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2 <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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9   Copyright 2010 Lennart Poettering
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24
25 <refentry id="systemd.exec">
26         <refentryinfo>
27                 <title>systemd.exec</title>
28                 <productname>systemd</productname>
29
30                 <authorgroup>
31                         <author>
32                                 <contrib>Developer</contrib>
33                                 <firstname>Lennart</firstname>
34                                 <surname>Poettering</surname>
35                                 <email>lennart@poettering.net</email>
36                         </author>
37                 </authorgroup>
38         </refentryinfo>
39
40         <refmeta>
41                 <refentrytitle>systemd.exec</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.exec</refname>
47                 <refpurpose>systemd execution environment configuration</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.service</filename>,
52                 <filename>systemd.socket</filename>,
53                 <filename>systemd.mount</filename></para>
54         </refsynopsisdiv>
55
56         <refsect1>
57                 <title>Description</title>
58
59                 <para>Unit configuration files for services, sockets
60                 and mount points share a subset of configuration
61                 options which define the execution environment of
62                 spawned processes.</para>
63
64                 <para>This man page lists the configuration options
65                 shared by these three unit types. See
66                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
67                 for the common options of all unit configuration
68                 files, and
69                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
70                 and
71                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
72                 for more information on the specific unit
73                 configuration files. The execution specific
74                 configuration options are configured in the [Service],
75                 [Socket] resp. [Mount] section, depending on the unit
76                 type.</para>
77         </refsect1>
78
79         <refsect1>
80                 <title>Options</title>
81
82                 <variablelist>
83
84                         <varlistentry>
85                                 <term><varname>WorkingDirectory=</varname></term>
86
87                                 <listitem><para>Takes an absolute
88                                 directory path. Sets the working
89                                 directory for executed
90                                 processes.</para></listitem>
91                         </varlistentry>
92
93                         <varlistentry>
94                                 <term><varname>RootDirectory=</varname></term>
95
96                                 <listitem><para>Takes an absolute
97                                 directory path. Sets the root
98                                 directory for executed processes, with
99                                 the
100                                 <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
101                                 system call. If this is used it must
102                                 be ensured that the process and all
103                                 its auxiliary files are available in
104                                 the <function>chroot()</function>
105                                 jail.</para></listitem>
106                         </varlistentry>
107
108                         <varlistentry>
109                                 <term><varname>User=</varname></term>
110                                 <term><varname>Group=</varname></term>
111
112                                 <listitem><para>Sets the Unix user
113                                 resp. group the processes are executed
114                                 as. Takes a single user resp. group
115                                 name or ID as argument. If no group is
116                                 set the default group of the user is
117                                 chosen.</para></listitem>
118                         </varlistentry>
119
120                         <varlistentry>
121                                 <term><varname>SupplementaryGroups=</varname></term>
122
123                                 <listitem><para>Sets the supplementary
124                                 Unix groups the processes are executed
125                                 as. This takes a space separated list
126                                 of group names or IDs. This option may
127                                 be specified more than once in which
128                                 case all listed groups are set as
129                                 supplementary groups. This option does
130                                 not override but extend the list of
131                                 supplementary groups configured in the
132                                 system group database for the
133                                 user.</para></listitem>
134                         </varlistentry>
135
136                         <varlistentry>
137                                 <term><varname>Nice=</varname></term>
138
139                                 <listitem><para>Sets the default nice
140                                 level (scheduling priority) for
141                                 executed processes. Takes an integer
142                                 between -20 (highest priority) and 19
143                                 (lowest priority). See
144                                 <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
145                                 for details.</para></listitem>
146                         </varlistentry>
147
148                         <varlistentry>
149                                 <term><varname>OOMScoreAdjust=</varname></term>
150
151                                 <listitem><para>Sets the adjustment
152                                 level for the Out-Of-Memory killer for
153                                 executed processes. Takes an integer
154                                 between -1000 (to disable OOM killing
155                                 for this process) and 1000 (to make
156                                 killing of this process under memory
157                                 pressure very likely). See <ulink
158                                 url="http://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
159                                 for details.</para></listitem>
160                         </varlistentry>
161
162                         <varlistentry>
163                                 <term><varname>IOSchedulingClass=</varname></term>
164
165                                 <listitem><para>Sets the IO scheduling
166                                 class for executed processes. Takes an
167                                 integer between 0 and 3 or one of the
168                                 strings <option>none</option>,
169                                 <option>realtime</option>,
170                                 <option>best-effort</option> or
171                                 <option>idle</option>. See
172                                 <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
173                                 for details.</para></listitem>
174                         </varlistentry>
175
176                         <varlistentry>
177                                 <term><varname>IOSchedulingPriority=</varname></term>
178
179                                 <listitem><para>Sets the IO scheduling
180                                 priority for executed processes. Takes
181                                 an integer between 0 (highest
182                                 priority) and 7 (lowest priority). The
