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c129bd5d | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
d1ab0ca0 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
5430f7f2 LP |
11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
d1ab0ca0 LP |
13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
d1ab0ca0 | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
d1ab0ca0 LP |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd.service"> | |
798d3a52 ZJS |
25 | <refentryinfo> |
26 | <title>systemd.service</title> | |
27 | <productname>systemd</productname> | |
28 | ||
29 | <authorgroup> | |
30 | <author> | |
31 | <contrib>Developer</contrib> | |
32 | <firstname>Lennart</firstname> | |
33 | <surname>Poettering</surname> | |
34 | <email>lennart@poettering.net</email> | |
35 | </author> | |
36 | </authorgroup> | |
37 | </refentryinfo> | |
38 | ||
39 | <refmeta> | |
40 | <refentrytitle>systemd.service</refentrytitle> | |
41 | <manvolnum>5</manvolnum> | |
42 | </refmeta> | |
43 | ||
44 | <refnamediv> | |
45 | <refname>systemd.service</refname> | |
46 | <refpurpose>Service unit configuration</refpurpose> | |
47 | </refnamediv> | |
48 | ||
49 | <refsynopsisdiv> | |
50 | <para><filename><replaceable>service</replaceable>.service</filename></para> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
56 | <para>A unit configuration file whose name ends in | |
57 | <filename>.service</filename> encodes information about a process | |
58 | controlled and supervised by systemd.</para> | |
59 | ||
60 | <para>This man page lists the configuration options specific to | |
61 | this unit type. See | |
62 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
63 | for the common options of all unit configuration files. The common | |
64 | configuration items are configured in the generic | |
65 | <literal>[Unit]</literal> and <literal>[Install]</literal> | |
66 | sections. The service specific configuration options are | |
67 | configured in the <literal>[Service]</literal> section.</para> | |
68 | ||
69 | <para>Additional options are listed in | |
70 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
71 | which define the execution environment the commands are executed | |
72 | in, and in | |
73 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
74 | which define the way the processes of the service are terminated, | |
75 | and in | |
76 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
77 | which configure resource control settings for the processes of the | |
78 | service.</para> | |
79 | ||
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80 | <para>If a service is requested under a certain name but no unit |
81 | configuration file is found, systemd looks for a SysV init script | |
82 | by the same name (with the <filename>.service</filename> suffix | |
83 | removed) and dynamically creates a service unit from that script. | |
84 | This is useful for compatibility with SysV. Note that this | |
85 | compatibility is quite comprehensive but not 100%. For details | |
86 | about the incompatibilities, see the <ulink | |
87 | url="http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities">Incompatibilities | |
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88 | with SysV</ulink> document.</para> |
89 | </refsect1> | |
90 | ||
91 | <refsect1> | |
92 | <title>Automatic Dependencies</title> | |
93 | ||
94 | <para>Services with <varname>Type=dbus</varname> set automatically | |
95 | acquire dependencies of type <varname>Requires=</varname> and | |
96 | <varname>After=</varname> on | |
97 | <filename>dbus.socket</filename>.</para> | |
98 | ||
99 | <para>Socket activated service are automatically ordered after | |
100 | their activated <filename>.socket</filename> units via an | |
101 | automatic <varname>After=</varname> dependency.</para> | |
102 | ||
103 | <para>Unless <varname>DefaultDependencies=</varname> is set to | |
104 | <option>false</option>, service units will implicitly have | |
105 | dependencies of type <varname>Requires=</varname> and | |
106 | <varname>After=</varname> on <filename>sysinit.target</filename>, | |
107 | a dependency of type <varname>After=</varname> on | |
108 | <filename>basic.target</filename> as well as dependencies of | |
109 | type <varname>Conflicts=</varname> and <varname>Before=</varname> | |
110 | on <filename>shutdown.target</filename>. These ensure that normal | |
111 | service units pull in basic system initialization, and are | |
112 | terminated cleanly prior to system shutdown. Only services | |
113 | involved with early boot or late system shutdown should disable | |
114 | this option.</para> | |
115 | ||
116 | <para>Additional implicit dependencies may be added as result of | |
117 | execution and resource control parameters as documented in | |
118 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
119 | and | |
120 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
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121 | </refsect1> |
122 | ||
123 | <refsect1> | |
124 | <title>Options</title> | |
125 | ||
126 | <para>Service files must include a <literal>[Service]</literal> | |
127 | section, which carries information about the service and the | |
128 | process it supervises. A number of options that may be used in | |
129 | this section are shared with other unit types. These options are | |
130 | documented in | |
131 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
132 | and | |
133 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
134 | The options specific to the <literal>[Service]</literal> section | |
135 | of service units are the following:</para> | |
136 | ||
137 | <variablelist class='unit-directives'> | |
138 | <varlistentry> | |
139 | <term><varname>Type=</varname></term> | |
140 | ||
141 | <listitem><para>Configures the process start-up type for this | |
142 | service unit. One of | |
143 | <option>simple</option>, | |
144 | <option>forking</option>, | |
145 | <option>oneshot</option>, | |
146 | <option>dbus</option>, | |
147 | <option>notify</option> or | |
148 | <option>idle</option>.</para> | |
149 | ||
150 | <para>If set to <option>simple</option> (the default if | |
151 | neither <varname>Type=</varname> nor | |
152 | <varname>BusName=</varname>, but <varname>ExecStart=</varname> | |
153 | are specified), it is expected that the process configured | |
154 | with <varname>ExecStart=</varname> is the main process of the | |
155 | service. In this mode, if the process offers functionality to | |
156 | other processes on the system, its communication channels | |
157 | should be installed before the daemon is started up (e.g. | |
158 | sockets set up by systemd, via socket activation), as systemd | |
159 | will immediately proceed starting follow-up units.</para> | |
160 | ||
161 | <para>If set to <option>forking</option>, it is expected that | |
162 | the process configured with <varname>ExecStart=</varname> will | |
163 | call <function>fork()</function> as part of its start-up. The | |
164 | parent process is expected to exit when start-up is complete | |
165 | and all communication channels are set up. The child continues | |
166 | to run as the main daemon process. This is the behavior of | |
167 | traditional UNIX daemons. If this setting is used, it is | |
168 | recommended to also use the <varname>PIDFile=</varname> | |
169 | option, so that systemd can identify the main process of the | |
170 | daemon. systemd will proceed with starting follow-up units as | |
171 | soon as the parent process exits.</para> | |
172 | ||
173 | <para>Behavior of <option>oneshot</option> is similar to | |
174 | <option>simple</option>; however, it is expected that the | |
175 | process has to exit before systemd starts follow-up units. | |
176 | <varname>RemainAfterExit=</varname> is particularly useful for | |
177 | this type of service. This is the implied default if neither | |
178 | <varname>Type=</varname> or <varname>ExecStart=</varname> are | |
179 | specified.</para> | |
180 | ||
181 | <para>Behavior of <option>dbus</option> is similar to | |
182 | <option>simple</option>; however, it is expected that the | |
183 | daemon acquires a name on the D-Bus bus, as configured by | |
184 | <varname>BusName=</varname>. systemd will proceed with | |
185 | starting follow-up units after the D-Bus bus name has been | |
186 | acquired. Service units with this option configured implicitly | |
187 | gain dependencies on the <filename>dbus.socket</filename> | |
188 | unit. This type is the default if <varname>BusName=</varname> | |
189 | is specified.</para> | |
190 | ||
191 | <para>Behavior of <option>notify</option> is similar to | |
