Ubuntu – Lubuntu brightness/backlight issue

backlightbrightnesslubuntulxqtshortcut-keys

I freshly installed Lubuntu 18.10 with LXQT environment and here's my issue :
I want to dim the backlight of my laptop with the keyboard shortcut (XF86) but when i press it, it changes the brightness(which seems to be a software change because it messes with gamma and contrast)

So i went to the keyboard shortcuts bindings to find the menu that changes what i want :

lxqt-config-brightness menu

^ the slider controls backlight (usual brightness) and the knob messes with contrast..

Here is the shortcut config menu :

lxqt shortcuts

However, there is no way i can find to inc or dec the slider instead of the knob, to have control over backlight. xbacklight and xrandr doesn't work as they output "no output with backlight property" but i can change backlight with echo 700 | sudo tee /sys/class/backlight/intel_backlignt/brightness
which sets backlight to 700, but i don't know how to implement inc or dec on a shortcut with this :c

Teach me some unix please 🙂

Best Answer

The simplest way I have discovered that doesn't require sudo is to use pkexec lxqt-backlight_backend --inc to increase the backlight brightness and pkexec lxqt-backlight_backend --dec to decrease it.

You can add keyboard shortcuts for these commands in LXQt. I hope this will be fixed soon and it will become the default action for brightness adjustement keyboard combinations instead of the rather useless contrast regulation.

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