How to set a permanent system brightness value for Ubuntu Linux

Reducing the brightness of your PC is a very good thing to do for several reasons, among which are the reduction of power (battery) consumption and the optical effects it can have on the eyes of a regular PC user. By default I set the brightness of all my systems to the lowest value possible (0). If you’re unlike me I know you’d prefer a brightness level between the maximum and minimum value, then this post is for you. So let’s get started.

After you set the brightness to your desired level open up a terminal and check what the brightness is set to that value by typing:

cat /sys/class/backlight/acpi_video0/brightness

Take the value shown from that command and

sudo gedit /etc/rc.local

In the file right above exit 0 add

echo your_value_here > /sys/class/backlight/acpi_video0/brightness

And then save the file.

This would permanently set the brightness to your value as rc.local is executed at each reboot.

If you don’t have the /sys/class/backlight/acpi_video0/brightness file, this would not be possible.

Using the GUI:

STEP 1. Go to SETTINGS>>BRIGHTNESS, and you would see a slider to adjust the brightness of your system to your desired value.


STEP 2. Then go to /sys/class/backlight/acpi_video0/ using the nautilus file explorer. Open the brightness file in a text editor, and copy the value of the brightness shown (mine is 0 because that’s what I set it to in the brightness setting earlier).


STEP 3. Go to /etc directory using the nautilus file explorer. Locate and open in a text editor the rc.local file.


STEP 4. In the file right above exit 0 add;

echo your_value_here > /sys/class/backlight/acpi_video0/brightness

and then save the file and reboot.


Happy Linux’NG!




Chief Editor/Founder at FossNaija
A Linux enthusiast with a focus on enriching the Nigeria Linux experience and keeping a keen eye on Ubuntu and other Foss related developments.
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