xbackcalc

xbackcalc

Preparation

1. Create group

sudo groupadd brightness

2. Add user to group

sudo usermod --append --groups video $USER

3. Add new udev rules

Create file /etc/udev/rules.d/90-backlight.rules and add the following two lines:

ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp brightness /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

4. Apply new udev rules

sudo udevadm control --reload && sudo udevadm trigger --action=add --subsystem-match=backlight

Examples

xbackcalc 10
xbackcalc 1180
xbackcalc current + 50
xbackcalc current - 50
xbackcalc current / 2
xbackcalc current \* 1.1
xbackcalc current \* 0.9 + 10