title: rubygems error installing rails
body: <p>I get this error when trying to install ruby gems on my amazon instance. Can anyone explain?</p>
  
  <pre><code>ubuntu@ip-myinstance:~$ sudo apt-get install rubygems
  
  Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Package rubygems is not available, but is referred to by another package.
  This may mean that the package is missing, has been obsoleted, or
  is only available from another source
  However the following packages replace it:
    ruby
  
  E: Package 'rubygems' has no installation candidate
  </code></pre>
  
  <p>I didn't understand that message. I was following directions from <a href="http://www.frontcoded.com/rails-on-amazon-ec2-ubuntu.html" rel="nofollow">http://www.frontcoded.com/rails-on-amazon-ec2-ubuntu.html</a> which says to do that. Also I tried</p>
  
  <pre><code>which rubygems
  </code></pre>
  
  <p>And that came out blank. If possible I would like to take down this question to stop the negative votes. Thank you.</p>