title: How do I use gems with Ubuntu?
body: <p>I recently upgraded to Ubuntu 9.04 and I have issues using gems.
  I installed Ruby, Rubygems and Rails using apt-get.
  The <code>rails</code> command does work.</p>
  
  <p>I then installed capistrano and other gems, such as heroku. 
  In order to do that, I used the command:</p>
  
  <pre><code>sudo gem install XXX
  </code></pre>
  
  <p>When I want to use the <code>cap</code> command it does not work:</p>
  
  <pre><code>bash: cap: command not found
  </code></pre>
  
  <p>It is the same with the other gem commands.</p>
  
  <p>Do I have something particular to do so that the gem commands work?</p>