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<refentry id="systemd.device">
- <refentryinfo>
- <title>systemd.device</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.device</refentrytitle>
- <manvolnum>5</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>systemd.device</refname>
- <refpurpose>Device unit configuration</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename><replaceable>device</replaceable>.device</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para>A unit configuration file whose name ends in
- <literal>.device</literal> encodes information about
- a device unit as exposed in the
- sysfs/<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- device tree.</para>
-
- <para>This unit type has no specific options. See
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for the common options of all unit configuration
- files. The common configuration items are configured
- in the generic <literal>[Unit]</literal> and
- <literal>[Install]</literal> sections. A separate
- <literal>[Device]</literal> section does not exist,
- since no device-specific options may be
- configured.</para>
-
- <para>systemd will dynamically create device units for
- all kernel devices that are marked with the "systemd"
- udev tag (by default all block and network devices,
- and a few others). This may be used to define
- dependencies between devices and other units. To tag a
- udev device, use <literal>TAG+="systemd"</literal> in
- the udev rules file, see
- <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.</para>
-
- <para>Device units are named after the
- <filename>/sys</filename> and
- <filename>/dev</filename> paths they control. Example:
- the device <filename noindex='true'>/dev/sda5</filename> is exposed
- in systemd as <filename>dev-sda5.device</filename>. For
- details about the escaping logic used to convert a
- file system path to a unit name see
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
-
- </refsect1>
-
- <refsect1>
- <title>The udev Database</title>
-
- <para>The settings of device units may either be
- configured via unit files, or directly from the udev
- database (which is recommended). The following udev device
- properties are understood by systemd:</para>
-
- <variablelist class='udev-directives'>
- <varlistentry>
- <term><varname>SYSTEMD_WANTS=</varname></term>
- <term><varname>SYSTEMD_USER_WANTS=</varname></term>
- <listitem><para>Adds dependencies of
- type <varname>Wants</varname> from the
- device unit to all listed units. The
- first form is used by the system
- systemd instance, the second by user
- systemd instances. Those settings may
- be used to activate arbitrary units
- when a specific device becomes
- available.</para>
-
- <para>Note that this and the
- other tags are not taken into account
- unless the device is tagged with the
- <literal>systemd</literal> string in
- the udev database, because otherwise
- the device is not exposed as a systemd
- unit (see above).</para>
-
- <para>Note that systemd will only act
- on <varname>Wants</varname>
- dependencies when a device first
- becomes active. It will not act on
- them if they are added to devices that
- are already active. Use
- <varname>SYSTEMD_READY=</varname> (see
- below) to influence on which udev
- event to trigger the dependencies.
- </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SYSTEMD_ALIAS=</varname></term>
- <listitem><para>Adds an additional
- alias name to the device unit. This
- must be an absolute path that is
- automatically transformed into a unit
- name. (See above.)</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SYSTEMD_READY=</varname></term>
- <listitem><para>If set to 0, systemd
- will consider this device unplugged
- even if it shows up in the udev
- tree. If this property is unset or set
- to 1, the device will be considered
- plugged if it is visible in the
- udev tree. This property has no
- influence on the behavior when a
- device disappears from the udev
- tree.</para>
-
- <para>This option is useful to support
- devices that initially show up in an
- uninitialized state in the tree, and
- for which a <literal>changed</literal>
- event is generated the moment they are
- fully set up. Note that
- <varname>SYSTEMD_WANTS=</varname> (see
- above) is not acted on as long as
- <varname>SYSTEMD_READY=0</varname> is
- set for a device.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ID_MODEL_FROM_DATABASE=</varname></term>
- <term><varname>ID_MODEL=</varname></term>
-
- <listitem><para>If set, this property is
- used as description string for the
- device unit.</para></listitem>
- </varlistentry>
-
- </variablelist>
-
-
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>systemd.device</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.device</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd.device</refname>
+ <refpurpose>Device unit configuration</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename><replaceable>device</replaceable>.device</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>A unit configuration file whose name ends in
+ <literal>.device</literal> encodes information about a device unit
+ as exposed in the
+ sysfs/<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ device tree.</para>
+
+ <para>This unit type has no specific options. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the common options of all unit configuration files. The common
+ configuration items are configured in the generic
+ <literal>[Unit]</literal> and <literal>[Install]</literal>
+ sections. A separate <literal>[Device]</literal> section does not
+ exist, since no device-specific options may be configured.</para>
+
+ <para>systemd will dynamically create device units for all kernel
+ devices that are marked with the "systemd" udev tag (by default
+ all block and network devices, and a few others). This may be used
+ to define dependencies between devices and other units. To tag a
+ udev device, use <literal>TAG+="systemd"</literal> in the udev
+ rules file, see
+ <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.</para>
+
+ <para>Device units are named after the <filename>/sys</filename>
+ and <filename>/dev</filename> paths they control. Example: the
+ device <filename noindex='true'>/dev/sda5</filename> is exposed in
+ systemd as <filename>dev-sda5.device</filename>. For details about
+ the escaping logic used to convert a file system path to a unit
+ name see
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+ </refsect1>
+
+ <refsect1>
+ <title>The udev Database</title>
+
+ <para>The settings of device units may either be configured via
+ unit files, or directly from the udev database (which is
+ recommended). The following udev device properties are understood
+ by systemd:</para>
+
+ <variablelist class='udev-directives'>
+ <varlistentry>
+ <term><varname>SYSTEMD_WANTS=</varname></term>
+ <term><varname>SYSTEMD_USER_WANTS=</varname></term>
+ <listitem><para>Adds dependencies of type
+ <varname>Wants</varname> from the device unit to all listed
+ units. The first form is used by the system systemd instance,
+ the second by user systemd instances. Those settings may be
+ used to activate arbitrary units when a specific device
+ becomes available.</para>
+
+ <para>Note that this and the other tags are not taken into
+ account unless the device is tagged with the
+ <literal>systemd</literal> string in the udev database,
+ because otherwise the device is not exposed as a systemd unit
+ (see above).</para>
+
+ <para>Note that systemd will only act on
+ <varname>Wants</varname> dependencies when a device first
+ becomes active. It will not act on them if they are added to
+ devices that are already active. Use
+ <varname>SYSTEMD_READY=</varname> (see below) to influence on
+ which udev event to trigger the dependencies.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SYSTEMD_ALIAS=</varname></term>
+ <listitem><para>Adds an additional alias name to the device
+ unit. This must be an absolute path that is automatically
+ transformed into a unit name. (See above.)</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SYSTEMD_READY=</varname></term>
+ <listitem><para>If set to 0, systemd will consider this device
+ unplugged even if it shows up in the udev tree. If this
+ property is unset or set to 1, the device will be considered
+ plugged if it is visible in the udev tree. This property has
+ no influence on the behavior when a device disappears from the
+ udev tree.</para>
+
+ <para>This option is useful to support devices that initially
+ show up in an uninitialized state in the tree, and for which a
+ <literal>changed</literal> event is generated the moment they
+ are fully set up. Note that <varname>SYSTEMD_WANTS=</varname>
+ (see above) is not acted on as long as
+ <varname>SYSTEMD_READY=0</varname> is set for a
+ device.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ID_MODEL_FROM_DATABASE=</varname></term>
+ <term><varname>ID_MODEL=</varname></term>
+
+ <listitem><para>If set, this property is used as description
+ string for the device unit.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+ </refsect1>
</refentry>
~ianmdlvl / elogind.git / blobdiff