htmlpar.rb

require 'open-uri'
require 'open_uri_redirections'
puts "Enter URL to parse HTML: "
url = gets.chomp
puts "Enter tag to parse from: "
tag = gets.chomp
response = open(url,:allow_redirections => :safe).read
title1 = response.index(tag) 
title2 = response.index(tag.insert(1,'/')) -1
result = response[(title1 + tag.length - 1)..title2]
print result

ERROR: /usr/local/rvm/rubies/ruby-2.1.4/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- open_uri_redirections (LoadError)                                                                                                                                       
        from /usr/local/rvm/rubies/ruby-2.1.4/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'                              
        from /home/ubuntu/workspace/htmlparse.rb:2:in `<main>'