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023a4f67 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
dd1eb43b | 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 | |
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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 | |
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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. |
dd1eb43b | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd.exec"> | |
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25 | <refentryinfo> |
26 | <title>systemd.exec</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.exec</refentrytitle> | |
41 | <manvolnum>5</manvolnum> | |
42 | </refmeta> | |
43 | ||
44 | <refnamediv> | |
45 | <refname>systemd.exec</refname> | |
46 | <refpurpose>Execution environment configuration</refpurpose> | |
47 | </refnamediv> | |
48 | ||
49 | <refsynopsisdiv> | |
50 | <para><filename><replaceable>service</replaceable>.service</filename>, | |
51 | <filename><replaceable>socket</replaceable>.socket</filename>, | |
52 | <filename><replaceable>mount</replaceable>.mount</filename>, | |
53 | <filename><replaceable>swap</replaceable>.swap</filename></para> | |
54 | </refsynopsisdiv> | |
55 | ||
56 | <refsect1> | |
57 | <title>Description</title> | |
58 | ||
59 | <para>Unit configuration files for services, sockets, mount | |
60 | points, and swap devices share a subset of configuration options | |
61 | which define the execution environment of spawned | |
62 | processes.</para> | |
63 | ||
64 | <para>This man page lists the configuration options shared by | |
65 | these four unit types. See | |
66 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
67 | for the common options of all unit configuration files, and | |
68 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
69 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
70 | <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
71 | and | |
72 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
73 | for more information on the specific unit configuration files. The | |
74 | execution specific configuration options are configured in the | |
75 | [Service], [Socket], [Mount], or [Swap] sections, depending on the | |
76 | unit type.</para> | |
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77 | |
78 | <para>In addition, options which control resources through cgroups | |
79 | are listed in | |
80 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
81 | Those options complement options listed here.</para> | |
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82 | </refsect1> |
83 | ||
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84 | <refsect1> |
85 | <title>Automatic Dependencies</title> | |
86 | ||
87 | <para>A few execution parameters result in additional, automatic | |
88 | dependencies to be added.</para> | |
89 | ||
90 | <para>Units with <varname>WorkingDirectory=</varname> or | |
91 | <varname>RootDirectory=</varname> set automatically gain | |
92 | dependencies of type <varname>Requires=</varname> and | |
93 | <varname>After=</varname> on all mount units required to access | |
94 | the specified paths. This is equivalent to having them listed | |
95 | explicitly in <varname>RequiresMountsFor=</varname>.</para> | |
96 | ||
97 | <para>Similar, units with <varname>PrivateTmp=</varname> enabled | |
98 | automatically get mount unit dependencies for all mounts | |
99 | required to access <filename>/tmp</filename> and | |
100 | <filename>/var/tmp</filename>.</para> | |
101 | ||
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102 | <para>Units whose standard output or error output is connected to <option>journal</option>, <option>syslog</option> |
103 | or <option>kmsg</option> (or their combinations with console output, see below) automatically acquire dependencies | |
104 | of type <varname>After=</varname> on <filename>systemd-journald.socket</filename>.</para> | |
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105 | </refsect1> |
106 | ||
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107 | <refsect1> |
108 | <title>Options</title> | |
109 | ||
110 | <variablelist class='unit-directives'> | |
111 | ||
112 | <varlistentry> | |
113 | <term><varname>WorkingDirectory=</varname></term> | |
114 | ||
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115 | <listitem><para>Takes a directory path relative to the service's root directory specified by |
116 | <varname>RootDirectory=</varname>, or the special value <literal>~</literal>. Sets the working directory for | |
117 | executed processes. If set to <literal>~</literal>, the home directory of the user specified in | |
118 | <varname>User=</varname> is used. If not set, defaults to the root directory when systemd is running as a | |
119 | system instance and the respective user's home directory if run as user. If the setting is prefixed with the | |
120 | <literal>-</literal> character, a missing working directory is not considered fatal. If | |
121 | <varname>RootDirectory=</varname> is not set, then <varname>WorkingDirectory=</varname> is relative to the root | |
122 | of the system running the service manager. Note that setting this parameter might result in additional | |
123 | dependencies to be added to the unit (see above).</para></listitem> | |
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124 | </varlistentry> |
125 | ||
126 | <varlistentry> | |
127 | <term><varname>RootDirectory=</varname></term> | |
128 | ||
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129 | <listitem><para>Takes a directory path relative to the host's root directory (i.e. the root of the system |
130 | running the service manager). Sets the root directory for executed processes, with the <citerefentry | |
131 | project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry> system | |
132 | call. If this is used, it must be ensured that the process binary and all its auxiliary files are available in | |
133 | the <function>chroot()</function> jail. Note that setting this parameter might result in additional | |
134 | dependencies to be added to the unit (see above).</para> | |
135 | ||
136 | <para>The <varname>PrivateUsers=</varname> setting is particularly useful in conjunction with | |
137 | <varname>RootDirectory=</varname>. For details, see below.</para></listitem> | |
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138 | </varlistentry> |
139 | ||
140 | <varlistentry> | |
141 | <term><varname>User=</varname></term> | |
142 | <term><varname>Group=</varname></term> | |
143 | ||
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144 | <listitem><para>Set the UNIX user or group that the processes are executed as, respectively. Takes a single |
145 | user or group name, or numeric ID as argument. If no group is set, the default group of the user is used. This | |
dadd6ecf | 146 | setting does not affect commands whose command line is prefixed with <literal>+</literal>.</para></listitem> |
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147 | </varlistentry> |
148 | ||
149 | <varlistentry> | |
150 | <term><varname>DynamicUser=</varname></term> | |
151 | ||
152 | <listitem><para>Takes a boolean parameter. If set, a UNIX user and group pair is allocated dynamically when the | |
153 | unit is started, and released as soon as it is stopped. The user and group will not be added to | |
154 | <filename>/etc/passwd</filename> or <filename>/etc/group</filename>, but are managed transiently during | |
155 | runtime. The <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
156 | glibc NSS module provides integration of these dynamic users/groups into the system's user and group | |
157 | databases. The user and group name to use may be configured via <varname>User=</varname> and | |
158 | <varname>Group=</varname> (see above). If these options are not used and dynamic user/group allocation is | |
159 | enabled for a unit, the name of the dynamic user/group is implicitly derived from the unit name. If the unit | |
160 | name without the type suffix qualifies as valid user name it is used directly, otherwise a name incorporating a | |
161 | hash of it is used. If a statically allocated user or group of the configured name already exists, it is used | |
162 | and no dynamic user/group is allocated. Dynamic users/groups are allocated from the UID/GID range | |
163 | 61184…65519. It is recommended to avoid this range for regular system or login users. At any point in time | |
164 | each UID/GID from this range is only assigned to zero or one dynamically allocated users/groups in | |
165 | use. However, UID/GIDs are recycled after a unit is terminated. Care should be taken that any processes running | |
166 | as part of a unit for which dynamic users/groups are enabled do not leave files or directories owned by these | |
167 | users/groups around, as a different unit might get the same UID/GID assigned later on, and thus gain access to | |
63bb64a0 | 168 | these files or directories. If <varname>DynamicUser=</varname> is enabled, <varname>RemoveIPC=</varname>, |
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169 | <varname>PrivateTmp=</varname> are implied. This ensures that the lifetime of IPC objects and temporary files |
170 | created by the executed processes is bound to the runtime of the service, and hence the lifetime of the dynamic | |
171 | user/group. Since <filename>/tmp</filename> and <filename>/var/tmp</filename> are usually the only | |
172 | world-writable directories on a system this ensures that a unit making use of dynamic user/group allocation | |
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173 | cannot leave files around after unit termination. Moreover <varname>ProtectSystem=strict</varname> and |
174 | <varname>ProtectHome=read-only</varname> are implied, thus prohibiting the service to write to arbitrary file | |
175 | system locations. In order to allow the service to write to certain directories, they have to be whitelisted | |
cfaf4b75 | 176 | using <varname>ReadWritePaths=</varname>, but care must be taken so that UID/GID recycling doesn't |
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177 | create security issues involving files created by the service. Use <varname>RuntimeDirectory=</varname> (see |
178 | below) in order to assign a writable runtime directory to a service, owned by the dynamic user/group and | |
179 | removed automatically when the unit is terminated. Defaults to off.</para></listitem> | |
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180 | </varlistentry> |
181 | ||
182 | <varlistentry> | |
183 | <term><varname>SupplementaryGroups=</varname></term> | |
184 | ||
185 | <listitem><para>Sets the supplementary Unix groups the | |
186 | processes are executed as. This takes a space-separated list | |
187 | of group names or IDs. This option may be specified more than | |
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188 | once, in which case all listed groups are set as supplementary |
189 | groups. When the empty string is assigned, the list of | |
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190 | supplementary groups is reset, and all assignments prior to |
191 | this one will have no effect. In any way, this option does not | |
192 | override, but extends the list of supplementary groups | |
193 | configured in the system group database for the | |
43eb109a | 194 | user. This does not affect commands prefixed with <literal>+</literal>.</para></listitem> |
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195 | </varlistentry> |
196 | ||
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197 | <varlistentry> |
198 | <term><varname>RemoveIPC=</varname></term> | |
199 | ||
200 | <listitem><para>Takes a boolean parameter. If set, all System V and POSIX IPC objects owned by the user and | |
201 | group the processes of this unit are run as are removed when the unit is stopped. This setting only has an | |
202 | effect if at least one of <varname>User=</varname>, <varname>Group=</varname> and | |
203 | <varname>DynamicUser=</varname> are used. It has no effect on IPC objects owned by the root user. Specifically, | |
204 | this removes System V semaphores, as well as System V and POSIX shared memory segments and message queues. If | |
205 | multiple units use the same user or group the IPC objects are removed when the last of these units is | |
206 | stopped. This setting is implied if <varname>DynamicUser=</varname> is set.</para></listitem> | |
207 | </varlistentry> | |
208 | ||
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209 | <varlistentry> |
210 | <term><varname>Nice=</varname></term> | |
211 | ||
212 | <listitem><para>Sets the default nice level (scheduling | |
213 | priority) for executed processes. Takes an integer between -20 | |
214 | (highest priority) and 19 (lowest priority). See | |
215 | <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
216 | for details.</para></listitem> | |
217 | </varlistentry> | |
218 | ||
219 | <varlistentry> | |
220 | <term><varname>OOMScoreAdjust=</varname></term> | |
221 | ||
222 | <listitem><para>Sets the adjustment level for the | |
223 | Out-Of-Memory killer for executed processes. Takes an integer | |
224 | between -1000 (to disable OOM killing for this process) and | |
225 | 1000 (to make killing of this process under memory pressure | |
226 | very likely). See <ulink | |
