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6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
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
13 (at your option) any later version.
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16 WITHOUT ANY WARRANTY; without even the implied warranty of
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24 <refentry id="systemd.exec">
26 <title>systemd.exec</title>
27 <productname>systemd</productname>
31 <contrib>Developer</contrib>
32 <firstname>Lennart</firstname>
33 <surname>Poettering</surname>
34 <email>lennart@poettering.net</email>
40 <refentrytitle>systemd.exec</refentrytitle>
41 <manvolnum>5</manvolnum>
45 <refname>systemd.exec</refname>
46 <refpurpose>Execution environment configuration</refpurpose>
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>
57 <title>Description</title>
59 <para>Unit configuration files for services, sockets,
60 mount points, and swap devices share a subset of
61 configuration options which define the execution
62 environment of spawned processes.</para>
64 <para>This man page lists the configuration options
65 shared by these four unit types. See
66 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
67 for the common options of all unit configuration
69 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
70 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
71 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
73 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
74 for more information on the specific unit
75 configuration files. The execution specific
76 configuration options are configured in the [Service],
77 [Socket], [Mount], or [Swap] sections, depending on the unit
82 <title>Options</title>
84 <variablelist class='unit-directives'>
87 <term><varname>WorkingDirectory=</varname></term>
89 <listitem><para>Takes an absolute
90 directory path. Sets the working
91 directory for executed processes. If
92 not set, defaults to the root directory
93 when systemd is running as a system
94 instance and the respective user's
95 home directory if run as
96 user.</para></listitem>
100 <term><varname>RootDirectory=</varname></term>
102 <listitem><para>Takes an absolute
103 directory path. Sets the root
104 directory for executed processes, with
106 <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
107 system call. If this is used, it must
108 be ensured that the process and all
109 its auxiliary files are available in
110 the <function>chroot()</function>
111 jail.</para></listitem>
115 <term><varname>User=</varname></term>
116 <term><varname>Group=</varname></term>
118 <listitem><para>Sets the Unix user
119 or group that the processes are executed
120 as, respectively. Takes a single user or group
121 name or ID as argument. If no group is
122 set, the default group of the user is
123 chosen.</para></listitem>
127 <term><varname>SupplementaryGroups=</varname></term>
129 <listitem><para>Sets the supplementary
130 Unix groups the processes are executed
131 as. This takes a space-separated list
132 of group names or IDs. This option may
133 be specified more than once in which
134 case all listed groups are set as
135 supplementary groups. When the empty
136 string is assigned the list of
137 supplementary groups is reset, and all
138 assignments prior to this one will
139 have no effect. In any way, this
140 option does not override, but extends
141 the list of supplementary groups
142 configured in the system group
144 user.</para></listitem>
148 <term><varname>Nice=</varname></term>
150 <listitem><para>Sets the default nice
151 level (scheduling priority) for
152 executed processes. Takes an integer
153 between -20 (highest priority) and 19
154 (lowest priority). See
155 <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
156 for details.</para></listitem>
160 <term><varname>OOMScoreAdjust=</varname></term>
162 <listitem><para>Sets the adjustment
163 level for the Out-Of-Memory killer for
164 executed processes. Takes an integer
165 between -1000 (to disable OOM killing
166 for this process) and 1000 (to make
167 killing of this process under memory
168 pressure very likely). See <ulink
169 url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
170 for details.</para></listitem>
174 <term><varname>IOSchedulingClass=</varname></term>
176 <listitem><para>Sets the IO scheduling
177 class for executed processes. Takes an
178 integer between 0 and 3 or one of the
179 strings <option>none</option>,
180 <option>realtime</option>,
181 <option>best-effort</option> or
182 <option>idle</option>. See
183 <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
184 for details.</para></listitem>
188 <term><varname>IOSchedulingPriority=</varname></term>
190 <listitem><para>Sets the IO scheduling
191 priority for executed processes. Takes
192 an integer between 0 (highest
193 priority) and 7 (lowest priority). The
194 available priorities depend on the
195 selected IO scheduling class (see
197 <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
198 for details.</para></listitem>
202 <term><varname>CPUSchedulingPolicy=</varname></term>
204 <listitem><para>Sets the CPU
205 scheduling policy for executed
206 processes. Takes one of
207 <option>other</option>,
208 <option>batch</option>,
209 <option>idle</option>,
210 <option>fifo</option> or
211 <option>rr</option>. See
212 <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
213 for details.</para></listitem>
217 <term><varname>CPUSchedulingPriority=</varname></term>
219 <listitem><para>Sets the CPU
220 scheduling priority for executed
221 processes. The available priority
222 range depends on the selected CPU
223 scheduling policy (see above). For
224 real-time scheduling policies an
225 integer between 1 (lowest priority)
226 and 99 (highest priority) can be used.
227 See <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
233 <term><varname>CPUSchedulingResetOnFork=</varname></term>
235 <listitem><para>Takes a boolean
236 argument. If true, elevated CPU
237 scheduling priorities and policies
238 will be reset when the executed
239 processes fork, and can hence not leak
240 into child processes. See
241 <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
242 for details. Defaults to false.</para></listitem>
246 <term><varname>CPUAffinity=</varname></term>
248 <listitem><para>Controls the CPU
249 affinity of the executed
250 processes. Takes a space-separated
251 list of CPU indices. This option may
252 be specified more than once in which
253 case the specified CPU affinity masks
254 are merged. If the empty string is
255 assigned, the mask is reset, all
256 assignments prior to this will have no
258 <citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
259 for details.</para></listitem>
263 <term><varname>UMask=</varname></term>
265 <listitem><para>Controls the file mode
266 creation mask. Takes an access mode in
268 <citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry>
269 for details. Defaults to
270 0022.</para></listitem>
274 <term><varname>Environment=</varname></term>
276 <listitem><para>Sets environment
277 variables for executed
278 processes. Takes a space-separated
279 list of variable assignments. This
280 option may be specified more than once
281 in which case all listed variables
282 will be set. If the same variable is
283 set twice, the later setting will
284 override the earlier setting. If the
285 empty string is assigned to this
286 option, the list of environment
287 variables is reset, all prior
288 assignments have no effect.
