title: git installation error missing installation candidate
body: <p>I tried installing <code>git</code> on Ubuntu 12.10 using the command <code>sudo apt-get install git</code>. But I am getting error message like this:</p>
  
  <pre><code>Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Package git 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
  
  E: Package 'git' has no installation candidate
  </code></pre>
  
  <p>What am I supposed to do further?</p>