rviz: cannot connect to X server
[rviz-3] process has died [pid 2860, exit code 1, cmd /opt/ros/indigo/lib/rviz/rviz -d /root/catkin_ws/src/didi_challenge_ros/launch/display.rviz __name:=rviz __log:=/root/.ros/log/9709d3a0-11f5-11e7-95d8-0242ac110002/rviz-3.log].
log file: /root/.ros/log/9709d3a0-11f5-11e7-95d8-0242ac110002/rviz-3*.log