Backlight
$ cd /sys/class/backlight/backlight
$ echo X > brightness
While X is a number between 0 and 7:
0 - backlight off
...
7 - max brightness
$ cd /sys/class/backlight/backlight
$ echo X > brightness
While X is a number between 0 and 7:
0 - backlight off
...
7 - max brightness