192 | <option>simple</option>; however, it is expected that the | |
193 | daemon sends a notification message via | |
194 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
195 | or an equivalent call when it has finished starting up. | |
196 | systemd will proceed with starting follow-up units after this | |
197 | notification message has been sent. If this option is used, | |
198 | <varname>NotifyAccess=</varname> (see below) should be set to | |
199 | open access to the notification socket provided by systemd. If | |
200 | <varname>NotifyAccess=</varname> is not set, it will be | |
201 | implicitly set to <option>main</option>. Note that currently | |
202 | <varname>Type=</varname><option>notify</option> will not work | |
203 | if used in combination with | |
204 | <varname>PrivateNetwork=</varname><option>yes</option>.</para> | |
205 | ||
206 | <para>Behavior of <option>idle</option> is very similar to | |
207 | <option>simple</option>; however, actual execution of the | |
208 | service binary is delayed until all jobs are dispatched. This | |
209 | may be used to avoid interleaving of output of shell services | |
210 | with the status output on the console.</para> | |
211 | </listitem> | |
212 | </varlistentry> | |
213 | ||
214 | <varlistentry> | |
215 | <term><varname>RemainAfterExit=</varname></term> | |
216 | ||
217 | <listitem><para>Takes a boolean value that specifies whether | |
218 | the service shall be considered active even when all its | |
219 | processes exited. Defaults to <option>no</option>.</para> | |
220 | </listitem> | |
221 | </varlistentry> | |
222 | ||
223 | <varlistentry> | |
224 | <term><varname>GuessMainPID=</varname></term> | |
225 | ||
226 | <listitem><para>Takes a boolean value that specifies whether | |
227 | systemd should try to guess the main PID of a service if it | |
228 | cannot be determined reliably. This option is ignored unless | |
229 | <option>Type=forking</option> is set and | |
230 | <option>PIDFile=</option> is unset because for the other types | |
231 | or with an explicitly configured PID file, the main PID is | |
232 | always known. The guessing algorithm might come to incorrect | |
233 | conclusions if a daemon consists of more than one process. If | |
234 | the main PID cannot be determined, failure detection and | |
235 | automatic restarting of a service will not work reliably. | |
236 | Defaults to <option>yes</option>.</para> | |
237 | </listitem> | |
238 | </varlistentry> | |
239 | ||
240 | <varlistentry> | |
241 | <term><varname>PIDFile=</varname></term> | |
242 | ||
243 | <listitem><para>Takes an absolute file name pointing to the | |
244 | PID file of this daemon. Use of this option is recommended for | |
245 | services where <varname>Type=</varname> is set to | |
246 | <option>forking</option>. systemd will read the PID of the | |
247 | main process of the daemon after start-up of the service. | |
341db20b FS |
248 | systemd will not write to the file configured here, although |
249 | it will remove the file after the service has shut down if it | |
250 | still exists. | |
251 | </para> | |
798d3a52 ZJS |
252 | </listitem> |
253 | </varlistentry> | |
254 | ||
255 | <varlistentry> | |
256 | <term><varname>BusName=</varname></term> | |
257 | ||
258 | <listitem><para>Takes a D-Bus bus name that this service is | |
259 | reachable as. This option is mandatory for services where | |
260 | <varname>Type=</varname> is set to | |
261 | <option>dbus</option>.</para> | |
262 | </listitem> | |
263 | </varlistentry> | |
264 | ||
265 | <varlistentry> | |
266 | <term><varname>BusPolicy=</varname></term> | |
267 | ||
b8332e7a | 268 | <listitem><para>If specified, a custom kdbus |
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269 | endpoint will be created and installed as the default bus node |
270 | for the service. Such a custom endpoint can hold an own set of | |
271 | policy rules that are enforced on top of the bus-wide ones. | |
272 | The custom endpoint is named after the service it was created | |
273 | for, and its node will be bind-mounted over the default bus | |
274 | node location, so the service can only access the bus through | |
275 | its own endpoint. Note that custom bus endpoints default to a | |
b938cb90 | 276 | "deny all" policy. Hence, if at least one |
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277 | <varname>BusPolicy=</varname> directive is given, you have to |
278 | make sure to add explicit rules for everything the service | |
279 | should be able to do.</para> | |
280 | <para>The value of this directive is comprised | |
281 | of two parts; the bus name, and a verb to | |
282 | specify to granted access, which is one of | |
283 | <option>see</option>, | |
284 | <option>talk</option>, or | |
285 | <option>own</option>. | |
286 | <option>talk</option> implies | |
287 | <option>see</option>, and <option>own</option> | |
288 | implies both <option>talk</option> and | |
289 | <option>see</option>. | |
290 | If multiple access levels are specified for the | |
291 | same bus name, the most powerful one takes | |
292 | effect. | |
293 | </para> | |
294 | <para>Examples:</para> | |
295 | <programlisting>BusPolicy=org.freedesktop.systemd1 talk</programlisting> | |
296 | <programlisting>BusPolicy=org.foo.bar see</programlisting> | |
297 | <para>This option is only available on kdbus enabled systems.</para> | |
298 | </listitem> | |
299 | </varlistentry> | |
300 | ||
301 | <varlistentry> | |
302 | <term><varname>ExecStart=</varname></term> | |
303 | <listitem><para>Commands with their arguments that are | |
304 | executed when this service is started. The value is split into | |
a8eaaee7 | 305 | zero or more command lines according to the rules described |
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306 | below (see section "Command Lines" below). |
307 | </para> | |
308 | ||
22065311 | 309 | <para>When <varname>Type=</varname> is not |
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310 | <option>oneshot</option>, only one command may and must be |
311 | given. When <varname>Type=oneshot</varname> is used, zero or | |
312 | more commands may be specified. This can be specified by | |
313 | providing multiple command lines in the same directive, or | |
314 | alternatively, this directive may be specified more than once | |
315 | with the same effect. If the empty string is assigned to this | |
316 | option, the list of commands to start is reset, prior | |
317 | assignments of this option will have no effect. If no | |
318 | <varname>ExecStart=</varname> is specified, then the service | |
319 | must have <varname>RemainAfterExit=yes</varname> set.</para> | |
320 | ||
321 | <para>For each of the specified commands, the first argument | |
322 | must be an absolute path to an executable. Optionally, if this | |
323 | file name is prefixed with <literal>@</literal>, the second | |
324 | token will be passed as <literal>argv[0]</literal> to the | |
325 | executed process, followed by the further arguments specified. | |
326 | If the absolute filename is prefixed with | |
327 | <literal>-</literal>, an exit code of the command normally | |
328 | considered a failure (i.e. non-zero exit status or abnormal | |
329 | exit due to signal) is ignored and considered success. If both | |
330 | <literal>-</literal> and <literal>@</literal> are used, they | |
331 | can appear in either order.</para> | |
332 | ||
333 | <para>If more than one command is specified, the commands are | |
334 | invoked sequentially in the order they appear in the unit | |
335 | file. If one of the commands fails (and is not prefixed with | |
336 | <literal>-</literal>), other lines are not executed, and the | |
337 | unit is considered failed.</para> | |
338 | ||
339 | <para>Unless <varname>Type=forking</varname> is set, the | |
340 | process started via this command line will be considered the | |
341 | main process of the daemon.</para> | |
342 | </listitem> | |
343 | </varlistentry> | |
344 | ||
345 | <varlistentry> | |
346 | <term><varname>ExecStartPre=</varname></term> | |
347 | <term><varname>ExecStartPost=</varname></term> | |
348 | <listitem><para>Additional commands that are executed before | |
349 | or after the command in <varname>ExecStart=</varname>, | |
350 | respectively. Syntax is the same as for | |
351 | <varname>ExecStart=</varname>, except that multiple command | |
352 | lines are allowed and the commands are executed one after the | |
353 | other, serially.</para> | |
354 | ||
355 | <para>If any of those commands (not prefixed with | |
356 | <literal>-</literal>) fail, the rest are not executed and the | |
357 | unit is considered failed.</para> | |
