man/systemd.exec.xml

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   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
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  18   Lesser General Public License for more details.
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  23
  24 <refentry id="systemd.exec">
  25         <refentryinfo>
  26                 <title>systemd.exec</title>
  27                 <productname>systemd</productname>
  28
  29                 <authorgroup>
  30                         <author>
  31                                 <contrib>Developer</contrib>
  32                                 <firstname>Lennart</firstname>
  33                                 <surname>Poettering</surname>
  34                                 <email>lennart@poettering.net</email>
  35                         </author>
  36                 </authorgroup>
  37         </refentryinfo>
  38
  39         <refmeta>
  40                 <refentrytitle>systemd.exec</refentrytitle>
  41                 <manvolnum>5</manvolnum>
  42         </refmeta>
  43
  44         <refnamediv>
  45                 <refname>systemd.exec</refname>
  46                 <refpurpose>Execution environment configuration</refpurpose>
  47         </refnamediv>
  48
  49         <refsynopsisdiv>
  50                 <para><filename><replaceable>service</replaceable>.service</filename>,
  51                 <filename><replaceable>socket</replaceable>.socket</filename>,
  52                 <filename><replaceable>mount</replaceable>.mount</filename>,
  53                 <filename><replaceable>swap</replaceable>.swap</filename></para>
  54         </refsynopsisdiv>
  55
  56         <refsect1>
  57                 <title>Description</title>
  58
  59                 <para>Unit configuration files for services, sockets,
  60                 mount points, and swap devices share a subset of
  61                 configuration options which define the execution
  62                 environment of spawned processes.</para>
  63
  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
  68                 files, and
  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>,
  72                 and
  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
  78                 type.</para>
  79         </refsect1>
  80
  81         <refsect1>
  82                 <title>Options</title>
  83
  84                 <variablelist class='unit-directives'>
  85
  86                         <varlistentry>
  87                                 <term><varname>WorkingDirectory=</varname></term>
  88
  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>
  97                         </varlistentry>
  98
  99                         <varlistentry>
 100                                 <term><varname>RootDirectory=</varname></term>
 101
 102                                 <listitem><para>Takes an absolute
 103                                 directory path. Sets the root
 104                                 directory for executed processes, with
 105                                 the
 106                                 <citerefentry><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>
 112                         </varlistentry>
 113
 114                         <varlistentry>
 115                                 <term><varname>User=</varname></term>
 116                                 <term><varname>Group=</varname></term>
 117
 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>
 124                         </varlistentry>
 125
 126                         <varlistentry>
 127                                 <term><varname>SupplementaryGroups=</varname></term>
 128
 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
 143                                 database for the
 144                                 user.</para></listitem>
 145                         </varlistentry>
 146
 147                         <varlistentry>
 148                                 <term><varname>Nice=</varname></term>
 149
 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>
 157                         </varlistentry>
 158
 159                         <varlistentry>
 160                                 <term><varname>OOMScoreAdjust=</varname></term>
 161
 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>
 171                         </varlistentry>
 172
 173                         <varlistentry>
 174                                 <term><varname>IOSchedulingClass=</varname></term>
 175
 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>
 185                         </varlistentry>
 186
 187                         <varlistentry>
 188                                 <term><varname>IOSchedulingPriority=</varname></term>
 189
 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
 196                                 above). See
 197                                 <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 198                                 for details.</para></listitem>
 199                         </varlistentry>
 200
 201                         <varlistentry>
 202                                 <term><varname>CPUSchedulingPolicy=</varname></term>
 203
 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>
 214                         </varlistentry>
 215
 216                         <varlistentry>
 217                                 <term><varname>CPUSchedulingPriority=</varname></term>
 218
 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>
 228                                 for details.
 229                                 </para></listitem>
 230                         </varlistentry>
 231
 232                         <varlistentry>
 233                                 <term><varname>CPUSchedulingResetOnFork=</varname></term>
 234
 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>
 243                         </varlistentry>
 244
 245                         <varlistentry>
 246                                 <term><varname>CPUAffinity=</varname></term>
 247
 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 specificed 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
 257                                 effect. See
 258                                 <citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 259                                 for details.</para></listitem>
 260                         </varlistentry>
 261
 262                         <varlistentry>
 263                                 <term><varname>UMask=</varname></term>
 264
 265                                 <listitem><para>Controls the file mode
 266                                 creation mask. Takes an access mode in
 267                                 octal notation. See
 268                                 <citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 269                                 for details. Defaults to
 270                                 0022.</para></listitem>
 271                         </varlistentry>
 272
 273                         <varlistentry>
 274                                 <term><varname>Environment=</varname></term>
 275
 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
 292                                 no special meaning.
 293                                 If you need to assign a value containing spaces
 294                                 to a variable, use double quotes (")
 295                                 for the assignment.</para>
 296
 297                                 <para>Example:
 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>.
