find equivalent domain names for the Stack Exchange network of sites for LastPass account settings

equivalentdomains_stackexchange.rb

#!/usr/bin/env ruby
#
# [this lives here now](https://github.com/qrkourier/stackdom/blob/master/bin/stackdom.rb)

#
# slurp some XML over HTTP and parse to find equivalent domain
# names for the Stack Exchange network of sites
#
# shell $ gem install xml-simple domainatrix
#
# tested with >= Ruby 1.9.2
#

# stdlib
require 'net/http'
# gems
require 'rubygems'
require 'xmlsimple'
require 'domainatrix'

equivalent_domains = []

# get the list of SE sites from their XML feed
feed = 'http://stackexchange.com/feeds/sites'
doc = Net::HTTP.get_response(URI.parse(feed)).body

# parse the document to compose a data object
data = XmlSimple.xml_in(doc)

# iterate over each id in the entry array and join the top-level and
# registrar-assigned domain names, discarding the subdomain and path parts, and
# push the result into an array
data['entry'].each do |entry|
  url = Domainatrix.parse(entry["id"][0])
  equivalent_domains << url.domain + "." + url.public_suffix
end

# print a comma-separated list of unique domain names
puts equivalent_domains.uniq * ","