The brightness of my laptop is reset to max on every restart. I tried the solution provided at this website but had no luck.

This command

cat /sys/class/backlight/acpi_video0/max_brightness


cat: /sys/class/backlight/acpi_video0/max_brightness: No such file or directory

Then I found that I don't have a folder named acpi_video0, but a folder called intel_backlight:

screenshot of /sys/class/backlight/intel_backlight in Nautilus

Every time I increase or decrease the brightness using the brightness control keys, the values in brightness and actual_brightness get updated.

Is there any method I could follow to set the brightness to a fixed value on every boot and vary it as and when I need it using the brightness control keys?


20 Answers 20


You could try adding a line to /etc/rc.local that will set the desired brightness level. To edit the file, run

sudo -H gedit /etc/rc.local

and add the following

echo X > /sys/class/backlight/intel_backlight/brightness

so that the end result looks like this

#!/bin/sh -e
# rc.local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# bits.
# By default this script does nothing.

echo X > /sys/class/backlight/intel_backlight/brightness

exit 0

Substitute X by the desired brightness level.

In case /etc/rc.local doesn't exist, as is the case with new Ubuntu releases, you'll need to create it, and make eecutable with the following commands:

printf '%s\n' '#!/bin/bash' 'exit 0' | sudo tee -a /etc/rc.local
sudo chmod +x /etc/rc.local

PS: Alternatively, there may be /sys/class/backlight/acpi_video0/brightness instead of the above. Brightness levels vary wildly, and may range from 0 to 10 or to 1000. To find the maximum value, try

cat /sys/class/backlight/acpi_video0/max_brightness
cat /sys/class/backlight/intel_backlight/max_brightness
  • 5
    Probably. Different computers will have different entries in /sys/class/backlight/, and figuring out the right location, basically, solved the problem. Commented Jun 16, 2012 at 13:28
  • 9
    X is the desired brightness level on a scale of 0-10 or 0-100?
    – Rakib
    Commented Oct 14, 2012 at 15:37
  • 9
    Depends. Different models have different scales. I only had to deal with 0-7. Check the current level by running cat /sys/class/backlight/intel_backlight/brightness. It's a good idea to experiment with several values, if you aren't sure which one is right. Commented Oct 14, 2012 at 23:33
  • 2
    Doesn't work for me in 12.04?
    – user24668
    Commented Jul 1, 2013 at 18:11
  • 1
    mine scales from 0-937
    – osa
    Commented Jun 3, 2014 at 19:01

I converted my small script for saving and restoring backlight (brightness) level to Ubuntu package. It is located in my PPA and named sysvinit-backlight.
It contains sysvinit init-script, placed in /etc/init.d/sysvinit-backlight.
It is compatible with Ubuntu 12.04 LTS and 14.04 LTS.

For newer versions of Ubuntu my PPA is not needed as they use builtin systemd-backlight service.

You can install my script with the following commands:

sudo add-apt-repository ppa:nrbrtx/sysvinit-backlight
sudo apt-get update
sudo apt-get install sysvinit-backlight

You can remove it by

sudo apt-get purge sysvinit-backlight

Please note: if you have installed the previous version of my script, please remove it by

sudo rm /etc/rc?.d/?25backlight /etc/init.d/brightness /etc/rc?.d/?25brightness

The script functionality is:

  • save backlight (brightness) levels of all video adapters and keyboard on reboot and shutdown (runlevel 0 and 6)
  • load backlight (brightness) levels for all video adapters and keyboard on boot (runlevels S, 1, 2, 3, 4 and 5)

The script options are:

  • sudo service sysvinit-backlight status (show current brightness levels and saved in files values)
  • sudo service sysvinit-backlight start (set saved levels from files)
  • sudo service sysvinit-backlight stop (save current levels to files)

You can contact me here or on launchpad.

