title: cannot load such file error in making app in ruby
body: <p>While making an application in <code>ruby on rails</code> I got the following error:  </p>
  
  <pre><code>ajeet@ajeetpc:~$ rails new first_app
  /home/ajeet/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- active_support (LoadError)
  from /home/ajeet/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
  from /usr/lib/ruby/vendor_ruby/railties/lib/rails_generator.rb:30:in `&lt;top (required)&gt;'
  from /home/ajeet/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
  from /home/ajeet/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
  from /usr/lib/ruby/vendor_ruby/railties/bin/rails:16:in `&lt;main&gt;'  
  </code></pre>