Adjust LCD brightness from command line

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dell 1501As many other Ubuntu users several days ago I’ve upgraded my Feisty to Gutsy at my Dell Inspiron 1501.

Unfortunately many things that worked for me in Feisty doesn’t work in Gutsy just after upgrading. Among them are: suspend/hibernate and brightness adjustment. At this moment I’m trying to get these features working and certainly share results here but not workable brightness adjustment really disturbed me. So, until I didn’t find a solution how to adjust LCD brightness with keyboard, there is nice workaround: execute the following command with root rights (sudo -s to get it):

echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

This will make you LCD screen as bright as possible and you can proceed with your work (like me :) ). To lower brightness just replace 100 with another value like 62 and watch the results.

Hope it helps!

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46 Responses to “Adjust LCD brightness from command line”


  1. 1 vivek

    Nice tip :)

  2. 2 aruvoski

    how?

  3. 3 artiomix

    Hi aruvoski,

    In your Ubuntu:
    Applications -> Accessories -> Terminal

    Then type `sudo -s` and enter your password. After you’ve got prompt like ~#, you can type:

    echo -n 100 > /proc/acpi/video/VGA/LCD/brightness
    to adjust LCD brightness where 100 is maximum value and 62 is minimum.

    Hope it helps! :)

    P.S. You’re welcome to ask any related questions here ;)

  4. 4 Cristian Navalici

    Pay attention that you might have GLX instead of VGA as in:

    /proc/acpi/video/GLX0/LCD/brightness

    Anyway, this is a ‘cool’ tip. Thanks for it!

  5. 5 Jillian

    oh good lord THANK YOU
    i have been trying to figure this out for weeks.
    YAY BRIGHT SCREEN AGAIN!!

  6. 6 artiomix

    Hey everybody, thanks for your comments! :)

  7. 7 Rasha

    I have a Dell Latitude C610 and I’ve tried running the line in Ubuntu tho I had to modify as my line is /proc/acpi/video/VID/LCD/brightness. But it’s saying the command is unknown.

  8. 8 artiomix

    Hello Rasha,

    try this:

    sudo -s or su

    then

    echo -n 100 > /proc/acpi/video/VID/LCD/brightness

    :D

  9. 9 Satish Vellanki

    No luck for me :-(

    # echo -n 50 > /proc/acpi/video/VGA/LCD/brightness
    bash: echo: write error: Invalid argument

    What could be wrong?

  10. 10 ross

    turn off acpi and it will work with fn keys

  11. 11 ross

    it might only work on opensuse. when you do this kpowersave doesnt work

  12. 12 animatt

    Try running cat /proc/acpi/video/VGA/LCD/brightness

    This will show supported brightness levels.

    Running it on my monitor gives

    root@Gateway-M-Series:/home/animatt# cat /proc/acpi/video/VGA/LCD/brightnesslevels: 100 37 12 25 37 50 62 75 87 100
    current: 12

  13. 13 Alex

    Thanks for posting this info. Every day, I learn something new about using linux. Much more fun than M$ Win!
    Seems to me this could easily be put in a script that would read the current setting and go up or down depending on which name it was called with.
    I’m going to work on it for myself and post it back here in case anyone else is interested.
    Can all of the hardware be controlled via the /proc dir?

    Thanks again for the pointer. :-)