  • 4
    I reported a bug about including such initscript to default Ubuntu installation - bugs.launchpad.net/bugs/1270579.
    – N0rbert
    Commented Jan 19, 2014 at 13:41
  • Works perfectly for my Dell laptop on Ubuntu 14.04. As the laptop has a on-chip graphics adapter plus another adapter (that is used by default), I just had to change /acpi_video0/ to /acpi_video1/.
    – BurninLeo
    Commented Sep 19, 2014 at 16:03
  • This script is practical. Worked for me too on my lenovo flex 2. I think it should also be included in default Ubuntu or Linux mint installs. Commented Oct 25, 2015 at 3:16
  • This script no longer works in 16.04+ Commented Jun 21, 2017 at 3:33
  • answerSeeker This script should not work in 16.04+, it is unneeded here. Use standard [email protected].
    – N0rbert
    Commented Jun 24, 2017 at 15:48

Easiest way:

  1. Open a terminal window.

  2. Type in the following command then hit Enter after it.

    sudo apt-get install xbacklight
  3. Open the Startup Applications Preferences menu.

  4. Click the Add button and add the following information:

    • Name: Brightness
    • Command: xbacklight -set 60
  5. Replace 60 with whatever brightness level you prefer.

Source: Set Startup Display Brightness

  • thank you, it works perfectly for me. Ubuntu 14.04 on Acer 5732Z
    – Sushiant
    Commented Feb 2, 2015 at 2:52
  • 1
    It doesn't work on ubuntu 16.10
    – Searene
    Commented Dec 5, 2016 at 12:19
  • 2
    Does not work ubuntu 18.04 Commented Sep 22, 2018 at 5:57
  • Worked for me, Ubuntu 18.04 - NVIDIA Drivers installed (430.26) - considering that I was already able to edit brightness manually with Fn keys in laptop - I just needed to set a default value for them on startup Commented Jun 16, 2019 at 21:05
  • Doesn't work in 20.04 (hp envy)
    – fikr4n
    Commented Jun 9, 2021 at 5:28

Before try workarounds in rc.local, it is worth to try the following:

  • adding simple: quiet splash acpi_backlight=vendor to grub looks to be enough on my configuration.

    1. sudo gedit /etc/default/grub
    2. replace
      GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
      GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"

    3. sudo update-grub and reboot.

worked on:

  • Ubuntu 12.04 LTS (Asus U31SD-XH51 )
  • Ubuntu 14.04 LTS (Dell 14z)
  • Ubuntu 14.04 LTS (Lenovo g500, remove nomodeset and it will work fine)
  • 2
    more details ubuntuka.com/ubuntu-command-line-tricks-set-1: sudo gedit /etc/default/grub and replace GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"
    – tbicr
    Commented Jun 7, 2014 at 5:40
  • Unfortunately it breaks the brightness adjustment from the fn keys on 14.04.
    – NoBugs
    Commented Jun 29, 2014 at 2:20
  • works for me as well on 14.04 ... fn keys for brightess were not working also previously so ... Commented Jul 3, 2014 at 9:08
  • This seemed to work fine - for one reboot (even the Fn keys on my Dell laptop worked). But after another reboot the Fn keys brightness did not affect the screen any more. And worse: The wakeup after standby (suspend to RAM) stopped working with a dark screen.
    – BurninLeo
    Commented Sep 19, 2014 at 15:37
  • GRUB_CMDLINE_LINUX_DEFAULT="nomodeset acpi_backlight=vendor" works for me
    – Sumit
    Commented Sep 1, 2021 at 9:25

Install xbacklight (sudo apt-get install xbacklight) and add

xbacklight -set x

(where 'x' = 0 to 100 desired brightness) to the startup applications via dashboard. For example:

xbacklight -set 50
  • 2
    And how does this fix the 'reset on reboot' issue in the question?
    – gertvdijk
    Commented Oct 16, 2013 at 0:55
  • 1
    this adjust the brightness just for current session. if you restart then the brightness is reset. Commented Feb 3, 2014 at 18:47
  • 2
    Not if you add it to startup applications. And yes this is a work-around, not a full resolution.
    – Brandex
    Commented Feb 5, 2014 at 19:23
  • Brightness is reset like other solutions but Addding this to Startup Applications Preferences works for me. Commented Jul 2, 2020 at 1:40

I modified the code in /etc/rc.local like this:

Get maximum brightness:

$ cat /sys/class/backlight/intel_backlight/max_brightness

Run gksudo gedit /etc/rc.local and edit the file:

#!/bin/sh -e
# rc.local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# bits.
# By default this script does nothing.

echo 4882 > /sys/class/backlight/intel_backlight/brightness
exit 0

That worked for me.