227 | url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink> | |
228 | for details.</para></listitem> | |
229 | </varlistentry> | |
230 | ||
231 | <varlistentry> | |
232 | <term><varname>IOSchedulingClass=</varname></term> | |
233 | ||
b938cb90 | 234 | <listitem><para>Sets the I/O scheduling class for executed |
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235 | processes. Takes an integer between 0 and 3 or one of the |
236 | strings <option>none</option>, <option>realtime</option>, | |
237 | <option>best-effort</option> or <option>idle</option>. See | |
238 | <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
239 | for details.</para></listitem> | |
240 | </varlistentry> | |
241 | ||
242 | <varlistentry> | |
243 | <term><varname>IOSchedulingPriority=</varname></term> | |
244 | ||
b938cb90 | 245 | <listitem><para>Sets the I/O scheduling priority for executed |
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246 | processes. Takes an integer between 0 (highest priority) and 7 |
247 | (lowest priority). The available priorities depend on the | |
b938cb90 | 248 | selected I/O scheduling class (see above). See |
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249 | <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> |
250 | for details.</para></listitem> | |
251 | </varlistentry> | |
252 | ||
253 | <varlistentry> | |
254 | <term><varname>CPUSchedulingPolicy=</varname></term> | |
255 | ||
256 | <listitem><para>Sets the CPU scheduling policy for executed | |
257 | processes. Takes one of | |
258 | <option>other</option>, | |
259 | <option>batch</option>, | |
260 | <option>idle</option>, | |
261 | <option>fifo</option> or | |
262 | <option>rr</option>. See | |
263 | <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
264 | for details.</para></listitem> | |
265 | </varlistentry> | |
266 | ||
267 | <varlistentry> | |
268 | <term><varname>CPUSchedulingPriority=</varname></term> | |
269 | ||
270 | <listitem><para>Sets the CPU scheduling priority for executed | |
271 | processes. The available priority range depends on the | |
272 | selected CPU scheduling policy (see above). For real-time | |
273 | scheduling policies an integer between 1 (lowest priority) and | |
274 | 99 (highest priority) can be used. See | |
275 | <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
276 | for details. </para></listitem> | |
277 | </varlistentry> | |
278 | ||
279 | <varlistentry> | |
280 | <term><varname>CPUSchedulingResetOnFork=</varname></term> | |
281 | ||
282 | <listitem><para>Takes a boolean argument. If true, elevated | |
283 | CPU scheduling priorities and policies will be reset when the | |
284 | executed processes fork, and can hence not leak into child | |
285 | processes. See | |
286 | <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
287 | for details. Defaults to false.</para></listitem> | |
288 | </varlistentry> | |
289 | ||
290 | <varlistentry> | |
291 | <term><varname>CPUAffinity=</varname></term> | |
292 | ||
293 | <listitem><para>Controls the CPU affinity of the executed | |
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294 | processes. Takes a list of CPU indices or ranges separated by |
295 | either whitespace or commas. CPU ranges are specified by the | |
296 | lower and upper CPU indices separated by a dash. | |
b938cb90 | 297 | This option may be specified more than once, in which case the |
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298 | specified CPU affinity masks are merged. If the empty string |
299 | is assigned, the mask is reset, all assignments prior to this | |
300 | will have no effect. See | |
301 | <citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
302 | for details.</para></listitem> | |
303 | </varlistentry> | |
304 | ||
305 | <varlistentry> | |
306 | <term><varname>UMask=</varname></term> | |
307 | ||
308 | <listitem><para>Controls the file mode creation mask. Takes an | |
309 | access mode in octal notation. See | |
310 | <citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
311 | for details. Defaults to 0022.</para></listitem> | |
312 | </varlistentry> | |
313 | ||
314 | <varlistentry> | |
315 | <term><varname>Environment=</varname></term> | |
316 | ||
317 | <listitem><para>Sets environment variables for executed | |
318 | processes. Takes a space-separated list of variable | |
b938cb90 | 319 | assignments. This option may be specified more than once, in |
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320 | which case all listed variables will be set. If the same |
321 | variable is set twice, the later setting will override the | |
322 | earlier setting. If the empty string is assigned to this | |
323 | option, the list of environment variables is reset, all prior | |
324 | assignments have no effect. Variable expansion is not | |
325 | performed inside the strings, however, specifier expansion is | |
326 | possible. The $ character has no special meaning. If you need | |
327 | to assign a value containing spaces to a variable, use double | |
328 | quotes (") for the assignment.</para> | |
329 | ||
330 | <para>Example: | |
331 | <programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</programlisting> | |
332 | gives three variables <literal>VAR1</literal>, | |
333 | <literal>VAR2</literal>, <literal>VAR3</literal> | |
334 | with the values <literal>word1 word2</literal>, | |
335 | <literal>word3</literal>, <literal>$word 5 6</literal>. | |
336 | </para> | |
337 | ||
338 | <para> | |
339 | See | |
340 | <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
341 | for details about environment variables.</para></listitem> | |
342 | </varlistentry> | |
343 | <varlistentry> | |
344 | <term><varname>EnvironmentFile=</varname></term> | |
345 | <listitem><para>Similar to <varname>Environment=</varname> but | |
346 | reads the environment variables from a text file. The text | |
347 | file should contain new-line-separated variable assignments. | |
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348 | Empty lines, lines without an <literal>=</literal> separator, |
349 | or lines starting with ; or # will be ignored, | |
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350 | which may be used for commenting. A line ending with a |
351 | backslash will be concatenated with the following one, | |
352 | allowing multiline variable definitions. The parser strips | |
353 | leading and trailing whitespace from the values of | |
354 | assignments, unless you use double quotes (").</para> | |
355 | ||
356 | <para>The argument passed should be an absolute filename or | |
357 | wildcard expression, optionally prefixed with | |
358 | <literal>-</literal>, which indicates that if the file does | |
359 | not exist, it will not be read and no error or warning message | |
360 | is logged. This option may be specified more than once in | |
361 | which case all specified files are read. If the empty string | |
362 | is assigned to this option, the list of file to read is reset, | |
363 | all prior assignments have no effect.</para> | |
364 | ||
365 | <para>The files listed with this directive will be read | |
366 | shortly before the process is executed (more specifically, | |
367 | after all processes from a previous unit state terminated. | |
368 | This means you can generate these files in one unit state, and | |
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369 | read it with this option in the next).</para> |
370 | ||
371 | <para>Settings from these | |
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372 | files override settings made with |
373 | <varname>Environment=</varname>. If the same variable is set | |
374 | twice from these files, the files will be read in the order | |
375 | they are specified and the later setting will override the | |
376 | earlier setting.</para></listitem> | |
377 | </varlistentry> | |
378 | ||
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379 | <varlistentry> |
380 | <term><varname>PassEnvironment=</varname></term> | |
381 | ||
382 | <listitem><para>Pass environment variables from the systemd system | |
383 | manager to executed processes. Takes a space-separated list of variable | |
384 | names. This option may be specified more than once, in which case all | |
385 | listed variables will be set. If the empty string is assigned to this | |
386 | option, the list of environment variables is reset, all prior | |
387 | assignments have no effect. Variables that are not set in the system | |
388 | manager will not be passed and will be silently ignored.</para> | |
389 | ||
390 | <para>Variables passed from this setting are overridden by those passed | |
391 | from <varname>Environment=</varname> or | |
392 | <varname>EnvironmentFile=</varname>.</para> | |
393 | ||
394 | <para>Example: | |
395 | <programlisting>PassEnvironment=VAR1 VAR2 VAR3</programlisting> | |
396 | passes three variables <literal>VAR1</literal>, | |
397 | <literal>VAR2</literal>, <literal>VAR3</literal> | |
398 | with the values set for those variables in PID1.</para> | |
399 | ||
400 | <para> | |
401 | See | |
402 | <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
403 | for details about environment variables.</para></listitem> | |
404 | </varlistentry> | |
405 | ||
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406 | <varlistentry> |
407 | <term><varname>StandardInput=</varname></term> | |
408 | <listitem><para>Controls where file descriptor 0 (STDIN) of | |
409 | the executed processes is connected to. Takes one of | |
410 | <option>null</option>, | |
411 | <option>tty</option>, | |
412 | <option>tty-force</option>, | |
413 | <option>tty-fail</option> or | |
414 | <option>socket</option>.</para> | |
415 | ||
416 | <para>If <option>null</option> is selected, standard input | |
417 | will be connected to <filename>/dev/null</filename>, i.e. all | |
418 | read attempts by the process will result in immediate | |
419 | EOF.</para> | |
420 | ||
421 | <para>If <option>tty</option> is selected, standard input is | |
422 | connected to a TTY (as configured by | |
423 | <varname>TTYPath=</varname>, see below) and the executed | |
424 | process becomes the controlling process of the terminal. If | |
425 | the terminal is already being controlled by another process, | |
426 | the executed process waits until the current controlling | |
427 | process releases the terminal.</para> | |
428 | ||
429 | <para><option>tty-force</option> is similar to | |
430 | <option>tty</option>, but the executed process is forcefully | |
431 | and immediately made the controlling process of the terminal, | |
432 | potentially removing previous controlling processes from the | |
433 | terminal.</para> | |
434 | ||
435 | <para><option>tty-fail</option> is similar to | |
436 | <option>tty</option> but if the terminal already has a | |
437 | controlling process start-up of the executed process | |
438 | fails.</para> | |
439 | ||
440 | <para>The <option>socket</option> option is only valid in | |
441 | socket-activated services, and only when the socket | |
442 | configuration file (see | |
443 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
444 | for details) specifies a single socket only. If this option is | |
445 | set, standard input will be connected to the socket the | |
446 | service was activated from, which is primarily useful for | |
447 | compatibility with daemons designed for use with the | |
448 | traditional | |
b5c7d097 | 449 | <citerefentry project='freebsd'><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
798d3a52 ZJS |
450 | daemon.</para> |
451 | ||
452 | <para>This setting defaults to | |
453 | <option>null</option>.</para></listitem> | |
454 | </varlistentry> | |
c129bd5d | 455 | |
798d3a52 ZJS |
456 | <varlistentry> |
457 | <term><varname>StandardOutput=</varname></term> | |
458 | <listitem><para>Controls where file descriptor 1 (STDOUT) of | |
459 | the executed processes is connected to. Takes one of | |
460 | <option>inherit</option>, | |
461 | <option>null</option>, | |
462 | <option>tty</option>, | |
463 | <option>journal</option>, | |
464 | <option>syslog</option>, | |
465 | <option>kmsg</option>, | |
466 | <option>journal+console</option>, | |
467 | <option>syslog+console</option>, | |
468 | <option>kmsg+console</option> or | |
469 | <option>socket</option>.</para> | |
470 | ||
471 | <para><option>inherit</option> duplicates the file descriptor | |
472 | of standard input for standard output.</para> | |
473 | ||
474 | <para><option>null</option> connects standard output to | |
475 | <filename>/dev/null</filename>, i.e. everything written to it | |
476 | will be lost.</para> | |
477 | ||
478 | <para><option>tty</option> connects standard output to a tty | |
479 | (as configured via <varname>TTYPath=</varname>, see below). If | |
480 | the TTY is used for output only, the executed process will not | |
481 | become the controlling process of the terminal, and will not | |
482 | fail or wait for other processes to release the | |
483 | terminal.</para> | |
484 | ||
485 | <para><option>journal</option> connects standard output with | |
486 | the journal which is accessible via | |
487 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. | |
488 | Note that everything that is written to syslog or kmsg (see | |
489 | below) is implicitly stored in the journal as well, the | |
490 | specific two options listed below are hence supersets of this | |
491 | one.</para> | |
492 | ||
