title: command not found when using sudo ulimit
body: <p>I was using ubuntu 12.04 ,on which I run ulimit -n ,it is showing 1024,
  I want to increase my open file limit from 1024 to 65535,so I tried the following command:</p>
  
  <pre><code>sudo ulimit -n 65535
  </code></pre>
  
  <p>but i get the following error:</p>
  
  <pre><code>sudo: ulimit: command not found
  </code></pre>
  
  <p>How to increase the file limit from 1024 to 65535? Any help will be appreciated.</p>