title: cannot connect to x server : running gui without displaying
body: <p>I have a ubuntu server in which the requests are to be processed by a complex application in the backend involving a gui. The gui is of no use to me and only the final results are used and stored.
  <br>
  I get this error when launching the app <b>cannot connect to X server</b><br><br>
  <b>How do i run a gui application on my linux instance without having me to actually see it</b></p>