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7 This file is part of systemd.
9 Copyright 2010 Lennart Poettering
11 systemd is free software; you can redistribute it and/or modify it
12 under the terms of the GNU Lesser General Public License as published by
13 the Free Software Foundation; either version 2.1 of the License, or
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25 <refentry id="systemd.swap">
27 <title>systemd.swap</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemd.swap</refentrytitle>
42 <manvolnum>5</manvolnum>
46 <refname>systemd.swap</refname>
47 <refpurpose>systemd swap configuration files</refpurpose>
51 <para><filename>systemd.swap</filename></para>
55 <title>Description</title>
57 <para>A unit configuration file whose name ends in
58 <filename>.swap</filename> encodes information about a
59 swap device or file for memory paging controlled and
60 supervised by systemd.</para>
62 <para>This man page lists the configuration options
63 specific to this unit type. 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. The swap
68 specific configuration options are configured in the
69 [Swap] section.</para>
71 <para>Swap units must be named after the devices
72 (resp. files) they control. Example: the swap device
73 <filename>/dev/sda5</filename> must be configured in a
74 unit file <filename>dev-sda5.swap</filename>. For
75 details about the escaping logic used to convert a
76 file system path to a unit name see
77 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
79 <para>All swap units automatically get the appropriate
80 dependencies on the devices (resp. on the mount points
81 of the files) they are activated from.</para>
84 <varname>DefaultDependencies=</varname> enabled
85 implicitly acquire a conflicting dependency to
86 <filename>umount.target</filename> so that they are
87 deactivated at shutdown.</para>
91 <title><filename>fstab</filename></title>
93 <para>Swap units may either be configured via unit
94 files, or via <filename>/etc/fstab</filename> (see
95 <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
98 <para>If a swap device or file is configured in both
99 <filename>/etc/fstab</filename> and a unit file the
100 configuration in the latter takes precedence.</para>
102 <para>Unless the <option>noauto</option> option is set
103 for them all swap units configured in
104 <filename>/etc/fstab</filename> are also added as
105 requirements to <filename>swap.target</filename>, so
106 that they are waited for and activated during
111 <title>Options</title>
113 <para>Swap files must include a [Swap] section, which
114 carries information about the swap device it
115 supervises. A number of options that may be used in
116 this section are shared with other unit types. These
117 options are documented in
118 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
119 options specific to the [Swap] section of swap units
120 are the following:</para>
125 <term><varname>What=</varname></term>
126 <listitem><para>Takes an absolute path
127 of a device node or file to use for
129 <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
130 for details. If this refers to a
131 device node, a dependency on the
132 respective device unit is
133 automatically created. (See
134 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
135 for more information.) If this refers
136 to a file, a dependency on the
137 respective mount unit is automatically
139 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
140 for more information.) This option is
141 mandatory.</para></listitem>
145 <term><varname>Priority=</varname></term>
147 <listitem><para>Swap priority to use
148 when activating the swap device or
149 file. This takes an integer. This
150 setting is optional.</para></listitem>
154 <term><varname>TimeoutSec=</varname></term>
155 <listitem><para>Configures the time to
156 wait for the swapon command to
157 finish. If a command does not exit
158 within the configured time the swap
159 will be considered failed and be shut
160 down again. All commands still running
161 will be terminated forcibly via
162 SIGTERM, and after another delay of
163 this time with SIGKILL. (See
164 <option>KillMode=</option> below.)
165 Takes a unit-less value in seconds, or
166 a time span value such as "5min
167 20s". Pass 0 to disable the timeout
169 90s.</para></listitem>
173 <term><varname>KillMode=</varname></term>
174 <listitem><para>Specifies how
175 processes of this swap shall be
177 <option>control-group</option>,
178 <option>process</option>,
179 <option>none</option>.</para>
181 <para>This option is mostly equivalent
182 to the <option>KillMode=</option>
183 option of service files. See
184 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
185 for details.</para></listitem>
189 <term><varname>KillSignal=</varname></term>
190 <listitem><para>Specifies which signal
191 to use when killing a process of this
192 swap. Defaults to SIGTERM.
197 <term><varname>SendSIGKILL=</varname></term>
198 <listitem><para>Specifies whether to
199 send SIGKILL to remaining processes
200 after a timeout, if the normal
201 shutdown procedure left processes of
202 the swap around. Takes a boolean
203 value. Defaults to "yes".
210 <title>See Also</title>
212 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
213 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
214 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
215 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
216 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
217 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
218 <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>