Is there a program that can adjust display brightness according to battery percentage?

Question

When i work in Kubuntu, KDE power management has a section that lets you automatically adjust display brightness according to battery percentage.

I want to know if there is a tool like that in Ubuntu 12.04?

thanks.

Answer 1

Here is a script that checks the remaining battery every minute and adjusts the brightness accordingly. However, once the battery is below 30%, it sets the brightness to 0.

#! /bin/bash

while true
do
    chargingState=$(grep "charging state:" /proc/acpi/battery/BAT0/state | awk '{print $3}')
    batteryFull=$(grep "design capacity:" /proc/acpi/battery/BAT0/info | awk '{print $3}')
    batteryRemaining=$(grep "remaining capacity:" /proc/acpi/battery/BAT0/state | awk '{print $3}')

    batteryPercentage=$((batteryRemaining * 100/batteryFull))

    if [ $chargingState == "discharging" ] 
    then
        if ((batteryPercentage > 30))
        then
            xbacklight -set $batteryPercentage
        else
            xbacklight -set 0
        fi
    fi

    sleep 60
done

• Copy this text to some file, say batteryBrightness.sh

• Make your script executable.

chmod +x /path/to/script

• Open Startup Applications, from the cog menu present at the upper right corner.

• Click on Add.

• Fill in all the details and click Add.

• Logout and login back to check.

Note:

• Change the name of the script to whatever you have named it, wherever required.
• You'd need the xbacklight package installed, if you don't have it installed, install it by running the following command:

    sudo apt-get install xbacklight