How to change the brightness of LCD display from command line in Ubuntu

Open your terminal and type this –

 $ xrandr -q | grep "connected" 

If you have multiple monitors, you will have output as –

VGA1 connected primary 1280x1024+1920+0 (normal left inverted right x axis y axis) 338mm x 270mm

HDMI1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 477mm x 268mm

here, VGA1 and HDMI1 are your display.

If you want to change the brightness of ‘VGA1’ type following

 $ xrandr --output LVDS1 --brightness 0.9

The brightness ranges from 0.0 to 1.0 and 1.0 means full black.