Index · Directives · Python · libudev · gudev systemd 220

## Name

systemd-backlight@.service, systemd-backlight — Load and save the display backlight brightness at boot and shutdown

## Synopsis

`systemd-backlight@.service`

`/usr/lib/systemd/systemd-backlight`

## Description

`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 udev property `ID_BACKLIGHT_CLAMP` is not set to false value, the brightness is clamped to a value of at least 1 or 5% of maximum brightness, whichever is greater. This restriction will be removed when the kernel allows user space to reliably set a brightness value which does not turn off the display.

## Kernel Command Line

`systemd-backlight` understands the following kernel command line parameter:

`systemd.restore_state=`

  Takes a boolean argument. Defaults to "`1`". If "`0`", does not restore the backlight settings on boot. However, settings will still be stored on shutdown.

## See Also

systemd(1)