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</style><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="systemd.swap"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd.swap — Swap unit configuration</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename"><em class="replaceable"><code>swap</code></em>.swap</code></p></div><div class="refsect1"><a name="idm140492669368032"></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
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"<code class="literal">.swap</code>" encodes information about a swap device
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or file for memory paging controlled and supervised by
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systemd.</p><p>This man page lists the configuration options specific to
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this unit type. See
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<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
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for the common options of all unit configuration files. The common
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configuration items are configured in the generic [Unit] and
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[Install] sections. The swap specific configuration options are
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configured in the [Swap] section.</p><p>Additional options are listed in
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<a href="systemd.exec.html"><span class="citerefentry"><span class="refentrytitle">systemd.exec</span>(5)</span></a>,
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which define the execution environment the
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<a href="swapon.html"><span class="citerefentry"><span class="refentrytitle">swapon</span>(8)</span></a>
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binary is executed in, and in
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<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>,
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which define the way the processes are terminated, and in
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<a href="systemd.resource-control.html"><span class="citerefentry"><span class="refentrytitle">systemd.resource-control</span>(5)</span></a>,
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which configure resource control settings for the processes of the
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service.</p><p>Swap units must be named after the devices
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or files they control. Example: the swap device
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<code class="filename">/dev/sda5</code> must be configured in a
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unit file <code class="filename">dev-sda5.swap</code>. For details about
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the escaping logic used to convert a file system path to a unit
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name, see
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<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>.</p><p>All swap units automatically get the appropriate
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dependencies on the devices or on the mount points of the files
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they are activated from.</p><p>Swap units with <code class="varname">DefaultDependencies=</code>
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enabled implicitly acquire a conflicting dependency to
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<code class="filename">umount.target</code> so that they are deactivated at
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shutdown.</p></div><div class="refsect1"><a name="idm140492669355712"></a><h2 id="fstab"><code class="filename">fstab</code><a class="headerlink" title="Permalink to this headline" href="#fstab">¶</a></h2><p>Swap units may either be configured via unit files, or via
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<code class="filename">/etc/fstab</code> (see
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<a href="fstab.html"><span class="citerefentry"><span class="refentrytitle">fstab</span>(5)</span></a>
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for details). Swaps listed in <code class="filename">/etc/fstab</code> will
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be converted into native units dynamically at boot and when the
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configuration of the system manager is reloaded. See
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<a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(8)</span></a>
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for details about the conversion.</p><p>If a swap device or file is configured in both
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<code class="filename">/etc/fstab</code> and a unit file, the configuration
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in the latter takes precedence.</p><p>When reading <code class="filename">/etc/fstab</code> a few special
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options are understood by systemd which influence how dependencies
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are created for swap units.</p><div class="variablelist"><dl class="variablelist"><dt id="noauto"><span class="term"><code class="option">noauto</code>, </span><span class="term"><code class="option">auto</code></span><a class="headerlink" title="Permalink to this term" href="#noauto">¶</a></dt><dd><p>With <code class="option">noauto</code> the swap unit
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will not be added as a dependency for
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<code class="filename">swap.target</code>. This means that it will not
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be activated automatically during boot, unless it is pulled in
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by some other unit. Option <code class="option">auto</code> has the
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opposite meaning and is the default.</p></dd><dt id="nofail"><span class="term"><code class="option">nofail</code></span><a class="headerlink" title="Permalink to this term" href="#nofail">¶</a></dt><dd><p>With <code class="option">nofail</code> the swap unit
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will be only wanted, not required by
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<code class="filename">swap.target</code>. This means that the boot
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will continue even if this swap device is not activated
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successfully.</p></dd></dl></div></div><div class="refsect1"><a name="idm140492673239392"></a><h2 id="Options">Options<a class="headerlink" title="Permalink to this headline" href="#Options">¶</a></h2><p>Swap files must include a [Swap] section, which carries
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information about the swap device it supervises. A number of
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options that may be used in this section are shared with other
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unit types. These options are documented in
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<a href="systemd.exec.html"><span class="citerefentry"><span class="refentrytitle">systemd.exec</span>(5)</span></a>
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and
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<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>.
