mirror of
https://github.com/systemd/systemd.git
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95 lines
3.2 KiB
XML
95 lines
3.2 KiB
XML
<?xml version="1.0"?>
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<!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'>
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<refentryinfo>
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<title>systemd-backlight@.service</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-backlight@.service</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-backlight@.service</refname>
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<refname>systemd-backlight</refname>
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<refpurpose>Load and save the display backlight brightness at boot and shutdown</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd-backlight@.service</filename></para>
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<para><filename>/usr/lib/systemd/systemd-backlight</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-backlight@.service</filename> is a service
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that restores the display backlight brightness at early boot and
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saves it at shutdown. On disk, the backlight brightness is stored
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in <filename>/var/lib/systemd/backlight/</filename>. During
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loading, if the udev property <option>ID_BACKLIGHT_CLAMP</option> is
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not set to false, the brightness is clamped to a value of at
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least 1 or 5% of maximum brightness, whichever is greater. This
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restriction will be removed when the kernel allows user space to
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reliably set a brightness value which does not turn off the
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display.</para>
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</refsect1>
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<refsect1>
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<title>Kernel Command Line</title>
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<para><filename>systemd-backlight</filename> understands the
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following kernel command line parameter:</para>
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<variablelist class='kernel-commandline-options'>
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<varlistentry>
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<term><varname>systemd.restore_state=</varname></term>
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<listitem><para>Takes a boolean argument. Defaults to
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<literal>1</literal>. If <literal>0</literal>, does not
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restore the backlight settings on boot. However, settings will
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still be stored on shutdown. </para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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