183                                 available priorities depend on the
184                                 selected IO scheduling class (see
185                                 above). See
186                                 <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
187                                 for details.</para></listitem>
188                         </varlistentry>
189
190                         <varlistentry>
191                                 <term><varname>CPUSchedulingPolicy=</varname></term>
192
193                                 <listitem><para>Sets the CPU
194                                 scheduling policy for executed
195                                 processes. Takes one of
196                                 <option>other</option>,
197                                 <option>batch</option>,
198                                 <option>idle</option>,
199                                 <option>fifo</option> or
200                                 <option>rr</option>. See
201                                 <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
202                                 for details.</para></listitem>
203                         </varlistentry>
204
205                         <varlistentry>
206                                 <term><varname>CPUSchedulingPriority=</varname></term>
207
208                                 <listitem><para>Sets the CPU
209                                 scheduling priority for executed
210                                 processes. Takes an integer between 1
211                                 (lowest priority) and 99 (highest
212                                 priority). The available priority
213                                 range depends on the selected CPU
214                                 scheduling policy (see above). See
215                                 <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
216                                 for details.</para></listitem>
217                         </varlistentry>
218
219                         <varlistentry>
220                                 <term><varname>CPUSchedulingResetOnFork=</varname></term>
221
222                                 <listitem><para>Takes a boolean
223                                 argument. If true elevated CPU
224                                 scheduling priorities and policies
225                                 will be reset when the executed
226                                 processes fork, and can hence not leak
227                                 into child processes. See
228                                 <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
229                                 for details. Defaults to false.</para></listitem>
230                         </varlistentry>
231
232                         <varlistentry>
233                                 <term><varname>CPUAffinity=</varname></term>
234
235                                 <listitem><para>Controls the CPU
236                                 affinity of the executed
237                                 processes. Takes a space-separated
238                                 list of CPU indexes. See
239                                 <citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
240                                 for details.</para></listitem>
241                         </varlistentry>
242
243                         <varlistentry>
244                                 <term><varname>UMask=</varname></term>
245
246                                 <listitem><para>Controls the file mode
247                                 creation mask. Takes an access mode in
248                                 octal notation. See
249                                 <citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry>
250                                 for details. Defaults to
251                                 0002.</para></listitem>
252                         </varlistentry>
253
254                         <varlistentry>
255                                 <term><varname>Environment=</varname></term>
256
257                                 <listitem><para>Sets environment
258                                 variables for executed
259                                 processes. Takes a space-separated
260                                 list of variable assignments. This
261                                 option may be specified more than once
262                                 in which case all listed variables
263                                 will be set. If the same variable is
264                                 set twice the later setting will
265                                 override the earlier setting. See
266                                 <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
267                                 for details.</para></listitem>
268                         </varlistentry>
269                         <varlistentry>
270                                 <term><varname>EnvironmentFile=</varname></term>
271                                 <listitem><para>Similar to
272                                 <varname>Environment=</varname> but
273                                 reads the environment variables from a
274                                 text file. The text file should
275                                 contain new-line separated variable
276                                 assignments. Empty lines and lines
277                                 starting with ; or # will be ignored,
278                                 which may be used for
279                                 commenting.</para></listitem>
280                         </varlistentry>
281
282                         <varlistentry>
283                                 <term><varname>StandardInput=</varname></term>
284                                 <listitem><para>Controls where file
285                                 descriptor 0 (STDIN) of the executed
286                                 processes is connected to. Takes one
287                                 of <option>null</option>,
288                                 <option>tty</option>,
289                                 <option>tty-force</option>,
290                                 <option>tty-fail</option> or
291                                 <option>socket</option>. If
292                                 <option>null</option> is selected
293                                 standard input will be connected to
294                                 <filename>/dev/null</filename>,
295                                 i.e. all read attempts by the process
296                                 will result in immediate EOF. If
297                                 <option>tty</option> is selected
298                                 standard input is connected to a TTY
299                                 (as configured by
300                                 <varname>TTYPath=</varname>, see
301                                 below) and the executed process
302                                 becomes the controlling process of the
303                                 terminal. If the terminal is already
304                                 being controlled by another process it
305                                 is waited until that process releases
306                                 the
307                                 terminal. <option>tty-force</option>
308                                 is similar to <option>tty</option>,
309                                 but the executed process is forcefully
310                                 and immediately made the controlling
311                                 process of the terminal, potentially
312                                 removing previous controlling
313                                 processes from the
314                                 terminal. <option>tty-fail</option> is
315                                 similar to <option>tty</option> but if
316                                 the terminal already has a controlling
317                                 process start-up of the executed
318                                 process fails.  The
