This morning I found that I cannot change the brightness of my Dell XPs 13 laptop's display anymore. I tried the following to change the brightness

  • Use keyboard brightness keys
  • Run the commands shown below
  • Boot with kernel option acpi_backlight=vendor. This resulted in a dell_something folder being present in the /sys/class/backlight folder. Changing the brightness file in that folder does not help.
  • Add 'intel_backlight' to xorg.conf
  • Set "load legacy option ROM" BIOS option to enabled and "secure boot" to disabled
  • Boot with kernel option i915.disable-pch_pwm=0
  • Boot from a fresh Ubuntu 12.04 USB stick installation. I can still not control the brightness. This is strange as the laptop came preinstalled with 12.04. Maybe this a hardware problem?
  • Install latest intel video driver

Any ideas why this broke suddendly? I've upgraded from 12.04 to 14.04 in April and till yesterday the brightness keys were working fine.


echo 100 > /sys/class/backlight/intel_backlight/brightness
echo 100 > /sys/class/backlight/acpi_video0/brightness
  • I used some help from this blog: itsfoss.com/fix-brightness-ubuntu-1310 It worked on a dell. Not able to run it on an acer.Hope it works for you – ishanbakshi Jun 4 '14 at 10:58
  • Thanks for your help. I found that article myself but I figured that solve the problem. The changes in the xorg.conf just make the brightness buttons work by echoing the appropriate value in thebrightness file. My problem, however, is that even when I manually changethe value the brightness does not changed. – Lespaul86 Jun 4 '14 at 13:09

16 Answers 16


I got a fix for my dell 5521 laptop, working for Ubuntu 14.04 but will work for kernels v3.13+.

  1. Open /etc/default/grub

    sudo nano /etc/default/grub
  2. to change the line



    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"
  3. then save and exit and

  4. run

    sudo update-grub
  5. then reboot

The explanation is that ACPI adds its own back light control even if one is already present which is intel_backlight, adding this line forces CPI to use the Intel back light.

  • 3
    I can conform, that this fix my problem in up-to-date Ubuntu 14.04.1 TLS version. – Jupeter Feb 6 '15 at 19:21
  • Perfect. worked under ubuntu 16.04 (Dell XPS 13). – Nasreddine Mar 24 '16 at 8:01
  • It worked on ubuntu 16.10, too. Thanks! – Searene Dec 8 '16 at 23:15
  • Didn't work for me on Ubuntu 16.10. – Jordan Silva Mar 26 '17 at 19:32

For me, solution listed on bug report #1249219.

Basically it works creating the /usr/share/X11/xorg.conf.d/20-intel.conf file with the following lines:

Section "Device"
        Identifier "card0"
        Driver "intel"
        Option "Backlight" "intel_backlight"
        BusID "PCI:0:2:0"

I used this solution, it's very simple and easy:

  • Install xbacklight
  • Open Startup Applications
  • Add a new startup item, (give it a name and in the command line type: xbacklight -set 50)

50 gave me the level of brightness I needed but you may need to experiment with the values for your particular system.

  • I find it easier to just use xbacklight -set 50 in the terminal. – I Like to Code May 29 '15 at 3:43
  • Doesn't work for me on mac dual boot ubuntu 14.04.3 – mau Aug 17 '15 at 0:23
  • This doesn't resolve the issue of xbacklight not being able to find the displays. – jackyalcine Dec 28 '17 at 0:54

I have read A LOT of articles

Here is what I did, as I've been struggling with this for a long time...

Creating and modifying /usr/share/X11/xorg.conf.d/20-intel.conf file with the following lines...

Section "Device"
   Identifier "card0"
   Driver "intel"
   Option "Backlight" "intel_backlight"
   BusID "PCI:0:2:0"

...didn't work at all

I was using xbacklight option for some time, but it didn't satisfy me, as I knew it must be possible with Linux native way.

I've tried many GRUB options without effect, so I was googling again and again, coming back to solve this issue.

