python script to set dns servers and search domains in os x

gistfile1.txt

#!/usr/bin/env python

'''
This script sets dns servers and search domains for all 
Ethernet adapters and Wi-fi interfaces.

Requirements
------------
+ OS X 10.9.x
+ python 2.7 
'''

##############################################################################
# Copyright 2014 Joseph Chilcote
# 
#  Licensed under the Apache License, Version 2.0 (the "License"); you may not
#  use this file except in compliance with the License. You may obtain a copy
#  of the License at  
# 
#       http://www.apache.org/licenses/LICENSE-2.0
# 
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#  License for the specific language governing permissions and limitations
#  under the License.
##############################################################################

import os, sys, subprocess
from SystemConfiguration import *

# Edit these lists
#-----------------#
search_domains = []
dns_servers = []
#-----------------#

prefs = SCPreferencesCreate(None, 'foo', None)
network_services = SCNetworkServiceCopyAll(prefs)

def usage():
    print 'Usage: ./pydns.py'

def get_networkservicelist():
    '''Returns a list of network interfaces'''
    l = []
    for service in network_services:
        l.append(SCNetworkServiceGetName(service))
    return l

def set_config(l, argument, category):
    '''Sets search domains and dns servers'''
    for i in l:
        if 'Ethernet' in i or 'Wi-Fi' in i:
            cmd = '/usr/sbin/networksetup %s "%s" %s' % (argument, 
                                    i, ' '.join(category))
            task = subprocess.Popen(cmd, stdout=subprocess.PIPE, 
                                    stderr=subprocess.PIPE, shell=True)
            (out, err) = task.communicate()
            if err:
                print 'Unable to set %s: %s' % (category, err)
                sys.exit(1)

def main():
    if len(sys.argv) == 1:
        service_list = get_networkservicelist()    
        set_config(service_list, '-setsearchdomains', search_domains)
        set_config(service_list, '-setdnsservers', dns_servers)
    else:
        usage()
        sys.exit(0)

if __name__ == "__main__":
    main()