Ttgjyuk

If the GUI tools fail, try to use the terminal for it.

1. Open a terminal



2. 
   

   Run: ls /sys/class/backlight/*/brightness. Example output would be:

   
   
   

   /sys/class/backlight/acpi_video0/brightness
   

   
   


3. 
   

   If nothing is found, the kernel does not support brightness control (missing drivers?). Otherwise, you can use the below commands (replace acpi_video0 accordingly):

   
   
   
   • 
     

     Get the current brightness level:

     
     
     

     cat /sys/class/backlight/acpi_video0/brightness
     

     
     
   
   
   • 
     

     Get the maximum brightness level:

     
     
     

     cat /sys/class/backlight/acpi_video0/max_brightness
     

     
     
   
   

   These commands return brightness levels which ranges from zero to max_brightness (see above).

   
   


4. 
   

   To change the brightness level, you need to write a number to the brightness file. This cannot be done by an editor like gedit. Say you want to change your brightness to 5, you have to run:

   
   
   

   echo 5 | sudo tee /sys/class/backlight/acpi_video0/brightness
   

   
   
   

   Alternatively, if you just want to set the brightness level to the highest available:

   
   
   

   sudo tee /sys/class/backlight/acpi_video0/brightness < /sys/class/backlight/acpi_video0/max_brightness
   

   
   

1. 
   

   Install linux-kamal-mjgbacklight - a patch for Linux kernel.

   
   
   
   • Check whether it will work for you:
     lsmod | grep ^i915
     
     Something like i915 331519 3 should appear. If there's no output, this will not work.
     
   
   
   • sudo add-apt-repository ppa:kamalmostafa/linux-kamal-mjgbacklight
   
   
   • Install updates (sudo apt-get update; sudo apt-get upgrade)
   
   



2. Reboot.




3. Now you can use the terminal to adjust brightness, as suggested by Lekensteyn.
   
   If it's OK for you to change brightness with terminal+sudo, this is the end of the answer.
   
   If you are on GNOME desktop, brightness may even function fully already.




4. Download my brightness changer script, allow it to be executed, and put it to /usr/local/bin/:
   wget -O brightness http://ideone.com/plain/yPlo5
chmod +x brightness
sudo mv brightness /usr/local/bin



5. 
   

   We have to allow the brightness file to be edited, so that sudo isn't needed everywhere.
   
   Also, we want to make the brightness setting restore itself to the previous setting when the system boots (it is not saved by default, unfortunately).

   
   
   

   The mentioned brightness script can handle it all (with restore parameter), just add it to autorun.
   
   To do this we will edit /etc/rc.local (sudo nano /etc/rc.local or any editor instead of nano).
   
   Add the following line before the exit 0 line:
   /usr/local/bin/brightness restore

   
   



6. It is best to reboot now.



7. 
   

   So the brightness script works. You may go to terminal any time and type these:

   
   
   
   • 
     brightness - get current brightness setting
   
   
   • 
     brightness value - set the brightness to value
     
   
   
   • 
     brightness inc step, brightness dec step - increase or decrease the brightness by step (if it's not specified, a default value is used from the configuration file, usually 10% of maximal brightness)
   
   


8. 
   

   Now you might want to map brightness change to your hotkeys.

   
   
   
   • Set XF86BrightnessUp to brightness inc
     
   
   
   • Set XF86BrightnessDown to brightness dec
     
   
   



9. If you want to tweak something, make sure to look at /etc/bx_brightness.conf
   
   You can change the step by which brightness is changed with brightness inc/dec

Thanks to Toz for his priceless help in this thread.

I think I found an easy and least effect to the existed things' way for adjusting intel_backlight using udev rules.