289 Variable expansion is not performed
290 inside the strings, however, specifier
291 expansion is possible. The $ character has
293 If you need to assign a value containing spaces
294 to a variable, use double quotes (")
295 for the assignment.</para>
298 <programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</programlisting>
299 gives three variables <literal>VAR1</literal>,
300 <literal>VAR2</literal>, <literal>VAR3</literal>
301 with the values <literal>word1 word2</literal>,
302 <literal>word3</literal>, <literal>$word 5 6</literal>.
307 <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
308 for details about environment variables.</para></listitem>
311 <term><varname>EnvironmentFile=</varname></term>
312 <listitem><para>Similar to
313 <varname>Environment=</varname> but
314 reads the environment variables from a
315 text file. The text file should
316 contain new-line-separated variable
317 assignments. Empty lines and lines
318 starting with ; or # will be ignored,
319 which may be used for commenting. A line
320 ending with a backslash will be concatenated
321 with the following one, allowing multiline variable
322 definitions. The parser strips leading
323 and trailing whitespace from the values
324 of assignments, unless you use
325 double quotes (").</para>
327 <para>The argument passed should be an
328 absolute filename or wildcard
329 expression, optionally prefixed with
330 <literal>-</literal>, which indicates
331 that if the file does not exist, it
332 will not be read and no error or warning
333 message is logged. This option may be
334 specified more than once in which case
335 all specified files are read. If the
336 empty string is assigned to this
337 option, the list of file to read is
338 reset, all prior assignments have no
341 <para>The files listed with this
342 directive will be read shortly before
343 the process is executed (more
344 specifically, after all
345 processes from a previous unit state
346 terminated. This means you can
347 generate these files in one unit
348 state, and read it with this option in
349 the next). Settings from these files
350 override settings made with
351 <varname>Environment=</varname>. If
352 the same variable is set twice from
353 these files, the files will be read in
354 the order they are specified and the
355 later setting will override the
356 earlier setting.</para></listitem>
360 <term><varname>StandardInput=</varname></term>
361 <listitem><para>Controls where file
362 descriptor 0 (STDIN) of the executed
363 processes is connected to. Takes one
364 of <option>null</option>,
365 <option>tty</option>,
366 <option>tty-force</option>,
367 <option>tty-fail</option> or
368 <option>socket</option>.</para>
370 <para>If <option>null</option> is
371 selected, standard input will be
373 <filename>/dev/null</filename>,
374 i.e. all read attempts by the process
375 will result in immediate EOF.</para>
377 <para>If <option>tty</option> is
378 selected, standard input is connected
379 to a TTY (as configured by
380 <varname>TTYPath=</varname>, see
381 below) and the executed process
382 becomes the controlling process of the
383 terminal. If the terminal is already
384 being controlled by another process,
385 the executed process waits until the
386 current controlling process releases
389 <para><option>tty-force</option> is similar
390 to <option>tty</option>, but the
391 executed process is forcefully and
392 immediately made the controlling
393 process of the terminal, potentially
394 removing previous controlling
398 <para><option>tty-fail</option> is
399 similar to <option>tty</option> but if
400 the terminal already has a controlling
401 process start-up of the executed
402 process fails.</para>
404 <para>The <option>socket</option>
405 option is only valid in
406 socket-activated services, and only
407 when the socket configuration file
409 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
410 for details) specifies a single socket
411 only. If this option is set, standard
412 input will be connected to the socket
413 the service was activated from, which
414 is primarily useful for compatibility
415 with daemons designed for use with the
417 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
420 <para>This setting defaults to
421 <option>null</option>.</para></listitem>
424 <term><varname>StandardOutput=</varname></term>
425 <listitem><para>Controls where file
426 descriptor 1 (STDOUT) of the executed
427 processes is connected to. Takes one
428 of <option>inherit</option>,
429 <option>null</option>,
430 <option>tty</option>,
431 <option>journal</option>,
432 <option>syslog</option>,
433 <option>kmsg</option>,
434 <option>journal+console</option>,
435 <option>syslog+console</option>,
436 <option>kmsg+console</option> or
437 <option>socket</option>.</para>
439 <para><option>inherit</option>
440 duplicates the file descriptor of
441 standard input for standard
444 <para><option>null</option> connects
446 <filename>/dev/null</filename>,
447 i.e. everything written to it will be
450 <para><option>tty</option> connects
451 standard output to a tty (as
453 <varname>TTYPath=</varname>, see
454 below). If the TTY is used for output
455 only, the executed process will not
456 become the controlling process of the
457 terminal, and will not fail or wait
458 for other processes to release the
461 <para><option>journal</option>
462 connects standard output with the
463 journal which is accessible via
464 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
465 Note that everything that is written
466 to syslog or kmsg (see below) is
467 implicitly stored in the journal as
468 well, the specific two options listed
469 below are hence supersets of this
472 <para><option>syslog</option> connects
473 standard output to the <citerefentry
474 project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
475 system syslog service, in addition to
476 the journal. Note that the journal
477 daemon is usually configured to
478 forward everything it receives to
479 syslog anyway, in which case this
480 option is no different from
481 <option>journal</option>.</para>
483 <para><option>kmsg</option> connects
484 standard output with the kernel log
485 buffer which is accessible via
487 project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
488 in addition to the journal. The
489 journal daemon might be configured to
490 send all logs to kmsg anyway, in which
491 case this option is no different from
492 <option>journal</option>.</para>
494 <para><option>journal+console</option>,
495 <option>syslog+console</option> and
496 <option>kmsg+console</option> work in
497 a similar way as the three options
498 above but copy the output to the
499 system console as well.</para>
501 <para><option>socket</option> connects
502 standard output to a socket acquired
503 via socket activation. The semantics
504 are similar to the same option of
505 <varname>StandardInput=</varname>.</para>
507 <para>This setting defaults to the
509 <option>DefaultStandardOutput=</option>
511 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
513 <option>journal</option>.</para></listitem>
516 <term><varname>StandardError=</varname></term>
517 <listitem><para>Controls where file
518 descriptor 2 (STDERR) of the
519 executed processes is connected to.