b481de3b | 358 | |
12e2683d RM |
359 | <para><varname>ExecStart=</varname> commands are only run after |
360 | all <varname>ExecStartPre=</varname> commands that were not prefixed | |
361 | with a <literal>-</literal> exit successfully.</para> | |
362 | ||
363 | <para><varname>ExecStartPost=</varname> commands are only run after | |
364 | the service has started, as determined by <varname>Type=</varname> | |
a8eaaee7 | 365 | (i.e. the process has been started for <varname>Type=simple</varname> |
12e2683d RM |
366 | or <varname>Type=idle</varname>, the process exits successfully for |
367 | <varname>Type=oneshot</varname>, the initial process exits successfully | |
368 | for <varname>Type=forking</varname>, <literal>READY=1</literal> is sent | |
369 | for <varname>Type=notify</varname>, or the <varname>BusName=</varname> | |
370 | has been taken for <varname>Type=dbus</varname>).</para> | |
371 | ||
b481de3b LP |
372 | <para>Note that <varname>ExecStartPre=</varname> may not be |
373 | used to start long-running processes. All processes forked | |
374 | off by processes invoked via <varname>ExecStartPre=</varname> will | |
375 | be killed before the next service process is run.</para> | |
798d3a52 ZJS |
376 | </listitem> |
377 | </varlistentry> | |
378 | ||
379 | <varlistentry> | |
380 | <term><varname>ExecReload=</varname></term> | |
381 | <listitem><para>Commands to execute to trigger a configuration | |
382 | reload in the service. This argument takes multiple command | |
383 | lines, following the same scheme as described for | |
384 | <varname>ExecStart=</varname> above. Use of this setting is | |
385 | optional. Specifier and environment variable substitution is | |
386 | supported here following the same scheme as for | |
387 | <varname>ExecStart=</varname>.</para> | |
388 | ||
389 | <para>One additional, special environment variable is set: if | |
390 | known, <varname>$MAINPID</varname> is set to the main process | |
391 | of the daemon, and may be used for command lines like the | |
392 | following:</para> | |
393 | ||
394 | <programlisting>/bin/kill -HUP $MAINPID</programlisting> | |
395 | ||
396 | <para>Note however that reloading a daemon by sending a signal | |
397 | (as with the example line above) is usually not a good choice, | |
398 | because this is an asynchronous operation and hence not | |
399 | suitable to order reloads of multiple services against each | |
400 | other. It is strongly recommended to set | |
401 | <varname>ExecReload=</varname> to a command that not only | |
402 | triggers a configuration reload of the daemon, but also | |
403 | synchronously waits for it to complete.</para> | |
404 | </listitem> | |
405 | </varlistentry> | |
406 | ||
407 | <varlistentry> | |
408 | <term><varname>ExecStop=</varname></term> | |
409 | <listitem><para>Commands to execute to stop the service | |
410 | started via <varname>ExecStart=</varname>. This argument takes | |
411 | multiple command lines, following the same scheme as described | |
412 | for <varname>ExecStart=</varname> above. Use of this setting | |
413 | is optional. After the commands configured in this option are | |
414 | run, all processes remaining for a service are terminated | |
415 | according to the <varname>KillMode=</varname> setting (see | |
416 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
cceb20c7 LP |
417 | If this option is not specified, the process is terminated by |
418 | sending the signal specified in <varname>KillSignal=</varname> | |
419 | when service stop is requested. Specifier and environment | |
420 | variable substitution is supported (including | |
421 | <varname>$MAINPID</varname>, see above).</para> | |
422 | ||
423 | <para>Note that it is usually not sufficient to specify a | |
424 | command for this setting that only asks the service to | |
b938cb90 | 425 | terminate (for example, by queuing some form of termination |
cceb20c7 LP |
426 | signal for it), but does not wait for it to do so. Since the |
427 | remaining processes of the services are killed using | |
428 | <constant>SIGKILL</constant> immediately after the command | |
b938cb90 | 429 | exited, this would not result in a clean stop. The specified |
cceb20c7 LP |
430 | command should hence be a synchronous operation, not an |
431 | asynchronous one.</para></listitem> | |
798d3a52 ZJS |
432 | </varlistentry> |
433 | ||
434 | <varlistentry> | |
435 | <term><varname>ExecStopPost=</varname></term> | |
436 | <listitem><para>Additional commands that are executed after | |
437 | the service was stopped. This includes cases where the | |
438 | commands configured in <varname>ExecStop=</varname> were used, | |
439 | where the service does not have any | |
440 | <varname>ExecStop=</varname> defined, or where the service | |
441 | exited unexpectedly. This argument takes multiple command | |
442 | lines, following the same scheme as described for | |
22065311 | 443 | <varname>ExecStart=</varname>. Use of these settings is |
798d3a52 ZJS |
444 | optional. Specifier and environment variable substitution is |
445 | supported.</para></listitem> | |
446 | </varlistentry> | |
447 | ||
448 | <varlistentry> | |
449 | <term><varname>RestartSec=</varname></term> | |
450 | <listitem><para>Configures the time to sleep before restarting | |
451 | a service (as configured with <varname>Restart=</varname>). | |
452 | Takes a unit-less value in seconds, or a time span value such | |
453 | as "5min 20s". Defaults to 100ms.</para></listitem> | |
454 | </varlistentry> | |
455 | ||
456 | <varlistentry> | |
457 | <term><varname>TimeoutStartSec=</varname></term> | |
458 | <listitem><para>Configures the time to wait for start-up. If a | |
459 | daemon service does not signal start-up completion within the | |
460 | configured time, the service will be considered failed and | |
461 | will be shut down again. Takes a unit-less value in seconds, | |
462 | or a time span value such as "5min 20s". Pass | |
463 | <literal>0</literal> to disable the timeout logic. Defaults to | |
464 | <varname>DefaultTimeoutStartSec=</varname> from the manager | |
465 | configuration file, except when | |
466 | <varname>Type=oneshot</varname> is used, in which case the | |
467 | timeout is disabled by default (see | |
468 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
469 | </para></listitem> | |
470 | </varlistentry> | |
471 | ||
472 | <varlistentry> | |
473 | <term><varname>TimeoutStopSec=</varname></term> | |
474 | <listitem><para>Configures the time to wait for stop. If a | |
475 | service is asked to stop, but does not terminate in the | |
476 | specified time, it will be terminated forcibly via | |
477 | <constant>SIGTERM</constant>, and after another timeout of | |
478 | equal duration with <constant>SIGKILL</constant> (see | |
479 | <varname>KillMode=</varname> in | |
480 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
481 | Takes a unit-less value in seconds, or a time span value such | |
482 | as "5min 20s". Pass <literal>0</literal> to disable the | |
483 | timeout logic. Defaults to | |
484 | <varname>DefaultTimeoutStopSec=</varname> from the manager | |
485 | configuration file (see | |
486 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>). | |
487 | </para></listitem> | |
488 | </varlistentry> | |
489 | ||
490 | <varlistentry> | |
491 | <term><varname>TimeoutSec=</varname></term> | |
492 | <listitem><para>A shorthand for configuring both | |
493 | <varname>TimeoutStartSec=</varname> and | |
494 | <varname>TimeoutStopSec=</varname> to the specified value. | |
495 | </para></listitem> | |
496 | </varlistentry> | |
497 | ||
498 | <varlistentry> | |
499 | <term><varname>WatchdogSec=</varname></term> | |
500 | <listitem><para>Configures the watchdog timeout for a service. | |
501 | The watchdog is activated when the start-up is completed. The | |
502 | service must call | |
503 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
504 | regularly with <literal>WATCHDOG=1</literal> (i.e. the | |
505 | "keep-alive ping"). If the time between two such calls is | |
506 | larger than the configured time, then the service is placed in | |
507 | a failed state and it will be terminated with | |
22065311 | 508 | <constant>SIGABRT</constant>. By setting |
798d3a52 ZJS |
509 | <varname>Restart=</varname> to <option>on-failure</option> or |
510 | <option>always</option>, the service will be automatically | |
511 | restarted. The time configured here will be passed to the | |
512 | executed service process in the | |
513 | <varname>WATCHDOG_USEC=</varname> environment variable. This | |
514 | allows daemons to automatically enable the keep-alive pinging | |
515 | logic if watchdog support is enabled for the service. If this | |
