title: Can't gem install rails
body: <p>This question has been asked many times before but it seems everyone else is trying it on OS X. I'm on Ubuntu.</p>
  
  <p>Here's what I get when I try to <code>sudo gem install rails</code>:</p>
  
  <pre><code>$ sudo gem install rails
  Successfully installed rails-3.0.3
  1 gem installed
  Installing ri documentation for rails-3.0.3...
  file 'lib' not found
  Installing RDoc documentation for rails-3.0.3...
  file 'lib' not found
  </code></pre>
  
  <p>What do I have to do to get it to work?</p>
  
  <p>I know it's not working because of this:</p>
  
  <pre><code>$ rails
  The program 'rails' is currently not installed.  To run 'rails' please ask your administrator to install the package 'rails'
  </code></pre>