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170 lines
8.0 KiB
XML
170 lines
8.0 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"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 2010 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.device">
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<refentryinfo>
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<title>systemd.device</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.device</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.device</refname>
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<refpurpose>Device unit configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd.device</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>A unit configuration file whose name ends in
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<filename>.device</filename> encodes information about
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a device unit as exposed in the
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sysfs/<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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device tree.</para>
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<para>This unit type has no specific options. See
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for the common options of all unit configuration
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files. The common configuration items are configured
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in the generic <literal>[Unit]</literal> and
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<literal>[Install]</literal> sections. A separate
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<literal>[Device]</literal> section does not exist,
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since no device-specific options may be
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configured.</para>
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<para>systemd will automatically create dynamic device
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units for all kernel devices that are marked with the
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"systemd" udev tag (by default all block and network
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devices, and a few others). This may be used to define
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dependencies between devices and other
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units.</para>
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<para>Device units are named after the
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<filename>/sys</filename> and
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<filename>/dev</filename> paths they control. Example:
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the device <filename>/dev/sda5</filename> is exposed
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in systemd as <filename>dev-sda5.device</filename>. For
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details about the escaping logic used to convert a
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file system path to a unit name see
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>The udev Database</title>
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<para>The settings of device units may either be
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configured via unit files, or directly from the udev
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database (which is recommended). The following udev
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properties are understood by systemd:</para>
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<variablelist class='udev-directives'>
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<varlistentry>
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<term><varname>SYSTEMD_WANTS=</varname></term>
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<listitem><para>Adds dependencies of
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type <varname>Wants</varname> from
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this unit to all listed units. This
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may be used to activate arbitrary
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units, when a specific device becomes
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available. Note that this and the
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other tags are not taken into account
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unless the device is tagged with the
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"<literal>systemd</literal>" string in
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the udev database, because otherwise
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the device is not exposed as systemd
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unit.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SYSTEMD_ALIAS=</varname></term>
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<listitem><para>Adds an additional
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alias name to the device unit. This
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must be an absolute path that is
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automatically transformed into a unit
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name. (See above.)</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SYSTEMD_READY=</varname></term>
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<listitem><para>If set to 0 systemd
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will consider this device unplugged
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even if it shows up in the udev
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tree. If this property is unset or set
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to 1 the device will be considered
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plugged the moment it shows up in the
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udev tree. This property has no
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influence on the behavior when a
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device disappears from the udev
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tree. This option is useful to support
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devices that initially show up in an
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uninitialized state in the tree, and for
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which a changed event is generated the
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moment they are fully set
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up.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>ID_MODEL_FROM_DATABASE=</varname></term>
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<term><varname>ID_MODEL=</varname></term>
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<listitem><para>If set, this property is
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used as description string for the
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device unit.</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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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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