systemd-backlight@.service, systemd-backlight — Load and save the display backlight brightness at boot and shutdown
systemd-backlight@.service
/usr/lib/systemd/systemd-backlight save [backlight|leds]:DEVICE
/usr/lib/systemd/systemd-backlight load [backlight|leds]:DEVICE
systemd-backlight@.service is a service that restores the display backlight
brightness at early boot and saves it at shutdown. On disk, the backlight brightness is stored in
/var/lib/systemd/backlight/. During loading, if the udev property
ID_BACKLIGHT_CLAMP is not set to false, the brightness is clamped to a value of at least
1 or 5% of maximum brightness, whichever is greater. The percentage can be adjusted by specifying a
percentage (needs to be suffixed with "%", e.g. "30%") to the property
ID_BACKLIGHT_CLAMP.