ref: 4fedd7d4fe1c3b509c84d12e971aaa466b8b4b3d
dir: /sys/src/cmd/bitsy/light.rc/
#!/bin/rc
#master file is /sys/src/cmd/bitsy/light.rc
switch($1){
case on
echo -n 2 1 0x80 > /dev/backlight
case off
echo -n 2 0 0x80 > /dev/backlight
case auto
echo -n 1 1 0x80 > /dev/backlight
case *
echo -n 2 1 $1 > /dev/backlight
}