  • 4
    I don't get it, what would that do? It's already maximum by default.
    – JMCF125
    Commented Aug 29, 2013 at 22:49
  • You should use cat /sys/class/backlight/intel_backlight/brightness 168 instead. I use 168 because my eyes don't hurt at that brightness level Commented Sep 18, 2015 at 16:15

The solutions offered here are somehow system-dependent.

A good design is to have one place that takes care of system-dependent details and provide a unified interface. It seems that currently the kernel does not offer such an easy interface through /sys. At X level, though, there is one : xbacklight.

A solution based on xbacklight is offered on How do I set default display brightness?, for 11.10 and up.

Plus, it should not have the problems reported on some areas (e.g. http://ubuntuguide.net/how-to-save-screen-brightness-settings-in-ubuntu-12-04-laptop ) that wrong brightness comes back in some situations.


How to debug backlighting:


Unfortunately just adding acpi_backlight=vendor doesn't seem to save the default value for my 12.04 Lenovo G575.


My laptop is Compaq Presario CQ62 111TU, installed Ubuntu 12.04. The Following steps worked for me well.

  1. Adjust the screen brightness to your preferred level.
  2. Open Terminal and enter cat /sys/class/backlight/intel_backlight/actual_brightness and take down the value.
  3. Enter cat /sys/class/backlight/acpi_video0/actual_brightness and take down the value.
  4. Enter sudo gedit /etc/rc.local and add these before the last line exit 0 in gedit:

    echo ValueFromStep2 > /sys/class/backlight/intel_backlight/brightness
    echo ValueFromStep3 > /sys/class/backlight/acpi_video0/brightness

save and enjoy.

My settings are shown below

#!/bin/sh -e
# rc.local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# bits.
# By default this script does nothing.

echo 478 > /sys/class/backlight/intel_backlight/brightness
echo 0 > /sys/class/backlight/acpi_video0/brightness

exit 0
  • This worked great for me. All I needed was the /sys/class/backlight/acpi_video0/brightness line.
    – bmaupin
    Commented Nov 15, 2013 at 16:44

I find N0rbert's solution to be the best one, as the script that he's provided allows to restore your previous brightness level on startup.

Although, there was a small modification that I had to introduce to his solution to make it work. Instead of creating symbolic links that he's mentioned, I've provided the following:

ln -s /etc/init.d/brightness /etc/rc0.d/S25backlight
ln -s /etc/init.d/brightness /etc/rc2.d/S25backlight
ln -s /etc/init.d/brightness /etc/rc6.d/S25backlight

Notice, that instead of rcS.d, I've added a symbolic link to rc2.d, which is a runlevel for "Graphical multi-user with networking" (see more). I believe that the reason why the former one doesn't work for me is Ubuntu overriding brightness level after it has been set up by the /etc/init.d/brightness script during S runlevel.

With that subtle change, restoring brightness level works like a charm, especially for Ubuntu 14.04 LTS on Lenovo ThinkPad L540.


I use a Sony Vaio S model and hybrid graphics. I disabled my ATI G card and so my intel HD 3000 serves as my only g card.

I found that setting the brightness value to the file actual_brightness in the intel_backlight folder will help. and the other wont.

for me my minimum brightness value is 236 and maximum is 4648, so you may set a value anywhere between this.

so try this:

echo 236 > /sys/class/backlight/intel_backlight/actual_brightness

No need to fall into scripting and coding.

