Set bindings in i3 to control keyboard backlight

backlighti3keyboard-backlight

For my i3 window-manager settings, I am looking for a command line tool, similar to xbacklight, but to control the brightness of the leds which are in the keyboard.

Basically, I can set up the leds through a command line, but it requires to be root:

# Light off the leds
echo 0 > /sys/class/leds/smc::kbd_backlight/brightness
# Light on the leds (full power)
echo 100 > /sys/class/leds/smc::kbd_backlight/brightness

I know that it is possible because Gnome3 has support for that, but I do not know exactly how they proceed…

For now, my ~/.config/i3/config looks like this:

# screen brightness controls
bindsym XF86MonBrightnessUp exec xbacklight -inc 10
bindsym XF86MonBrightnessDown exec xbacklight -dec 10

# keyboard backlight controls
#TODO
# XF86KbdBrightnessUp
# XF86KbdBrightnessDown

So, is there a tool, similar to xbacklight to do the same than screen brightness with keyboard backlight? It would be even better if this tool would have the control on both (screen and keyboard).

Best Answer

You could write your own pretty easily.

Create two shell scripts containing the echo lines above somewhere in your path (/usr/local is the normal place). Set the permissions 755 owned by root. Then either edit your sudoers file to allow them to be run as root, or use chmod +s to set them SUID.

This sort of thing is considered a security risk, BTW, so make absolutely sure the permissions are set appropriately. You don't want anyone without root permissions to be able to edit the scripts, and you don't want the scripts to use any input.

It would be trivial to add support for a brightness level flag, but unless you're an accomplished shell scripter I'd recommend against it as a bug in your code would be a security hole.

Related Solutions

Linux – Backlight control manjaro linux

There are many ways to do this, but since it seems that your graphics card is made by Nvidia, I think the way which works best is the following (assuming you use nvidia-driver):

Create a file called 10-brightness.conf to /etc/X11/xorg.conf.d/

Write the following lines to the file you just created:

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection

Now restart X (use pkill X to kill X, and then display manager should cause new instance of X to be spawned. If you don't have a display manager (such as GDM, KDM), then log in to virtual console and write startx) or reboot your computer, and then you should be able to adjust the brightness of backlight by hitting brightness keys.

Another way of doing it

This way should work with all graphics cards, and this is also some kind of fallback way if your brightness keys don't work.

Note: In the following commands, # states for root prompt, although you actually don't need root rights until the last point, and acpi_video0 is just placeholder for the actual card name, replace it with the name you will find in the point 1.

To find the card which manages the screen, run this command:
```
# ls /sys/class/backlight/
```
There should be only one entry, so it's the card.
To find the maximum brightness, run this command:
```
# cat /sys/class/backlight/acpi_video0/max_brightness
```
This command often prints 15.
To adjust the brightness, run this command (as root, as stated previously):
```
# echo 5 > /sys/class/backlight/acpi_video0/brightness
```
You can echo there any number you want, although the screen cannot be brighter than its maximum brightness, so if you echo higher number, say 50, there, the screen should just set its brightness to the maximum.

Sources

How to control keyboard backlight using hotkeys

The keys usually used to control keyboard backlight are XF86KbdBrightnessUp and XF86KbdBrightnessDown. You just need to find a way to bind it to the following shell command lines (and set the sudoers as needed):

# Light off the leds
sudo echo 0 > /sys/class/leds/asus::kbd_backlight/brightness
# Light on the leds (full power)
sudo echo 100 > /sys/class/leds/asus::kbd_backlight/brightness

Best Answer

Related Solutions

Linux – Backlight control manjaro linux

How to control keyboard backlight using hotkeys

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