Ruby web scraping using mechanize and nokogiri gems

scraper.rb

# http://www.icicletech.com/blog/web-scraping-with-ruby-using-mechanize-and-nokogiri-gems
require "mechanize"

url = ARGV[0]
fp = File.new("wikilinks.txt", "w")

agent = Mechanize.new { |agent| agent.user_agent_alias = "Mac Safari" }

html = agent.get(url).body

html_doc = Nokogiri::HTML(html)

fp.write("References\n\n")

list = html_doc.xpath("//ol[@class='references']")
list.each { |i| fp.write(i.text + "\n") }

fp.write("Further Reading\n\n")

list = html_doc.xpath("//span[@class='citation']")
list.each { |i| fp.write(i.text + "\n") }

# code usage 
#$ ruby scraper.rb "http://en.wikipedia.org/wiki/Ruby_(programming_language)"