title: Jenkins cannot start xvnc, because USER variable is not set
body: <p>Jenkins cannot start xvnc, because USER variable is not set. Here is the output that I get:</p>
  
  <pre><code>Starting xvnc
  [workspace] $ vncserver :10 -localhost -nolisten tcp
  vncserver: The USER environment variable is not set.
  </code></pre>
  
  <p>Where should the variable be set? What should it be set to?</p>