319                                 <option>socket</option> option is only
320                                 valid in socket-activated services,
321                                 and only when the socket configuration
322                                 file (see
323                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
324                                 for details) specifies a single socket
325                                 only. If this option is set standard
326                                 input will be connected to the socket
327                                 the service was activated from, which
328                                 is primarily useful for compatibility
329                                 with daemons designed for use with the
330                                 traditional
331                                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
332                                 daemon. This setting defaults to
333                                 <option>null</option>.</para></listitem>
334                         </varlistentry>
335                         <varlistentry>
336                                 <term><varname>StandardOutput=</varname></term>
337                                 <listitem><para>Controls where file
338                                 descriptor 1 (STDOUT) of the executed
339                                 processes is connected to. Takes one
340                                 of <option>inherit</option>,
341                                 <option>null</option>,
342                                 <option>tty</option>,
343                                 <option>syslog</option>,
344                                 <option>kmsg</option> or
345                                 <option>socket</option>. If set to
346                                 <option>inherit</option> the file
347                                 descriptor of standard input is
348                                 duplicated for standard output. If set
349                                 to <option>null</option> standard
350                                 output will be connected to
351                                 <filename>/dev/null</filename>,
352                                 i.e. everything written to it will be
353                                 lost. If set to <option>tty</option>
354                                 standard output will be connected to a
355                                 tty (as configured via
356                                 <varname>TTYPath=</varname>, see
357                                 below). If the TTY is used for output
358                                 only the executed process will not
359                                 become the controlling process of the
360                                 terminal, and will not fail or wait
361                                 for other processes to release the
362                                 terminal. <option>syslog</option>
363                                 connects standard output to the
364                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
365                                 system logger. <option>kmsg</option>
366                                 connects it with the kernel log buffer
367                                 which is accessible via
368                                 <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>socket</option>
369                                 connects standard output to a socket
370                                 from socket activation, semantics are
371                                 similar to the respective option of
372                                 <varname>StandardInput=</varname>.
373                                 This setting defaults to
374                                 <option>inherit</option>.</para></listitem>
375                         </varlistentry>
376                         <varlistentry>
377                                 <term><varname>StandardError=</varname></term>
378                                 <listitem><para>Controls where file
379                                 descriptor 2 (STDERR) of the executed
380                                 processes is connected to. The
381                                 available options are identical to
382                                 those of
383                                 <varname>StandardOutput=</varname>,
384                                 whith one exception: if set to
385                                 <option>inherit</option> the file
386                                 descriptor used for standard output is
387                                 duplicated for standard error. This
388                                 setting defaults to
389                                 <option>inherit</option>.</para></listitem>
390                         </varlistentry>
391                         <varlistentry>
392                                 <term><varname>TTYPath=</varname></term>
393                                 <listitem><para>Sets the terminal
394                                 device node to use if standard input,
395                                 output or stderr are connected to a
396                                 TTY (see above). Defaults to
397                                 <filename>/dev/console</filename>.</para></listitem>
398                         </varlistentry>
399                         <varlistentry>
400                                 <term><varname>SyslogIdentifer=</varname></term>
401                                 <listitem><para>Sets the process name
402                                 to prefix log lines sent to syslog or
403                                 the kernel log buffer with. If not set
404                                 defaults to the process name of the
405                                 executed process. This option is only
406                                 useful when
407                                 <varname>StandardOutput=</varname> or
408                                 <varname>StandardError=</varname> are
409                                 set to <option>syslog</option> or
410                                 <option>kmsg</option>.</para></listitem>
411                         </varlistentry>
412                         <varlistentry>
413                                 <term><varname>SyslogFacility=</varname></term>
414                                 <listitem><para>Sets the syslog
415                                 facility to use when logging to
416                                 syslog. One of <option>kern</option>,
417                                 <option>user</option>,
418                                 <option>mail</option>,
419                                 <option>daemon</option>,
420                                 <option>auth</option>,
421                                 <option>syslog</option>,
422                                 <option>lpr</option>,
423                                 <option>news</option>,
424                                 <option>uucp</option>,
425                                 <option>cron</option>,
426                                 <option>authpriv</option>,
427                                 <option>ftp</option>,
428                                 <option>local0</option>,
429                                 <option>local1</option>,
430                                 <option>local2</option>,
431                                 <option>local3</option>,
432                                 <option>local4</option>,
433                                 <option>local5</option>,
434                                 <option>local6</option> or
435                                 <option>local7</option>. See
436                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
437                                 for details. This option is only
438                                 useful when
439                                 <varname>StandardOutput=</varname> or
440                                 <varname>StandardError=</varname> are
441                                 set to <option>syslog</option>.
