backlightx

#!/bin/bash
# Dependencies: coreutils sed grep
# Add `chmod 777 /sys/class/backlight/acpi_video0/brightness` to your /etc/rc.local so this script will work without root access (sudo)

where="/sys/class/backlight/acpi_video0"
max=`cat $where/max_brightness`
current=`cat $where/actual_brightness`

if [ "$1" == "--set" ];then
    if [ ! "`echo $2 | sed 's/[a-Z]//g'`" == "$2" ];then
        `dirname $0`/`basename $0`
        exit
    elif [ 0`echo "$2" | sed 's/.//' | grep "^[0-9]*$"` -gt 0 ] && [ ! "`echo \"$2\" | grep \"^[0-9]*$\"`" == "$2" ];then
        if [ "`echo ${2:0:1}`" == "+" ];then
            X=$(($current+`echo ${2:1}`))
        elif [ "`echo ${2:0:1}`" == "-" ];then
            X=$(($current-`echo ${2:1}`))
        else
            echo "${2:0:1} is not a +/-"
            exit
        fi
        if [ $X -gt $max ];then
            echo $max > $where/brightness
        elif [ $X -lt 0 ];then
            echo 0 > $where/brightness
        else
            echo $X > $where/brightness
        fi
        exit
    fi
    if [ ! "`echo \"$2\" | grep \"^[0-9]*$\"`" == "$2" ];then
        echo "$2 is not a Intiger"
    elif [ "$2" -lt $(($max+1)) ] && [ "$2" -gt -1 ];then
        echo $2 > $where/brightness
    elif [ "$2" -lt 0 ];then
        echo 0 > $where/brightness
    else
        echo $max > $where/brightness
    fi
elif [ "$1" == "--get" ];then
    if [ "$2" == "current" ];then
        echo $current
    elif [ "$2" == "max" ];then
        echo $max
    else
        echo -e "Current: $current\nMaximum: $max"
    fi
else
    echo -e "Usage:\n\t`basename $0` --set Int | +Int | -Int"
    echo -e "\t`basename $0` --get current | max | NULL"
fi
exit