Just follow these simple steps:

If screen brightness is stuck at maximum every startup, install xbacklight (sudo apt-get install xbacklight) and add "xbacklight -set x" (where 'x' = 0 to 100 desired brightness) to the startup applications via dashboard. For example, "xbacklight -set 50".

I have set brightness for my laptop to 30.

Source: https://help.ubuntu.com/community/AsusZenbookPrime [Search for word "brightness" and read related paragraphs on this source page.]



I added the following into /etc/rc.local, to manage the display brightness and keyboard backlit and it works perfectly

echo 30 | sudo tee /sys/class/backlight/acpi_video0/brightness
echo 3 | sudo tee /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness

exit 0

Use this command to discover your current brightness level:

cat /sys/class/backlight/intel_backlight/brightness

Then, edit rc.local file using this command:

gksudo gedit /etc/rc.local

Add this line before exit 0 line:

echo X > /sys/class/backlight/intel_backlight/brightness

If this don't solve the problem, can be that something in your system is overwriting the brightness level. Then, you can try add a sleep command to delay the execution of the previous command:

(sleep 10 && echo X > /sys/class/backlight/intel_backlight/brightness)



This works on ubuntu 16.10

Create a file brightness.service in /lib/systemd/system with the following contents(Change 100 to whatever brightness you want, roughly it's between 0 ~ 1000).

Description=Lower default brightness

ExecStart=/usr/bin/zsh -c "echo 100 > /sys/class/backlight/intel_backlight/brightness"


Enable it.

sudo systemctl enable brightness.

Restart. It will work.


It is well worth checking the max_brightness files for the absolute maximum values in /sys/class/backlight/intel_backlight and /sys/class/backlight/acpi_video0 directories to avoid setting unusable values.

My Dell Inspiron 5720 uses maximum values of 4882 and 100 respectively. I have set these to 2508 and 52 to prolong battery life. ACPI value in this case is equivalent to the percentage of the maximum brightness.

Editing rc.local works for me. I added comments to clarify how the values were determined. set required brightness with function keys and read values in brightness or actual_brightness files in each of the above Intel / ACPI directories.


For mint mate 17, you can set the default brightness by following steps:

  • sudo apt-get install dconf-tools
  • Applications -> System Tools -> dconf tools,
  • search for backlight, find and change following options:

    • brightness-ac
      brightness when use AC powser (charged),
    • brightness-dim-battery
      brightness when use battery (not charged),

all replies are helpful but didnt help me what i was trying to achieve. i wanted pre-defined levels of brightness for battery and ac power.

  1. use laptop mode tools from here laptop mode tools
  2. edit the conf file for brightness and replace [values] with the values you want. like "echo 1" for battery.wiki

works for me :)


Change default brightness level in Ubuntu 14. 04 LTS / Brightness is reset to Maximum on every Restart on Ubuntu 14.04 LTS

Here is what i found out.

In my case I had both the folders.

And when I changed the default brightness level, it took the change from the file in the folder acpi_video0. i.e. from the second line of code.

Here is the code that will be helpful for setting the default brightness level for Ubuntu 14.04 LTS.

#!/bin/sh -e
#This script is executed at the end of each multiuser runlevel.
#Make sure that the script will "exit 0" on success or any other
#Value on error.
#In order to enable or disable this script just change the execution
#By default this script does nothing.
#if you are changing the default brightness in Ubuntu 14.4 LTS
#the brightness under the folder acpi_video0 is important.
#Because brightness is set from that folder and not from intel_backlight
#(in case of my PC. It may very in others)
#That means you can omit the first echo line.
#However the command lines are given if any one has some problem and doesnot
#have the acpi_video0 folder
echo 1020 > /sys/class/backlight/intel_backlight/brightness
#Under the above given address the range of brightness is from 0 to 4648.
echo 3 > /sys/class/backlight/acpi_video0/brightness
#Under the above given address the range of brightness is from 0 to 7.
exit 0

This is yet another workaround

$ sudo dd if=/dev/tty of=/sys/class/backlight/intel_backlight/brightness

Press Ctrl+D

less typing for fumble fingers...

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