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3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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24
25 <refentry id="systemd.swap">
26         <refentryinfo>
27                 <title>systemd.swap</title>
28                 <productname>systemd</productname>
29
30                 <authorgroup>
31                         <author>
32                                 <contrib>Developer</contrib>
33                                 <firstname>Lennart</firstname>
34                                 <surname>Poettering</surname>
35                                 <email>lennart@poettering.net</email>
36                         </author>
37                 </authorgroup>
38         </refentryinfo>
39
40         <refmeta>
41                 <refentrytitle>systemd.swap</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.swap</refname>
47                 <refpurpose>systemd swap configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.swap</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
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>
61
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>
70
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>
78
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>
82
83                 <para>Swap units with
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>
88         </refsect1>
89
90         <refsect1>
91                 <title><filename>fstab</filename></title>
92
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>
96                 for details).</para>
97
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>
101
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
107                 boot.</para>
108         </refsect1>
109
110         <refsect1>
111                 <title>Options</title>
112
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>
121
122                 <variablelist>
123
124                         <varlistentry>
125                                 <term><varname>What=</varname></term>
126                                 <listitem><para>Takes an absolute path
127                                 of a device node or file to use for
128                                 paging. See
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
138                                 created. (See
139                                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
140                                 for more information.) This option is
141                                 mandatory.</para></listitem>
142                         </varlistentry>
143
144                         <varlistentry>
145                                 <term><varname>Priority=</varname></term>
146
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>
151                         </varlistentry>
152
153                         <varlistentry>
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
168                                 logic. Defaults to
169                                 90s.</para></listitem>
170                         </varlistentry>
171
172                         <varlistentry>
173                                 <term><varname>KillMode=</varname></term>
174                                 <listitem><para>Specifies how
175                                 processes of this swap shall be
176                                 killed. One of
177                                 <option>control-group</option>,
178                                 <option>process</option>,
179                                 <option>none</option>.</para>
180
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>
186                         </varlistentry>
187
188                         <varlistentry>
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.
193                                 </para></listitem>
194                         </varlistentry>
195
196                         <varlistentry>
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".
204                                 </para></listitem>
205                         </varlistentry>
206                 </variablelist>
207         </refsect1>
208
209         <refsect1>
210                   <title>See Also</title>
211                   <para>
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>
219                   </para>
220         </refsect1>
221
222 </refentry>