decrease brightness level:
xdotool key XF86MonBrightnessDown
increase brightness level:
xdotool key XF86MonBrightnessUp
Turn off the monitor:
sleep 2; xset dpms force off
In case any keyboard or mouse event happened the monitor will turn on.
Alternatively we can make the brighness 0
xrandr --output <DISPLAY_NAME> --brightness 0
To make switch back the brightness:
xrandr --output <DISPLAY_NAME> --brightness 1
https://askubuntu.com/questions/253818/manually-turn-off-monitor
Fix Fn keys for changing brightness:
https://askubuntu.com/questions/866437/function-keys-do-not-work-brightness-sound-ubuntu-16-04
Change screen brightness:
https://askubuntu.com/questions/62249/how-do-you-change-brightness-color-and-sharpness-from-command-line
https://askubuntu.com/questions/773155/artificially-increase-maximum-screen-brightness
.... LVDS-1 connected primary 1366x768+0+0 ........
- xrandr --output LVDS-1 --brightness 1.2