493 | <para><option>syslog</option> connects standard output to the | |
494 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
495 | system syslog service, in addition to the journal. Note that | |
496 | the journal daemon is usually configured to forward everything | |
497 | it receives to syslog anyway, in which case this option is no | |
498 | different from <option>journal</option>.</para> | |
499 | ||
500 | <para><option>kmsg</option> connects standard output with the | |
501 | kernel log buffer which is accessible via | |
502 | <citerefentry project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
503 | in addition to the journal. The journal daemon might be | |
504 | configured to send all logs to kmsg anyway, in which case this | |
505 | option is no different from <option>journal</option>.</para> | |
506 | ||
507 | <para><option>journal+console</option>, | |
508 | <option>syslog+console</option> and | |
509 | <option>kmsg+console</option> work in a similar way as the | |
510 | three options above but copy the output to the system console | |
511 | as well.</para> | |
512 | ||
513 | <para><option>socket</option> connects standard output to a | |
514 | socket acquired via socket activation. The semantics are | |
515 | similar to the same option of | |
516 | <varname>StandardInput=</varname>.</para> | |
517 | ||
dfe85b38 LP |
518 | <para>If the standard output (or error output, see below) of a unit is connected to the journal, syslog or the |
519 | kernel log buffer, the unit will implicitly gain a dependency of type <varname>After=</varname> on | |
28c75e25 LP |
520 | <filename>systemd-journald.socket</filename> (also see the automatic dependencies section above).</para> |
521 | ||
798d3a52 ZJS |
522 | <para>This setting defaults to the value set with |
523 | <option>DefaultStandardOutput=</option> in | |
524 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
c129bd5d LP |
525 | which defaults to <option>journal</option>. Note that setting |
526 | this parameter might result in additional dependencies to be | |
527 | added to the unit (see above).</para></listitem> | |
798d3a52 | 528 | </varlistentry> |
c129bd5d | 529 | |
798d3a52 ZJS |
530 | <varlistentry> |
531 | <term><varname>StandardError=</varname></term> | |
532 | <listitem><para>Controls where file descriptor 2 (STDERR) of | |
533 | the executed processes is connected to. The available options | |
534 | are identical to those of <varname>StandardOutput=</varname>, | |
535 | with one exception: if set to <option>inherit</option> the | |
536 | file descriptor used for standard output is duplicated for | |
537 | standard error. This setting defaults to the value set with | |
538 | <option>DefaultStandardError=</option> in | |
539 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
c129bd5d LP |
540 | which defaults to <option>inherit</option>. Note that setting |
541 | this parameter might result in additional dependencies to be | |
542 | added to the unit (see above).</para></listitem> | |
798d3a52 | 543 | </varlistentry> |
c129bd5d | 544 | |
798d3a52 ZJS |
545 | <varlistentry> |
546 | <term><varname>TTYPath=</varname></term> | |
547 | <listitem><para>Sets the terminal device node to use if | |
548 | standard input, output, or error are connected to a TTY (see | |
549 | above). Defaults to | |
550 | <filename>/dev/console</filename>.</para></listitem> | |
551 | </varlistentry> | |
552 | <varlistentry> | |
553 | <term><varname>TTYReset=</varname></term> | |
554 | <listitem><para>Reset the terminal device specified with | |
555 | <varname>TTYPath=</varname> before and after execution. | |
556 | Defaults to <literal>no</literal>.</para></listitem> | |
557 | </varlistentry> | |
558 | <varlistentry> | |
559 | <term><varname>TTYVHangup=</varname></term> | |
560 | <listitem><para>Disconnect all clients which have opened the | |
561 | terminal device specified with <varname>TTYPath=</varname> | |
562 | before and after execution. Defaults to | |
563 | <literal>no</literal>.</para></listitem> | |
564 | </varlistentry> | |
565 | <varlistentry> | |
566 | <term><varname>TTYVTDisallocate=</varname></term> | |
567 | <listitem><para>If the terminal device specified with | |
568 | <varname>TTYPath=</varname> is a virtual console terminal, try | |
569 | to deallocate the TTY before and after execution. This ensures | |
570 | that the screen and scrollback buffer is cleared. Defaults to | |
571 | <literal>no</literal>.</para></listitem> | |
572 | </varlistentry> | |
573 | <varlistentry> | |
574 | <term><varname>SyslogIdentifier=</varname></term> | |
575 | <listitem><para>Sets the process name to prefix log lines sent | |
576 | to the logging system or the kernel log buffer with. If not | |
577 | set, defaults to the process name of the executed process. | |
578 | This option is only useful when | |
579 | <varname>StandardOutput=</varname> or | |
580 | <varname>StandardError=</varname> are set to | |
581 | <option>syslog</option>, <option>journal</option> or | |
582 | <option>kmsg</option> (or to the same settings in combination | |
583 | with <option>+console</option>).</para></listitem> | |
584 | </varlistentry> | |
585 | <varlistentry> | |
586 | <term><varname>SyslogFacility=</varname></term> | |
587 | <listitem><para>Sets the syslog facility to use when logging | |
588 | to syslog. One of <option>kern</option>, | |
589 | <option>user</option>, <option>mail</option>, | |
590 | <option>daemon</option>, <option>auth</option>, | |
591 | <option>syslog</option>, <option>lpr</option>, | |
592 | <option>news</option>, <option>uucp</option>, | |
593 | <option>cron</option>, <option>authpriv</option>, | |
594 | <option>ftp</option>, <option>local0</option>, | |
595 | <option>local1</option>, <option>local2</option>, | |
596 | <option>local3</option>, <option>local4</option>, | |
597 | <option>local5</option>, <option>local6</option> or | |
598 | <option>local7</option>. See | |
599 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
600 | for details. This option is only useful when | |
601 | <varname>StandardOutput=</varname> or | |
602 | <varname>StandardError=</varname> are set to | |
603 | <option>syslog</option>. Defaults to | |
604 | <option>daemon</option>.</para></listitem> | |
605 | </varlistentry> | |
606 | <varlistentry> | |
607 | <term><varname>SyslogLevel=</varname></term> | |
a8eaaee7 | 608 | <listitem><para>The default syslog level to use when logging to |
798d3a52 ZJS |
609 | syslog or the kernel log buffer. One of |
610 | <option>emerg</option>, | |
611 | <option>alert</option>, | |
612 | <option>crit</option>, | |
613 | <option>err</option>, | |
614 | <option>warning</option>, | |
615 | <option>notice</option>, | |
616 | <option>info</option>, | |
617 | <option>debug</option>. See | |
618 | <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
619 | for details. This option is only useful when | |
620 | <varname>StandardOutput=</varname> or | |
621 | <varname>StandardError=</varname> are set to | |
622 | <option>syslog</option> or <option>kmsg</option>. Note that | |
623 | individual lines output by the daemon might be prefixed with a | |
624 | different log level which can be used to override the default | |
625 | log level specified here. The interpretation of these prefixes | |
626 | may be disabled with <varname>SyslogLevelPrefix=</varname>, | |
b938cb90 | 627 | see below. For details, see |
798d3a52 ZJS |
628 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
629 | ||
630 | Defaults to | |
631 | <option>info</option>.</para></listitem> | |
632 | </varlistentry> | |
633 | ||
634 | <varlistentry> | |
635 | <term><varname>SyslogLevelPrefix=</varname></term> | |
636 | <listitem><para>Takes a boolean argument. If true and | |
637 | <varname>StandardOutput=</varname> or | |
638 | <varname>StandardError=</varname> are set to | |
639 | <option>syslog</option>, <option>kmsg</option> or | |
640 | <option>journal</option>, log lines written by the executed | |
641 | process that are prefixed with a log level will be passed on | |
642 | to syslog with this log level set but the prefix removed. If | |
643 | set to false, the interpretation of these prefixes is disabled | |
644 | and the logged lines are passed on as-is. For details about | |
645 | this prefixing see | |
646 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
647 | Defaults to true.</para></listitem> | |
648 | </varlistentry> | |
649 | ||
650 | <varlistentry> | |
651 | <term><varname>TimerSlackNSec=</varname></term> | |
652 | <listitem><para>Sets the timer slack in nanoseconds for the | |
653 | executed processes. The timer slack controls the accuracy of | |
654 | wake-ups triggered by timers. See | |
655 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
656 | for more information. Note that in contrast to most other time | |
657 | span definitions this parameter takes an integer value in | |
658 | nano-seconds if no unit is specified. The usual time units are | |
659 | understood too.</para></listitem> | |
660 | </varlistentry> | |
661 | ||
662 | <varlistentry> | |
663 | <term><varname>LimitCPU=</varname></term> | |
664 | <term><varname>LimitFSIZE=</varname></term> | |
665 | <term><varname>LimitDATA=</varname></term> | |
666 | <term><varname>LimitSTACK=</varname></term> | |
667 | <term><varname>LimitCORE=</varname></term> | |
668 | <term><varname>LimitRSS=</varname></term> | |
669 | <term><varname>LimitNOFILE=</varname></term> | |
670 | <term><varname>LimitAS=</varname></term> | |
671 | <term><varname>LimitNPROC=</varname></term> | |
672 | <term><varname>LimitMEMLOCK=</varname></term> | |
673 | <term><varname>LimitLOCKS=</varname></term> | |
674 | <term><varname>LimitSIGPENDING=</varname></term> | |
675 | <term><varname>LimitMSGQUEUE=</varname></term> | |
676 | <term><varname>LimitNICE=</varname></term> | |
677 | <term><varname>LimitRTPRIO=</varname></term> | |
678 | <term><varname>LimitRTTIME=</varname></term> | |
29857001 LP |
679 | <listitem><para>Set soft and hard limits on various resources for executed processes. See |
680 | <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry> for details on | |
681 | the resource limit concept. Resource limits may be specified in two formats: either as single value to set a | |
682 | specific soft and hard limit to the same value, or as colon-separated pair <option>soft:hard</option> to set | |
683 | both limits individually (e.g. <literal>LimitAS=4G:16G</literal>). Use the string <varname>infinity</varname> | |
684 | to configure no limit on a specific resource. The multiplicative suffixes K, M, G, T, P and E (to the base | |
685 | 1024) may be used for resource limits measured in bytes (e.g. LimitAS=16G). For the limits referring to time | |
686 | values, the usual time units ms, s, min, h and so on may be used (see | |
687 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
688 | details). Note that if no time unit is specified for <varname>LimitCPU=</varname> the default unit of seconds | |
689 | is implied, while for <varname>LimitRTTIME=</varname> the default unit of microseconds is implied. Also, note | |
690 | that the effective granularity of the limits might influence their enforcement. For example, time limits | |
691 | specified for <varname>LimitCPU=</varname> will be rounded up implicitly to multiples of 1s. For | |
692 | <varname>LimitNICE=</varname> the value may be specified in two syntaxes: if prefixed with <literal>+</literal> | |
693 | or <literal>-</literal>, the value is understood as regular Linux nice value in the range -20..19. If not | |
694 | prefixed like this the value is understood as raw resource limit parameter in the range 0..40 (with 0 being | |
695 | equivalent to 1).</para> | |
a4c18002 LP |
696 | |
697 | <para>Note that most process resource limits configured with | |
698 | these options are per-process, and processes may fork in order | |
699 | to acquire a new set of resources that are accounted | |
700 | independently of the original process, and may thus escape | |
701 | limits set. Also note that <varname>LimitRSS=</varname> is not | |
702 | implemented on Linux, and setting it has no effect. Often it | |
703 | is advisable to prefer the resource controls listed in | |
704 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
705 | over these per-process limits, as they apply to services as a | |
706 | whole, may be altered dynamically at runtime, and are | |
707 | generally more expressive. For example, | |
708 | <varname>MemoryLimit=</varname> is a more powerful (and | |
709 | working) replacement for <varname>LimitRSS=</varname>.</para> | |
798d3a52 | 710 | |
f4c9356d LP |
711 | <para>For system units these resource limits may be chosen freely. For user units however (i.e. units run by a |
712 | per-user instance of | |
713 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>), these limits are | |
714 | bound by (possibly more restrictive) per-user limits enforced by the OS.</para> | |
715 | ||
716 | <para>Resource limits not configured explicitly for a unit default to the value configured in the various | |
717 | <varname>DefaultLimitCPU=</varname>, <varname>DefaultLimitFSIZE=</varname>, … options available in | |
718 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, and – | |
719 | if not configured there – the kernel or per-user defaults, as defined by the OS (the latter only for user | |
720 | services, see above).</para> | |
721 | ||
798d3a52 | 722 | <table> |
