOSTS_PATH + '.bak')

with open(KNOWN_HOSTS_PATH, 'wb') as f:
    copyfileobj(urlopen(SLAC_KNOWN_HOSTS_URL), f)

if my_hosts:
    with open(KNOWN_HOSTS_PATH, 'a') as f:
        f.write('\n#below are non-slac hosts\n')
        f.write('\n'.join(my_hosts))
        f.write('\n')