520 The available options are identical to
522 <varname>StandardOutput=</varname>,
523 with one exception: if set to
524 <option>inherit</option> the file
525 descriptor used for standard output is
526 duplicated for standard error. This
527 setting defaults to the value set with
528 <option>DefaultStandardError=</option>
530 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
532 <option>inherit</option>.</para></listitem>
535 <term><varname>TTYPath=</varname></term>
536 <listitem><para>Sets the terminal
537 device node to use if standard input, output,
538 or error are connected to a
539 TTY (see above). Defaults to
540 <filename>/dev/console</filename>.</para></listitem>
543 <term><varname>TTYReset=</varname></term>
544 <listitem><para>Reset the terminal
545 device specified with
546 <varname>TTYPath=</varname> before and
547 after execution. Defaults to
548 <literal>no</literal>.</para></listitem>
551 <term><varname>TTYVHangup=</varname></term>
552 <listitem><para>Disconnect all clients
553 which have opened the terminal device
555 <varname>TTYPath=</varname>
556 before and after execution. Defaults
558 <literal>no</literal>.</para></listitem>
561 <term><varname>TTYVTDisallocate=</varname></term>
562 <listitem><para>If the terminal
563 device specified with
564 <varname>TTYPath=</varname> is a
565 virtual console terminal, try to
566 deallocate the TTY before and after
567 execution. This ensures that the
568 screen and scrollback buffer is
570 <literal>no</literal>.</para></listitem>
573 <term><varname>SyslogIdentifier=</varname></term>
574 <listitem><para>Sets the process name
575 to prefix log lines sent to the
576 logging system or the kernel log
577 buffer with. If not set, defaults to
578 the process name of the executed
579 process. This option is only useful
581 <varname>StandardOutput=</varname> or
582 <varname>StandardError=</varname> are
583 set to <option>syslog</option>,
584 <option>journal</option> or
585 <option>kmsg</option> (or to the same
586 settings in combination with
587 <option>+console</option>).</para></listitem>
590 <term><varname>SyslogFacility=</varname></term>
591 <listitem><para>Sets the syslog
592 facility to use when logging to
593 syslog. One of <option>kern</option>,
594 <option>user</option>,
595 <option>mail</option>,
596 <option>daemon</option>,
597 <option>auth</option>,
598 <option>syslog</option>,
599 <option>lpr</option>,
600 <option>news</option>,
601 <option>uucp</option>,
602 <option>cron</option>,
603 <option>authpriv</option>,
604 <option>ftp</option>,
605 <option>local0</option>,
606 <option>local1</option>,
607 <option>local2</option>,
608 <option>local3</option>,
609 <option>local4</option>,
610 <option>local5</option>,
611 <option>local6</option> or
612 <option>local7</option>. See
613 <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
614 for details. This option is only
616 <varname>StandardOutput=</varname> or
617 <varname>StandardError=</varname> are
618 set to <option>syslog</option>.
