Open terminal and run command:
$ sudo apt install brightnessctl
See a list of available devices on the machine:
$ brightnessctl -l
Turn on and set brightness by running command:
$ sudo brightnessctl –device=’smc::kbd_backlight’ s 25
Note:
– (device= see in the list above)
– (25 is the brightness, see in the list above)
Turn off light:
$ sudo brightnessctl –device=’smc::kbd_backlight’ s 0