442                                 Defaults to
443                                 <option>daemon</option>.</para></listitem>
444                         </varlistentry>
445                         <varlistentry>
446                                 <term><varname>SyslogLevel=</varname></term>
447                                 <listitem><para>Default syslog level
448                                 to use when logging to syslog or the
449                                 kernel log buffer. One of
450                                 <option>emerg</option>,
451                                 <option>alert</option>,
452                                 <option>crit</option>,
453                                 <option>err</option>,
454                                 <option>warning</option>,
455                                 <option>notice</option>,
456                                 <option>info</option>,
457                                 <option>debug</option>. See
458                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
459                                 for details. This option is only
460                                 useful when
461                                 <varname>StandardOutput=</varname> or
462                                 <varname>StandardError=</varname> are
463                                 set to <option>syslog</option> or
464                                 <option>kmsg</option>. Note that
465                                 individual lines output by the daemon
466                                 might be prefixed with a different log
467                                 level which can be used to override
468                                 the default log level specified
469                                 here. The interpretation of these
470                                 prefixes may be disabled with
471                                 <varname>SyslogLevelPrefix=</varname>,
472                                 see below. For details see
473                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
474
475                                 Defaults to
476                                 <option>info</option>.</para></listitem>
477                         </varlistentry>
478
479                         <varlistentry>
480                                 <term><varname>SyslogLevelPrefix=</varname></term>
481                                 <listitem><para>Takes a boolean
482                                 argument. If true and
483                                 <varname>StandardOutput=</varname> or
484                                 <varname>StandardError=</varname> are
485                                 set to <option>syslog</option> or
486                                 <option>kmsg</option> log lines
487                                 written by the executed process that
488                                 are prefixed with a log level will be
489                                 passed on to syslog with this log
490                                 level set but the prefix removed. If
491                                 set to false, the interpretation of
492                                 these prefixes is disabled and the
493                                 logged lines are passed on as-is. For
494                                 details about this prefixing see
495                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
496                                 Defaults to true.</para></listitem>
497                         </varlistentry>
498
499                         <varlistentry>
500                                 <term><varname>TimerSlackNSec=</varname></term>
501                                 <listitem><para>Sets the timer slack
502                                 in nanoseconds for the executed
503                                 processes The timer slack controls the
504                                 accuracy of wake-ups triggered by
505                                 timers. See
506                                 <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
507                                 for more information. Note that in
508                                 contrast to most other time span
509                                 definitions this value is takes a
510                                 nano-seconds integer and does not
511                                 understand any other
512                                 units.</para></listitem>
513                         </varlistentry>
514
515                         <varlistentry>
516                                 <term><varname>LimitCPU=</varname></term>
517                                 <term><varname>LimitFSIZE=</varname></term>
518                                 <term><varname>LimitDATA=</varname></term>
519                                 <term><varname>LimitSTACK=</varname></term>
520                                 <term><varname>LimitCORE=</varname></term>
521                                 <term><varname>LimitRSS=</varname></term>
522                                 <term><varname>LimitNOFILE=</varname></term>
523                                 <term><varname>LimitAS=</varname></term>
524                                 <term><varname>LimitNPROC=</varname></term>
525                                 <term><varname>LimitMEMLOCK=</varname></term>
526                                 <term><varname>LimitLOCKS=</varname></term>
527                                 <term><varname>LimitSIGPENDING=</varname></term>
528                                 <term><varname>LimitMSGQUEUE=</varname></term>
529                                 <term><varname>LimitNICE=</varname></term>
530                                 <term><varname>LimitRTPRIO=</varname></term>
531                                 <term><varname>LimitRTTIME=</varname></term>
532                                 <listitem><para>These settings control
533                                 various resource limits for executed
534                                 processes. See
535                                 <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
536                                 for details.</para></listitem>
537                         </varlistentry>
538
539                         <varlistentry>
540                                 <term><varname>PAMName=</varname></term>
541                                 <listitem><para>Sets the PAM service
542                                 name to set up a session as. If set
543                                 the executed process will be
544                                 registered as a PAM session under the
545                                 specified service name. This is only
546                                 useful in conjunction with the