620 <option>daemon</option>.</para></listitem>
623 <term><varname>SyslogLevel=</varname></term>
624 <listitem><para>Default syslog level
625 to use when logging to syslog or the
626 kernel log buffer. One of
627 <option>emerg</option>,
628 <option>alert</option>,
629 <option>crit</option>,
630 <option>err</option>,
631 <option>warning</option>,
632 <option>notice</option>,
633 <option>info</option>,
634 <option>debug</option>. See
635 <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
636 for details. This option is only
638 <varname>StandardOutput=</varname> or
639 <varname>StandardError=</varname> are
640 set to <option>syslog</option> or
641 <option>kmsg</option>. Note that
642 individual lines output by the daemon
643 might be prefixed with a different log
644 level which can be used to override
645 the default log level specified
646 here. The interpretation of these
647 prefixes may be disabled with
648 <varname>SyslogLevelPrefix=</varname>,
649 see below. For details see
650 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
653 <option>info</option>.</para></listitem>
657 <term><varname>SyslogLevelPrefix=</varname></term>
658 <listitem><para>Takes a boolean
659 argument. If true and
660 <varname>StandardOutput=</varname> or
661 <varname>StandardError=</varname> are
662 set to <option>syslog</option>,
663 <option>kmsg</option> or
664 <option>journal</option>, log lines
665 written by the executed process that
666 are prefixed with a log level will be
667 passed on to syslog with this log
668 level set but the prefix removed. If
669 set to false, the interpretation of
670 these prefixes is disabled and the
671 logged lines are passed on as-is. For
672 details about this prefixing see
673 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
674 Defaults to true.</para></listitem>
678 <term><varname>TimerSlackNSec=</varname></term>
679 <listitem><para>Sets the timer slack
680 in nanoseconds for the executed
681 processes. The timer slack controls
682 the accuracy of wake-ups triggered by
684 <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
685 for more information. Note that in
686 contrast to most other time span
687 definitions this parameter takes an
688 integer value in nano-seconds if no
689 unit is specified. The usual time
691 too.</para></listitem>
695 <term><varname>LimitCPU=</varname></term>
696 <term><varname>LimitFSIZE=</varname></term>
697 <term><varname>LimitDATA=</varname></term>
698 <term><varname>LimitSTACK=</varname></term>
699 <term><varname>LimitCORE=</varname></term>
700 <term><varname>LimitRSS=</varname></term>
701 <term><varname>LimitNOFILE=</varname></term>
702 <term><varname>LimitAS=</varname></term>
703 <term><varname>LimitNPROC=</varname></term>
704 <term><varname>LimitMEMLOCK=</varname></term>
705 <term><varname>LimitLOCKS=</varname></term>
706 <term><varname>LimitSIGPENDING=</varname></term>
707 <term><varname>LimitMSGQUEUE=</varname></term>
708 <term><varname>LimitNICE=</varname></term>
709 <term><varname>LimitRTPRIO=</varname></term>
710 <term><varname>LimitRTTIME=</varname></term>
711 <listitem><para>These settings set both
712 soft and hard limits of various resources for
713 executed processes. See
714 <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
715 for details. Use the string
716 <varname>infinity</varname> to
717 configure no limit on a specific
718 resource.</para></listitem>
721 <title>Limit directives and their equivalent with ulimit</title>
724 <colspec colname='directive' />
725 <colspec colname='equivalent' />
728 <entry>Directive</entry>
729 <entry>ulimit equivalent</entry>
734 <entry>LimitCPU</entry>
735 <entry>ulimit -t</entry>
738 <entry>LimitFSIZE</entry>
739 <entry>ulimit -f</entry>
742 <entry>LimitDATA</entry>
743 <entry>ulimit -d</entry>
746 <entry>LimitSTACK</entry>
747 <entry>ulimit -s</entry>
750 <entry>LimitCORE</entry>
751 <entry>ulimit -c</entry>
754 <entry>LimitRSS</entry>
755 <entry>ulimit -m</entry>
758 <entry>LimitNOFILE</entry>
759 <entry>ulimit -n</entry>
762 <entry>LimitAS</entry>
763 <entry>ulimit -v</entry>
766 <entry>LimitNPROC</entry>
767 <entry>ulimit -u</entry>
770 <entry>LimitMEMLOCK</entry>
771 <entry>ulimit -l</entry>
774 <entry>LimitLOCKS</entry>
775 <entry>ulimit -x</entry>
778 <entry>LimitSIGPENDING</entry>
779 <entry>ulimit -i</entry>
782 <entry>LimitMSGQUEUE</entry>
783 <entry>ulimit -q</entry>
786 <entry>LimitNICE</entry>
787 <entry>ulimit -e</entry>
790 <entry>LimitRTPRIO</entry>
791 <entry>ulimit -r</entry>
794 <entry>LimitRTTIME</entry>
795 <entry>No equivalent</entry>
803 <term><varname>PAMName=</varname></term>
804 <listitem><para>Sets the PAM service
805 name to set up a session as. If set,
806 the executed process will be
807 registered as a PAM session under the
808 specified service name. This is only
809 useful in conjunction with the
810 <varname>User=</varname> setting. If
811 not set, no PAM session will be opened
812 for the executed processes. See
813 <citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
814 for details.</para></listitem>
818 <term><varname>CapabilityBoundingSet=</varname></term>
820 <listitem><para>Controls which
821 capabilities to include in the
822 capability bounding set for the
823 executed process. See
824 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
825 for details. Takes a whitespace-separated
826 list of capability names as read by
827 <citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
828 e.g. <constant>CAP_SYS_ADMIN</constant>,
829 <constant>CAP_DAC_OVERRIDE</constant>,
830 <constant>CAP_SYS_PTRACE</constant>.
831 Capabilities listed will be included
832 in the bounding set, all others are
833 removed. If the list of capabilities
834 is prefixed with <literal>~</literal>,
835 all but the listed capabilities will
836 be included, the effect of the
837 assignment inverted. Note that this
838 option also affects the respective
839 capabilities in the effective,
840 permitted and inheritable capability
842 <varname>Capabilities=</varname>
843 does. If this option is not used, the
844 capability bounding set is not
845 modified on process execution, hence
846 no limits on the capabilities of the
847 process are enforced. This option may
848 appear more than once in which case
849 the bounding sets are merged. If the
850 empty string is assigned to this
851 option, the bounding set is reset to
852 the empty capability set, and all
853 prior settings have no effect. If set
854 to <literal>~</literal> (without any
855 further argument), the bounding set is
856 reset to the full set of available
857 capabilities, also undoing any
858 previous settings.</para></listitem>
862 <term><varname>SecureBits=</varname></term>
863 <listitem><para>Controls the secure
864 bits set for the executed process.
865 Takes a space-separated combination of
866 options from the following list:
867 <option>keep-caps</option>,
868 <option>keep-caps-locked</option>,
869 <option>no-setuid-fixup</option>,
870 <option>no-setuid-fixup-locked</option>,
871 <option>noroot</option>, and
872 <option>noroot-locked</option>. This
873 option may appear more than once in
874 which case the secure bits are ORed.