516 | option is used, <varname>NotifyAccess=</varname> (see below) | |
517 | should be set to open access to the notification socket | |
518 | provided by systemd. If <varname>NotifyAccess=</varname> is | |
519 | not set, it will be implicitly set to <option>main</option>. | |
520 | Defaults to 0, which disables this feature.</para></listitem> | |
521 | </varlistentry> | |
522 | ||
523 | <varlistentry> | |
524 | <term><varname>Restart=</varname></term> | |
525 | <listitem><para>Configures whether the service shall be | |
526 | restarted when the service process exits, is killed, or a | |
527 | timeout is reached. The service process may be the main | |
528 | service process, but it may also be one of the processes | |
529 | specified with <varname>ExecStartPre=</varname>, | |
530 | <varname>ExecStartPost=</varname>, | |
531 | <varname>ExecStop=</varname>, | |
532 | <varname>ExecStopPost=</varname>, or | |
533 | <varname>ExecReload=</varname>. When the death of the process | |
534 | is a result of systemd operation (e.g. service stop or | |
535 | restart), the service will not be restarted. Timeouts include | |
536 | missing the watchdog "keep-alive ping" deadline and a service | |
537 | start, reload, and stop operation timeouts.</para> | |
538 | ||
539 | <para>Takes one of | |
540 | <option>no</option>, | |
541 | <option>on-success</option>, | |
542 | <option>on-failure</option>, | |
543 | <option>on-abnormal</option>, | |
544 | <option>on-watchdog</option>, | |
545 | <option>on-abort</option>, or | |
546 | <option>always</option>. | |
547 | If set to <option>no</option> (the default), the service will | |
548 | not be restarted. If set to <option>on-success</option>, it | |
549 | will be restarted only when the service process exits cleanly. | |
550 | In this context, a clean exit means an exit code of 0, or one | |
551 | of the signals | |
552 | <constant>SIGHUP</constant>, | |
553 | <constant>SIGINT</constant>, | |
554 | <constant>SIGTERM</constant> or | |
555 | <constant>SIGPIPE</constant>, and | |
556 | additionally, exit statuses and signals specified in | |
557 | <varname>SuccessExitStatus=</varname>. If set to | |
558 | <option>on-failure</option>, the service will be restarted | |
559 | when the process exits with a non-zero exit code, is | |
560 | terminated by a signal (including on core dump, but excluding | |
ff9b60f3 | 561 | the aforementioned four signals), when an operation (such as |
798d3a52 ZJS |
562 | service reload) times out, and when the configured watchdog |
563 | timeout is triggered. If set to <option>on-abnormal</option>, | |
564 | the service will be restarted when the process is terminated | |
565 | by a signal (including on core dump, excluding the | |
566 | aforementioned four signals), when an operation times out, or | |
567 | when the watchdog timeout is triggered. If set to | |
568 | <option>on-abort</option>, the service will be restarted only | |
569 | if the service process exits due to an uncaught signal not | |
570 | specified as a clean exit status. If set to | |
571 | <option>on-watchdog</option>, the service will be restarted | |
572 | only if the watchdog timeout for the service expires. If set | |
573 | to <option>always</option>, the service will be restarted | |
574 | regardless of whether it exited cleanly or not, got terminated | |
575 | abnormally by a signal, or hit a timeout.</para> | |
576 | ||
577 | <table> | |
578 | <title>Exit causes and the effect of the <varname>Restart=</varname> settings on them</title> | |
579 | ||
580 | <tgroup cols='2'> | |
581 | <colspec colname='path' /> | |
582 | <colspec colname='expl' /> | |
583 | <thead> | |
584 | <row> | |
585 | <entry>Restart settings/Exit causes</entry> | |
586 | <entry><option>no</option></entry> | |
587 | <entry><option>always</option></entry> | |
588 | <entry><option>on-success</option></entry> | |
589 | <entry><option>on-failure</option></entry> | |
590 | <entry><option>on-abnormal</option></entry> | |
591 | <entry><option>on-abort</option></entry> | |
592 | <entry><option>on-watchdog</option></entry> | |
593 | </row> | |
594 | </thead> | |
595 | <tbody> | |
596 | <row> | |
597 | <entry>Clean exit code or signal</entry> | |
598 | <entry/> | |
599 | <entry>X</entry> | |
600 | <entry>X</entry> | |
601 | <entry/> | |
602 | <entry/> | |
603 | <entry/> | |
604 | <entry/> | |
605 | </row> | |
606 | <row> | |
607 | <entry>Unclean exit code</entry> | |
608 | <entry/> | |
609 | <entry>X</entry> | |
610 | <entry/> | |
611 | <entry>X</entry> | |
612 | <entry/> | |
613 | <entry/> | |
614 | <entry/> | |
615 | </row> | |
616 | <row> | |
617 | <entry>Unclean signal</entry> | |
618 | <entry/> | |
619 | <entry>X</entry> | |
620 | <entry/> | |
621 | <entry>X</entry> | |
622 | <entry>X</entry> | |
623 | <entry>X</entry> | |
624 | <entry/> | |
625 | </row> | |
626 | <row> | |
627 | <entry>Timeout</entry> | |
628 | <entry/> | |
629 | <entry>X</entry> | |
630 | <entry/> | |
631 | <entry>X</entry> | |
632 | <entry>X</entry> | |
633 | <entry/> | |
634 | <entry/> | |
635 | </row> | |
636 | <row> | |
637 | <entry>Watchdog</entry> | |
638 | <entry/> | |
639 | <entry>X</entry> | |
640 | <entry/> | |
641 | <entry>X</entry> | |
642 | <entry>X</entry> | |
643 | <entry/> | |
644 | <entry>X</entry> | |
645 | </row> | |
646 | </tbody> | |
647 | </tgroup> | |
648 | </table> | |
649 | ||
b938cb90 | 650 | <para>As exceptions to the setting above, the service will not |
798d3a52 ZJS |
651 | be restarted if the exit code or signal is specified in |
652 | <varname>RestartPreventExitStatus=</varname> (see below). | |
653 | Also, the services will always be restarted if the exit code | |
654 | or signal is specified in | |
655 | <varname>RestartForceExitStatus=</varname> (see below).</para> | |
656 | ||
657 | <para>Setting this to <option>on-failure</option> is the | |
658 | recommended choice for long-running services, in order to | |
659 | increase reliability by attempting automatic recovery from | |
660 | errors. For services that shall be able to terminate on their | |
661 | own choice (and avoid immediate restarting), | |
662 | <option>on-abnormal</option> is an alternative choice.</para> | |
663 | </listitem> | |
664 | </varlistentry> | |
665 | ||
666 | <varlistentry> | |
667 | <term><varname>SuccessExitStatus=</varname></term> | |
b938cb90 JE |
668 | <listitem><para>Takes a list of exit status definitions that, |
669 | when returned by the main service process, will be considered | |
798d3a52 ZJS |
670 | successful termination, in addition to the normal successful |
671 | exit code 0 and the signals <constant>SIGHUP</constant>, | |
672 | <constant>SIGINT</constant>, <constant>SIGTERM</constant>, and | |
673 | <constant>SIGPIPE</constant>. Exit status definitions can | |
674 | either be numeric exit codes or termination signal names, | |
675 | separated by spaces. For example: | |
676 | <programlisting>SuccessExitStatus=1 2 8 | |
677 | SIGKILL</programlisting> ensures that exit codes 1, 2, 8 and | |
678 | the termination signal <constant>SIGKILL</constant> are | |
679 | considered clean service terminations. | |
680 | </para> | |
681 | ||
682 | <para>Note that if a process has a signal handler installed | |
683 | and exits by calling | |
684 | <citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
685 | in response to a signal, the information about the signal is | |
686 | lost. Programs should instead perform cleanup and kill | |
687 | themselves with the same signal instead. See | |
688 | <ulink url="http://www.cons.org/cracauer/sigint.html">Proper | |
689 | handling of SIGINT/SIGQUIT — How to be a proper | |
690 | program</ulink>.</para> | |
691 | ||
692 | <para>This option may appear more than once, in which case the | |
693 | list of successful exit statuses is merged. If the empty | |
694 | string is assigned to this option, the list is reset, all | |
695 | prior assignments of this option will have no | |
696 | effect.</para></listitem> | |
697 | </varlistentry> | |
698 | ||
699 | <varlistentry> | |
700 | <term><varname>RestartPreventExitStatus=</varname></term> | |
b938cb90 JE |
701 | <listitem><para>Takes a list of exit status definitions that, |
702 | when returned by the main service process, will prevent | |
798d3a52 ZJS |
703 | automatic service restarts, regardless of the restart setting |
704 | configured with <varname>Restart=</varname>. Exit status | |
705 | definitions can either be numeric exit codes or termination | |
706 | signal names, and are separated by spaces. Defaults to the | |
707 | empty list, so that, by default, no exit status is excluded | |
708 | from the configured restart logic. For example: | |
