systemd/man/systemd.device.html
2014-04-27 12:02:08 +02:00

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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>systemd.device</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 208</span><hr><div class="refentry"><a name="systemd.device"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd.device — Device unit configuration</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename"><em class="replaceable"><code>device</code></em>.device</code></p></div><div class="refsect1"><a name="idm274686387808"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description"></a></h2><p>A unit configuration file whose name ends in
"<code class="literal">.device</code>" encodes information about
a device unit as exposed in the
sysfs/<a href="udev.html"><span class="citerefentry"><span class="refentrytitle">udev</span>(7)</span></a>
device tree.</p><p>This unit type has no specific options. See
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
for the common options of all unit configuration
files. The common configuration items are configured
in the generic "<code class="literal">[Unit]</code>" and
"<code class="literal">[Install]</code>" sections. A separate
"<code class="literal">[Device]</code>" section does not exist,
since no device-specific options may be
configured.</p><p>systemd will automatically create dynamic 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.</p><p>Device units are named after the
<code class="filename">/sys</code> and
<code class="filename">/dev</code> paths they control. Example:
the device <code class="filename">/dev/sda5</code> is exposed
in systemd as <code class="filename">dev-sda5.device</code>. For
details about the escaping logic used to convert a
file system path to a unit name see
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>.</p></div><div class="refsect1"><a name="idm274686250208"></a><h2 id="The udev Database">The udev Database<a class="headerlink" title="Permalink to this headline" href="#The%20udev%20Database"></a></h2><p>The settings of device units may either be
configured via unit files, or directly from the udev
database (which is recommended). The following udev
properties are understood by systemd:</p><div class="variablelist"><dl class="variablelist"><dt id="SYSTEMD_WANTS="><span class="term"><code class="varname">SYSTEMD_WANTS=</code></span><a class="headerlink" title="Permalink to this term" href="#SYSTEMD_WANTS="></a></dt><dd><p>Adds dependencies of
type <code class="varname">Wants</code> from
this unit to all listed units. This
may be used to activate arbitrary
units, when a specific device becomes
available. Note that this and the
other tags are not taken into account
unless the device is tagged with the
"<code class="literal">systemd</code>" string in
the udev database, because otherwise
the device is not exposed as systemd
unit.</p></dd><dt id="SYSTEMD_ALIAS="><span class="term"><code class="varname">SYSTEMD_ALIAS=</code></span><a class="headerlink" title="Permalink to this term" href="#SYSTEMD_ALIAS="></a></dt><dd><p>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.)</p></dd><dt id="SYSTEMD_READY="><span class="term"><code class="varname">SYSTEMD_READY=</code></span><a class="headerlink" title="Permalink to this term" href="#SYSTEMD_READY="></a></dt><dd><p>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 the moment it shows up in the
udev tree. This property has no
influence on the behavior when a
device disappears from the udev
tree. This option is useful to support
devices that initially show up in an
uninitialized state in the tree, and for
which a changed event is generated the
moment they are fully set
up.</p></dd><dt id="ID_MODEL_FROM_DATABASE="><span class="term"><code class="varname">ID_MODEL_FROM_DATABASE=</code>, </span><span class="term"><code class="varname">ID_MODEL=</code></span><a class="headerlink" title="Permalink to this term" href="#ID_MODEL_FROM_DATABASE="></a></dt><dd><p>If set, this property is
used as description string for the
device unit.</p></dd></dl></div></div><div class="refsect1"><a name="idm274686440672"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also"></a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(8)</span></a>,
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>,
<a href="udev.html"><span class="citerefentry"><span class="refentrytitle">udev</span>(7)</span></a>,
<a href="systemd.directives.html"><span class="citerefentry"><span class="refentrytitle">systemd.directives</span>(7)</span></a>
</p></div></div></body></html>