#!/usr/bin/env ruby
require 'open-uri'
LOOKUP_URL = 'http://toolbar.netcraft.com/site_report?url=%s'
MATCH_RE = /<td><b>IP address<\/b><\/td><td.*?>([\d\.]+)<\/td>/
host = ARGV.select { |arg| arg !~ /^\-/ }.first
open(LOOKUP_URL % host).read =~ MATCH_RE ?
puts("#{host} 对应的IP地址为: #{$1}") :
puts('主机解析失败!')