709 | <programlisting>RestartPreventExitStatus=1 6 | |
710 | SIGABRT</programlisting> ensures that exit codes 1 and 6 and | |
711 | the termination signal <constant>SIGABRT</constant> will not | |
712 | result in automatic service restarting. This option may appear | |
713 | more than once, in which case the list of restart-preventing | |
714 | statuses is merged. If the empty string is assigned to this | |
715 | option, the list is reset and all prior assignments of this | |
716 | option will have no effect.</para></listitem> | |
717 | </varlistentry> | |
718 | ||
719 | <varlistentry> | |
720 | <term><varname>RestartForceExitStatus=</varname></term> | |
b938cb90 JE |
721 | <listitem><para>Takes a list of exit status definitions that, |
722 | when returned by the main service process, will force automatic | |
798d3a52 ZJS |
723 | service restarts, regardless of the restart setting configured |
724 | with <varname>Restart=</varname>. The argument format is | |
725 | similar to | |
726 | <varname>RestartPreventExitStatus=</varname>.</para></listitem> | |
727 | </varlistentry> | |
728 | ||
729 | <varlistentry> | |
730 | <term><varname>PermissionsStartOnly=</varname></term> | |
731 | <listitem><para>Takes a boolean argument. If true, the | |
732 | permission-related execution options, as configured with | |
733 | <varname>User=</varname> and similar options (see | |
734 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
735 | for more information), are only applied to the process started | |
736 | with | |
737 | <varname>ExecStart=</varname>, and not to the various other | |
738 | <varname>ExecStartPre=</varname>, | |
739 | <varname>ExecStartPost=</varname>, | |
740 | <varname>ExecReload=</varname>, | |
741 | <varname>ExecStop=</varname>, and | |
742 | <varname>ExecStopPost=</varname> | |
743 | commands. If false, the setting is applied to all configured | |
744 | commands the same way. Defaults to false.</para></listitem> | |
745 | </varlistentry> | |
746 | ||
747 | <varlistentry> | |
748 | <term><varname>RootDirectoryStartOnly=</varname></term> | |
749 | <listitem><para>Takes a boolean argument. If true, the root | |
750 | directory, as configured with the | |
751 | <varname>RootDirectory=</varname> option (see | |
752 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
753 | for more information), is only applied to the process started | |
754 | with <varname>ExecStart=</varname>, and not to the various | |
755 | other <varname>ExecStartPre=</varname>, | |
756 | <varname>ExecStartPost=</varname>, | |
757 | <varname>ExecReload=</varname>, <varname>ExecStop=</varname>, | |
758 | and <varname>ExecStopPost=</varname> commands. If false, the | |
759 | setting is applied to all configured commands the same way. | |
760 | Defaults to false.</para></listitem> | |
761 | </varlistentry> | |
762 | ||
763 | <varlistentry> | |
764 | <term><varname>NonBlocking=</varname></term> | |
765 | <listitem><para>Set the <constant>O_NONBLOCK</constant> flag | |
766 | for all file descriptors passed via socket-based activation. | |
767 | If true, all file descriptors >= 3 (i.e. all except stdin, | |
768 | stdout, and stderr) will have the | |
769 | <constant>O_NONBLOCK</constant> flag set and hence are in | |
770 | non-blocking mode. This option is only useful in conjunction | |
771 | with a socket unit, as described in | |
772 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
773 | Defaults to false.</para></listitem> | |
774 | </varlistentry> | |
775 | ||
776 | <varlistentry> | |
777 | <term><varname>NotifyAccess=</varname></term> | |
778 | <listitem><para>Controls access to the service status | |
779 | notification socket, as accessible via the | |
780 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
781 | call. Takes one of <option>none</option> (the default), | |
782 | <option>main</option> or <option>all</option>. If | |
783 | <option>none</option>, no daemon status updates are accepted | |
784 | from the service processes, all status update messages are | |
785 | ignored. If <option>main</option>, only service updates sent | |
786 | from the main process of the service are accepted. If | |
787 | <option>all</option>, all services updates from all members of | |
788 | the service's control group are accepted. This option should | |
789 | be set to open access to the notification socket when using | |
790 | <varname>Type=notify</varname> or | |
791 | <varname>WatchdogSec=</varname> (see above). If those options | |
792 | are used but <varname>NotifyAccess=</varname> is not | |
793 | configured, it will be implicitly set to | |
794 | <option>main</option>.</para></listitem> | |
795 | </varlistentry> | |
796 | ||
797 | <varlistentry> | |
798 | <term><varname>Sockets=</varname></term> | |
799 | <listitem><para>Specifies the name of the socket units this | |
800 | service shall inherit socket file descriptors from when the | |
b938cb90 JE |
801 | service is started. Normally, it should not be necessary to use |
802 | this setting, as all socket file descriptors whose unit shares | |
798d3a52 ZJS |
803 | the same name as the service (subject to the different unit |
804 | name suffix of course) are passed to the spawned | |
805 | process.</para> | |
806 | ||
807 | <para>Note that the same socket file descriptors may be passed | |
808 | to multiple processes simultaneously. Also note that a | |
809 | different service may be activated on incoming socket traffic | |
810 | than the one which is ultimately configured to inherit the | |
b938cb90 | 811 | socket file descriptors. Or, in other words: the |
798d3a52 ZJS |
812 | <varname>Service=</varname> setting of |
813 | <filename>.socket</filename> units does not have to match the | |
814 | inverse of the <varname>Sockets=</varname> setting of the | |
815 | <filename>.service</filename> it refers to.</para> | |
816 | ||
817 | <para>This option may appear more than once, in which case the | |
818 | list of socket units is merged. If the empty string is | |
819 | assigned to this option, the list of sockets is reset, and all | |
820 | prior uses of this setting will have no | |
821 | effect.</para></listitem> | |
822 | </varlistentry> | |
823 | ||
824 | <varlistentry> | |
825 | <term><varname>StartLimitInterval=</varname></term> | |
826 | <term><varname>StartLimitBurst=</varname></term> | |
827 | ||
828 | <listitem><para>Configure service start rate limiting. By | |
829 | default, services which are started more than 5 times within | |
830 | 10 seconds are not permitted to start any more times until the | |
831 | 10 second interval ends. With these two options, this rate | |
832 | limiting may be modified. Use | |
833 | <varname>StartLimitInterval=</varname> to configure the | |
834 | checking interval (defaults to | |
835 | <varname>DefaultStartLimitInterval=</varname> in manager | |
836 | configuration file, set to 0 to disable any kind of rate | |
837 | limiting). Use <varname>StartLimitBurst=</varname> to | |
838 | configure how many starts per interval are allowed (defaults | |
839 | to <varname>DefaultStartLimitBurst=</varname> in manager | |
840 | configuration file). These configuration options are | |
841 | particularly useful in conjunction with | |
842 | <varname>Restart=</varname>; however, they apply to all kinds | |
843 | of starts (including manual), not just those triggered by the | |
844 | <varname>Restart=</varname> logic. Note that units which are | |
845 | configured for <varname>Restart=</varname> and which reach the | |
846 | start limit are not attempted to be restarted anymore; | |
847 | however, they may still be restarted manually at a later | |
848 | point, from which point on, the restart logic is again | |
849 | activated. Note that <command>systemctl reset-failed</command> | |
850 | will cause the restart rate counter for a service to be | |
851 | flushed, which is useful if the administrator wants to | |
852 | manually start a service and the start limit interferes with | |
853 | that.</para></listitem> | |
854 | </varlistentry> | |
855 | ||
856 | <varlistentry> | |
857 | <term><varname>StartLimitAction=</varname></term> | |
858 | ||
859 | <listitem><para>Configure the action to take if the rate limit | |
860 | configured with <varname>StartLimitInterval=</varname> and | |
861 | <varname>StartLimitBurst=</varname> is hit. Takes one of | |
862 | <option>none</option>, | |
863 | <option>reboot</option>, | |
864 | <option>reboot-force</option>, | |
865 | <option>reboot-immediate</option>, | |
866 | <option>poweroff</option>, | |
867 | <option>poweroff-force</option> or | |
868 | <option>poweroff-immediate</option>. If | |