f4c9356d | 723 | <title>Resource limit directives, their equivalent <command>ulimit</command> shell commands and the unit used</title> |
798d3a52 | 724 | |
a4c18002 | 725 | <tgroup cols='3'> |
798d3a52 ZJS |
726 | <colspec colname='directive' /> |
727 | <colspec colname='equivalent' /> | |
a4c18002 | 728 | <colspec colname='unit' /> |
798d3a52 ZJS |
729 | <thead> |
730 | <row> | |
731 | <entry>Directive</entry> | |
f4c9356d | 732 | <entry><command>ulimit</command> equivalent</entry> |
a4c18002 | 733 | <entry>Unit</entry> |
798d3a52 ZJS |
734 | </row> |
735 | </thead> | |
736 | <tbody> | |
737 | <row> | |
a4c18002 | 738 | <entry>LimitCPU=</entry> |
798d3a52 | 739 | <entry>ulimit -t</entry> |
a4c18002 | 740 | <entry>Seconds</entry> |
798d3a52 ZJS |
741 | </row> |
742 | <row> | |
a4c18002 | 743 | <entry>LimitFSIZE=</entry> |
798d3a52 | 744 | <entry>ulimit -f</entry> |
a4c18002 | 745 | <entry>Bytes</entry> |
798d3a52 ZJS |
746 | </row> |
747 | <row> | |
a4c18002 | 748 | <entry>LimitDATA=</entry> |
798d3a52 | 749 | <entry>ulimit -d</entry> |
a4c18002 | 750 | <entry>Bytes</entry> |
798d3a52 ZJS |
751 | </row> |
752 | <row> | |
a4c18002 | 753 | <entry>LimitSTACK=</entry> |
798d3a52 | 754 | <entry>ulimit -s</entry> |
a4c18002 | 755 | <entry>Bytes</entry> |
798d3a52 ZJS |
756 | </row> |
757 | <row> | |
a4c18002 | 758 | <entry>LimitCORE=</entry> |
798d3a52 | 759 | <entry>ulimit -c</entry> |
a4c18002 | 760 | <entry>Bytes</entry> |
798d3a52 ZJS |
761 | </row> |
762 | <row> | |
a4c18002 | 763 | <entry>LimitRSS=</entry> |
798d3a52 | 764 | <entry>ulimit -m</entry> |
a4c18002 | 765 | <entry>Bytes</entry> |
798d3a52 ZJS |
766 | </row> |
767 | <row> | |
a4c18002 | 768 | <entry>LimitNOFILE=</entry> |
798d3a52 | 769 | <entry>ulimit -n</entry> |
a4c18002 | 770 | <entry>Number of File Descriptors</entry> |
798d3a52 ZJS |
771 | </row> |
772 | <row> | |
a4c18002 | 773 | <entry>LimitAS=</entry> |
798d3a52 | 774 | <entry>ulimit -v</entry> |
a4c18002 | 775 | <entry>Bytes</entry> |
798d3a52 ZJS |
776 | </row> |
777 | <row> | |
a4c18002 | 778 | <entry>LimitNPROC=</entry> |
798d3a52 | 779 | <entry>ulimit -u</entry> |
a4c18002 | 780 | <entry>Number of Processes</entry> |
798d3a52 ZJS |
781 | </row> |
782 | <row> | |
a4c18002 | 783 | <entry>LimitMEMLOCK=</entry> |
798d3a52 | 784 | <entry>ulimit -l</entry> |
a4c18002 | 785 | <entry>Bytes</entry> |
798d3a52 ZJS |
786 | </row> |
787 | <row> | |
a4c18002 | 788 | <entry>LimitLOCKS=</entry> |
798d3a52 | 789 | <entry>ulimit -x</entry> |
a4c18002 | 790 | <entry>Number of Locks</entry> |
798d3a52 ZJS |
791 | </row> |
792 | <row> | |
a4c18002 | 793 | <entry>LimitSIGPENDING=</entry> |
798d3a52 | 794 | <entry>ulimit -i</entry> |
a4c18002 | 795 | <entry>Number of Queued Signals</entry> |
798d3a52 ZJS |
796 | </row> |
797 | <row> | |
a4c18002 | 798 | <entry>LimitMSGQUEUE=</entry> |
798d3a52 | 799 | <entry>ulimit -q</entry> |
a4c18002 | 800 | <entry>Bytes</entry> |
798d3a52 ZJS |
801 | </row> |
802 | <row> | |
a4c18002 | 803 | <entry>LimitNICE=</entry> |
798d3a52 | 804 | <entry>ulimit -e</entry> |
a4c18002 | 805 | <entry>Nice Level</entry> |
798d3a52 ZJS |
806 | </row> |
807 | <row> | |
a4c18002 | 808 | <entry>LimitRTPRIO=</entry> |
798d3a52 | 809 | <entry>ulimit -r</entry> |
a4c18002 | 810 | <entry>Realtime Priority</entry> |
798d3a52 ZJS |
811 | </row> |
812 | <row> | |
a4c18002 | 813 | <entry>LimitRTTIME=</entry> |
798d3a52 | 814 | <entry>No equivalent</entry> |
a4c18002 | 815 | <entry>Microseconds</entry> |
798d3a52 ZJS |
816 | </row> |
817 | </tbody> | |
818 | </tgroup> | |
a4c18002 | 819 | </table></listitem> |
798d3a52 ZJS |
820 | </varlistentry> |
821 | ||
822 | <varlistentry> | |
823 | <term><varname>PAMName=</varname></term> | |
824 | <listitem><para>Sets the PAM service name to set up a session | |
825 | as. If set, the executed process will be registered as a PAM | |
826 | session under the specified service name. This is only useful | |
827 | in conjunction with the <varname>User=</varname> setting. If | |
828 | not set, no PAM session will be opened for the executed | |
829 | processes. See | |
830 | <citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
831 | for details.</para></listitem> | |
832 | </varlistentry> | |
833 | ||
834 | <varlistentry> | |
835 | <term><varname>CapabilityBoundingSet=</varname></term> | |
836 | ||
479050b3 LP |
837 | <listitem><para>Controls which capabilities to include in the capability bounding set for the executed |
838 | process. See <citerefentry | |
839 | project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> for | |
b2656f1b LP |
840 | details. Takes a whitespace-separated list of capability names, e.g. <constant>CAP_SYS_ADMIN</constant>, |
841 | <constant>CAP_DAC_OVERRIDE</constant>, <constant>CAP_SYS_PTRACE</constant>. Capabilities listed will be | |
842 | included in the bounding set, all others are removed. If the list of capabilities is prefixed with | |
843 | <literal>~</literal>, all but the listed capabilities will be included, the effect of the assignment | |
844 | inverted. Note that this option also affects the respective capabilities in the effective, permitted and | |
845 | inheritable capability sets. If this option is not used, the capability bounding set is not modified on process | |
846 | execution, hence no limits on the capabilities of the process are enforced. This option may appear more than | |
847 | once, in which case the bounding sets are merged. If the empty string is assigned to this option, the bounding | |
848 | set is reset to the empty capability set, and all prior settings have no effect. If set to | |
849 | <literal>~</literal> (without any further argument), the bounding set is reset to the full set of available | |
850 | capabilities, also undoing any previous settings. This does not affect commands prefixed with | |
851 | <literal>+</literal>.</para></listitem> | |
798d3a52 ZJS |
852 | </varlistentry> |
853 | ||
ece87975 IP |
854 | <varlistentry> |
855 | <term><varname>AmbientCapabilities=</varname></term> | |
856 | ||
b2656f1b LP |
857 | <listitem><para>Controls which capabilities to include in the ambient capability set for the executed |
858 | process. Takes a whitespace-separated list of capability names, e.g. <constant>CAP_SYS_ADMIN</constant>, | |
859 | <constant>CAP_DAC_OVERRIDE</constant>, <constant>CAP_SYS_PTRACE</constant>. This option may appear more than | |
860 | once in which case the ambient capability sets are merged. If the list of capabilities is prefixed with | |
861 | <literal>~</literal>, all but the listed capabilities will be included, the effect of the assignment | |
862 | inverted. If the empty string is assigned to this option, the ambient capability set is reset to the empty | |
863 | capability set, and all prior settings have no effect. If set to <literal>~</literal> (without any further | |
864 | argument), the ambient capability set is reset to the full set of available capabilities, also undoing any | |
865 | previous settings. Note that adding capabilities to ambient capability set adds them to the process's inherited | |
866 | capability set. </para><para> Ambient capability sets are useful if you want to execute a process as a | |
867 | non-privileged user but still want to give it some capabilities. Note that in this case option | |
868 | <constant>keep-caps</constant> is automatically added to <varname>SecureBits=</varname> to retain the | |
869 | capabilities over the user change. <varname>AmbientCapabilities=</varname> does not affect commands prefixed | |
870 | with <literal>+</literal>.</para></listitem> | |
ece87975 IP |
871 | </varlistentry> |
872 | ||
798d3a52 ZJS |
873 | <varlistentry> |
874 | <term><varname>SecureBits=</varname></term> | |
875 | <listitem><para>Controls the secure bits set for the executed | |
876 | process. Takes a space-separated combination of options from | |
877 | the following list: | |
878 | <option>keep-caps</option>, | |
879 | <option>keep-caps-locked</option>, | |
880 | <option>no-setuid-fixup</option>, | |
881 | <option>no-setuid-fixup-locked</option>, | |
882 | <option>noroot</option>, and | |
883 | <option>noroot-locked</option>. | |
b938cb90 | 884 | This option may appear more than once, in which case the secure |
798d3a52 | 885 | bits are ORed. If the empty string is assigned to this option, |
43eb109a | 886 | the bits are reset to 0. This does not affect commands prefixed with <literal>+</literal>. |
cf677fe6 | 887 | See <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
798d3a52 ZJS |
888 | for details.</para></listitem> |
889 | </varlistentry> | |
890 | ||
798d3a52 | 891 | <varlistentry> |
2a624c36 AP |
892 | <term><varname>ReadWritePaths=</varname></term> |
893 | <term><varname>ReadOnlyPaths=</varname></term> | |
894 | <term><varname>InaccessiblePaths=</varname></term> | |
798d3a52 | 895 | |
effbd6d2 LP |
896 | <listitem><para>Sets up a new file system namespace for executed processes. These options may be used to limit |
897 | access a process might have to the file system hierarchy. Each setting takes a space-separated list of paths | |
898 | relative to the host's root directory (i.e. the system running the service manager). Note that if paths | |
899 | contain symlinks, they are resolved relative to the root directory set with | |
900 | <varname>RootDirectory=</varname>.</para> | |
901 | ||
902 | <para>Paths listed in <varname>ReadWritePaths=</varname> are accessible from within the namespace with the same | |
903 | access modes as from outside of it. Paths listed in <varname>ReadOnlyPaths=</varname> are accessible for | |
904 | reading only, writing will be refused even if the usual file access controls would permit this. Nest | |
905 | <varname>ReadWritePaths=</varname> inside of <varname>ReadOnlyPaths=</varname> in order to provide writable | |
906 | subdirectories within read-only directories. Use <varname>ReadWritePaths=</varname> in order to whitelist | |
907 | specific paths for write access if <varname>ProtectSystem=strict</varname> is used. Paths listed in | |
908 | <varname>InaccessiblePaths=</varname> will be made inaccessible for processes inside the namespace (along with | |
909 | everything below them in the file system hierarchy).</para> | |
910 | ||
911 | <para>Note that restricting access with these options does not extend to submounts of a directory that are | |
912 | created later on. Non-directory paths may be specified as well. These options may be specified more than once, | |
913 | in which case all paths listed will have limited access from within the namespace. If the empty string is | |
914 | assigned to this option, the specific list is reset, and all prior assignments have no effect.</para> | |
915 | ||
e778185b DH |
916 | <para>Paths in <varname>ReadWritePaths=</varname>, <varname>ReadOnlyPaths=</varname> and |
917 | <varname>InaccessiblePaths=</varname> may be prefixed with <literal>-</literal>, in which case they will be ignored | |
918 | when they do not exist. Note that using this setting will disconnect propagation of mounts from the service to | |
919 | the host (propagation in the opposite direction continues to work). This means that this setting may not be used | |
920 | for services which shall be able to install mount points in the main mount namespace. Note that the effect of | |
921 | these settings may be undone by privileged processes. In order to set up an effective sandboxed environment for | |
922 | a unit it is thus recommended to combine these settings with either | |
923 | <varname>CapabilityBoundingSet=~CAP_SYS_ADMIN</varname> or <varname>SystemCallFilter=~@mount</varname>.</para></listitem> | |
798d3a52 ZJS |
924 | </varlistentry> |
925 | ||
926 | <varlistentry> | |
927 | <term><varname>PrivateTmp=</varname></term> | |
928 | ||
00d9ef85 LP |
929 | <listitem><para>Takes a boolean argument. If true, sets up a new file system namespace for the executed |
930 | processes and mounts private <filename>/tmp</filename> and <filename>/var/tmp</filename> directories inside it | |
931 | that is not shared by processes outside of the namespace. This is useful to secure access to temporary files of | |
932 | the process, but makes sharing between processes via <filename>/tmp</filename> or <filename>/var/tmp</filename> | |
933 | impossible. If this is enabled, all temporary files created by a service in these directories will be removed | |
934 | after the service is stopped. Defaults to false. It is possible to run two or more units within the same | |
935 | private <filename>/tmp</filename> and <filename>/var/tmp</filename> namespace by using the | |
798d3a52 | 936 | <varname>JoinsNamespaceOf=</varname> directive, see |
00d9ef85 | 937 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for |
effbd6d2 LP |
938 | details. This setting is implied if <varname>DynamicUser=</varname> is set. For this setting the same |
939 | restrictions regarding mount propagation and privileges apply as for <varname>ReadOnlyPaths=</varname> and | |
940 | related calls, see above.</para></listitem> | |
941 | ||
798d3a52 ZJS |
942 | </varlistentry> |
943 | ||
944 | <varlistentry> | |
945 | <term><varname>PrivateDevices=</varname></term> | |
946 | ||
effbd6d2 LP |
947 | <listitem><para>Takes a boolean argument. If true, sets up a new /dev namespace for the executed processes and |
948 | only adds API pseudo devices such as <filename>/dev/null</filename>, <filename>/dev/zero</filename> or | |
