A simple shell script for Ubuntu to adjust screen brightness

adjust_brightness.sh

#!/bin/sh

# Usage:
# sh /path/to/adjust_brightness.sh [up|down|<an integer between 0-100>]

# Requires the change of ownership of the baclight file to the user

# Run this once to change the ownership:
# "sudo chown $(whoami):$(whoami) /sys/class/backlight/intel_backlight/brightness"

# You can then assign keyboard shortcuts to adjust brightness. For example,
# "sh /path/to/adjust_brightness.sh up"   -> "CTRL + B"
# "sh /path/to/adjust_brightness.sh down" -> "CTRL + N"

command=$1
brightness="/sys/class/backlight/intel_backlight/brightness"
max_brightness="/sys/class/backlight/intel_backlight/max_brightness"

if [ "$command" = "up" ]; then
    echo $(( $(cat $backlight) + $(cat $max_brightness) / 10 )) | tee $backlight
elif [ "$command" = "down" ]; then
    echo $(( $(cat $backlight) - $(cat $max_brightness) / 10 )) | tee $backlight
else
    echo $(( $1 * $(cat $max_brightness) / 100)) | tee $backlight
fi

best script ever, i have been using it for years now :) many thx