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I've tried the solution at Ubuntu 19.04 cannot change brightness on laptop but it doesn't seem to be working for me. I am using Ubuntu 19.10 instead of 19.04 as in that answer.

The main script xps-brightness.sh from that answer:

#!/bin/sh

# Where the backlight brightness is stored
BR_DIR="/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight"

test -d "$BR_DIR" || exit 0

MIN=0
MAX=$(cat "$BR_DIR/max_brightness")
VAL=$(cat "$BR_DIR/brightness")

if [ "$1" = down ]; then
    VAL=$((VAL-6000))
else
    VAL=$((VAL+6000))
fi

if [ "$VAL" -lt $MIN ]; then
    VAL=$MIN
elif [ "$VAL" -gt $MAX ]; then
    VAL=$MAX
fi

PERCENT=`echo "$VAL / $MAX" | bc -l`

export XAUTHORITY=/home/derek/.Xauthority  # CHANGE "user" TO YOUR USER
export DISPLAY=:0.0

echo "xrandr --output eDP-1 --brightness $PERCENT" > /tmp/xps-brightness.log
xrandr --output eDP-1 --brightness $PERCENT

echo $VAL > "$BR_DIR/brightness"

When I use the brightness keys on my keyboard, both the value in $BR_DIR/brightness and the /tmp/xps-brightness.log log file get updated, but the script doesn't seem to execute the xrandr --output eDP-1 --brightness $PERCENT command. This command works when I enter it directly into a console or in a script such as test.sh

#!/bin/sh
xrand --output eDP-1 --brightness .7

and then run sh test.sh.

Why doesn't xps-brightness.sh work?

1
  • I have the same problem. 'but I got it to work yesterday no it does not anymore) – masterleo Dec 23 '19 at 17:51

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