I noticed "change" action of "backlight" subsystem when I press Fn+Up/Down on my Lenovo G360 notebook running kernel 3.2. So I wrote a rules of /etc/udev/rules.d/99-writeintelbacklight.rules as below:

ACTION=="change", SUBSYSTEM=="backlight", RUN+="/usr/sbin/writeintelbacklight.sh"

Make the shell script /usr/sbin/writeintelbacklight.sh contain:

#!/bin/bash

intelmaxbrightness=`cat /sys/class/backlight/intel_backlight/max_brightness`
acpimaxbrightness=`cat /sys/class/backlight/acpi_video0/max_brightness`
scale=`expr $intelmaxbrightness / $acpimaxbrightness`
acpibrightness=`cat /sys/class/backlight/acpi_video0/brightness`
newintelbrightness=`expr $acpibrightness * $scale`
curintelbrightness=`cat /sys/class/backlight/intel_backlight/actual_brightness`
if [ "$newintelbrightness" -ne "$curintelbrightness" ]
then
 echo $newintelbrightness > /sys/class/backlight/intel_backlight/brightness
fi
exit 0

Of course, you need do a sudo chmod +x /usr/sbin/writeintelbacklight.sh.

This will not get your Fn keys working, but you will be able to assign any other key to adjust brightness.

I tried several of these solutions, but nothing worked for me until I found this little indicator program http://codevanrohde.nl/wordpress/?p=128. With it you can set up hot keys to control brightness, use your mousewheel or select from a drop down list in the indicator. I have replaced 'Fn' with 'Win+Alt' which is very similar for my hands and now I can also use it with an external keyboard!

To add PPA and install:

sudo add-apt-repository ppa:indicator-brightness/ppa
sudo apt-get update && sudo apt-get install indicator-brightness

Hot keys should be assigned to:

/opt/extras.ubuntu.com/indicator-brightness/indicator-brightness-adjust --up

and

/opt/extras.ubuntu.com/indicator-brightness/indicator-brightness-adjust --down

Footnote: Out of the box, the birghtness indicator recognizes 7 levels of brightness in my system. By adding acpi_backlight=vendor to the line GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub, that number is bumped up to 16!

I have a lenovo ideapad z400.

I tried all the TIPS listed above, no success.

So I found a different one that worked very well :

Put the following line in /etc/default/grub

GRUB_CMDLINE_LINUX="acpi_backlight=vendor acpi_osi=Linux resume=/dev/sdYY"

YY = Swap area, use swapon -s to see you swap device.

Execute an update-grub as root

After the reboot the problem was solved.

I have a Thinkpad T450s with Nvidia graphics and binary drivers on Ubuntu 14.04. In order to get the backlight working I had to edit the /etc/X11/xorg.conf file by adding the following line to the intel device definition (The xorg.conf-file is created when installing the binary drivers):

Option "Backlight" "intel_backlight"

The complete section is now:

Section "Device"
 Identifier "intel"
 Driver "intel"
 BusID "PCI:0@0:2:0"
 Option "Backlight" "intel_backlight"
 Option "AccelMethod" "SNA"
EndSection

This doesn't work for KDE users as it written in https://launchpad.net/~kamalmostafa/+archive/linux-kamal-mjgbacklight

NOTES FOR KDE DESKTOP USERS

KDE desktop users: This PPA may NOT fix your backlight control hotkeys: This fix requires a kernel module to supply the new /sys/class/backlight/intel_backlight interface (which will work regardless of your desktop) and also a desktop module to access that interface. For Gnome, the updated gnome-power-manager in this PPA supplies that, but the equivalent for KDE has not yet been developed."

However you can try a workaround found here.

That says to type in the terminal echo XXX | sudo tee /sys/class/backlight/intel_backlight/brightness where XXX is an integer value.

In my case XXX can be a value from 0 to 4882, but be careful: if you write 0 the screen will be completely black and you'll se nothing.

Here is a patch you can do.