949 | <filename>/dev/random</filename> (as well as the pseudo TTY subsystem) to it, but no physical devices such as | |
9221aec8 DH |
950 | <filename>/dev/sda</filename>, system memory <filename>/dev/mem</filename>, system ports |
951 | <filename>/dev/port</filename> and others. This is useful to securely turn off physical device access by the | |
8f81a5f6 DH |
952 | executed process. Defaults to false. Enabling this option will install a system call filter to block low-level |
953 | I/O system calls that are grouped in the <varname>@raw-io</varname> set, will also remove | |
2cd0a735 DH |
954 | <constant>CAP_MKNOD</constant> and <constant>CAP_SYS_RAWIO</constant> from the capability bounding set for |
955 | the unit (see above), and set <varname>DevicePolicy=closed</varname> (see | |
798d3a52 | 956 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
effbd6d2 LP |
957 | for details). Note that using this setting will disconnect propagation of mounts from the service to the host |
958 | (propagation in the opposite direction continues to work). This means that this setting may not be used for | |
959 | services which shall be able to install mount points in the main mount namespace. The /dev namespace will be | |
960 | mounted read-only and 'noexec'. The latter may break old programs which try to set up executable memory by | |
961 | using <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry> of | |
962 | <filename>/dev/zero</filename> instead of using <constant>MAP_ANON</constant>. This setting is implied if | |
963 | <varname>DynamicUser=</varname> is set. For this setting the same restrictions regarding mount propagation and | |
964 | privileges apply as for <varname>ReadOnlyPaths=</varname> and related calls, see above.</para></listitem> | |
798d3a52 ZJS |
965 | </varlistentry> |
966 | ||
967 | <varlistentry> | |
968 | <term><varname>PrivateNetwork=</varname></term> | |
969 | ||
970 | <listitem><para>Takes a boolean argument. If true, sets up a | |
971 | new network namespace for the executed processes and | |
972 | configures only the loopback network device | |
973 | <literal>lo</literal> inside it. No other network devices will | |
974 | be available to the executed process. This is useful to | |
975 | securely turn off network access by the executed process. | |
976 | Defaults to false. It is possible to run two or more units | |
977 | within the same private network namespace by using the | |
978 | <varname>JoinsNamespaceOf=</varname> directive, see | |
979 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
980 | for details. Note that this option will disconnect all socket | |
981 | families from the host, this includes AF_NETLINK and AF_UNIX. | |
982 | The latter has the effect that AF_UNIX sockets in the abstract | |
983 | socket namespace will become unavailable to the processes | |
984 | (however, those located in the file system will continue to be | |
985 | accessible).</para></listitem> | |
986 | </varlistentry> | |
987 | ||
988 | <varlistentry> | |
d251207d LP |
989 | <term><varname>PrivateUsers=</varname></term> |
990 | ||
991 | <listitem><para>Takes a boolean argument. If true, sets up a new user namespace for the executed processes and | |
992 | configures a minimal user and group mapping, that maps the <literal>root</literal> user and group as well as | |
993 | the unit's own user and group to themselves and everything else to the <literal>nobody</literal> user and | |
994 | group. This is useful to securely detach the user and group databases used by the unit from the rest of the | |
995 | system, and thus to create an effective sandbox environment. All files, directories, processes, IPC objects and | |
2dd67817 | 996 | other resources owned by users/groups not equaling <literal>root</literal> or the unit's own will stay visible |
d251207d LP |
997 | from within the unit but appear owned by the <literal>nobody</literal> user and group. If this mode is enabled, |
998 | all unit processes are run without privileges in the host user namespace (regardless if the unit's own | |
999 | user/group is <literal>root</literal> or not). Specifically this means that the process will have zero process | |
1000 | capabilities on the host's user namespace, but full capabilities within the service's user namespace. Settings | |
1001 | such as <varname>CapabilityBoundingSet=</varname> will affect only the latter, and there's no way to acquire | |
1002 | additional capabilities in the host's user namespace. Defaults to off.</para> | |
1003 | ||
1004 | <para>This setting is particularly useful in conjunction with <varname>RootDirectory=</varname>, as the need to | |
1005 | synchronize the user and group databases in the root directory and on the host is reduced, as the only users | |
1006 | and groups who need to be matched are <literal>root</literal>, <literal>nobody</literal> and the unit's own | |
1007 | user and group.</para></listitem> | |
1008 | </varlistentry> | |
1009 | ||
798d3a52 ZJS |
1010 | <varlistentry> |
1011 | <term><varname>ProtectSystem=</varname></term> | |
1012 | ||
3f815163 LP |
1013 | <listitem><para>Takes a boolean argument or the special values <literal>full</literal> or |
1014 | <literal>strict</literal>. If true, mounts the <filename>/usr</filename> and <filename>/boot</filename> | |
1015 | directories read-only for processes invoked by this unit. If set to <literal>full</literal>, the | |
1016 | <filename>/etc</filename> directory is mounted read-only, too. If set to <literal>strict</literal> the entire | |
1017 | file system hierarchy is mounted read-only, except for the API file system subtrees <filename>/dev</filename>, | |
1018 | <filename>/proc</filename> and <filename>/sys</filename> (protect these directories using | |
1019 | <varname>PrivateDevices=</varname>, <varname>ProtectKernelTunables=</varname>, | |
1020 | <varname>ProtectControlGroups=</varname>). This setting ensures that any modification of the vendor-supplied | |
1021 | operating system (and optionally its configuration, and local mounts) is prohibited for the service. It is | |
1022 | recommended to enable this setting for all long-running services, unless they are involved with system updates | |
1023 | or need to modify the operating system in other ways. If this option is used, | |
effbd6d2 LP |
1024 | <varname>ReadWritePaths=</varname> may be used to exclude specific directories from being made read-only. This |
1025 | setting is implied if <varname>DynamicUser=</varname> is set. For this setting the same restrictions regarding | |
1026 | mount propagation and privileges apply as for <varname>ReadOnlyPaths=</varname> and related calls, see | |
1027 | above. Defaults to off.</para></listitem> | |
798d3a52 ZJS |
1028 | </varlistentry> |
1029 | ||
1030 | <varlistentry> | |
1031 | <term><varname>ProtectHome=</varname></term> | |
1032 | ||
effbd6d2 LP |
1033 | <listitem><para>Takes a boolean argument or <literal>read-only</literal>. If true, the directories |
1034 | <filename>/home</filename>, <filename>/root</filename> and <filename>/run/user</filename> are made inaccessible | |
1035 | and empty for processes invoked by this unit. If set to <literal>read-only</literal>, the three directories are | |
1036 | made read-only instead. It is recommended to enable this setting for all long-running services (in particular | |
1037 | network-facing ones), to ensure they cannot get access to private user data, unless the services actually | |
1038 | require access to the user's private data. This setting is implied if <varname>DynamicUser=</varname> is | |
1039 | set. For this setting the same restrictions regarding mount propagation and privileges apply as for | |
1040 | <varname>ReadOnlyPaths=</varname> and related calls, see above.</para></listitem> | |
59eeb84b LP |
1041 | </varlistentry> |
1042 | ||
1043 | <varlistentry> | |
1044 | <term><varname>ProtectKernelTunables=</varname></term> | |
1045 | ||
1046 | <listitem><para>Takes a boolean argument. If true, kernel variables accessible through | |
49accde7 DH |
1047 | <filename>/proc/sys</filename>, <filename>/sys</filename>, <filename>/proc/sysrq-trigger</filename>, |
1048 | <filename>/proc/latency_stats</filename>, <filename>/proc/acpi</filename>, | |
1049 | <filename>/proc/timer_stats</filename>, <filename>/proc/fs</filename> and <filename>/proc/irq</filename> will | |
1050 | be made read-only to all processes of the unit. Usually, tunable kernel variables should only be written at | |
e778185b DH |
1051 | boot-time, with the <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
1052 | mechanism. Almost no services need to write to these at runtime; it is hence recommended to turn this on for | |
1053 | most services. For this setting the same restrictions regarding mount propagation and privileges apply as for | |
ac246d98 DH |
1054 | <varname>ReadOnlyPaths=</varname> and related calls, see above. Defaults to off. |
1055 | Note that this option does not prevent kernel tuning through IPC interfaces and exeternal programs. However | |
1056 | <varname>InaccessiblePaths=</varname> can be used to make some IPC file system objects | |
1057 | inaccessible.</para></listitem> | |
59eeb84b LP |
1058 | </varlistentry> |
1059 | ||
1060 | <varlistentry> | |
1061 | <term><varname>ProtectControlGroups=</varname></term> | |
1062 | ||
effbd6d2 LP |
1063 | <listitem><para>Takes a boolean argument. If true, the Linux Control Groups (<citerefentry |
1064 | project='man-pages'><refentrytitle>cgroups</refentrytitle><manvolnum>7</manvolnum></citerefentry>) hierarchies | |
1065 | accessible through <filename>/sys/fs/cgroup</filename> will be made read-only to all processes of the | |
1066 | unit. Except for container managers no services should require write access to the control groups hierarchies; | |
1067 | it is hence recommended to turn this on for most services. For this setting the same restrictions regarding | |
1068 | mount propagation and privileges apply as for <varname>ReadOnlyPaths=</varname> and related calls, see | |
1069 | above. Defaults to off.</para></listitem> | |
798d3a52 ZJS |
1070 | </varlistentry> |
1071 | ||
1072 | <varlistentry> | |
1073 | <term><varname>MountFlags=</varname></term> | |
1074 | ||
effbd6d2 LP |
1075 | <listitem><para>Takes a mount propagation flag: <option>shared</option>, <option>slave</option> or |
1076 | <option>private</option>, which control whether mounts in the file system namespace set up for this unit's | |
1077 | processes will receive or propagate mounts or unmounts. See <citerefentry | |
1078 | project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry> for | |
1079 | details. Defaults to <option>shared</option>. Use <option>shared</option> to ensure that mounts and unmounts | |
1080 | are propagated from the host to the container and vice versa. Use <option>slave</option> to run processes so | |
1081 | that none of their mounts and unmounts will propagate to the host. Use <option>private</option> to also ensure | |
1082 | that no mounts and unmounts from the host will propagate into the unit processes' namespace. Note that | |
1083 | <option>slave</option> means that file systems mounted on the host might stay mounted continuously in the | |
1084 | unit's namespace, and thus keep the device busy. Note that the file system namespace related options | |
1085 | (<varname>PrivateTmp=</varname>, <varname>PrivateDevices=</varname>, <varname>ProtectSystem=</varname>, | |
1086 | <varname>ProtectHome=</varname>, <varname>ProtectKernelTunables=</varname>, | |
1087 | <varname>ProtectControlGroups=</varname>, <varname>ReadOnlyPaths=</varname>, | |
1088 | <varname>InaccessiblePaths=</varname>, <varname>ReadWritePaths=</varname>) require that mount and unmount | |
1089 | propagation from the unit's file system namespace is disabled, and hence downgrade <option>shared</option> to | |
798d3a52 ZJS |
1090 | <option>slave</option>. </para></listitem> |
1091 | </varlistentry> | |
1092 | ||
1093 | <varlistentry> | |
1094 | <term><varname>UtmpIdentifier=</varname></term> | |
1095 | ||
1096 | <listitem><para>Takes a four character identifier string for | |
023a4f67 LP |
1097 | an <citerefentry |
1098 | project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1099 | and wtmp entry for this service. This should only be | |
1100 | set for services such as <command>getty</command> | |
1101 | implementations (such as <citerefentry | |
1102 | project='die-net'><refentrytitle>agetty</refentrytitle><manvolnum>8</manvolnum></citerefentry>) | |
798d3a52 | 1103 | where utmp/wtmp entries must be created and cleared before and |
023a4f67 LP |
1104 | after execution, or for services that shall be executed as if |
1105 | they were run by a <command>getty</command> process (see | |
1106 | below). If the configured string is longer than four | |
798d3a52 ZJS |
1107 | characters, it is truncated and the terminal four characters |
1108 | are used. This setting interprets %I style string | |
1109 | replacements. This setting is unset by default, i.e. no | |
1110 | utmp/wtmp entries are created or cleaned up for this | |
1111 | service.</para></listitem> | |
1112 | </varlistentry> | |
1113 | ||
023a4f67 LP |
1114 | <varlistentry> |
1115 | <term><varname>UtmpMode=</varname></term> | |
1116 | ||
1117 | <listitem><para>Takes one of <literal>init</literal>, | |
1118 | <literal>login</literal> or <literal>user</literal>. If | |
