man/systemd.device.xml

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   7   This file is part of systemd.
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   9   Copyright 2010 Lennart Poettering
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  24
  25 <refentry id="systemd.device">
  26         <refentryinfo>
  27                 <title>systemd.device</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd.device</refentrytitle>
  42                 <manvolnum>5</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.device</refname>
  47                 <refpurpose>systemd device configuration files</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename>systemd.device</filename></para>
  52         </refsynopsisdiv>
  53
  54         <refsect1>
  55                 <title>Description</title>
  56
  57                 <para>A unit configuration file whose name ends in
  58                 <filename>.device</filename> encodes information about
  59                 a device unit as exposed in the
  60                 sysfs/<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  61                 device tree.</para>
  62
  63                 <para>This unit type has no specific options. See
  64                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  65                 for the common options of all unit configuration
  66                 files. The common configuration items are configured
  67                 in the generic [Unit] and [Install] sections. A
  68                 separate [Device] section does not exist, since no
  69                 device-specific options may be configured.</para>
  70
  71                 <para>systemd will automatically create dynamic device
  72                 units for all kernel devices that are marked with the
  73                 "systemd" udev tag (by default all block and network
  74                 devices, and a few others). This may be used to define
  75                 dependencies between devices and other
  76                 units.</para>
  77
  78                 <para>Device units are named after the
  79                 <filename>/sys</filename> and
  80                 <filename>/dev</filename> paths they control. Example:
  81                 the device <filename>/dev/sda5</filename> is exposed
  82                 in systemd as <filename>dev-sda5.device</filename>. For
  83                 details about the escaping logic used to convert a
  84                 file system path to a unit name see
  85                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  86
  87         </refsect1>
  88
  89         <refsect1>
  90                 <title>The udev Database</title>
  91
  92                 <para>The settings of device units may either be
  93                 configured via unit files, or directly from the udev
  94                 database (which is recommended). The following udev
  95                 properties are understood by systemd:</para>
  96
  97                 <variablelist>
  98                         <varlistentry>
  99                                 <term><varname>SYSTEMD_WANTS=</varname></term>
 100                                 <listitem><para>Adds dependencies of
 101                                 type <varname>Wants</varname> from
 102                                 this unit to all listed units. This
 103                                 may be used to activate arbitrary units,
 104                                 when a specific device becomes
 105                                 available.</para></listitem>
 106                         </varlistentry>
 107
 108                         <varlistentry>
 109                                 <term><varname>SYSTEMD_ALIAS=</varname></term>
 110                                 <listitem><para>Adds an additional
 111                                 alias name to the device unit. This
 112                                 must be an absolute path that is
 113                                 automatically transformed into a unit
 114                                 name. (See above.)</para></listitem>
 115                         </varlistentry>
 116
 117                         <varlistentry>
 118                                 <term><varname>ID_MODEL_FROM_DATABASE=</varname></term>
 119                                 <term><varname>ID_MODEL=</varname></term>
 120
 121                                 <listitem><para>If set, this property is
 122                                 used as description string for the
 123                                 device unit.</para></listitem>
 124                         </varlistentry>
 125
 126                 </variablelist>
 127
 128
 129         </refsect1>
 130
 131         <refsect1>
 132                   <title>See Also</title>
 133                   <para>
 134                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 135                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 136                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 137                           <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 138                   </para>
 139         </refsect1>
 140
 141 </refentry>