875 If the empty string is assigned to
876 this option, the bits are reset to 0.
878 project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
879 for details.</para></listitem>
883 <term><varname>Capabilities=</varname></term>
884 <listitem><para>Controls the
885 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
886 set for the executed process. Take a
887 capability string describing the
888 effective, permitted and inherited
889 capability sets as documented in
890 <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
891 Note that these capability sets are
892 usually influenced (and filtered) by the capabilities
893 attached to the executed file. Due to
895 <varname>CapabilityBoundingSet=</varname>
896 is probably a much more useful
897 setting.</para></listitem>
901 <term><varname>ReadWriteDirectories=</varname></term>
902 <term><varname>ReadOnlyDirectories=</varname></term>
903 <term><varname>InaccessibleDirectories=</varname></term>
905 <listitem><para>Sets up a new file
906 system namespace for executed
907 processes. These options may be used
908 to limit access a process might have
909 to the main file system
910 hierarchy. Each setting takes a
911 space-separated list of absolute
912 directory paths. Directories listed in
913 <varname>ReadWriteDirectories=</varname>
914 are accessible from within the
915 namespace with the same access rights
916 as from outside. Directories listed in
917 <varname>ReadOnlyDirectories=</varname>
918 are accessible for reading only,
919 writing will be refused even if the
920 usual file access controls would
921 permit this. Directories listed in
922 <varname>InaccessibleDirectories=</varname>
923 will be made inaccessible for
924 processes inside the namespace. Note
925 that restricting access with these
926 options does not extend to submounts
927 of a directory that are created later
928 on. These options may be specified
929 more than once in which case all
930 directories listed will have limited
931 access from within the namespace. If
932 the empty string is assigned to this
933 option, the specific list is reset,
934 and all prior assignments have no
937 <varname>ReadOnlyDirectories=</varname>
939 <varname>InaccessibleDirectories=</varname>
941 <literal>-</literal>, in which case
942 they will be ignored when they do not
943 exist. Note that using this
944 setting will disconnect propagation of
945 mounts from the service to the host
946 (propagation in the opposite direction
947 continues to work). This means that
948 this setting may not be used for
949 services which shall be able to
950 install mount points in the main mount
951 namespace.</para></listitem>
955 <term><varname>PrivateTmp=</varname></term>
957 <listitem><para>Takes a boolean
958 argument. If true, sets up a new file
959 system namespace for the executed
960 processes and mounts private
961 <filename>/tmp</filename> and
962 <filename>/var/tmp</filename>
963 directories inside it that is not
964 shared by processes outside of the
965 namespace. This is useful to secure
966 access to temporary files of the
967 process, but makes sharing between
969 <filename>/tmp</filename> or
970 <filename>/var/tmp</filename>
971 impossible. If this is enabled, all
972 temporary files created by a service
973 in these directories will be removed
974 after the service is stopped. Defaults
975 to false. It is possible to run two or
976 more units within the same private
977 <filename>/tmp</filename> and
978 <filename>/var/tmp</filename>
979 namespace by using the
980 <varname>JoinsNamespaceOf=</varname>
982 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
983 for details. Note that using this
984 setting will disconnect propagation of
985 mounts from the service to the host
986 (propagation in the opposite direction
987 continues to work). This means that
988 this setting may not be used for
989 services which shall be able to install
990 mount points in the main mount
991 namespace.</para></listitem>
995 <term><varname>PrivateDevices=</varname></term>
997 <listitem><para>Takes a boolean
998 argument. If true, sets up a new /dev
999 namespace for the executed processes
1000 and only adds API pseudo devices such
1001 as <filename>/dev/null</filename>,
1002 <filename>/dev/zero</filename> or
1003 <filename>/dev/random</filename> (as
1004 well as the pseudo TTY subsystem) to
1005 it, but no physical devices such as
1006 <filename>/dev/sda</filename>. This is
1007 useful to securely turn off physical
1008 device access by the executed
1009 process. Defaults to false. Enabling
1010 this option will also remove
1011 <constant>CAP_MKNOD</constant> from
1012 the capability bounding set for the
1013 unit (see above), and set
1014 <varname>DevicePolicy=closed</varname>
1016 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1017 for details). Note that using this
1018 setting will disconnect propagation of
1019 mounts from the service to the host
1020 (propagation in the opposite direction
1021 continues to work). This means that
1022 this setting may not be used for
1023 services which shall be able to
1024 install mount points in the main mount
1025 namespace.</para></listitem>
1029 <term><varname>PrivateNetwork=</varname></term>
1031 <listitem><para>Takes a boolean
1032 argument. If true, sets up a new
1033 network namespace for the executed
1034 processes and configures only the
1035 loopback network device
1036 <literal>lo</literal> inside it. No
1037 other network devices will be
1038 available to the executed process.