869 | <option>none</option> is set, hitting the rate limit will | |
870 | trigger no action besides that the start will not be | |
871 | permitted. <option>reboot</option> causes a reboot following | |
872 | the normal shutdown procedure (i.e. equivalent to | |
873 | <command>systemctl reboot</command>). | |
874 | <option>reboot-force</option> causes a forced reboot which | |
875 | will terminate all processes forcibly but should cause no | |
876 | dirty file systems on reboot (i.e. equivalent to | |
877 | <command>systemctl reboot -f</command>) and | |
878 | <option>reboot-immediate</option> causes immediate execution | |
879 | of the | |
880 | <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
a8eaaee7 | 881 | system call, which might result in data loss. Similarly, |
798d3a52 ZJS |
882 | <option>poweroff</option>, <option>poweroff-force</option>, |
883 | <option>poweroff-immediate</option> have the effect of | |
884 | powering down the system with similar semantics. Defaults to | |
885 | <option>none</option>.</para></listitem> | |
886 | </varlistentry> | |
887 | ||
888 | <varlistentry> | |
889 | <term><varname>FailureAction=</varname></term> | |
890 | <listitem><para>Configure the action to take when the service | |
891 | enters a failed state. Takes the same values as | |
892 | <varname>StartLimitAction=</varname> and executes the same | |
893 | actions. Defaults to <option>none</option>. </para></listitem> | |
894 | </varlistentry> | |
895 | ||
896 | <varlistentry> | |
897 | <term><varname>RebootArgument=</varname></term> | |
898 | <listitem><para>Configure the optional argument for the | |
899 | <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
900 | system call if <varname>StartLimitAction=</varname> or | |
901 | <varname>FailureAction=</varname> is a reboot action. This | |
902 | works just like the optional argument to <command>systemctl | |
903 | reboot</command> command.</para></listitem> | |
904 | </varlistentry> | |
905 | ||
906 | <varlistentry> | |
907 | <term><varname>FileDescriptorStoreMax=</varname></term> | |
908 | <listitem><para>Configure how many file descriptors may be | |
909 | stored in the service manager for the service using | |
910 | <citerefentry><refentrytitle>sd_pid_notify_with_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s | |
911 | <literal>FDSTORE=1</literal> messages. This is useful for | |
912 | implementing service restart schemes where the state is | |
913 | serialized to <filename>/run</filename> and the file | |
914 | descriptors passed to the service manager, to allow restarts | |
915 | without losing state. Defaults to 0, i.e. no file descriptors | |
916 | may be stored in the service manager by default. All file | |
917 | descriptors passed to the service manager from a specific | |
918 | service are passed back to the service's main process on the | |
919 | next service restart. Any file descriptors passed to the | |
920 | service manager are automatically closed when POLLHUP or | |
921 | POLLERR is seen on them, or when the service is fully stopped | |
922 | and no job queued or being executed for it.</para></listitem> | |
923 | </varlistentry> | |
924 | ||
8c7c9839 PS |
925 | <varlistentry> |
926 | <term><varname>USBFunctionDescriptors=</varname></term> | |
3d314510 LP |
927 | <listitem><para>Configure the location of a file containing |
928 | <ulink | |
929 | url="https://www.kernel.org/doc/Documentation/usb/functionfs.txt">USB | |
930 | FunctionFS</ulink> descriptors, for implementation of USB | |
a8eaaee7 | 931 | gadget functions. This is used only in conjunction with a |
3d314510 | 932 | socket unit with <varname>ListenUSBFunction=</varname> |
a8eaaee7 | 933 | configured. The contents of this file are written to the |
3d314510 LP |
934 | <filename>ep0</filename> file after it is |
935 | opened.</para></listitem> | |
8c7c9839 PS |
936 | </varlistentry> |
937 | ||
938 | <varlistentry> | |
939 | <term><varname>USBFunctionStrings=</varname></term> | |
3d314510 LP |
940 | <listitem><para>Configure the location of a file containing |
941 | USB FunctionFS strings. Behavior is similar to | |
942 | <varname>USBFunctionDescriptors=</varname> | |
943 | above.</para></listitem> | |
8c7c9839 PS |
944 | </varlistentry> |
945 | ||
798d3a52 ZJS |
946 | </variablelist> |
947 | ||
948 | <para>Check | |
949 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
950 | and | |
951 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
952 | for more settings.</para> | |
953 | ||
954 | </refsect1> | |
955 | ||
956 | <refsect1> | |
957 | <title>Command lines</title> | |
958 | ||
959 | <para>This section describes command line parsing and | |
ff9b60f3 | 960 | variable and specifier substitutions for |
798d3a52 ZJS |
961 | <varname>ExecStart=</varname>, |
962 | <varname>ExecStartPre=</varname>, | |
963 | <varname>ExecStartPost=</varname>, | |
964 | <varname>ExecReload=</varname>, | |
965 | <varname>ExecStop=</varname>, and | |
966 | <varname>ExecStopPost=</varname> options.</para> | |
967 | ||
968 | <para>Multiple command lines may be concatenated in a single | |
969 | directive by separating them with semicolons (these semicolons | |
970 | must be passed as separate words). Lone semicolons may be escaped | |
971 | as <literal>\;</literal>.</para> | |
972 | ||
973 | <para>Each command line is split on whitespace, with the first | |
974 | item being the command to execute, and the subsequent items being | |
975 | the arguments. Double quotes ("...") and single quotes ('...') may | |
976 | be used, in which case everything until the next matching quote | |
977 | becomes part of the same argument. C-style escapes are also | |
388a91b0 ZJS |
978 | supported. The table below contains the list of allowed escape |
979 | patterns. Only patterns which match the syntax in the table are | |
980 | allowed; others will result in an error, and must be escaped by | |
981 | doubling the backslash. Quotes themselves are removed after | |
798d3a52 ZJS |
982 | parsing and escape sequences substituted. In addition, a trailing |
983 | backslash (<literal>\</literal>) may be used to merge lines. | |
984 | </para> | |
985 | ||
986 | <para>This syntax is intended to be very similar to shell syntax, | |
987 | but only the meta-characters and expansions described in the | |
988 | following paragraphs are understood. Specifically, redirection | |
989 | using | |
990 | <literal><</literal>, | |
991 | <literal><<</literal>, | |
992 | <literal>></literal>, and | |
993 | <literal>>></literal>, pipes using | |
994 | <literal>|</literal>, running programs in the background using | |
995 | <literal>&</literal>, and <emphasis>other elements of shell | |
996 | syntax are not supported</emphasis>.</para> | |
997 | ||
388a91b0 | 998 | <para>The command to execute must be an absolute path name. It may |
798d3a52 ZJS |
999 | contain spaces, but control characters are not allowed.</para> |
1000 | ||
1001 | <para>The command line accepts <literal>%</literal> specifiers as | |
1002 | described in | |
1003 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
1004 | Note that the first argument of the command line (i.e. the program | |
1005 | to execute) may not include specifiers.</para> | |
1006 | ||
1007 | <para>Basic environment variable substitution is supported. Use | |
1008 | <literal>${FOO}</literal> as part of a word, or as a word of its | |
1009 | own, on the command line, in which case it will be replaced by the | |
1010 | value of the environment variable including all whitespace it | |
1011 | contains, resulting in a single argument. Use | |
1012 | <literal>$FOO</literal> as a separate word on the command line, in | |
1013 | which case it will be replaced by the value of the environment | |
b938cb90 | 1014 | variable split at whitespace, resulting in zero or more arguments. |
3faf145d | 1015 | For this type of expansion, quotes are respected when splitting |
798d3a52 ZJS |
1016 | into words, and afterwards removed.</para> |
1017 | ||
1018 | <para>Example:</para> | |
1019 | ||
1020 | <programlisting>Environment="ONE=one" 'TWO=two two' | |
5d9a2698 ZJS |
1021 | ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting> |
1022 | ||
798d3a52 ZJS |
1023 | <para>This will execute <command>/bin/echo</command> with four |
1024 | arguments: <literal>one</literal>, <literal>two</literal>, | |
1025 | <literal>two</literal>, and <literal>two two</literal>.</para> | |
5d9a2698 | 1026 | |
798d3a52 ZJS |
1027 | <para>Example:</para> |
1028 | <programlisting>Environment=ONE='one' "TWO='two two' too" THREE= | |
5d9a2698 ZJS |
1029 | ExecStart=/bin/echo ${ONE} ${TWO} ${THREE} |
1030 | ExecStart=/bin/echo $ONE $TWO $THREE</programlisting> | |
798d3a52 ZJS |
