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systemd/man/systemd-backlight@.service.xml
Zbigniew Jędrzejewski-Szmek 11a1589223 tree-wide: drop license boilerplate
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.

I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
2018-04-06 18:58:55 +02:00

84 lines
2.7 KiB
XML

<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1+
This file is part of systemd.
Copyright 2013 Lennart Poettering
-->
<refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'>
<refentryinfo>
<title>systemd-backlight@.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-backlight@.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-backlight@.service</refname>
<refname>systemd-backlight</refname>
<refpurpose>Load and save the display backlight brightness at boot and shutdown</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-backlight@.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-backlight</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-backlight@.service</filename> 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 <filename>/var/lib/systemd/backlight/</filename>. During
loading, if the udev property <option>ID_BACKLIGHT_CLAMP</option> is
not set to false, 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.</para>
</refsect1>
<refsect1>
<title>Kernel Command Line</title>
<para><filename>systemd-backlight</filename> understands the
following kernel command line parameter:</para>
<variablelist class='kernel-commandline-options'>
<varlistentry>
<term><varname>systemd.restore_state=</varname></term>
<listitem><para>Takes a boolean argument. Defaults to
<literal>1</literal>. If <literal>0</literal>, does not
restore the backlight settings on boot. However, settings will
still be stored on shutdown. </para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>