547                                 <varname>User=</varname> setting. If
548                                 not set no PAM session will be opened
549                                 for the executed processes. See
550                                 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
551                                 for details.</para></listitem>
552                         </varlistentry>
553
554                         <varlistentry>
555                                 <term><varname>TCPWrapName=</varname></term>
556                                 <listitem><para>If this is a
557                                 socket-activated service this sets the
558                                 tcpwrap service name to check the
559                                 permission for the current connection
560                                 with. This is only useful in
561                                 conjunction with socket-activated
562                                 services, and stream sockets (TCP) in
563                                 particular. It has no effect on other
564                                 socket types (e.g. datagram/UDP) and on processes
565                                 unrelated to socket-based
566                                 activation. If the tcpwrap
567                                 verification fails daemon start-up
568                                 will fail and the connection is
569                                 terminated. See
570                                 <citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
571                                 for details.</para></listitem>
572                         </varlistentry>
573
574                         <varlistentry>
575                                 <term><varname>Capabilities=</varname></term>
576                                 <listitem><para>Controls the
577                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
578                                 set for the executed process. Take a
579                                 capability string as described in
580                                 <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
581                                 Note that this capability set is
582                                 usually influenced by the capabilities
583                                 attached to the executed
584                                 file.</para></listitem>
585                         </varlistentry>
586
587                         <varlistentry>
588                                 <term><varname>SecureBits=</varname></term>
589                                 <listitem><para>Controls the secure
590                                 bits set for the executed process. See
591                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
592                                 for details. Takes a list of strings:
593                                 <option>keep-caps</option>,
594                                 <option>keep-caps-locked</option>,
595                                 <option>no-setuid-fixup</option>,
596                                 <option>no-setuid-fixup-locked</option>,
597                                 <option>no-setuid-noroot</option> and/or
598                                 <option>no-setuid-noroot-locked</option>.
599                                 </para></listitem>
600                         </varlistentry>
601
602                         <varlistentry>
603                                 <term><varname>CapabilityBoundingSetDrop=</varname></term>
604
605                                 <listitem><para>Controls the
606                                 capability bounding set drop set for
607                                 the executed process. See
608                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
609                                 for details. Takes a list of
610                                 capability names as read by
611                                 <citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
612                                 </para></listitem>
613                         </varlistentry>
614
615                         <varlistentry>
616                                 <term><varname>ControlGroup=</varname></term>
617
618                                 <listitem><para>Controls the control
619                                 groups the executed processes shall be
620                                 made members of. Takes a
621                                 space-separated list of cgroup
622                                 identifiers. A cgroup identifier has a
623                                 format like
624                                 <filename>cpu:/foo/bar</filename>,
625                                 where "cpu" identifies the kernel
626                                 control group controller used, and
627                                 <filename>/foo/bar</filename> is the
628                                 control group path. The controller name
629                                 and ":" may be omitted in which case
630                                 the named systemd control group
631                                 hierarchy is implied. Alternatively,
632                                 the path and ":" may be omitted, in
633                                 which case the default control group
634                                 path for this unit is implied. This
635                                 option may be used to place executed
636                                 processes in arbitrary groups in
637                                 arbitrary hierachies -- which can be
638                                 configured externally with additional execution limits. By default
639                                 systemd will place all executed
640                                 processes in separate per-unit control
641                                 groups (named after the unit) in the
642                                 systemd named hierarchy. Since every
643                                 process can be in one group per
644                                 hierarchy only overriding the control group
645                                 path in the named systemd hierarchy
646                                 will disable automatic placement in
647                                 the default group. For details about control
648                                 groups see <ulink
649                                 url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>.</para></listitem>
650                         </varlistentry>
651
652                         <varlistentry>
653                                 <term><varname>ReadWriteDirectories=</varname></term>
