#!/bin/bash

DEVICE=/sys/devices/platform/thinkpad_acpi/leds/tpacpi\:\:kbd_backlight/brightness
CUR_VAL=$(cat $DEVICE)

case $CUR_VAL in
    0)
       echo "1" > $DEVICE
      ;;
    1)
       echo "2" > $DEVICE
       ;;
    2)
       echo "0" > $DEVICE
       ;;
esac