 303                                 </para>
 304
 305                                 <para>
 306                                 See
 307                                 <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 308                                 for details about environment variables.</para></listitem>
 309                         </varlistentry>
 310                         <varlistentry>
 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>
 326
 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
 339                                 effect.</para>
 340
 341                                 <para>The files listed with this
 342                                 directive will be read shortly before
 343                                 the process is executed. Settings from
 344                                 these files override settings made
 345                                 with
 346                                 <varname>Environment=</varname>. If
 347                                 the same variable is set twice from
 348                                 these files, the files will be read in
 349                                 the order they are specified and the
 350                                 later setting will override the
 351                                 earlier setting.</para></listitem>
 352                         </varlistentry>
 353
 354                         <varlistentry>
 355                                 <term><varname>StandardInput=</varname></term>
 356                                 <listitem><para>Controls where file
 357                                 descriptor 0 (STDIN) of the executed
 358                                 processes is connected to. Takes one
 359                                 of <option>null</option>,
 360                                 <option>tty</option>,
 361                                 <option>tty-force</option>,
 362                                 <option>tty-fail</option> or
 363                                 <option>socket</option>. If
 364                                 <option>null</option> is selected,
 365                                 standard input will be connected to
 366                                 <filename>/dev/null</filename>,
 367                                 i.e. all read attempts by the process
 368                                 will result in immediate EOF. If
 369                                 <option>tty</option> is selected,
 370                                 standard input is connected to a TTY
 371                                 (as configured by
 372                                 <varname>TTYPath=</varname>, see
 373                                 below) and the executed process
 374                                 becomes the controlling process of the
 375                                 terminal. If the terminal is already
 376                                 being controlled by another process, the
 377                                 executed process waits until the current
 378                                 controlling process releases the
 379                                 terminal.
 380                                 <option>tty-force</option>
 381                                 is similar to <option>tty</option>,
 382                                 but the executed process is forcefully
 383                                 and immediately made the controlling
 384                                 process of the terminal, potentially
 385                                 removing previous controlling
 386                                 processes from the
 387                                 terminal. <option>tty-fail</option> is
 388                                 similar to <option>tty</option> but if
 389                                 the terminal already has a controlling
 390                                 process start-up of the executed
 391                                 process fails.  The
 392                                 <option>socket</option> option is only
 393                                 valid in socket-activated services,
 394                                 and only when the socket configuration
 395                                 file (see
 396                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 397                                 for details) specifies a single socket
 398                                 only. If this option is set, standard
 399                                 input will be connected to the socket
 400                                 the service was activated from, which
 401                                 is primarily useful for compatibility
 402                                 with daemons designed for use with the
 403                                 traditional
 404                                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 405                                 daemon. This setting defaults to
 406                                 <option>null</option>.</para></listitem>
 407                         </varlistentry>
 408                         <varlistentry>
 409                                 <term><varname>StandardOutput=</varname></term>
 410                                 <listitem><para>Controls where file
 411                                 descriptor 1 (STDOUT) of the executed
 412                                 processes is connected to. Takes one
 413                                 of <option>inherit</option>,
 414                                 <option>null</option>,
 415                                 <option>tty</option>,
 416                                 <option>syslog</option>,
 417                                 <option>kmsg</option>,
 418                                 <option>journal</option>,
 419                                 <option>syslog+console</option>,
 420                                 <option>kmsg+console</option>,
 421                                 <option>journal+console</option> or
 422                                 <option>socket</option>. If set to
 423                                 <option>inherit</option>, the file
 424                                 descriptor of standard input is
 425                                 duplicated for standard output. If set
 426                                 to <option>null</option>, standard
 427                                 output will be connected to
 428                                 <filename>/dev/null</filename>,
 429                                 i.e. everything written to it will be
 430                                 lost. If set to <option>tty</option>,
 431                                 standard output will be connected to a
 432                                 tty (as configured via
 433                                 <varname>TTYPath=</varname>, see
 434                                 below). If the TTY is used for output
 435                                 only, the executed process will not
 436                                 become the controlling process of the
 437                                 terminal, and will not fail or wait
 438                                 for other processes to release the
 439                                 terminal. <option>syslog</option>
 440                                 connects standard output to the
 441                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 442                                 system syslog
 443                                 service. <option>kmsg</option>
 444                                 connects it with the kernel log buffer
 445                                 which is accessible via
 446                                 <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>journal</option>
 447                                 connects it with the journal which is
 448                                 accessible via
 449                                 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 450                                 (Note that everything that is written
 451                                 to syslog or kmsg is implicitly stored
 452                                 in the journal as well, those options
 453                                 are hence supersets of this
 454                                 one). <option>syslog+console</option>,
 455                                 <option>journal+console</option> and
 456                                 <option>kmsg+console</option> work
 457                                 similarly but copy the output to the
 458                                 system console as
 459                                 well. <option>socket</option> connects
 460                                 standard output to a socket from
 461                                 socket activation, semantics are
 462                                 similar to the respective option of
 463                                 <varname>StandardInput=</varname>.