1031 | <para>This results in <filename>echo</filename> being |
1032 | called twice, the first time with arguments | |
1033 | <literal>'one'</literal>, | |
1034 | <literal>'two two' too</literal>, <literal></literal>, | |
1035 | and the second time with arguments | |
1036 | <literal>one</literal>, <literal>two two</literal>, | |
1037 | <literal>too</literal>. | |
1038 | </para> | |
1039 | ||
1040 | <para>To pass a literal dollar sign, use <literal>$$</literal>. | |
1041 | Variables whose value is not known at expansion time are treated | |
1042 | as empty strings. Note that the first argument (i.e. the program | |
1043 | to execute) may not be a variable.</para> | |
1044 | ||
1045 | <para>Variables to be used in this fashion may be defined through | |
1046 | <varname>Environment=</varname> and | |
1047 | <varname>EnvironmentFile=</varname>. In addition, variables listed | |
1048 | in the section "Environment variables in spawned processes" in | |
1049 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1050 | which are considered "static configuration", may be used (this | |
1051 | includes e.g. <varname>$USER</varname>, but not | |
1052 | <varname>$TERM</varname>).</para> | |
1053 | ||
1054 | <para>Note that shell command lines are not directly supported. If | |
1055 | shell command lines are to be used, they need to be passed | |
1056 | explicitly to a shell implementation of some kind. Example:</para> | |
1057 | <programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting> | |
1058 | ||
1059 | <para>Example:</para> | |
1060 | ||
1061 | <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting> | |
1062 | ||
1063 | <para>This will execute <command>/bin/echo</command> two times, | |
1064 | each time with one argument: <literal>one</literal> and | |
1065 | <literal>two two</literal>, respectively. Because two commands are | |
1066 | specified, <varname>Type=oneshot</varname> must be used.</para> | |
1067 | ||
1068 | <para>Example:</para> | |
1069 | ||
1070 | <programlisting>ExecStart=/bin/echo / >/dev/null & \; \ | |
30d88d54 ZJS |
1071 | /bin/ls</programlisting> |
1072 | ||
798d3a52 ZJS |
1073 | <para>This will execute <command>/bin/echo</command> |
1074 | with five arguments: <literal>/</literal>, | |
1075 | <literal>>/dev/null</literal>, | |
1076 | <literal>&</literal>, <literal>;</literal>, and | |
1077 | <literal>/bin/ls</literal>.</para> | |
1078 | ||
1079 | <table> | |
1080 | <title>C escapes supported in command lines and environment variables</title> | |
1081 | <tgroup cols='2'> | |
1082 | <colspec colname='escape' /> | |
1083 | <colspec colname='meaning' /> | |
1084 | <thead> | |
1085 | <row> | |
1086 | <entry>Literal</entry> | |
1087 | <entry>Actual value</entry> | |
1088 | </row> | |
1089 | </thead> | |
1090 | <tbody> | |
1091 | <row> | |
1092 | <entry><literal>\a</literal></entry> | |
1093 | <entry>bell</entry> | |
1094 | </row> | |
1095 | <row> | |
1096 | <entry><literal>\b</literal></entry> | |
1097 | <entry>backspace</entry> | |
1098 | </row> | |
1099 | <row> | |
1100 | <entry><literal>\f</literal></entry> | |
1101 | <entry>form feed</entry> | |
1102 | </row> | |
1103 | <row> | |
1104 | <entry><literal>\n</literal></entry> | |
1105 | <entry>newline</entry> | |
1106 | </row> | |
1107 | <row> | |
1108 | <entry><literal>\r</literal></entry> | |
1109 | <entry>carriage return</entry> | |
1110 | </row> | |
1111 | <row> | |
1112 | <entry><literal>\t</literal></entry> | |
1113 | <entry>tab</entry> | |
1114 | </row> | |
1115 | <row> | |
1116 | <entry><literal>\v</literal></entry> | |
1117 | <entry>vertical tab</entry> | |
1118 | </row> | |
1119 | <row> | |
1120 | <entry><literal>\\</literal></entry> | |
1121 | <entry>backslash</entry> | |
1122 | </row> | |
1123 | <row> | |
1124 | <entry><literal>\"</literal></entry> | |
1125 | <entry>double quotation mark</entry> | |
1126 | </row> | |
1127 | <row> | |
1128 | <entry><literal>\'</literal></entry> | |
1129 | <entry>single quotation mark</entry> | |
1130 | </row> | |
1131 | <row> | |
1132 | <entry><literal>\s</literal></entry> | |
1133 | <entry>space</entry> | |
1134 | </row> | |
1135 | <row> | |
1136 | <entry><literal>\x<replaceable>xx</replaceable></literal></entry> | |
1137 | <entry>character number <replaceable>xx</replaceable> in hexadecimal encoding</entry> | |
1138 | </row> | |
1139 | <row> | |
1140 | <entry><literal>\<replaceable>nnn</replaceable></literal></entry> | |
1141 | <entry>character number <replaceable>nnn</replaceable> in octal encoding</entry> | |
1142 | </row> | |
1143 | </tbody> | |
1144 | </tgroup> | |
1145 | </table> | |
1146 | </refsect1> | |
1147 | ||
1148 | <refsect1> | |
1149 | <title>Examples</title> | |
1150 | ||
1151 | <example> | |
1152 | <title>Simple service</title> | |
1153 | ||
1154 | <para>The following unit file creates a service that will | |
1155 | execute <filename>/usr/sbin/foo-daemon</filename>. Since no | |
1156 | <varname>Type=</varname> is specified, the default | |
1157 | <varname>Type=</varname><option>simple</option> will be assumed. | |
1158 | systemd will assume the unit to be started immediately after the | |
1159 | program has begun executing.</para> | |
1160 | ||
1161 | <programlisting>[Unit] | |
d44efb62 CS |
1162 | Description=Foo |
1163 | ||
1164 | [Service] | |
1165 | ExecStart=/usr/sbin/foo-daemon | |
1166 | ||
1167 | [Install] | |
1168 | WantedBy=multi-user.target</programlisting> | |
1169 | ||
798d3a52 ZJS |
1170 | <para>Note that systemd assumes here that the process started by |
1171 | systemd will continue running until the service terminates. If | |
1172 | the program daemonizes itself (i.e. forks), please use | |
1173 | <varname>Type=</varname><option>forking</option> instead.</para> | |
1174 | ||
1175 | <para>Since no <varname>ExecStop=</varname> was specified, | |
1176 | systemd will send SIGTERM to all processes started from this | |
1177 | service, and after a timeout also SIGKILL. This behavior can be | |
1178 | modified, see | |
1179 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1180 | for details.</para> | |
1181 | ||
1182 | <para>Note that this unit type does not include any type of | |
1183 | notification when a service has completed initialization. For | |
1184 | this, you should use other unit types, such as | |
1185 | <varname>Type=</varname><option>notify</option> if the service | |
1186 | understands systemd's notification protocol, | |
1187 | <varname>Type=</varname><option>forking</option> if the service | |
1188 | can background itself or | |
1189 | <varname>Type=</varname><option>dbus</option> if the unit | |
1190 | acquires a DBus name once initialization is complete. See | |
1191 | below.</para> | |
1192 | </example> | |
1193 | ||
1194 | <example> | |
1195 | <title>Oneshot service</title> | |
1196 | ||
b938cb90 | 1197 | <para>Sometimes, units should just execute an action without |
798d3a52 ZJS |
1198 | keeping active processes, such as a filesystem check or a |
1199 | cleanup action on boot. For this, | |
1200 | <varname>Type=</varname><option>oneshot</option> exists. Units | |
1201 | of this type will wait until the process specified terminates | |
1202 | and then fall back to being inactive. The following unit will | |
ff9b60f3 | 1203 | perform a cleanup action:</para> |
798d3a52 ZJS |
1204 | |
1205 | <programlisting>[Unit] | |
d44efb62 CS |
1206 | Description=Cleanup old Foo data |
1207 | ||
1208 | [Service] | |
1209 | Type=oneshot | |
1210 | ExecStart=/usr/sbin/foo-cleanup | |
1211 | ||
1212 | [Install] | |
1213 | WantedBy=multi-user.target</programlisting> | |
1214 | ||
798d3a52 | 1215 | <para>Note that systemd will consider the unit to be in the |
b938cb90 | 1216 | state "starting" until the program has terminated, so ordered |
798d3a52 | 1217 | dependencies will wait for the program to finish before starting |
b938cb90 JE |
1218 | themselves. The unit will revert to the "inactive" state after |
1219 | the execution is done, never reaching the "active" state. That | |
798d3a52 ZJS |
1220 | means another request to start the unit will perform the action |
1221 | again.</para> | |
1222 | ||
1223 | <para><varname>Type=</varname><option>oneshot</option> are the | |
1224 | only service units that may have more than one | |
1225 | <varname>ExecStart=</varname> specified. They will be executed | |
1226 | in order until either they are all successful or one of them | |
1227 | fails.</para> | |
1228 | </example> | |
1229 | ||
1230 | <example> | |
1231 | <title>Stoppable oneshot service</title> | |
1232 | ||
1233 | <para>Similarly to the oneshot services, there are sometimes | |
1234 | units that need to execute a program to set up something and | |
1235 | then execute another to shut it down, but no process remains | |