  14. 14 Alex

    The following is working nicely for me:
    #!/bin/sh
    # adjust lcd brightness on Dell Inspiron 1501 – 080303 Alex P Janssen Jr – alex@ourwoods.org
    # INSTRUCTIONS:
    # Save this script to a file named brightup.sh in /home/yourusername/bin
    # Make it executable: chmod +x brightup.sh
    # Save yourself having to run it in a terminal and enter your password each time
    # edit sudoers: sudo visudo
    # add to sudoers: yourusername ALL=(ALL) NOPASSWD:/bin/bash
    # save and exit
    # link brightup and brightdn to brightup.sh:
    # ln -s /home/yourusername/bin/brightup.sh /home/yourusername/bin/brightup
    # ln -s /home/yourusername/bin/brightup.sh /home/yourusername/bin/brightdn
    # Add a couple of custum launchers to your panel ( I run Gnome )
    # Right-click the panel and select Add to Panel
    # Click Custom Launcher
    # Type=Application, Name=Darker, Command=sudo bash -c /home/apjjr/bin/brightdn
    # Select a down-arrow for an icon and Close
    # Do the same for brightup, except set the name to Lighter and pick an up-arrow
    #
    # check our id
    #echo `id`
    ourname=$0
    ourname=`basename “$ourname”`
    xx=`cat /proc/acpi/video/VGA/LCD/brightness | grep current | cut -c 9-`
    curbright=`echo $xx`
    # check process name and current brightness setting
    #echo “${ourname},${curbright}:”
    case $curbright in
    0) # after boot my brightness value is 0
    # echo “12″
    echo -n 12 >/proc/acpi/video/VGA/LCD/brightness
    ;;
    12) if [ "$ourname" = "brightup" ]; then
    #echo “12 to 25″
    echo -n 25 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    25) if [ "$ourname" = "brightup" ]; then
    #echo “25 to 37″
    echo -n 37 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 12 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    37) if [ "$ourname" = "brightup" ]; then
    #echo “37 to 50″
    echo -n 50 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 25 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    50) if [ "$ourname" = "brightup" ]; then
    #echo “50 to 62″
    echo -n 62 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 37 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    62) if [ "$ourname" = "brightup" ]; then
    #echo “62 to 75″
    echo -n 75 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 50 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    75) if [ "$ourname" = "brightup" ]; then
    #echo “75 to 87″
    echo -n 87 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 62 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    87) if [ "$ourname" = "brightup" ]; then
    #echo “87 to 100″
    echo -n 100 >/proc/acpi/video/VGA/LCD/brightness
    else
    echo -n 75 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    100) if [ "$ourname" != "brightup" ]; then
    echo -n 87 >/proc/acpi/video/VGA/LCD/brightness
    fi
    ;;
    esac
    exit 0

    That’s it.
    Alex

  15. 15 Petko

    Hello. Here is another way to do this. I add in the file ~/.bashrc :

    Bup ()
    {
    FILE=/proc/acpi/video/VID/LCD/brightness
    current=`cat $FILE | grep current | cut -c 10-`
    prev=12
    for i in `cat $FILE | grep levels | cut -c 17-`; do
    if [[ $i -eq $current && "$1" == "-" ]]; then
    echo -n $prev > $FILE
    break;
    elif [ $i -gt $current ]; then
    echo -n $i > $FILE ;
    break;
    fi;
    prev=$i
    done
    }
    Bdown (){ Bup -; }

    (Just make sure the line FILE=/proc/acpi/video/… points to your correct file.)
    This way, I can type in a terminal “Bup” or “Bdown” to set the brightness up or down.

    Greetings.

  16. 16 Geoffroy

    BRIGHTNESS on UBUNTU:

    This has worked for me in the directory, for me
    /proc/acpi/video/OVGA/DD03$
    and I did the command
    echo -n 100> brightness
    in my directory.
    Don’t forget to change the rights and owner for the file brightness

    Thanks for this artiomix:
    ” echo -n 100 > /proc/acpi/video/VGA/LCD/brightness
    to adjust LCD brightness where 100 is maximum value and 62 is minimum.
    Hope it helps! :)

  17. 17 Ohnoesmilk

    thank you so much!!! you saved my eyes from burning! :D

  18. 18 Radha

    guys do this work on windows?
    i need to know pls make me know the fast you can my email is
    elmenoldr@hotmail.com

  19. 19 Dan

    Is there anyway to control the brightness on an LCD panel monitor for a desktop. Mine is too bright and there is no video folder. I’m sure this is possible as when the computer is left idle it gradually dims until it goes blank. There must be a way to dim the screen a set amount.

  20. 20 Neal Stephenson

    got “persmission denied” on xubuntu 8.10 (sudo used! when tried as root in that dir got invalid argument)

    when
    sudo echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

    visit eye saving tips&cool surf
    http://izobrazba.naspletu.com/eye_sensivity/index.html

  21. 21 ???????? ?????

    ??? ??? ??????? ????????? ?? ????. ??? ???????? ?????? ??????????????.

  22. 22 Benneh

    Hi Neal Stephenson!

    I use Kubuntu 8.04 and the following is working nicely for me:
    sudo su

    and next:
    echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

    Hope it helps!

  23. 23 Tyrone Dimery

    Hello, I just found your website while searching around online as I’m seeking some information on LCD TVs!. It’s a very interesting site so I bookmarked your site and intend to return tomorrow to enjoy a more detailed look when I have more time.

  24. 24 RProgrammer

    I have GFX0 instead of VGA on Karmic and I get the Invalid Argument error too.

