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LittleSandra

Member

Registered: 2021-01-25

Posts: 86

[SOLVED] can't get "light" to change brightness in Wayland/Sway?

Dear all

In i3wm I had the following in my config

bindsym XF86MonBrightnessUp exec xbacklight -inc 5 # increase screen brightness
bindsym XF86MonBrightnessDown exec xbacklight -dec 5 # decrease screen brightness

which of course won't work with sway.

If I as root do this

# cat /sys/class/backlight/intel_backlight/max_brightness 
6818
# cat /sys/class/backlight/intel_backlight/brightness 
2218
# echo 3000 >  /sys/class/backlight/intel_backlight/brightness

then I can change the brightness.

But when I do

light -s sysfs/backlight/intel_backlight -T 0.72

the screen doesn't get darker.

Can anyone see what I am doing wrong?

Hugs
Sandra

Last edited by LittleSandra (2023-03-11 18:25:24)

Trilby

Inspector Parrot

Registered: 2011-11-29

Posts: 30,471

Website

Re: [SOLVED] can't get "light" to change brightness in Wayland/Sway?

First, see the huge warning on the upstream page of the "light" project.  Then second, ask why in the world you would need such a program.  Add your user to the video group and just have a script echo values to your backlight file - here's mine:

#!/bin/sh

cd /sys/class/backlight/intel_backlight
read max < max_brightness
read cur < brightness
echo "[$max]sa [0]sb $cur $((max/20)) $1 d 0 >b d $max <a p" \
	| dc >> brightness 2>/dev/null

This can take as parameters "+", "-", or a number to increment, decrement, or set to a specific value.

---

"UNIX is simple and coherent" - Dennis Ritchie; "GNU's Not Unix" - Richard Stallman

LittleSandra

Member

Registered: 2021-01-25

Posts: 86

Re: [SOLVED] can't get "light" to change brightness in Wayland/Sway?

Ok, that is really cool! Thanks a lot