Keyboard backlight

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Any vendor

You can control your computer keyboard backlight via the D-Bus interface. The benefits of using it are that no modification to device files is required and it is vendor agnostic.

Here is an example implementation in Python 3.

Install upower and python-dbus packages then place the following script in /usr/local/bin/ and make it executable. You can then map your keyboard shortcuts to run /usr/local/bin/kb-light.py + x and /usr/local/bin/kb-light.py - x to increase and decrease your keyboard backlight level by x.

Tip: You should try with an x = 1 to determine the limits of the keyboard backlight levels
/usr/local/bin/kb-light.py
#!/usr/bin/env python3

import dbus
import sys

def kb_light_set(delta):
    bus = dbus.SystemBus()
    kbd_backlight_proxy = bus.get_object('org.freedesktop.UPower', '/org/freedesktop/UPower/KbdBacklight')
    kbd_backlight = dbus.Interface(kbd_backlight_proxy, 'org.freedesktop.UPower.KbdBacklight')

    current = kbd_backlight.GetBrightness()
    maximum = kbd_backlight.GetMaxBrightness()
    new = max(0, min(current + delta, maximum))

    if 0 <= new  <= maximum:
        current = new
        kbd_backlight.SetBrightness(current)

    # Return current backlight level percentage
    return 100 * current / maximum

if __name__ ==  '__main__':
    if len(sys.argv) == 2 or len(sys.argv) == 3:
        if sys.argv[1] == "--up" or sys.argv[1] == "+":
            if len(sys.argv) == 3:
                print(kb_light_set(int(sys.argv[2])))
            else:
                print(kb_light_set(17))
        elif sys.argv[1] == "--down" or sys.argv[1] == "-":
            if len(sys.argv) == 3:
                print(kb_light_set(-int(sys.argv[2])))
            else:
                print(kb_light_set(-17))
        else:
            print("Unknown argument:", sys.argv[1])
    else:
        print("Script takes one or two argument.", len(sys.argv) - 1, "arguments provided.")


Alternatively the following bash oneliner will set the backlight to the value specified in argument:


setKeyboardLight () {
    dbus-send --system --type=method_call  --dest="org.freedesktop.UPower" "/org/freedesktop/UPower/KbdBacklight" "org.freedesktop.UPower.KbdBacklight.SetBrightness" int32:$1 
}

Asus

Warning: The following way is not recommended. It provides world-writeable permissions to the keyboard backlight device file meaning that any and every user can control it.

The keyboard backlight file is usually locked out from editing. To unlock this file at bootup, you will need to create a systemd service.

/usr/lib/systemd/system/asus-kbd-backlight.service
[Unit]
Description=Asus Keyboard Backlight
Wants=systemd-backlight@leds:asus::kbd_backlight.service
After=systemd-backlight@leds:asus::kbd_backlight.service

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/chmod 666 /sys/class/leds/asus::kbd_backlight/brightness

[Install]
WantedBy=multi-user.target

You are now able to use a keyboard backlight changer script. For an example, see ASUS G55VW#keyboard backlight script.

For an example of how you might set up a tiny daemon (running as root) that edits these files, hook it up to dbus, and map the keyboard brightness keys to dbus method calls, see [1].