EOS and i3W
xrandr -q | grep ’ connected’ | head -n 2 | cut -d ’ ’ -f1
returns:
eDP1 - laptop
HDMI1 - external Samsung monitor
With F5 and F6 I can change the laptop’s screen brightness.
How do I change the external monitor’s brightness?
The normal way of controlling a monitor is via its physical buttons.
However, you might also find success with https://aur.archlinux.org/packages/gddccontrol
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Thank you
a while ago I wrote myself a little script to do this
brightness.sh:
#!/bin/sh
EXTERNALMONITOR=$(xrandr | grep DisplayPort | grep 3840 | cut -d " " -f 1)
CURRBRIGHT=$(xrandr --verbose |grep $EXTERNALMONITOR -A 5 | grep -m 1 'Brightness:' | cut -f2- -d:)
if [ "$1" = "more" ] && [ $(echo "$CURRBRIGHT < 1" | bc) -eq 1 ]
then
xrandr --output $EXTERNALMONITOR --brightness $(echo "$CURRBRIGHT + 0.1" | bc)
elif [ "$1" = "less" ] && [ $(echo "$CURRBRIGHT > 0" | bc) -eq 1 ]
then
xrandr --output $EXTERNALMONITOR --brightness $(echo "$CURRBRIGHT - 0.1" | bc)
fi
CURRBRIGHT=$(xrandr --verbose |grep $EXTERNALMONITOR -A 5 | grep -m 1 'Brightness:' | cut -f2- -d:)
CURRBRIGHT=$(echo "$CURRBRIGHT * 100" | bc | cut -f 1 -d . )
I then created keyboard shortcuts Meta+Numpad+ and Meta+Numpad- to call “brightness.sh more” and “brightness.sh less” you should just need to change the EXTERNALMONITOR detection line to get your external monitor and should be fine to use the script.
Hope it works for you.
Don’t know it it works on Wayland but on X11 it should.
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This is very kind of you.
I am playing with it and just putting this line in the command line
also
and the echo $EXTERNALMONITOR
returns empty line.
Is that correct?
You should first remove the " | grep 3840 " from the command and check again.
If you don’t have your Monitor connected to DisplayPort but HDMI you can replace the “DisplayPort” with “HDMI”
In the end this was the line I needed for my special configuration.
The EXTERNALMONITOR should contain the first string-part of your monitor.
Example for MY setup:
plain xrandr output:
Screen 0: minimum 320 x 200, current 3840 x 1600, maximum 16384 x 16384
eDP connected (normal left inverted right x axis y axis)
1920x1080 60.03 +
1680x1050 60.03
1280x1024 60.03
1440x900 60.03
1280x800 60.03
1280x720 60.03
1024x768 60.03
800x600 60.03
640x480 60.03
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 connected primary 3840x1600+0+0 (normal left inverted right x axis y axis) 880mm x 367mm
3840x1600 59.99*+ 30.00
2560x1440 59.95
2560x1080 60.00 59.94 59.98
1920x1200 59.99
1920x1080 60.00 50.00 59.94
1600x1200 60.00
1680x1050 59.99
1280x1024 75.02 60.02
1440x900 59.99
1280x800 59.81
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
Command from EXTERNALMONITOR should return:
xrandr | grep DisplayPort | grep 3840 | cut -d " " -f 1
DisplayPort-0
So play around with the command until you receive the desired Monitor-String from xrandr. This will be used to set brightness with the other xrandr commands.
This doesn’t affect the backlight, it adjusts the image brightness value (so you can end up with a blown out image rather than a brighter display).
Still useful, but not quite the same thing.
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As I did not exceed 100% brightness it worked for me to dim brightness a little bit in the evening.
Optical impression was fine for me. But thanks for the hint 
1 Like
Thank you for taking the time.
I am not confident enough playing around with it.
I thank you for your help.
If I take the output from your inital post this line should work
EXTERNALMONITOR=$(xrandr | grep HDMI1 | cut -d " " -f 1)
I needed some more grepping as I have a DELL 38" Monitor with integrated hub. This has some more “connected” outputs…