1119 | <varname>UtmpIdentifier=</varname> is set, controls which | |
1120 | type of <citerefentry | |
1121 | project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry>/wtmp | |
1122 | entries for this service are generated. This setting has no | |
1123 | effect unless <varname>UtmpIdentifier=</varname> is set | |
1124 | too. If <literal>init</literal> is set, only an | |
1125 | <constant>INIT_PROCESS</constant> entry is generated and the | |
6cd16034 LP |
1126 | invoked process must implement a |
1127 | <command>getty</command>-compatible utmp/wtmp logic. If | |
1128 | <literal>login</literal> is set, first an | |
a8eaaee7 | 1129 | <constant>INIT_PROCESS</constant> entry, followed by a |
6cd16034 | 1130 | <constant>LOGIN_PROCESS</constant> entry is generated. In |
b938cb90 | 1131 | this case, the invoked process must implement a <citerefentry |
023a4f67 LP |
1132 | project='die-net'><refentrytitle>login</refentrytitle><manvolnum>1</manvolnum></citerefentry>-compatible |
1133 | utmp/wtmp logic. If <literal>user</literal> is set, first an | |
1134 | <constant>INIT_PROCESS</constant> entry, then a | |
a8eaaee7 | 1135 | <constant>LOGIN_PROCESS</constant> entry and finally a |
023a4f67 | 1136 | <constant>USER_PROCESS</constant> entry is generated. In this |
b938cb90 | 1137 | case, the invoked process may be any process that is suitable |
023a4f67 LP |
1138 | to be run as session leader. Defaults to |
1139 | <literal>init</literal>.</para></listitem> | |
1140 | </varlistentry> | |
1141 | ||
798d3a52 ZJS |
1142 | <varlistentry> |
1143 | <term><varname>SELinuxContext=</varname></term> | |
1144 | ||
1145 | <listitem><para>Set the SELinux security context of the | |
1146 | executed process. If set, this will override the automated | |
1147 | domain transition. However, the policy still needs to | |
1148 | authorize the transition. This directive is ignored if SELinux | |
1149 | is disabled. If prefixed by <literal>-</literal>, all errors | |
43eb109a | 1150 | will be ignored. This does not affect commands prefixed with <literal>+</literal>. |
cf677fe6 | 1151 | See <citerefentry project='die-net'><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
798d3a52 ZJS |
1152 | for details.</para></listitem> |
1153 | </varlistentry> | |
1154 | ||
1155 | <varlistentry> | |
1156 | <term><varname>AppArmorProfile=</varname></term> | |
1157 | ||
1158 | <listitem><para>Takes a profile name as argument. The process | |
1159 | executed by the unit will switch to this profile when started. | |
1160 | Profiles must already be loaded in the kernel, or the unit | |
1161 | will fail. This result in a non operation if AppArmor is not | |
1162 | enabled. If prefixed by <literal>-</literal>, all errors will | |
43eb109a | 1163 | be ignored. This does not affect commands prefixed with <literal>+</literal>.</para></listitem> |
798d3a52 ZJS |
1164 | </varlistentry> |
1165 | ||
1166 | <varlistentry> | |
1167 | <term><varname>SmackProcessLabel=</varname></term> | |
1168 | ||
1169 | <listitem><para>Takes a <option>SMACK64</option> security | |
1170 | label as argument. The process executed by the unit will be | |
1171 | started under this label and SMACK will decide whether the | |
b938cb90 | 1172 | process is allowed to run or not, based on it. The process |
798d3a52 ZJS |
1173 | will continue to run under the label specified here unless the |
1174 | executable has its own <option>SMACK64EXEC</option> label, in | |
1175 | which case the process will transition to run under that | |
1176 | label. When not specified, the label that systemd is running | |
1177 | under is used. This directive is ignored if SMACK is | |
1178 | disabled.</para> | |
1179 | ||
1180 | <para>The value may be prefixed by <literal>-</literal>, in | |
1181 | which case all errors will be ignored. An empty value may be | |
cf677fe6 | 1182 | specified to unset previous assignments. This does not affect |
43eb109a | 1183 | commands prefixed with <literal>+</literal>.</para> |
798d3a52 ZJS |
1184 | </listitem> |
1185 | </varlistentry> | |
1186 | ||
1187 | <varlistentry> | |
1188 | <term><varname>IgnoreSIGPIPE=</varname></term> | |
1189 | ||
1190 | <listitem><para>Takes a boolean argument. If true, causes | |
1191 | <constant>SIGPIPE</constant> to be ignored in the executed | |
1192 | process. Defaults to true because <constant>SIGPIPE</constant> | |
1193 | generally is useful only in shell pipelines.</para></listitem> | |
1194 | </varlistentry> | |
1195 | ||
1196 | <varlistentry> | |
1197 | <term><varname>NoNewPrivileges=</varname></term> | |
1198 | ||
1199 | <listitem><para>Takes a boolean argument. If true, ensures | |
1200 | that the service process and all its children can never gain | |
1201 | new privileges. This option is more powerful than the | |
1202 | respective secure bits flags (see above), as it also prohibits | |
1203 | UID changes of any kind. This is the simplest, most effective | |
1204 | way to ensure that a process and its children can never | |
1205 | elevate privileges again.</para></listitem> | |
1206 | </varlistentry> | |
1207 | ||
1208 | <varlistentry> | |
1209 | <term><varname>SystemCallFilter=</varname></term> | |
1210 | ||
1211 | <listitem><para>Takes a space-separated list of system call | |
1212 | names. If this setting is used, all system calls executed by | |
1213 | the unit processes except for the listed ones will result in | |
1214 | immediate process termination with the | |
1215 | <constant>SIGSYS</constant> signal (whitelisting). If the | |
1216 | first character of the list is <literal>~</literal>, the | |
1217 | effect is inverted: only the listed system calls will result | |
1218 | in immediate process termination (blacklisting). If running in | |
19c0b0b9 | 1219 | user mode, or in system mode, but without the |
008dce38 | 1220 | <constant>CAP_SYS_ADMIN</constant> capability (e.g. setting |
19c0b0b9 | 1221 | <varname>User=nobody</varname>), |
798d3a52 ZJS |
1222 | <varname>NoNewPrivileges=yes</varname> is implied. This |
1223 | feature makes use of the Secure Computing Mode 2 interfaces of | |
1224 | the kernel ('seccomp filtering') and is useful for enforcing a | |
1225 | minimal sandboxing environment. Note that the | |
1226 | <function>execve</function>, | |
1227 | <function>rt_sigreturn</function>, | |
1228 | <function>sigreturn</function>, | |
1229 | <function>exit_group</function>, <function>exit</function> | |
1230 | system calls are implicitly whitelisted and do not need to be | |
b938cb90 | 1231 | listed explicitly. This option may be specified more than once, |
798d3a52 ZJS |
1232 | in which case the filter masks are merged. If the empty string |
1233 | is assigned, the filter is reset, all prior assignments will | |
43eb109a | 1234 | have no effect. This does not affect commands prefixed with <literal>+</literal>.</para> |
798d3a52 ZJS |
1235 | |
1236 | <para>If you specify both types of this option (i.e. | |
1237 | whitelisting and blacklisting), the first encountered will | |
1238 | take precedence and will dictate the default action | |
1239 | (termination or approval of a system call). Then the next | |
1240 | occurrences of this option will add or delete the listed | |
1241 | system calls from the set of the filtered system calls, | |
1242 | depending of its type and the default action. (For example, if | |
1243 | you have started with a whitelisting of | |
1244 | <function>read</function> and <function>write</function>, and | |
1245 | right after it add a blacklisting of | |
1246 | <function>write</function>, then <function>write</function> | |
201c1cc2 TM |
1247 | will be removed from the set.)</para> |
1248 | ||
1249 | <para>As the number of possible system | |
1250 | calls is large, predefined sets of system calls are provided. | |
1251 | A set starts with <literal>@</literal> character, followed by | |
1252 | name of the set. | |
1253 | ||
1254 | <table> | |
1255 | <title>Currently predefined system call sets</title> | |
1256 | ||
1257 | <tgroup cols='2'> | |
1258 | <colspec colname='set' /> | |
1259 | <colspec colname='description' /> | |
1260 | <thead> | |
1261 | <row> | |
1262 | <entry>Set</entry> | |
1263 | <entry>Description</entry> | |
1264 | </row> | |
1265 | </thead> | |
1266 | <tbody> | |
1267 | <row> | |
1268 | <entry>@clock</entry> | |
1f9ac68b LP |
1269 | <entry>System calls for changing the system clock (<citerefentry project='man-pages'><refentrytitle>adjtimex</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>settimeofday</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> |
1270 | </row> | |
1271 | <row> | |
1272 | <entry>@cpu-emulation</entry> | |
1273 | <entry>System calls for CPU emulation functionality (<citerefentry project='man-pages'><refentrytitle>vm86</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
1274 | </row> | |
1275 | <row> | |
1276 | <entry>@debug</entry> | |
1277 | <entry>Debugging, performance monitoring and tracing functionality (<citerefentry project='man-pages'><refentrytitle>ptrace</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>perf_event_open</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
201c1cc2 TM |
1278 | </row> |
1279 | <row> | |
1280 | <entry>@io-event</entry> | |
1f9ac68b | 1281 | <entry>Event loop system calls (<citerefentry project='man-pages'><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>select</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>eventfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> |
201c1cc2 TM |
1282 | </row> |
1283 | <row> | |
1284 | <entry>@ipc</entry> | |
1f9ac68b LP |
1285 | <entry>SysV IPC, POSIX Message Queues or other IPC (<citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>svipc</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry> |
1286 | </row> | |
1287 | <row> | |
1288 | <entry>@keyring</entry> | |
1289 | <entry>Kernel keyring access (<citerefentry project='man-pages'><refentrytitle>keyctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> | |
201c1cc2 TM |
1290 | </row> |
1291 | <row> | |
1292 | <entry>@module</entry> | |
1f9ac68b | 1293 | <entry>Kernel module control (<citerefentry project='man-pages'><refentrytitle>init_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>delete_module</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry> |
201c1cc2 TM |
1294 | </row> |
1295 | <row> | |
1296 | <entry>@mount</entry> | |
1f9ac68b | 1297 | <entry>File system mounting and unmounting (<citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry> |
201c1cc2 TM |
1298 | </row> |
1299 | <row> | |
1300 | <entry>@network-io</entry> | |
1f9ac68b | 1301 | <entry>Socket I/O (including local AF_UNIX): <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry></entry> |
201c1cc2 TM |
1302 | </row> |
1303 | <row> | |
1304 | <entry>@obsolete</entry> | |
1f9ac68b | 1305 | <entry>Unusual, obsolete or unimplemented (<citerefentry project='man-pages'><refentrytitle>create_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>gtty</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry> |
201c1cc2 TM |
1306 | </row> |
1307 | <row> | |
1308 | <entry>@privileged</entry> | |
1f9ac68b | 1309 | <entry>All system calls which need super-user capabilities (<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry> |
201c1cc2 TM |
1310 | </row> |
1311 | <row> | |
1312 | <entry>@process</entry> | |
1f9ac68b | 1313 | <entry>Process control, execution, namespaces (<citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>, …</entry> |
201c1cc2 TM |
1314 | </row> |
1315 | <row> | |
1316 | <entry>@raw-io</entry> | |
1f9ac68b | 1317 | <entry>Raw I/O port access (<citerefentry project='man-pages'><refentrytitle>ioperm</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>iopl</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <function>pciconfig_read()</function>, …</entry> |
201c1cc2 TM |
1318 | </row> |
1319 | </tbody> | |
1320 | </tgroup> | |
1321 | </table> | |
1322 | ||
1323 | Note, that as new system calls are added to the kernel, additional system calls might be added to the groups | |
effbd6d2 LP |
1324 | above, so the contents of the sets may change between systemd versions.</para> |
1325 | ||
1326 | <para>It is recommended to combine the file system namespacing related options with | |
1327 | <varname>SystemCallFilter=~@mount</varname>, in order to prohibit the unit's processes to undo the | |
1328 | mappings. Specifically these are the options <varname>PrivateTmp=</varname>, | |
1329 | <varname>PrivateDevices=</varname>, <varname>ProtectSystem=</varname>, <varname>ProtectHome=</varname>, | |
1330 | <varname>ProtectKernelTunables=</varname>, <varname>ProtectControlGroups=</varname>, | |
1331 | <varname>ReadOnlyPaths=</varname>, <varname>InaccessiblePaths=</varname> and | |
1332 | <varname>ReadWritePaths=</varname>.</para></listitem> | |
798d3a52 ZJS |
1333 | </varlistentry> |
1334 | ||
1335 | <varlistentry> | |
1336 | <term><varname>SystemCallErrorNumber=</varname></term> | |
1337 | ||
1338 | <listitem><para>Takes an <literal>errno</literal> error number | |
1339 | name to return when the system call filter configured with | |
1340 | <varname>SystemCallFilter=</varname> is triggered, instead of | |
1341 | terminating the process immediately. Takes an error name such | |
1342 | as <constant>EPERM</constant>, <constant>EACCES</constant> or | |
1343 | <constant>EUCLEAN</constant>. When this setting is not used, | |
1344 | or when the empty string is assigned, the process will be | |
1345 | terminated immediately when the filter is | |