Create this script with the name .modificarBrillo.sh (in my case I created it in my home folder: ~/.modificarBrillo.sh)

#!/bin/bash
if [ -z "$1" ]; then
 echo "ERROR: Tiene que introducir un parámetro: "a" para aumentar o "d" para disminuir"
 exit
else
 if [ "$1" != "a" ] && [ "$1" != "d" ]; then
 echo "ERROR: el parámetro de entrada sólo puede ser o "a" para aumentar el brillo o "d" para disminuirlo"
 exit
 fi
fi
MAX_BRILLO=`cat /sys/class/backlight/intel_backlight/max_brightness`
MIN_BRILLO_ABSOLUTO="0"
MIN_BRILLO="100" #el brillo mínimo puede ser 0 pero eso deja la pantalla completamente a oscuras
INTERVALO=`expr $MAX_BRILLO - $MIN_BRILLO_ABSOLUTO`
INTERVALO=`expr $INTERVALO / 10`
brillo=`cat /sys/class/backlight/intel_backlight/actual_brightness`
if [ "$1" = "a" ]; then
 let "brillo = brillo + INTERVALO"
 if [ "$brillo" -gt "$MAX_BRILLO" ]; then
 let "brillo = MAX_BRILLO"
 fi
else
 let "brillo = brillo - INTERVALO"
 if [ "$brillo" -lt "$MIN_BRILLO" ]; then
 let "brillo = MIN_BRILLO"
 fi
fi
echo "$brillo" | tee /sys/class/backlight/intel_backlight/brightness

However as the previous script needs execution permission and /sys/class/backlight/intel_backlight/brightness can only be edited by root and you have to execute in terminal:

chmod a+x ~/.modificarBrillo.sh
sudo chmod a+w /sys/class/backlight/intel_backlight/brightness`

The last command has to be executed every startup because the permissions of the brightness file are renewed with the startup. For doing so sudo vim /etc/rc.local and add the command sudo chmod a+w /sys/class/backlight/intel_backlight/brightness before the "exit 0" line

Finally you should install xbindkeys to assgin the Function key to execute the script.

In my case I add the lines to the configuration file ~/.xbindkeysrc

#Aumentar brillo
"/home/alvaro/.modificarBrillo.sh a"
 m:0x0 + c:233
 XF86MonBrightnessUp 

#Disminuir brillo
"/home/alvaro/.modificarBrillo.sh d"
 XF86MonBrightnessDown

But you could also install the program xbindkeys-config to do the proccess graphically.

Edit the /etc/default/grub file and add
pcie_aspm=force acpi_backlight=vendor after
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Then the whole line will look like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=vendor"

For more detail visit this link.

I had the same issue, I am using Gnome3.10 in ubuntu 14.04 ( Unity). I installed tlp for temperature control in my laptop. I just removed 'tlp' and I rebooted my system and I am able to adjust screen brightness using function(fn) + arrow keys.

It might help check it once.

Had same problem (apparently) with a Lenovo IP G50-70. - In fact, none of the function keys 'appeared' to work. Eventually in the Bios I found a 'Hotkey' enable/disable function. Paradoxically, it was 'Enabled', but this in fact enables a single key press operation for the function keys. In fact, if you use the traditional 'Fn + Function keyX' technique, they don't work.

If you 'Disable' the hotkey function in the Bios, then the function keys work 'as expected' (Fn + Function Keyx). - After doing this, all the function keys worked OK. So much for progress

I had to add these lines to grub:

acpi_backlight=vendor acpi_osi=linux thinkpad-acpi.brightness_enable=1

Note that last one. That was the one that made the brightness keys work.

I was having a problem on a Thinkpad W510 running kubuntu 18.04.

I found this on a Lenovo forum:

tpb - program to use the IBM ThinkPad(tm) special keys

sudo apt-get install tpb

Voila! Brightness adjustment keys now work perfectly! I did not even need to log out and back in.

You can use this package to deal with brightness from the command line (terminal), with the xbacklight command.

xbacklight can be installed in the Software Center. Or in the Terminal:

sudo apt-get update && sudo apt-get install xbacklight

you can use

• xbacklight -inc <range from 0 to 100> to increase brightness with value < ... >




• xbacklight -dec <range from 0 to 100> to decrease brightness with value < ... >