title: Ubuntu: "Could not find rails locally or in a repository"
body: <p>I'm following <a href="https://help.ubuntu.com/community/RubyOnRails" rel="nofollow noreferrer">these instructions</a> to set up Ruby on Rails on my Ubuntu machine. For now at least, I'm planning to use Mongrel.</p>
  
  <p>When I get to this step:</p>
  
  <pre><code>sudo gem install rails
  </code></pre>
  
  <p>...I get this message:</p>
  
  <pre>
  Bulk updating Gem source index for: http://gems.rubyforge.org/
  ERROR: could not find rails locally or in a repository
  </pre>
  
  <p>What should I do next?</p>