1346 | triggered.</para></listitem> | |
1347 | </varlistentry> | |
1348 | ||
1349 | <varlistentry> | |
1350 | <term><varname>SystemCallArchitectures=</varname></term> | |
1351 | ||
b938cb90 | 1352 | <listitem><para>Takes a space-separated list of architecture |
798d3a52 ZJS |
1353 | identifiers to include in the system call filter. The known |
1354 | architecture identifiers are <constant>x86</constant>, | |
1355 | <constant>x86-64</constant>, <constant>x32</constant>, | |
6abfd303 HB |
1356 | <constant>arm</constant>, <constant>s390</constant>, |
1357 | <constant>s390x</constant> as well as the special identifier | |
798d3a52 ZJS |
1358 | <constant>native</constant>. Only system calls of the |
1359 | specified architectures will be permitted to processes of this | |
1360 | unit. This is an effective way to disable compatibility with | |
1361 | non-native architectures for processes, for example to | |
1362 | prohibit execution of 32-bit x86 binaries on 64-bit x86-64 | |
1363 | systems. The special <constant>native</constant> identifier | |
1364 | implicitly maps to the native architecture of the system (or | |
1365 | more strictly: to the architecture the system manager is | |
19c0b0b9 RC |
1366 | compiled for). If running in user mode, or in system mode, |
1367 | but without the <constant>CAP_SYS_ADMIN</constant> | |
008dce38 | 1368 | capability (e.g. setting <varname>User=nobody</varname>), |
19c0b0b9 | 1369 | <varname>NoNewPrivileges=yes</varname> is implied. Note |
798d3a52 ZJS |
1370 | that setting this option to a non-empty list implies that |
1371 | <constant>native</constant> is included too. By default, this | |
1372 | option is set to the empty list, i.e. no architecture system | |
1373 | call filtering is applied.</para></listitem> | |
1374 | </varlistentry> | |
1375 | ||
1376 | <varlistentry> | |
1377 | <term><varname>RestrictAddressFamilies=</varname></term> | |
1378 | ||
1379 | <listitem><para>Restricts the set of socket address families | |
1380 | accessible to the processes of this unit. Takes a | |
1381 | space-separated list of address family names to whitelist, | |
1382 | such as | |
1383 | <constant>AF_UNIX</constant>, | |
1384 | <constant>AF_INET</constant> or | |
1385 | <constant>AF_INET6</constant>. When | |
1386 | prefixed with <constant>~</constant> the listed address | |
1387 | families will be applied as blacklist, otherwise as whitelist. | |
1388 | Note that this restricts access to the | |
3ba3a79d | 1389 | <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry> |
798d3a52 ZJS |
1390 | system call only. Sockets passed into the process by other |
1391 | means (for example, by using socket activation with socket | |
1392 | units, see | |
1393 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>) | |
1394 | are unaffected. Also, sockets created with | |
1395 | <function>socketpair()</function> (which creates connected | |
1396 | AF_UNIX sockets only) are unaffected. Note that this option | |
1397 | has no effect on 32-bit x86 and is ignored (but works | |
19c0b0b9 RC |
1398 | correctly on x86-64). If running in user mode, or in system |
1399 | mode, but without the <constant>CAP_SYS_ADMIN</constant> | |
008dce38 | 1400 | capability (e.g. setting <varname>User=nobody</varname>), |
19c0b0b9 | 1401 | <varname>NoNewPrivileges=yes</varname> is implied. By |
798d3a52 ZJS |
1402 | default, no restriction applies, all address families are |
1403 | accessible to processes. If assigned the empty string, any | |
1404 | previous list changes are undone.</para> | |
1405 | ||
1406 | <para>Use this option to limit exposure of processes to remote | |
1407 | systems, in particular via exotic network protocols. Note that | |
1408 | in most cases, the local <constant>AF_UNIX</constant> address | |
1409 | family should be included in the configured whitelist as it is | |
1410 | frequently used for local communication, including for | |
1411 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
43eb109a | 1412 | logging. This does not affect commands prefixed with <literal>+</literal>.</para></listitem> |
798d3a52 ZJS |
1413 | </varlistentry> |
1414 | ||
502d704e DH |
1415 | <varlistentry> |
1416 | <term><varname>ProtectKernelModules=</varname></term> | |
1417 | ||
1418 | <listitem><para>Takes a boolean argument. If true, explicit module loading will | |
1419 | be denied. This allows to turn off module load and unload operations on modular | |
1420 | kernels. It is recomended to turn this on for most services that do not need special | |
1421 | file systems or extra kernel modules to work. Default to off. Enabling this option | |
1422 | removes <constant>CAP_SYS_MODULE</constant> from the capability bounding set for | |
c575770b DH |
1423 | the unit, and installs a system call filter to block module system calls, |
1424 | also <filename>/usr/lib/modules</filename> is made inaccessible. For this | |
1425 | setting the same restrictions regarding mount propagation and privileges | |
1426 | apply as for <varname>ReadOnlyPaths=</varname> and related calls, see above. | |
502d704e DH |
1427 | Note that limited automatic module loading due to user configuration or kernel |
1428 | mapping tables might still happen as side effect of requested user operations, | |
1429 | both privileged and unprivileged. To disable module auto-load feature please see | |
1430 | <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
1431 | <constant>kernel.modules_disabled</constant> mechanism and | |
1432 | <filename>/proc/sys/kernel/modules_disabled</filename> documentation.</para></listitem> | |
1433 | </varlistentry> | |
1434 | ||
798d3a52 ZJS |
1435 | <varlistentry> |
1436 | <term><varname>Personality=</varname></term> | |
1437 | ||
7882632d LP |
1438 | <listitem><para>Controls which kernel architecture <citerefentry |
1439 | project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry> shall report, | |
1440 | when invoked by unit processes. Takes one of the architecture identifiers <constant>x86</constant>, | |
1441 | <constant>x86-64</constant>, <constant>ppc</constant>, <constant>ppc-le</constant>, <constant>ppc64</constant>, | |
1442 | <constant>ppc64-le</constant>, <constant>s390</constant> or <constant>s390x</constant>. Which personality | |
1443 | architectures are supported depends on the system architecture. Usually the 64bit versions of the various | |
1444 | system architectures support their immediate 32bit personality architecture counterpart, but no others. For | |
1445 | example, <constant>x86-64</constant> systems support the <constant>x86-64</constant> and | |
1446 | <constant>x86</constant> personalities but no others. The personality feature is useful when running 32-bit | |
1447 | services on a 64-bit host system. If not specified, the personality is left unmodified and thus reflects the | |
1448 | personality of the host system's kernel.</para></listitem> | |
798d3a52 ZJS |
1449 | </varlistentry> |
1450 | ||
1451 | <varlistentry> | |
1452 | <term><varname>RuntimeDirectory=</varname></term> | |
1453 | <term><varname>RuntimeDirectoryMode=</varname></term> | |
1454 | ||
1455 | <listitem><para>Takes a list of directory names. If set, one | |
1456 | or more directories by the specified names will be created | |
1457 | below <filename>/run</filename> (for system services) or below | |
1458 | <varname>$XDG_RUNTIME_DIR</varname> (for user services) when | |
1459 | the unit is started, and removed when the unit is stopped. The | |
1460 | directories will have the access mode specified in | |
1461 | <varname>RuntimeDirectoryMode=</varname>, and will be owned by | |
1462 | the user and group specified in <varname>User=</varname> and | |
1463 | <varname>Group=</varname>. Use this to manage one or more | |
1464 | runtime directories of the unit and bind their lifetime to the | |
1465 | daemon runtime. The specified directory names must be | |
1466 | relative, and may not include a <literal>/</literal>, i.e. | |
1467 | must refer to simple directories to create or remove. This is | |
1468 | particularly useful for unprivileged daemons that cannot | |
1469 | create runtime directories in <filename>/run</filename> due to | |
1470 | lack of privileges, and to make sure the runtime directory is | |
1471 | cleaned up automatically after use. For runtime directories | |
1472 | that require more complex or different configuration or | |
1473 | lifetime guarantees, please consider using | |
1474 | <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
1475 | </varlistentry> | |
1476 | ||
f3e43635 TM |
1477 | <varlistentry> |
1478 | <term><varname>MemoryDenyWriteExecute=</varname></term> | |
1479 | ||
1480 | <listitem><para>Takes a boolean argument. If set, attempts to create memory mappings that are writable and | |
1481 | executable at the same time, or to change existing memory mappings to become executable are prohibited. | |
1482 | Specifically, a system call filter is added that rejects | |
1483 | <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1484 | system calls with both <constant>PROT_EXEC</constant> and <constant>PROT_WRITE</constant> set | |
1485 | and <citerefentry><refentrytitle>mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
1486 | system calls with <constant>PROT_EXEC</constant> set. Note that this option is incompatible with programs | |
1487 | that generate program code dynamically at runtime, such as JIT execution engines, or programs compiled making | |
1488 | use of the code "trampoline" feature of various C compilers. This option improves service security, as it makes | |
1489 | harder for software exploits to change running code dynamically. | |
1490 | </para></listitem> | |
1491 | </varlistentry> | |
1492 | ||
f4170c67 LP |
1493 | <varlistentry> |
1494 | <term><varname>RestrictRealtime=</varname></term> | |
1495 | ||
1496 | <listitem><para>Takes a boolean argument. If set, any attempts to enable realtime scheduling in a process of | |
1497 | the unit are refused. This restricts access to realtime task scheduling policies such as | |
1498 | <constant>SCHED_FIFO</constant>, <constant>SCHED_RR</constant> or <constant>SCHED_DEADLINE</constant>. See | |
0a07667d | 1499 | <citerefentry project='man-pages'><refentrytitle>sched</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details about |
f4170c67 LP |
1500 | these scheduling policies. Realtime scheduling policies may be used to monopolize CPU time for longer periods |
1501 | of time, and may hence be used to lock up or otherwise trigger Denial-of-Service situations on the system. It | |
1502 | is hence recommended to restrict access to realtime scheduling to the few programs that actually require | |
1503 | them. Defaults to off.</para></listitem> | |
1504 | </varlistentry> | |
1505 | ||
798d3a52 ZJS |
1506 | </variablelist> |
1507 | </refsect1> | |
1508 | ||
1509 | <refsect1> | |
1510 | <title>Environment variables in spawned processes</title> | |
1511 | ||
1512 | <para>Processes started by the system are executed in a clean | |
1513 | environment in which select variables listed below are set. System | |
1514 | processes started by systemd do not inherit variables from PID 1, | |
1515 | but processes started by user systemd instances inherit all | |
1516 | environment variables from the user systemd instance. | |
1517 | </para> | |
1518 | ||
1519 | <variablelist class='environment-variables'> | |
1520 | <varlistentry> | |
1521 | <term><varname>$PATH</varname></term> | |
1522 | ||
1523 | <listitem><para>Colon-separated list of directories to use | |
1524 | when launching executables. Systemd uses a fixed value of | |
1525 | <filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>. | |
1526 | </para></listitem> | |
1527 | </varlistentry> | |
1528 | ||
1529 | <varlistentry> | |
1530 | <term><varname>$LANG</varname></term> | |
1531 | ||
1532 | <listitem><para>Locale. Can be set in | |
3ba3a79d | 1533 | <citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
798d3a52 ZJS |
1534 | or on the kernel command line (see |
1535 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
1536 | and | |
1537 | <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>). | |
1538 | </para></listitem> | |
1539 | </varlistentry> | |
1540 | ||
1541 | <varlistentry> | |
1542 | <term><varname>$USER</varname></term> | |
1543 | <term><varname>$LOGNAME</varname></term> | |
1544 | <term><varname>$HOME</varname></term> | |
1545 | <term><varname>$SHELL</varname></term> | |
1546 | ||
1547 | <listitem><para>User name (twice), home directory, and the | |
1548 | login shell. The variables are set for the units that have | |
1549 | <varname>User=</varname> set, which includes user | |
1550 | <command>systemd</command> instances. See | |
3ba3a79d | 1551 | <citerefentry project='die-net'><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
798d3a52 ZJS |
1552 | </para></listitem> |
1553 | </varlistentry> | |
1554 | ||
4b58153d LP |
1555 | <varlistentry> |
1556 | <term><varname>$INVOCATION_ID</varname></term> | |
1557 | ||
1558 | <listitem><para>Contains a randomized, unique 128bit ID identifying each runtime cycle of the unit, formatted | |
1559 | as 32 character hexadecimal string. A new ID is assigned each time the unit changes from an inactive state into | |
1560 | an activating or active state, and may be used to identify this specific runtime cycle, in particular in data | |
1561 | stored offline, such as the journal. The same ID is passed to all processes run as part of the | |
