mjhjmtu

I'm trying to set custom screen bindings in i3WM and looking for a way to decrease/increase the brightness on button press. I've tried using the following:

xbacklight -dec10
xbacklight -set 70

xbacklight would work however it does not affect my HDMI connected monitor, no backlight apparently:

xrandr --verbose

HDMI-0 has no "Backlight" property unlike the laptop screen, the above code works fine on my laptop screen, however I want to reduce the brightness on all monitors.

Next I tried:

xrandr --output DP-0 --brightness 0.5
xrandr --output HMDI-0 --brightness 0.5

Which works! Well, for about 1 second then it defaults back. My question: is there any way I can get these changes to stick, at least until the next reboot?

PS - Running Debian GNU/Linux 8.5 | 4.5.0-0.bpo.1-amd64 | i3 4.8-2

PPS - I can easily set the i3 configuration and key bindings, no assistance needed with that part :)

You can use the following script found on doc.ubuntu-fr.org(based on xbacklight tool):

Create a new configuration file brightness under /usr/local/bin with the following contents:

#!/bin/bash

error="Usage: $0 up | $0 down"
xbl=`xbacklight`
limite1=2
limite2=10
limite3=40
limite4=100

if [ "$#" -eq 1 ]
 then
 if [ $1 = "up" ]
 then
 # Augmenter le rétroéclairage
 if [ $(echo "$xbl == $limite4"|bc) -eq 1 ]
 then
 echo "Rétroéclairage au maximum !"
 xbacklight = 100
 else
 if [ $(echo "$xbl < $limite2"|bc) -eq 1 ]
 then
 xbacklight +1
 else
 if [ $(echo "$xbl < $limite3"|bc) -eq 1 ]
 then
 xbacklight +10
 else
 xbacklight +20
 fi
 fi
 fi
 elif [ $1 = "down" ]
 then
 # Diminuer le rétroéclairage
 if [ $(echo "$xbl < $limite1"|bc) -eq 1 ]
 then
 echo "Rétroéclairage au minimum !"
 xbacklight =1
 else
 if [ $(echo "$xbl < $limite2"|bc) -eq 1 ]
 then
 xbacklight -1
 else 
 if [ $(echo "$xbl < $limite3"|bc) -eq 1 ]
 then
 xbacklight -10
 else
 xbacklight -20
 fi
 fi
 fi
 else
 echo $error
 fi
 else
 echo $error
fi
exit

Make it executable:

sudo chmod +x /usr/local/bin/brightness

To increase the brightness , open the terminal and type:

brightness up

To decrease the brightness ,type:

brightness down