xrandrexport DISPLAY=:0
alton@alton:~$ export DISPLAY=:0xrandr
Screen 0: minimum 8 x 8, current 4480 x 2160, maximum 16384 x 16384
HDMI-0 connected primary 640x350+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   640x350       85.08*+
DP-0 connected 3840x2160+640+0 (normal left inverted right x axis y axis) 620mm x 340mm
   3840x2160     60.01*+  29.99  
   2560x1440     59.96  
   1920x2160     60.00  
   1920x1080     60.00    59.95    50.00  
   1680x1050     59.96  
   1440x900      59.89  
   1280x1024     75.03    60.00  
   1280x960      60.00  
   1280x720      60.00    59.94    50.00  
   1024x768      75.03    70.07    60.01  
   832x624       75.05  
   800x600       75.00    72.19    60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   720x400       70.04  
   640x480       75.00    72.81    67.06    59.94  
alton@alton:~$