1562 | unit.</para></listitem> | |
1563 | </varlistentry> | |
1564 | ||
798d3a52 ZJS |
1565 | <varlistentry> |
1566 | <term><varname>$XDG_RUNTIME_DIR</varname></term> | |
1567 | ||
1568 | <listitem><para>The directory for volatile state. Set for the | |
1569 | user <command>systemd</command> instance, and also in user | |
1570 | sessions. See | |
1571 | <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>. | |
1572 | </para></listitem> | |
1573 | </varlistentry> | |
1574 | ||
1575 | <varlistentry> | |
1576 | <term><varname>$XDG_SESSION_ID</varname></term> | |
1577 | <term><varname>$XDG_SEAT</varname></term> | |
1578 | <term><varname>$XDG_VTNR</varname></term> | |
1579 | ||
1580 | <listitem><para>The identifier of the session, the seat name, | |
1581 | and virtual terminal of the session. Set by | |
1582 | <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
1583 | for login sessions. <varname>$XDG_SEAT</varname> and | |
1584 | <varname>$XDG_VTNR</varname> will only be set when attached to | |
1585 | a seat and a tty.</para></listitem> | |
1586 | </varlistentry> | |
1587 | ||
1588 | <varlistentry> | |
1589 | <term><varname>$MAINPID</varname></term> | |
1590 | ||
2dd67817 | 1591 | <listitem><para>The PID of the unit's main process if it is |
798d3a52 ZJS |
1592 | known. This is only set for control processes as invoked by |
1593 | <varname>ExecReload=</varname> and similar. </para></listitem> | |
1594 | </varlistentry> | |
1595 | ||
1596 | <varlistentry> | |
1597 | <term><varname>$MANAGERPID</varname></term> | |
1598 | ||
1599 | <listitem><para>The PID of the user <command>systemd</command> | |
1600 | instance, set for processes spawned by it. </para></listitem> | |
1601 | </varlistentry> | |
1602 | ||
1603 | <varlistentry> | |
1604 | <term><varname>$LISTEN_FDS</varname></term> | |
1605 | <term><varname>$LISTEN_PID</varname></term> | |
5c019cf2 | 1606 | <term><varname>$LISTEN_FDNAMES</varname></term> |
798d3a52 ZJS |
1607 | |
1608 | <listitem><para>Information about file descriptors passed to a | |
1609 | service for socket activation. See | |
1610 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
1611 | </para></listitem> | |
1612 | </varlistentry> | |
1613 | ||
5c019cf2 EV |
1614 | <varlistentry> |
1615 | <term><varname>$NOTIFY_SOCKET</varname></term> | |
1616 | ||
1617 | <listitem><para>The socket | |
1618 | <function>sd_notify()</function> talks to. See | |
1619 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
1620 | </para></listitem> | |
1621 | </varlistentry> | |
1622 | ||
1623 | <varlistentry> | |
1624 | <term><varname>$WATCHDOG_PID</varname></term> | |
1625 | <term><varname>$WATCHDOG_USEC</varname></term> | |
1626 | ||
1627 | <listitem><para>Information about watchdog keep-alive notifications. See | |
1628 | <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
1629 | </para></listitem> | |
1630 | </varlistentry> | |
1631 | ||
798d3a52 ZJS |
1632 | <varlistentry> |
1633 | <term><varname>$TERM</varname></term> | |
1634 | ||
1635 | <listitem><para>Terminal type, set only for units connected to | |
1636 | a terminal (<varname>StandardInput=tty</varname>, | |
1637 | <varname>StandardOutput=tty</varname>, or | |
1638 | <varname>StandardError=tty</varname>). See | |
1639 | <citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
1640 | </para></listitem> | |
1641 | </varlistentry> | |
7bce046b LP |
1642 | |
1643 | <varlistentry> | |
1644 | <term><varname>$JOURNAL_STREAM</varname></term> | |
1645 | ||
1646 | <listitem><para>If the standard output or standard error output of the executed processes are connected to the | |
1647 | journal (for example, by setting <varname>StandardError=journal</varname>) <varname>$JOURNAL_STREAM</varname> | |
1648 | contains the device and inode numbers of the connection file descriptor, formatted in decimal, separated by a | |
1649 | colon (<literal>:</literal>). This permits invoked processes to safely detect whether their standard output or | |
1650 | standard error output are connected to the journal. The device and inode numbers of the file descriptors should | |
1651 | be compared with the values set in the environment variable to determine whether the process output is still | |
1652 | connected to the journal. Note that it is generally not sufficient to only check whether | |
1653 | <varname>$JOURNAL_STREAM</varname> is set at all as services might invoke external processes replacing their | |
1654 | standard output or standard error output, without unsetting the environment variable.</para> | |
1655 | ||
1656 | <para>This environment variable is primarily useful to allow services to optionally upgrade their used log | |
1657 | protocol to the native journal protocol (using | |
1658 | <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry> and other | |
1659 | functions) if their standard output or standard error output is connected to the journal anyway, thus enabling | |
1660 | delivery of structured metadata along with logged messages.</para></listitem> | |
1661 | </varlistentry> | |
136dc4c4 LP |
1662 | |
1663 | <varlistentry> | |
1664 | <term><varname>$SERVICE_RESULT</varname></term> | |
1665 | ||
1666 | <listitem><para>Only defined for the service unit type, this environment variable is passed to all | |
1667 | <varname>ExecStop=</varname> and <varname>ExecStopPost=</varname> processes, and encodes the service | |
1668 | "result". Currently, the following values are defined: <literal>timeout</literal> (in case of an operation | |
1669 | timeout), <literal>exit-code</literal> (if a service process exited with a non-zero exit code; see | |
81c8acee LP |
1670 | <varname>$EXIT_CODE</varname> below for the actual exit code returned), <literal>signal</literal> (if a |
1671 | service process was terminated abnormally by a signal; see <varname>$EXIT_CODE</varname> below for the actual | |
136dc4c4 LP |
1672 | signal used for the termination), <literal>core-dump</literal> (if a service process terminated abnormally and |
1673 | dumped core), <literal>watchdog</literal> (if the watchdog keep-alive ping was enabled for the service but it | |
1674 | missed the deadline), or <literal>resources</literal> (a catch-all condition in case a system operation | |
1675 | failed).</para> | |
1676 | ||
1677 | <para>This environment variable is useful to monitor failure or successful termination of a service. Even | |
1678 | though this variable is available in both <varname>ExecStop=</varname> and <varname>ExecStopPost=</varname>, it | |
1679 | is usually a better choice to place monitoring tools in the latter, as the former is only invoked for services | |
1680 | that managed to start up correctly, and the latter covers both services that failed during their start-up and | |
1681 | those which failed during their runtime.</para></listitem> | |
1682 | </varlistentry> | |
1683 | ||
1684 | <varlistentry> | |
1685 | <term><varname>$EXIT_CODE</varname></term> | |
1686 | <term><varname>$EXIT_STATUS</varname></term> | |
1687 | ||
1688 | <listitem><para>Only defined for the service unit type, these environment variables are passed to all | |
1689 | <varname>ExecStop=</varname>, <varname>ExecStopPost=</varname> processes and contain exit status/code | |
1690 | information of the main process of the service. For the precise definition of the exit code and status, see | |
1691 | <citerefentry><refentrytitle>wait</refentrytitle><manvolnum>2</manvolnum></citerefentry>. <varname>$EXIT_CODE</varname> | |
1692 | is one of <literal>exited</literal>, <literal>killed</literal>, | |
1693 | <literal>dumped</literal>. <varname>$EXIT_STATUS</varname> contains the numeric exit code formatted as string | |
1694 | if <varname>$EXIT_CODE</varname> is <literal>exited</literal>, and the signal name in all other cases. Note | |
1695 | that these environment variables are only set if the service manager succeeded to start and identify the main | |
e64e1bfd ZJS |
1696 | process of the service.</para> |
1697 | ||
1698 | <table> | |
1699 | <title>Summary of possible service result variable values</title> | |
1700 | <tgroup cols='3'> | |
1701 | <colspec colname='result' /> | |
1702 | <colspec colname='status' /> | |
1703 | <colspec colname='code' /> | |
1704 | <thead> | |
1705 | <row> | |
1706 | <entry><varname>$SERVICE_RESULT</varname></entry> | |
1707 | <entry><varname>$EXIT_STATUS</varname></entry> | |
1708 | <entry><varname>$EXIT_CODE</varname></entry> | |
1709 | </row> | |
1710 | </thead> | |
1711 | ||
1712 | <tbody> | |
29df65f9 ZJS |
1713 | <row> |
1714 | <entry morerows="1" valign="top"><literal>timeout</literal></entry> | |
1715 | <entry valign="top"><literal>killed</literal></entry> | |
6757c06a | 1716 | <entry><literal>TERM</literal>, <literal>KILL</literal></entry> |
29df65f9 ZJS |
1717 | </row> |
1718 | ||
1719 | <row> | |
1720 | <entry valign="top"><literal>exited</literal></entry> | |
6757c06a LP |
1721 | <entry><literal>0</literal>, <literal>1</literal>, <literal>2</literal>, <literal |
1722 | >3</literal>, …, <literal>255</literal></entry> | |
29df65f9 ZJS |
1723 | </row> |
1724 | ||
e64e1bfd ZJS |
1725 | <row> |
1726 | <entry valign="top"><literal>exit-code</literal></entry> | |
1727 | <entry valign="top"><literal>exited</literal></entry> | |
6757c06a LP |
1728 | <entry><literal>0</literal>, <literal>1</literal>, <literal>2</literal>, <literal |
1729 | >3</literal>, …, <literal>255</literal></entry> | |
e64e1bfd ZJS |
1730 | </row> |
1731 | ||
1732 | <row> | |
1733 | <entry valign="top"><literal>signal</literal></entry> | |
1734 | <entry valign="top"><literal>killed</literal></entry> | |
6757c06a | 1735 | <entry><literal>HUP</literal>, <literal>INT</literal>, <literal>KILL</literal>, …</entry> |
e64e1bfd ZJS |
1736 | </row> |
1737 | ||
1738 | <row> | |
1739 | <entry valign="top"><literal>core-dump</literal></entry> | |
1740 | <entry valign="top"><literal>dumped</literal></entry> | |
6757c06a | 1741 | <entry><literal>ABRT</literal>, <literal>SEGV</literal>, <literal>QUIT</literal>, …</entry> |
e64e1bfd | 1742 | </row> |
136dc4c4 | 1743 | |
e64e1bfd ZJS |
1744 | <row> |
1745 | <entry morerows="2" valign="top"><literal>watchdog</literal></entry> | |
1746 | <entry><literal>dumped</literal></entry> | |
1747 | <entry><literal>ABRT</literal></entry> | |
1748 | </row> | |
1749 | <row> | |
1750 | <entry><literal>killed</literal></entry> | |
6757c06a | 1751 | <entry><literal>TERM</literal>, <literal>KILL</literal></entry> |
e64e1bfd ZJS |
1752 | </row> |
1753 | <row> | |
1754 | <entry><literal>exited</literal></entry> | |
6757c06a LP |
1755 | <entry><literal>0</literal>, <literal>1</literal>, <literal>2</literal>, <literal |
1756 | >3</literal>, …, <literal>255</literal></entry> | |
e64e1bfd ZJS |
1757 | </row> |
1758 | ||
1759 | <row> | |
1760 | <entry><literal>resources</literal></entry> | |
1761 | <entry>any of the above</entry> | |
1762 | <entry>any of the above</entry> | |
1763 | </row> | |
29df65f9 ZJS |
1764 | |
1765 | <row> | |
1766 | <entry namest="results" nameend="code">Note: the process may be also terminated by a signal not sent by systemd. In particular the process may send an arbitrary signal to itself in a handler for any of the non-maskable signals. Nevertheless, in the <literal>timeout</literal> and <literal>watchdog</literal> rows above only the signals that systemd sends have been included.</entry> | |
1767 | </row> | |
e64e1bfd ZJS |
1768 | </tbody> |
1769 | </tgroup> | |
1770 | </table> | |
1771 | ||
1772 | </listitem> | |
1773 | </varlistentry> | |
798d3a52 ZJS |
1774 | </variablelist> |
1775 | ||
1776 | <para>Additional variables may be configured by the following | |
1777 | means: for processes spawned in specific units, use the | |
5c019cf2 EV |
1778 | <varname>Environment=</varname>, <varname>EnvironmentFile=</varname> |
1779 | and <varname>PassEnvironment=</varname> options above; to specify | |
798d3a52 ZJS |
1780 | variables globally, use <varname>DefaultEnvironment=</varname> |
1781 | (see | |
1782 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>) | |
1783 | or the kernel option <varname>systemd.setenv=</varname> (see | |
1784 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). | |
1785 | Additional variables may also be set through PAM, | |
1786 | cf. <citerefentry project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> | |
1787 | </refsect1> | |
1788 | ||
1789 | <refsect1> | |
1790 | <title>See Also</title> | |
1791 | <para> | |
1792 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
1793 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
1794 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
1795 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1796 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1797 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1798 | <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1799 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1800 | <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1801 | <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
a4c18002 | 1802 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
798d3a52 ZJS |
1803 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
1804 | <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
1805 | <citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
1806 | </para> | |
1807 | </refsect1> | |
dd1eb43b | 1808 | |
e64e1bfd | 1809 | |
dd1eb43b | 1810 | </refentry> |