1039 This is useful to securely turn off
1040 network access by the executed
1041 process. Defaults to false. It is
1042 possible to run two or more units
1043 within the same private network
1044 namespace by using the
1045 <varname>JoinsNamespaceOf=</varname>
1047 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1048 for details. Note that this option
1049 will disconnect all socket families
1050 from the host, this includes
1051 AF_NETLINK and AF_UNIX. The latter has
1052 the effect that AF_UNIX sockets in the
1053 abstract socket namespace will become
1054 unavailable to the processes (however,
1055 those located in the file system will
1057 accessible).</para></listitem>
1061 <term><varname>ProtectSystem=</varname></term>
1063 <listitem><para>Takes a boolean
1065 <literal>full</literal>. If true,
1066 mounts the <filename>/usr</filename>
1067 directory read-only for processes
1068 invoked by this unit. If set to
1069 <literal>full</literal>, the
1070 <filename>/etc</filename> directory is mounted
1071 read-only, too. This setting ensures
1072 that any modification of the vendor
1073 supplied operating system (and
1074 optionally its configuration) is
1075 prohibited for the service. It is
1076 recommended to enable this setting for
1077 all long-running services, unless they
1078 are involved with system updates or
1079 need to modify the operating system in
1080 other ways. Note however that
1081 processes retaining the CAP_SYS_ADMIN
1082 capability can undo the effect of this
1083 setting. This setting is hence
1084 particularly useful for daemons which
1085 have this capability removed, for
1087 <varname>CapabilityBoundingSet=</varname>. Defaults
1088 to off.</para></listitem>
1092 <term><varname>ProtectHome=</varname></term>
1094 <listitem><para>Takes a boolean
1096 <literal>read-only</literal>. If true,
1098 <filename>/home</filename> and
1099 <filename>/run/user</filename> are
1100 made inaccessible and empty for
1101 processes invoked by this unit. If set
1102 to <literal>read-only</literal>, the
1103 two directories are made read-only
1104 instead. It is recommended to enable
1105 this setting for all long-running
1106 services (in particular network-facing
1107 ones), to ensure they cannot get access
1108 to private user data, unless the
1109 services actually require access to
1110 the user's private data. Note however
1111 that processes retaining the
1112 CAP_SYS_ADMIN capability can undo the
1113 effect of this setting. This setting
1114 is hence particularly useful for
1115 daemons which have this capability
1116 removed, for example with
1117 <varname>CapabilityBoundingSet=</varname>. Defaults
1118 to off.</para></listitem>
1122 <term><varname>MountFlags=</varname></term>
1124 <listitem><para>Takes a mount
1126 <option>shared</option>,
1127 <option>slave</option> or
1128 <option>private</option>, which
1129 control whether mounts in the file
1130 system namespace set up for this
1131 unit's processes will receive or
1132 propagate mounts or unmounts. See
1133 <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1134 for details. Defaults to
1135 <option>shared</option>. Use
1136 <option>shared</option> to ensure that
1137 mounts and unmounts are propagated
1138 from the host to the container and
1139 vice versa. Use <option>slave</option>
1140 to run processes so that none of their
1141 mounts and unmounts will propagate to
1142 the host. Use <option>private</option>
1143 to also ensure that no mounts and
1144 unmounts from the host will propagate
1145 into the unit processes'
1146 namespace. Note that
1147 <option>slave</option> means that file
1148 systems mounted on the host might stay
1149 mounted continuously in the unit's
1150 namespace, and thus keep the device
1151 busy. Note that the file system
1152 namespace related options
1153 (<varname>PrivateTmp=</varname>,
1154 <varname>PrivateDevices=</varname>,
1155 <varname>ProtectSystem=</varname>,
1156 <varname>ProtectHome=</varname>,
1157 <varname>ReadOnlyDirectories=</varname>,
1158 <varname>InaccessibleDirectories=</varname>
1160 <varname>ReadWriteDirectories=</varname>)
1161 require that mount and unmount
1162 propagation from the unit's file
1163 system namespace is disabled, and
1165 <option>shared</option> to
1166 <option>slave</option>.
1171 <term><varname>UtmpIdentifier=</varname></term>
1173 <listitem><para>Takes a four
1174 character identifier string for an
1175 utmp/wtmp entry for this service. This
1176 should only be set for services such
1177 as <command>getty</command>
1178 implementations where utmp/wtmp
1179 entries must be created and cleared
1180 before and after execution. If the
1181 configured string is longer than four
1182 characters, it is truncated and the
1183 terminal four characters are
1184 used. This setting interprets %I style
1185 string replacements. This setting is
1186 unset by default, i.e. no utmp/wtmp
1187 entries are created or cleaned up for
1188 this service.</para></listitem>
1192 <term><varname>SELinuxContext=</varname></term>
1194 <listitem><para>Set the SELinux
1195 security context of the executed
1196 process. If set, this will override
1197 the automated domain
1198 transition. However, the policy still
1199 needs to authorize the transition. This
1200 directive is ignored if SELinux is
1201 disabled. If prefixed by
1202 <literal>-</literal>, all errors will
1204 <citerefentry><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
1205 for details.</para></listitem>
1209 <term><varname>AppArmorProfile=</varname></term>
1211 <listitem><para>Takes a profile name as argument.
1212 The process executed by the unit will switch to
1213 this profile when started. Profiles must already
1214 be loaded in the kernel, or the unit will fail.
