Create the following file (
/etc/udev/rules.d/backlight.rules) and reboot:
>$ cat /etc/udev/rules.d/backlight.rules ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness" ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
Note, if you don’t create the file
/etc/udev/rules.d/backlight.rules file then you will need to execute the commands as root.
As a member of the video group …. it will allow you to do the following:
>$ cat /sys/class/backlight/intel_backlight/actual_brightness 3000 >$ cat /sys/class/backlight/intel_backlight/max_brightness 7500 >$ echo 4000 > /sys/class/backlight/intel_backlight/brightness
also see the arch backlight guide
also see the arch udev guide