b938cb90 | 1236 | active while they are considered "started". Network |
798d3a52 | 1237 | configuration can sometimes fall into this category. Another use |
a8eaaee7 | 1238 | case is if a oneshot service shall not be executed each time |
798d3a52 ZJS |
1239 | when they are pulled in as a dependency, but only the first |
1240 | time.</para> | |
1241 | ||
1242 | <para>For this, systemd knows the setting | |
1243 | <varname>RemainAfterExit=</varname><option>yes</option>, which | |
1244 | causes systemd to consider the unit to be active if the start | |
1245 | action exited successfully. This directive can be used with all | |
1246 | types, but is most useful with | |
1247 | <varname>Type=</varname><option>oneshot</option> and | |
1248 | <varname>Type=</varname><option>simple</option>. With | |
b938cb90 | 1249 | <varname>Type=</varname><option>oneshot</option>, systemd waits |
798d3a52 ZJS |
1250 | until the start action has completed before it considers the |
1251 | unit to be active, so dependencies start only after the start | |
1252 | action has succeeded. With | |
b938cb90 | 1253 | <varname>Type=</varname><option>simple</option>, dependencies |
798d3a52 ZJS |
1254 | will start immediately after the start action has been |
1255 | dispatched. The following unit provides an example for a simple | |
1256 | static firewall.</para> | |
1257 | ||
1258 | <programlisting>[Unit] | |
d44efb62 CS |
1259 | Description=Simple firewall |
1260 | ||
1261 | [Service] | |
1262 | Type=oneshot | |
1263 | RemainAfterExit=yes | |
1264 | ExecStart=/usr/local/sbin/simple-firewall-start | |
1265 | ExecStop=/usr/local/sbin/simple-firewall-stop | |
1266 | ||
1267 | [Install] | |
1268 | WantedBy=multi-user.target</programlisting> | |
1269 | ||
798d3a52 ZJS |
1270 | <para>Since the unit is considered to be running after the start |
1271 | action has exited, invoking <command>systemctl start</command> | |
1272 | on that unit again will cause no action to be taken.</para> | |
1273 | </example> | |
1274 | ||
1275 | <example> | |
1276 | <title>Traditional forking services</title> | |
1277 | ||
1278 | <para>Many traditional daemons/services background (i.e. fork, | |
1279 | daemonize) themselves when starting. Set | |
1280 | <varname>Type=</varname><option>forking</option> in the | |
1281 | service's unit file to support this mode of operation. systemd | |
1282 | will consider the service to be in the process of initialization | |
1283 | while the original program is still running. Once it exits | |
1284 | successfully and at least a process remains (and | |
1285 | <varname>RemainAfterExit=</varname><option>no</option>), the | |
1286 | service is considered started.</para> | |
1287 | ||
b938cb90 | 1288 | <para>Often, a traditional daemon only consists of one process. |
798d3a52 ZJS |
1289 | Therefore, if only one process is left after the original |
1290 | process terminates, systemd will consider that process the main | |
1291 | process of the service. In that case, the | |
1292 | <varname>$MAINPID</varname> variable will be available in | |
1293 | <varname>ExecReload=</varname>, <varname>ExecStop=</varname>, | |
1294 | etc.</para> | |
1295 | ||
1296 | <para>In case more than one process remains, systemd will be | |
1297 | unable to determine the main process, so it will not assume | |
1298 | there is one. In that case, <varname>$MAINPID</varname> will not | |
1299 | expand to anything. However, if the process decides to write a | |
1300 | traditional PID file, systemd will be able to read the main PID | |
1301 | from there. Please set <varname>PIDFile=</varname> accordingly. | |
1302 | Note that the daemon should write that file before finishing | |
b938cb90 | 1303 | with its initialization. Otherwise, systemd might try to read the |
798d3a52 ZJS |
1304 | file before it exists.</para> |
1305 | ||
1306 | <para>The following example shows a simple daemon that forks and | |
1307 | just starts one process in the background:</para> | |
1308 | ||
1309 | <programlisting>[Unit] | |
d44efb62 CS |
1310 | Description=Some simple daemon |
1311 | ||
1312 | [Service] | |
1313 | Type=forking | |
1314 | ExecStart=/usr/sbin/my-simple-daemon -d | |
1315 | ||
1316 | [Install] | |
1317 | WantedBy=multi-user.target</programlisting> | |
1318 | ||
798d3a52 ZJS |
1319 | <para>Please see |
1320 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1321 | for details on how you can influence the way systemd terminates | |
1322 | the service.</para> | |
1323 | </example> | |
1324 | ||
1325 | <example> | |
1326 | <title>DBus services</title> | |
1327 | ||
1328 | <para>For services that acquire a name on the DBus system bus, | |
1329 | use <varname>Type=</varname><option>dbus</option> and set | |
1330 | <varname>BusName=</varname> accordingly. The service should not | |
1331 | fork (daemonize). systemd will consider the service to be | |
1332 | initialized once the name has been acquired on the system bus. | |
1333 | The following example shows a typical DBus service:</para> | |
1334 | ||
1335 | <programlisting>[Unit] | |
d44efb62 CS |
1336 | Description=Simple DBus service |
1337 | ||
1338 | [Service] | |
1339 | Type=dbus | |
1340 | BusName=org.example.simple-dbus-service | |
1341 | ExecStart=/usr/sbin/simple-dbus-service | |
1342 | ||
1343 | [Install] | |
1344 | WantedBy=multi-user.target</programlisting> | |
1345 | ||
7ca41557 | 1346 | <para>For <emphasis>bus-activatable</emphasis> services, do not |
798d3a52 ZJS |
1347 | include a <literal>[Install]</literal> section in the systemd |
1348 | service file, but use the <varname>SystemdService=</varname> | |
1349 | option in the corresponding DBus service file, for example | |
1350 | (<filename>/usr/share/dbus-1/system-services/org.example.simple-dbus-service.service</filename>):</para> | |
d44efb62 | 1351 | |
798d3a52 | 1352 | <programlisting>[D-BUS Service] |
d44efb62 CS |
1353 | Name=org.example.simple-dbus-service |
1354 | Exec=/usr/sbin/simple-dbus-service | |
1355 | User=root | |
1356 | SystemdService=simple-dbus-service.service</programlisting> | |
1357 | ||
798d3a52 ZJS |
1358 | <para>Please see |
1359 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1360 | for details on how you can influence the way systemd terminates | |
1361 | the service.</para> | |
1362 | </example> | |
1363 | ||
1364 | <example> | |
1365 | <title>Services that notify systemd about their initialization</title> | |
1366 | ||
1367 | <para><varname>Type=</varname><option>simple</option> services | |
1368 | are really easy to write, but have the major disadvantage of | |
1369 | systemd not being able to tell when initialization of the given | |
1370 | service is complete. For this reason, systemd supports a simple | |
1371 | notification protocol that allows daemons to make systemd aware | |
1372 | that they are done initializing. Use | |
1373 | <varname>Type=</varname><option>notify</option> for this. A | |
1374 | typical service file for such a daemon would look like | |
1375 | this:</para> | |
1376 | ||
1377 | <programlisting>[Unit] | |
d44efb62 CS |
1378 | Description=Simple notifying service |
1379 | ||
1380 | [Service] | |
1381 | Type=notify | |
1382 | ExecStart=/usr/sbin/simple-notifying-service | |
1383 | ||
1384 | [Install] | |
1385 | WantedBy=multi-user.target</programlisting> | |
1386 | ||
798d3a52 | 1387 | <para>Note that the daemon has to support systemd's notification |
7ca41557 | 1388 | protocol, else systemd will think the service has not started yet |
798d3a52 ZJS |
1389 | and kill it after a timeout. For an example of how to update |
1390 | daemons to support this protocol transparently, take a look at | |
1391 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
1392 | systemd will consider the unit to be in the 'starting' state | |
1393 | until a readiness notification has arrived.</para> | |
1394 | ||
1395 | <para>Please see | |
1396 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1397 | for details on how you can influence the way systemd terminates | |
1398 | the service.</para> | |
1399 | </example> | |
1400 | </refsect1> | |
1401 | ||
1402 | <refsect1> | |
1403 | <title>See Also</title> | |
1404 | <para> | |
1405 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
1406 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
1407 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1408 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1409 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1410 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1411 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
1412 | </para> | |
1413 | </refsect1> | |
d1ab0ca0 LP |
1414 | |
1415 | </refentry> |