Use the Domai.nr API to see what domains are available.

domainr.rb

#!/usr/bin/env ruby

# A tiny script to check available domain names
# Uses the Domai.nr API http://domai.nr/api/docs/json
# A blatent ripoff of http://blog.jerodsanto.net/2012/11/a-domainr-cli-in-less-than-15-lines-of-ruby/

require 'rubygems'
require 'open-uri'

# `[sudo] install colorize json`
require 'colorize'
require 'json'

if ARGV.count != 1
  puts "Usage: ./domainr.rb [URL]".red
  exit
end

response = open("https://domai.nr/api/json/search?q=#{ ARGV.shift }").read

JSON.parse(response)["results"].each do |domain|
  domain_name = domain["domain"]
  case domain["availability"]
  when "available"
    puts domain_name.green
  when "maybe"
    puts domain_name.yellow
  when "taken"
    puts domain_name.red
  end
end