1215 This result in a non operation if AppArmor is not
1216 enabled. If prefixed by <literal>-</literal>, all errors
1222 <term><varname>SmackProcessLabel=</varname></term>
1224 <listitem><para>Takes a
1225 <option>SMACK64</option> security
1226 label as argument. The process
1227 executed by the unit will be started
1228 under this label and SMACK will decide
1229 whether the processes is allowed to
1230 run or not based on it. The process
1231 will continue to run under the label
1232 specified here unless the executable
1234 <option>SMACK64EXEC</option> label, in
1235 which case the process will transition
1236 to run under that label. When not
1237 specified, the label that systemd is
1238 running under is used. This directive
1239 is ignored if SMACK is
1242 <para>The value may be prefixed by
1243 <literal>-</literal>, in which case
1244 all errors will be ignored. An empty
1245 value may be specified to unset
1246 previous assignments.</para>
1251 <term><varname>IgnoreSIGPIPE=</varname></term>
1253 <listitem><para>Takes a boolean
1254 argument. If true, causes <constant>SIGPIPE</constant> to be
1255 ignored in the executed
1256 process. Defaults to true because
1257 <constant>SIGPIPE</constant> generally is useful only in
1258 shell pipelines.</para></listitem>
1262 <term><varname>NoNewPrivileges=</varname></term>
1264 <listitem><para>Takes a boolean
1265 argument. If true, ensures that the
1266 service process and all its children
1267 can never gain new privileges. This
1268 option is more powerful than the respective
1269 secure bits flags (see above), as it
1270 also prohibits UID changes of any
1271 kind. This is the simplest, most
1272 effective way to ensure that a process
1273 and its children can never elevate
1274 privileges again.</para></listitem>
1278 <term><varname>SystemCallFilter=</varname></term>
1280 <listitem><para>Takes a
1281 space-separated list of system call
1282 names. If this setting is used, all
1283 system calls executed by the unit
1284 processes except for the listed ones
1285 will result in immediate process
1286 termination with the
1287 <constant>SIGSYS</constant> signal
1288 (whitelisting). If the first character
1289 of the list is <literal>~</literal>,
1290 the effect is inverted: only the
1291 listed system calls will result in
1292 immediate process termination
1293 (blacklisting). If running in user
1294 mode and this option is used,
1295 <varname>NoNewPrivileges=yes</varname>
1296 is implied. This feature makes use of the
1297 Secure Computing Mode 2 interfaces of
1298 the kernel ('seccomp filtering') and
1299 is useful for enforcing a minimal
1300 sandboxing environment. Note that the
1301 <function>execve</function>,
1302 <function>rt_sigreturn</function>,
1303 <function>sigreturn</function>,
1304 <function>exit_group</function>,
1305 <function>exit</function> system calls
1306 are implicitly whitelisted and do not
1307 need to be listed explicitly. This
1308 option may be specified more than once
1309 in which case the filter masks are
1310 merged. If the empty string is
1311 assigned, the filter is reset, all
1312 prior assignments will have no
1315 <para>If you specify both types of
1316 this option (i.e. whitelisting and
1317 blacklisting), the first encountered
1318 will take precedence and will dictate
1319 the default action (termination or
1320 approval of a system call). Then the
1321 next occurrences of this option will
1322 add or delete the listed system calls
1323 from the set of the filtered system
1324 calls, depending of its type and the
1325 default action. (For example, if you have started
1326 with a whitelisting of
1327 <function>read</function> and
1328 <function>write</function>, and right
1329 after it add a blacklisting of
1330 <function>write</function>, then
1331 <function>write</function> will be
1332 removed from the set.)
1337 <term><varname>SystemCallErrorNumber=</varname></term>
1339 <listitem><para>Takes an
1340 <literal>errno</literal> error number
1341 name to return when the system call
1342 filter configured with
1343 <varname>SystemCallFilter=</varname>
1344 is triggered, instead of terminating
1345 the process immediately. Takes an
1347 <constant>EPERM</constant>,
1348 <constant>EACCES</constant> or
1349 <constant>EUCLEAN</constant>. When this
1350 setting is not used, or when the empty
1351 string is assigned, the process will be
1352 terminated immediately when the filter
1353 is triggered.</para></listitem>
1357 <term><varname>SystemCallArchitectures=</varname></term>
1359 <listitem><para>Takes a space
1360 separated list of architecture
1361 identifiers to include in the system
1362 call filter. The known architecture
1364 <constant>x86</constant>,
1365 <constant>x86-64</constant>,
1366 <constant>x32</constant>,
1367 <constant>arm</constant> as well as
1368 the special identifier
1369 <constant>native</constant>. Only
1370 system calls of the specified
1371 architectures will be permitted to
1372 processes of this unit. This is an
1373 effective way to disable compatibility
1374 with non-native architectures for
1375 processes, for example to prohibit
1376 execution of 32-bit x86 binaries on
1377 64-bit x86-64 systems. The special
1378 <constant>native</constant> identifier
1379 implicitly maps to the native
1380 architecture of the system (or more
1381 strictly: to the architecture the
1382 system manager is compiled for). If
1383 running in user mode and this option
1385 <varname>NoNewPrivileges=yes</varname>
1386 is implied. Note that setting this
1387 option to a non-empty list implies
1388 that <constant>native</constant> is
1389 included too. By default, this option
1390 is set to the empty list, i.e. no
1391 architecture system call filtering is
1392 applied.</para></listitem>
1396 <term><varname>RestrictAddressFamilies=</varname></term>
1398 <listitem><para>Restricts the set of
1399 socket address families accessible to
1400 the processes of this unit. Takes a
1401 space-separated list of address family
1402 names to whitelist, such as
1403 <constant>AF_UNIX</constant>,
1404 <constant>AF_INET</constant> or
1405 <constant>AF_INET6</constant>. When
1406 prefixed with <constant>~</constant>
1407 the listed address families will be
1408 applied as blacklist, otherwise as
1409 whitelist. Note that this restricts
1411 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1412 system call only. Sockets passed into
1413 the process by other means (for
1414 example, by using socket activation
1415 with socket units, see
1416 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1417 are unaffected. Also, sockets created
1418 with <function>socketpair()</function>
1419 (which creates connected AF_UNIX
1420 sockets only) are unaffected. Note
1421 that this option has no effect on
1422 32-bit x86 and is ignored (but works
1423 correctly on x86-64). If running in user
1424 mode and this option is used,
1425 <varname>NoNewPrivileges=yes</varname>
1426 is implied. By default, no
1427 restriction applies, all address