    /proc/acpi/video/GFX0/LCD# echo -n 100 > brightness
    bash: echo: write error: Invalid argument
    /proc/acpi/video/GFX0/LCD# cat brightness

    /proc/acpi/video/GFX0/LCD#

  25. 25 RProgrammer

    Sorry, the forum ate my <> signs

    /proc/acpi/video/GFX0/LCD# cat brightness
    <not supported>
    /proc/acpi/video/GFX0/LCD#

  26. 26 ?e??????a

    ??? ???????? ???????????????, ?? ??? ??????? ??? ?? ???????????? ????? ???????? ?????? ????? ?????-?? ?????.

  27. 27 Anaconda

    for all of you, who have the “invalid argument” problem. And who can’t change the brightnes value, because you are unable to edit the brightness file.

    Install xbacklight (eg. sudo apt-get install xbacklight) and use it to change the brightness value eg.
    xbacklight -set 100

    Just change the 100 to anything you want between 0-100
    In my machine the numbers are not in logical order, but once you know how bright each seting is you can “remember those numbers”, or write a script

    And xbacklight does change the brightness value too…

  28. 28 nomad

    i installed xbacklight and typed in “xbacklight -set 100″
    then it says “No outputs have backlight property”

    what’s the problem..??

  29. 29 Nevyn

    Hi Guys,

    Okay – those guys having problems… Type in:
    cat /procacpi/video/VGA/LCD/brightness

    In that above line, LCD may be something different – mines LLCD. Anyway, there’s the possibility that yours isn’t on a scale from 0 to 100. Mine goes from 0 to 15. So if you’re looking at your monitor and it’s already pretty bright, and you’ve run that command above, that’s probably going to be your maximum value.

    So go to the original command, and alter your values to match.

    Regards,
    Nevyn.

  30. 30 raff

    i keep getting “bash: /proc/acpi/video/GLX0/LCD/brightness: No such file or directory”
    but it is there, i checked by browsing the file system, but the file is read-only

    anything i can do?

  31. 31 Ismas

    One note: If you don’t have /proc/acpi/video, do this:

    sudo modprobe video

    Now you have. :)

  32. 32 kanna

    Hi,

    I am also getting “No outputs have backlight property”.

    After installing back light. What should i do??

  33. 33 free Daily Review

    hey excellent for this site really helpfull,please visit our site Daily Review

  34. 34 prakash

    hey i am sing ubuntu 10.04 version. my system brightness is not changing with Fn key.
    /proc/acpi/video/VGA/LCD/brightness is not there. there is /proc/acpi/video/GFX0/DD01/brightness file. but when i followed with echo -n /proc/acpi/video/GFX0/DD01/brightness it is saying that echo is invalid arguement… please help me .. i am facing problem to my eyes with high brightness.

  35. 35 Sergey Shlykovich

    If you use gnome, you could just add Brightness Applet to you Panel

  36. 36 Agilar

    Thanks – it works!

  37. 37 Iklswt

    Thank you for shfwaring youwr admin would get ready a severely beneficial write-up I congratulate.

  38. 38 Linux noob

    hi i tried it but it did not work and it says root@me~#

  39. 39 Alex

    Check my tool for the brightness adjustment.
    https://github.com/akozadaev/xbright

  40. 40 peliculas online gratis estrenos

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  41. 41 Ricky

    wow, thank you very much. I’m really a new guy of Linux.

  42. 42 computer courses london

    I was just searching for this info for a while. After six hours of continuous Googleing, at last I got it in your web site. I wonder what is the lack of Google strategy that do not rank this kind of informative sites in top of the list. Generally the top sites are full of garbage.

  43. 43 ppm

    It worked for my HP Pavilion tx 1000 / 1215 laptop.Thanks buddy.

  1. 1 Personal Computers and Tech News » Ajust LCD brightness from command line (works at Dell 1501)
  2. 2 eraser’s blog » Blog Archive » Ajust LCD brightness from command line (works at Dell 1501)
  3. 3 dell » Ajust LCD brightness from command line (works at Dell 1501)

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My name is Artem N. (artiomix AT gmail DOT com) and I'm Linux/Unix, Cisco systems engineer. The main idea of Linux Screw is to share relevant knowledge, skills and observations over The Web. Here you can find a lot of information related to different Linux distributions, FreeBSD, IOS as well as a other Open Source around staff. Read more ››