Filter only free wifi spots

#!/bin/env ruby

# Usage: ruby wifi.rb wifi.kml.xml > free_wifi.kml.xml

require 'rubygems'
require 'pp'
require 'nokogiri'

xml_doc = Nokogiri::XML(File.open(ARGV.first))

xml_doc.css('Placemark').each do |placemark|
  description = placemark.css('description').first.inner_html
  placemark.remove unless description =~ /Security: None/
end

puts xml_doc.to_s