Today I came to the solution, which is following:

  1. You need to kill your display manager, to create new Xorg.conf file (because it runs X server):
    • Press Ctrl+Alt+F1 (Dont panic, while your Window system is runing, you can go back with Ctrl+Alt+F7)
    • typesudo service lightdm stop and press Enter(e.g. gdm, kdm, xdm)
  2. Create new Xorg configuration file
    • type X -configure and press Enter
    • type mv xorg.conf.new /etc/X11/xorg.conf and press Enter
  3. Start X Server (you can do it all without GUI via command line, but I was more comfortable with this aproach):
    • typesudo service lightdm start and press Enter(e.g. gdm, kdm, xdm)
  4. Modify Xorg.conf file
    • navigate to /etc/X11/xorg.conf and open Xorg.conf (in my case latest was xorg.conf.05312015) via leafpad (e.g. gedit, pluma)
    • search for Section "Device" and then for Driver (on my PC it said Driver "intel" by default, but it could be something else, so change it to intel)
    • add line Option "Backlight" "intel_backlight" after Driver "intel" (it doesn't really matter where, as long as it stays in Device Section)
    • save
  5. Modify GRUB

    • sudo gedit /etc/default/grub (e.g. leafpad, pluma...)
    • set to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=" (acpi_osi= did it for me, other options didn't work...)
    • in terminal type sudo update-grub and press Enter
    • or use GRUB customizer:

    sudo add-apt-repository ppa:danielrichter2007/grub-customizer sudo apt-get update sudo apt-get install grub-customizer

Grub customizer

  • press Save in upper left corner, which will update GRUB for you

    1. Restart and profit

Funny thing is, that code is exactly the same as in /usr/share/X11/xorg.conf.d/20-intel.conf, but that way it worked as expected!

  • Works for me! In a Samsung ATIV Smart PC Pro XE700T1C – Glats Oct 1 '18 at 1:24

I created a simply script:

touch /usr/bin/brightness

The contents as follows:

echo $1 | sudo tee /sys/class/backlight/intel_backlight/brightness

This allows you to then run the following from the command line:

brightness 100
brightness 4000

The values depend on your max brightness values which you can get by running:

cat /sys/class/backlight/intel_backlight/max_brightness 

Don't forget to make the script executable:

chmod +x /usr/bin/brightness

I opted not to change the permissions of the brightness file and keep the sudo part for security reasons.

  1. Open Terminal, run gksudo gedit /etc/rc.local

  2. It will ask for password. Type your password.

  3. Then, the text editor will pop up with rc.local file opened. It contains some stuff and in the end exit 0.

  4. Before that exit 0 line, add below commands to reduce brightness in Ubuntu:

    echo x > /sys/class/backlight/intel_backlight/brightness
    echo y | tee /sys/class/backlight/acpi_video?*/brightness # (optional) > /dev/null

    where 0 ≤ x ≤ 4882 and 0 ≤ y ≤ 10.

  5. That's it. Save and restart your machine.

  • 1
    how/where did you find the maximum value? – erjoalgo Mar 19 '16 at 2:25

It works for ubuntu 14.04 for me. Minimum brightness setting:

echo 0 | sudo tee /sys/class/backlight/acpi_video0/brightness 


echo 7 | sudo tee /sys/class/backlight/acpi_video0/brightness

This worked for Acer 5830TG in Ubuntu 16.04 LTS

  1. First make sure your system uses Intel Graphics card

    $ ls /sys/class/backlight

    At least intel_backlight should be mentioned

  2. Now download and install Intel graphics driver and follow instructions.

  3. On the grub configuration file /etc/default/grub modify the following line:



    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
  4. Then update grub

    sudo update-grub
  5. Create and open the file /usr/share/X11/xorg.conf.d/20-intel.conf:

    gksudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
  6. Add the following text:

    Section "Device"
            Driver      "intel"
            Option      "Backlight"  "intel_backlight"
            Identifier "card0"
  7. Save and reboot.


I had the same issue on my Samsung laptop with my Ubuntu 14.04 and kernel 3.19.

For me the solution was setting the line in the configuration file /etc/default/grub as following:

 GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=0"

and then updating settings:

sudo grub-update

If t will not help you can try to turn off Legacy (CMS) boot option in BIOS.

