On Debian (Buster), there is a package, brightness-udev, which includes only the udev scripts of brightnessctl (scripts to allow users of video group to manage brightness and input group manage leds).
Installing this package avoids the need to modify system files (like /etc/rc.local noted above). Also, brightnessctl works to control the backlight in this case.
On Debian (Buster), there is a package, brightness-udev, which includes only the udev scripts of brightnessctl (scripts to allow users of video group to manage brightness and input group manage leds).
Installing this package avoids the need to modify system files (like /etc/rc.local noted above). Also, brightnessctl works to control the backlight in this case.