- Execute 
x11vnc -storepasswd YOURPASSWORD /etc/x11vnc.passto store your password. - Edit the xsession file, which can be found in the UR robot controller at 
../root/xsession. - Add 
/usr/bin/x11vnc -xkb -noxrecord -noxfixes -noxdamage -display :0 -rfbauth /etc/x11vnc.pass -rfbport 5900 -forever -auth root -bg -o /var/log/x11vnc.logat the beginning of this file (after the#!/bin/bashline). This will start a x11 VNC server with all the necessary options to make it run in the background. 
More information at: https://dof.robotiq.com/discussion/553/remote-control-of-universal-robots-user-interface