get_sucatalog.py

#!/usr/bin/python

import objc
from Cocoa import NSObject, NSURL, NSBundle

# disturbing hack warning!
# this works around an issue with App Transport Security on 10.11
bundle = NSBundle.mainBundle()
info = bundle.localizedInfoDictionary() or bundle.infoDictionary()
info['NSAppTransportSecurity'] = {'NSAllowsArbitraryLoads': True}

# load private framework
framework="/System/Library/PrivateFrameworks/SoftwareUpdate.framework"
objc.loadBundle("SoftwareUpdate", globals(), framework)

# Instantaite a SUCatalogFetch object and pull the catalogURL
catalog_fetch = SUCatalogFetch.alloc().init()
print(catalog_fetch.finalURL())