1428 families are accessible to
1429 processes. If assigned the empty
1430 string, any previous list changes are
1433 <para>Use this option to limit
1434 exposure of processes to remote
1435 systems, in particular via exotic
1436 network protocols. Note that in most
1438 <constant>AF_UNIX</constant> address
1439 family should be included in the
1440 configured whitelist as it is
1441 frequently used for local
1442 communication, including for
1443 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1444 logging.</para></listitem>
1448 <term><varname>Personality=</varname></term>
1450 <listitem><para>Controls which
1452 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1453 shall report, when invoked by unit
1454 processes. Takes one of
1455 <constant>x86</constant> and
1456 <constant>x86-64</constant>. This is
1457 useful when running 32-bit services on
1458 a 64-bit host system. If not specified,
1459 the personality is left unmodified and
1460 thus reflects the personality of the
1462 kernel.</para></listitem>
1466 <term><varname>RuntimeDirectory=</varname></term>
1467 <term><varname>RuntimeDirectoryMode=</varname></term>
1469 <listitem><para>Takes a list of
1470 directory names. If set, one or more
1471 directories by the specified names
1472 will be created below
1473 <filename>/run</filename> (for system
1475 <varname>$XDG_RUNTIME_DIR</varname>
1476 (for user services) when the unit is
1477 started, and removed when the unit is
1478 stopped. The directories will have the
1479 access mode specified in
1480 <varname>RuntimeDirectoryMode=</varname>,
1481 and will be owned by the user and
1483 <varname>User=</varname> and
1484 <varname>Group=</varname>. Use this to
1485 manage one or more runtime directories
1486 of the unit and bind their lifetime to
1487 the daemon runtime. The specified
1488 directory names must be relative, and
1490 <literal>/</literal>, i.e. must refer
1491 to simple directories to create or
1492 remove. This is particularly useful
1493 for unprivileged daemons that cannot
1494 create runtime directories in
1495 <filename>/run</filename> due to lack
1496 of privileges, and to make sure the
1497 runtime directory is cleaned up
1498 automatically after use. For runtime
1499 directories that require more complex
1500 or different configuration or lifetime
1501 guarantees, please consider using
1502 <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
1509 <title>Environment variables in spawned processes</title>
1511 <para>Processes started by the system are executed in
1512 a clean environment in which select variables
1513 listed below are set. System processes started by systemd
1514 do not inherit variables from PID 1, but processes
1515 started by user systemd instances inherit all
1516 environment variables from the user systemd instance.
1519 <variablelist class='environment-variables'>
1521 <term><varname>$PATH</varname></term>
1523 <listitem><para>Colon-separated list
1524 of directories to use when launching
1525 executables. Systemd uses a fixed
1527 <filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>.
1532 <term><varname>$LANG</varname></term>
1534 <listitem><para>Locale. Can be set in
1535 <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1536 or on the kernel command line (see
1537 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1539 <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
1544 <term><varname>$USER</varname></term>
1545 <term><varname>$LOGNAME</varname></term>
1546 <term><varname>$HOME</varname></term>
1547 <term><varname>$SHELL</varname></term>
1549 <listitem><para>User name (twice), home
1550 directory, and the login shell.
1551 The variables are set for the units that
1552 have <varname>User=</varname> set,
1554 <command>systemd</command> instances.
1556 <citerefentry><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1561 <term><varname>$XDG_RUNTIME_DIR</varname></term>
1563 <listitem><para>The directory for volatile
1564 state. Set for the user <command>systemd</command>
1565 instance, and also in user sessions.
1567 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
1572 <term><varname>$XDG_SESSION_ID</varname></term>
1573 <term><varname>$XDG_SEAT</varname></term>
1574 <term><varname>$XDG_VTNR</varname></term>
1576 <listitem><para>The identifier of the
1577 session, the seat name, and
1578 virtual terminal of the session. Set
1580 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1582 <varname>$XDG_SEAT</varname> and
1583 <varname>$XDG_VTNR</varname> will
1584 only be set when attached to a seat and a
1585 tty.</para></listitem>
1589 <term><varname>$MAINPID</varname></term>
1591 <listitem><para>The PID of the units
1592 main process if it is known. This is
1593 only set for control processes as
1595 <varname>ExecReload=</varname> and
1596 similar. </para></listitem>
1600 <term><varname>$MANAGERPID</varname></term>
1602 <listitem><para>The PID of the user
1603 <command>systemd</command> instance,
1604 set for processes spawned by it.
1609 <term><varname>$LISTEN_FDS</varname></term>
1610 <term><varname>$LISTEN_PID</varname></term>
1612 <listitem><para>Information about file
1613 descriptors passed to a service for
1614 socket activation. See
1615 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1620 <term><varname>$TERM</varname></term>
1622 <listitem><para>Terminal type, set
1623 only for units connected to a terminal
1624 (<varname>StandardInput=tty</varname>,
1625 <varname>StandardOutput=tty</varname>,
1627 <varname>StandardError=tty</varname>).
1629 <citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1634 <para>Additional variables may be configured by the
1635 following means: for processes spawned in specific
1636 units, use the <varname>Environment=</varname> and
1637 <varname>EnvironmentFile=</varname> options above; to
1638 specify variables globally, use
1639 <varname>DefaultEnvironment=</varname> (see
1640 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1641 or the kernel option
1642 <varname>systemd.setenv=</varname> (see
1643 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Additional
1644 variables may also be set through PAM,
1645 cf. <citerefentry project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
1649 <title>See Also</title>
1651 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1652 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1653 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1654 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1655 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1656 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1657 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1658 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1659 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1660 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1661 <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1662 <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1663 <citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>