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The options specific to the [Swap] section of swap units are the
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following:</p><div class="variablelist"><dl class="variablelist"><dt id="What="><span class="term"><code class="varname">What=</code></span><a class="headerlink" title="Permalink to this term" href="#What=">¶</a></dt><dd><p>Takes an absolute path of a device node or
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file to use for paging. See
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<a href="swapon.html"><span class="citerefentry"><span class="refentrytitle">swapon</span>(8)</span></a>
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for details. If this refers to a device node, a dependency on
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the respective device unit is automatically created. (See
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<a href="systemd.device.html"><span class="citerefentry"><span class="refentrytitle">systemd.device</span>(5)</span></a>
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for more information.) If this refers to a file, a dependency
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on the respective mount unit is automatically created. (See
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<a href="systemd.mount.html"><span class="citerefentry"><span class="refentrytitle">systemd.mount</span>(5)</span></a>
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for more information.) This option is
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mandatory.</p></dd><dt id="Priority="><span class="term"><code class="varname">Priority=</code></span><a class="headerlink" title="Permalink to this term" href="#Priority=">¶</a></dt><dd><p>Swap priority to use when activating the swap
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device or file. This takes an integer. This setting is
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optional.</p></dd><dt id="Options="><span class="term"><code class="varname">Options=</code></span><a class="headerlink" title="Permalink to this term" href="#Options=">¶</a></dt><dd><p>May contain an option string for the swap
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device. This may be used for controlling discard options among
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other functionality, if the swap backing device supports the
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discard or trim operation. (See
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<a href="swapon.html"><span class="citerefentry"><span class="refentrytitle">swapon</span>(8)</span></a>
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for more information.) </p></dd><dt id="TimeoutSec="><span class="term"><code class="varname">TimeoutSec=</code></span><a class="headerlink" title="Permalink to this term" href="#TimeoutSec=">¶</a></dt><dd><p>Configures the time to wait for the swapon
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command to finish. If a command does not exit within the
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configured time, the swap will be considered failed and be
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shut down again. All commands still running will be terminated
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forcibly via <code class="constant">SIGTERM</code>, and after another
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delay of this time with <code class="constant">SIGKILL</code>. (See
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<code class="option">KillMode=</code> in
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<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>.)
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Takes a unit-less value in seconds, or a time span value such
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as "5min 20s". Pass "<code class="literal">0</code>" to disable the
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timeout logic. Defaults to
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<code class="varname">DefaultTimeoutStartSec=</code> from the manager
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configuration file (see
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<a href="systemd-system.conf.html"><span class="citerefentry"><span class="refentrytitle">systemd-system.conf</span>(5)</span></a>).
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</p></dd></dl></div><p>Check
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<a href="systemd.exec.html"><span class="citerefentry"><span class="refentrytitle">systemd.exec</span>(5)</span></a>
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and
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<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>
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for more settings.</p></div><div class="refsect1"><a name="idm140492673212176"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
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<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
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<a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(1)</span></a>,
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<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>,
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<a href="systemd.exec.html"><span class="citerefentry"><span class="refentrytitle">systemd.exec</span>(5)</span></a>,
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<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>,
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<a href="systemd.resource-control.html"><span class="citerefentry"><span class="refentrytitle">systemd.resource-control</span>(5)</span></a>,
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<a href="systemd.device.html"><span class="citerefentry"><span class="refentrytitle">systemd.device</span>(5)</span></a>,
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<a href="systemd.mount.html"><span class="citerefentry"><span class="refentrytitle">systemd.mount</span>(5)</span></a>,
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<a href="swapon.html"><span class="citerefentry"><span class="refentrytitle">swapon</span>(8)</span></a>,
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<a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(8)</span></a>,
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<a href="systemd.directives.html"><span class="citerefentry"><span class="refentrytitle">systemd.directives</span>(7)</span></a>
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</p></div></div></body></html>
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