654                                 <term><varname>ReadOnlyDirectories=</varname></term>
655                                 <term><varname>InaccessibleDirectories=</varname></term>
656
657                                 <listitem><para>Sets up a new
658                                 file-system name space for executed
659                                 processes. These options may be used
660                                 to limit access a process might have
661                                 to the main file-system
662                                 hierarchy. Each setting takes a
663                                 space-separated list of absolute
664                                 directory paths. Directories listed in
665                                 <varname>ReadWriteDirectories=</varname>
666                                 are accessible from within the
667                                 namespace with the same access rights
668                                 as from outside. Directories listed in
669                                 <varname>ReadOnlyDirectories=</varname>
670                                 are accessible for reading only,
671                                 writing will be refused even if the
672                                 usual file access controls would
673                                 permit this. Directories listed in
674                                 <varname>InaccessibleDirectories=</varname>
675                                 will be made inaccesible for processes
676                                 inside the namespace. Note that
677                                 restricting access with these options
678                                 does not extend to submounts of a
679                                 directory. You must list submounts
680                                 separately in these setttings to
681                                 ensure the same limited access. These
682                                 options may be specified more than
683                                 once in which case all directories
684                                 listed will have limited access from
685                                 within the
686                                 namespace.</para></listitem>
687                         </varlistentry>
688
689                         <varlistentry>
690                                 <term><varname>PrivateTmp=</varname></term>
691
692                                 <listitem><para>Takes a boolean
693                                 argument. If true sets up a new
694                                 namespace for the executed processes
695                                 and mounts a private
696                                 <filename>/tmp</filename> directory
697                                 inside it, that is not shared by
698                                 processes outside of the
699                                 namespace. This is useful to secure
700                                 access to temporary files of the
701                                 process, but makes sharing between
702                                 processes via
703                                 <filename>/tmp</filename>
704                                 impossible. Defaults to false.</para></listitem>
705                         </varlistentry>
706
707                         <varlistentry>
708                                 <term><varname>MountFlags=</varname></term>
709
710                                 <listitem><para>Takes a mount
711                                 propagation flag:
712                                 <option>shared</option>,
713                                 <option>slave</option> or
714                                 <option>private</option>, which
715                                 control whether namespaces set up with
716                                 <varname>ReadWriteDirectories=</varname>,
717                                 <varname>ReadOnlyDirectories=</varname>
718                                 and
719                                 <varname>InaccessibleDirectories=</varname>
720                                 receive or propagate new mounts
721                                 from/to the main namespace. See
722                                 <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>
723                                 for details. Defaults to
724                                 <option>shared</option>, i.e. the new
725                                 namespace will both receive new mount
726                                 points from the main namespace as well
727                                 as propagate new mounts to
728                                 it.</para></listitem>
729                         </varlistentry>
730
731                         <varlistentry>
732                                 <term><varname>UtmpIdentifier=</varname></term>
733
734                                 <listitem><para>Takes a a four
735                                 character identifier string for an
736                                 utmp/wtmp entry for this service. This
737                                 should only be set for services such
738                                 as <command>getty</command>
739                                 implementations where utmp/wtmp
740                                 entries must be created and cleared
741                                 before and after execution. If the
742                                 configured string is longer than four
743                                 characters it is truncated and the
744                                 terminal four characters are
745                                 used. This setting interprets %I style
746                                 string replacements. This setting is
747                                 unset by default, i.e. no utmp/wtmp
748                                 entries are created or cleaned up for
749                                 this service.</para></listitem>
750                         </varlistentry>
751
752                 </variablelist>
753         </refsect1>
754
755         <refsect1>
756                   <title>See Also</title>
757                   <para>
758                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
759                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
760                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
761                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
762                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
763                           <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
764                   </para>
765         </refsect1>
766
767 </refentry>