Before I was trying:

  • Setting /usr/share/X11/xorg.conf.d/80-backlight.conf file
  • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
  • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"

I have an answer that worked for me on 16.04 and now on 18.04. I believe this answer applies only if the following two statements apply to your system. Please don't waste your time if these statements aren't true:

  1. ls /sys/class/backlight/ returns acpi_video0 and exactly one other, such as intel_backlight
  2. echo 450 | sudo tee /sys/class/backlight/intel_backlight/brightness makes your brightness about half, and echo 900 | sudo tee /sys/class/backlight/intel_backlight/brightness makes full brightness.

    (Here you should be replacing intel_backlight with whatever you found in step 1 and replacing 450 and 900 according to your device's maximum brightness setting, which is found by the command cat /sys/class/backlight/intel_backlight/max_brightness or your equivalent.)

In this case your problem is likely to be because the system has added the acpi_video0 module incorrectly, and the brightness keys use this instead of intel_backlight (or your equivalent).

To solve this, you need to add the boot option
acpi_backlight=none which will remove the directory acpi_video0 from /sys/class/backlight/. The brightness keys now apply their logic to the only directory in /sys/class/backlight/ which is what we want.

I gleaned this knowledge from this helpful page https://wiki.archlinux.org/index.php/backlight which states that "If you find that changing the acpi_video0 backlight does not actually change the brightness, you may need to use acpi_backlight=none."


clone the following script and run it from a root terminal after pasting the script in /bin

git clone https://github.com/el-beth/backlight.sh.git

  • 6
    Can you edit this to expand it with an explanation of what you mean by "pasting the script in /bin"? Do you mean to copy it to that directory? Can you add instructions for the steps besides running git clone? – Eliah Kagan Nov 17 '17 at 14:40

This worked for my eeepc seashell series:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"

This is from http://ubuntuforums.org/showthread.php?t=1412922, and they got it from http://wiki.debian.org/DebianEeePC/Model/1005pe.


I found solution after years of searching and it's works very well.

Just added in /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT string acpi_backlight=video.

Lenovo Ideapad Z500: Intel HD4000, GeForce 740m


I had the same problem on my Lenovo Ideapad Z500.

I found this trick that worked on my Ubuntu 16.04:

In the GRUB configuration file /etc/default/grub modify the following line:


by adding this string: acpi_backlight=vendor. In my case I removed acpi-osi=linux and replaced, so, in the end it was:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Update grub by running:

sudo update-grub

Then create an xorg configuration file like this:

sudo touch /usr/share/X11/xorg.conf.d/80-backlight.conf

and copy in it this text:

Section "Device"
     Identifier  "Intel Graphics"
     Driver      "intel"
     Option      "AccelMethod"     "sna"
     Option      "Backlight"       "ideapad" 
     BusID       "PCI:0:2:0"

Save the file, and reboot.

Also you can try to use Fn brightness keys outside of Ubuntu (before it starts or in the BIOS settings). It could work.


Xubuntu 16.04 (Samsung N150 - Intel GMA3150):

Fixed brightness control issue by creating /usr/share/X11/xorg.conf.d/20-intel.conf with the following text:

Section "Device"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        Identifier "card0"

Thanks to: ArchLinux - Samsung_N150_Backlight and Daria


Here is what I did:

$sudo su -
#more /sys/class/backlight/intel_backlight/brightness 

I changed the value to 50200

#nano /sys/class/backlight/intel_backlight/brightness

and saved it. It changed the brightness immediately. I am using An Asus X441N laptop: https://www.asus.com/Laptops/ASUS-VivoBook-Max-X441NA/

  • 2
    You should use sudo, if necessary. Besides, I do not see what your answer adds to the existing ones. – Marc Vanhoomissen Nov 17 '17 at 12:32
  • 1
    Text editors are the wrong tools to edit files in /proc or /sys since they don't behave like normal files. Since you assume the use of a terminal anyway, it's better to use shell features like stream redirection or tools like tee for the job. The “files” in question are really short anyway, so a text editor won't provide any benefit. – David Foerster Nov 17 '17 at 14:33

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