title: How do you find out which packages installed has `apache2` as its dependency?
body: <p>When installing softwares like nginx on an Ubuntu 12.04 server, <code>apache2</code> appears to be installed as one of the dependency which is not what we need.</p>
  
  <p><strong>Question:</strong> How do you find out which packages installed has <code>apache2</code> as its dependency?</p>