Ubuntu – Save screen brightness adjustment


My laptop is Thinkpad T400 and I am running 14.04. Every time I decrease the brightness of my screen, it will be back to 100% next time I reboot. How can I save the adjustment and apply it once for all? Thanks.

Best Answer

  • Assuming you are using the Intel 4500MHD - you need to set a value in /sys/class/backlight/intel_backlight/brightness to whatever is comfortable. A value is simply written here. First, find out what the max value is by running

    cat /sys/class/backlight/intel_backlight/max_brightness

    In my case it is 5273. After you reduce the brightness to something comfortable, check the value in /sys/class/backlight/intel_backlight/brightness by running

    cat /sys/class/backlight/intel_backlight/brightness

    In my case it was 2040. To set this value at boot time just type

    sudo echo "echo "2040 > /sys/class/backlight/intel_backlight/brightness" >> /etc/rc.local" so that this value is set at boot up.

    This is what I did on my Lenovo G510 using the Intel 4500 graphics. If you are running the AMD M82XT Graphics I'm afraid I can't help you.