So, when I run xbacklight locally with i3 as my window manager, I get:

No outputs have backlight property

I’ve tried multiple “proper” fixes to this and they either bork my desktop environment or just plain do not work. I’ve hacked around it with some terrible bash that I thought I’d share on the off-chance others have had this happen to them.

Here we go:

reduce_brightness() {
    brightness=$(echo "$(cat /sys/class/backlight/intel_backlight/brightness) - 1000" | bc)
    echo "Reducing brightness to $brightness"
    sudo bash -c "echo $brightness > /sys/class/backlight/intel_backlight/brightness"
}

increase_brightness() {
    brightness=$(echo "$(cat /sys/class/backlight/intel_backlight/brightness) + 1000" | bc)
    echo "Increasing brightness to $brightness"
    sudo bash -c "echo $brightness > /sys/class/backlight/intel_backlight/brightness"
}

Standard stuff really. Just subtract 1000 from the current value and set that as our new value.

Enjoy!