man/systemd-backlight@.service.xml

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  10   Copyright 2013 Lennart Poettering
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  25 <refentry id="systemd-backlight@.service" conditional='ENABLE_BACKLIGHT'>
  26
  27   <refentryinfo>
  28     <title>systemd-backlight@.service</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd-backlight@.service</refentrytitle>
  43     <manvolnum>8</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd-backlight@.service</refname>
  48     <refname>systemd-backlight</refname>
  49     <refpurpose>Load and save the display backlight brightness at boot and shutdown</refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <para><filename>systemd-backlight@.service</filename></para>
  54     <para><filename>&rootlibexecdir;/systemd-backlight</filename></para>
  55   </refsynopsisdiv>
  56
  57   <refsect1>
  58     <title>Description</title>
  59
  60     <para><filename>systemd-backlight@.service</filename> is a service
  61     that restores the display backlight brightness at early boot and
  62     saves it at shutdown. On disk, the backlight brightness is stored
  63     in <filename>/var/lib/systemd/backlight/</filename>. During
  64     loading, if udev property <option>ID_BACKLIGHT_CLAMP</option> is
  65     not set to false value, the brightness is clamped to a value of at
  66     least 1 or 5% of maximum brightness, whichever is greater. This
  67     restriction will be removed when the kernel allows user space to
  68     reliably set a brightness value which does not turn off the
  69     display.</para>
  70   </refsect1>
  71
  72   <refsect1>
  73     <title>Kernel Command Line</title>
  74
  75     <para><filename>systemd-backlight</filename> understands the
  76     following kernel command line parameter:</para>
  77
  78     <variablelist class='kernel-commandline-options'>
  79       <varlistentry>
  80         <term><varname>systemd.restore_state=</varname></term>
  81
  82         <listitem><para>Takes a boolean argument. Defaults to
  83         <literal>1</literal>. If <literal>0</literal>, does not
  84         restore the backlight settings on boot. However, settings will
  85         still be stored on shutdown. </para></listitem>
  86       </varlistentry>
  87     </variablelist>
  88   </refsect1>
  89
  90   <refsect1>
  91     <title>See Also</title>
  92     <para>
  93       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  94     </para>
  95   </refsect1>
  96
  97 </refentry>