 464                                 This setting defaults to the value set
 465                                 with
 466                                 <option>DefaultStandardOutput=</option>
 467                                 in
 468                                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 469                                 which defaults to
 470                                 <option>journal</option>.</para></listitem>
 471                         </varlistentry>
 472                         <varlistentry>
 473                                 <term><varname>StandardError=</varname></term>
 474                                 <listitem><para>Controls where file
 475                                 descriptor 2 (STDERR) of the
 476                                 executed processes is connected to.
 477                                 The available options are identical to
 478                                 those of
 479                                 <varname>StandardOutput=</varname>,
 480                                 with one exception: if set to
 481                                 <option>inherit</option> the file
 482                                 descriptor used for standard output is
 483                                 duplicated for standard error. This
 484                                 setting defaults to the value set with
 485                                 <option>DefaultStandardError=</option>
 486                                 in
 487                                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 488                                 which defaults to
 489                                 <option>inherit</option>.</para></listitem>
 490                         </varlistentry>
 491                         <varlistentry>
 492                                 <term><varname>TTYPath=</varname></term>
 493                                 <listitem><para>Sets the terminal
 494                                 device node to use if standard input, output,
 495                                 or error are connected to a
 496                                 TTY (see above). Defaults to
 497                                 <filename>/dev/console</filename>.</para></listitem>
 498                         </varlistentry>
 499                         <varlistentry>
 500                                 <term><varname>TTYReset=</varname></term>
 501                                 <listitem><para>Reset the terminal
 502                                 device specified with
 503                                 <varname>TTYPath=</varname> before and
 504                                 after execution. Defaults to
 505                                 <literal>no</literal>.</para></listitem>
 506                         </varlistentry>
 507                         <varlistentry>
 508                                 <term><varname>TTYVHangup=</varname></term>
 509                                 <listitem><para>Disconnect all clients
 510                                 which have opened the terminal device
 511                                 specified with
 512                                 <varname>TTYPath=</varname>
 513                                 before and after execution. Defaults
 514                                 to
 515                                 <literal>no</literal>.</para></listitem>
 516                         </varlistentry>
 517                         <varlistentry>
 518                                 <term><varname>TTYVTDisallocate=</varname></term>
 519                                 <listitem><para>If the terminal
 520                                 device specified with
 521                                 <varname>TTYPath=</varname> is a
 522                                 virtual console terminal, try to
 523                                 deallocate the TTY before and after
 524                                 execution. This ensures that the
 525                                 screen and scrollback buffer is
 526                                 cleared. Defaults to
 527                                 <literal>no</literal>.</para></listitem>
 528                         </varlistentry>
 529                         <varlistentry>
 530                                 <term><varname>SyslogIdentifier=</varname></term>
 531                                 <listitem><para>Sets the process name
 532                                 to prefix log lines sent to syslog or
 533                                 the kernel log buffer with. If not set,
 534                                 defaults to the process name of the
 535                                 executed process. This option is only
 536                                 useful when
 537                                 <varname>StandardOutput=</varname> or
 538                                 <varname>StandardError=</varname> are
 539                                 set to <option>syslog</option> or
 540                                 <option>kmsg</option>.</para></listitem>
 541                         </varlistentry>
 542                         <varlistentry>
 543                                 <term><varname>SyslogFacility=</varname></term>
 544                                 <listitem><para>Sets the syslog
 545                                 facility to use when logging to
 546                                 syslog. One of <option>kern</option>,
 547                                 <option>user</option>,
 548                                 <option>mail</option>,
 549                                 <option>daemon</option>,
 550                                 <option>auth</option>,
 551                                 <option>syslog</option>,
 552                                 <option>lpr</option>,
 553                                 <option>news</option>,
 554                                 <option>uucp</option>,
 555                                 <option>cron</option>,
 556                                 <option>authpriv</option>,
 557                                 <option>ftp</option>,
 558                                 <option>local0</option>,
 559                                 <option>local1</option>,
 560                                 <option>local2</option>,
 561                                 <option>local3</option>,
 562                                 <option>local4</option>,
 563                                 <option>local5</option>,
 564                                 <option>local6</option> or
 565                                 <option>local7</option>. See
 566                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 567                                 for details. This option is only
 568                                 useful when
 569                                 <varname>StandardOutput=</varname> or
 570                                 <varname>StandardError=</varname> are
 571                                 set to <option>syslog</option>.
 572                                 Defaults to
 573                                 <option>daemon</option>.</para></listitem>
 574                         </varlistentry>
 575                         <varlistentry>
 576                                 <term><varname>SyslogLevel=</varname></term>
 577                                 <listitem><para>Default syslog level
 578                                 to use when logging to syslog or the
 579                                 kernel log buffer. One of
 580                                 <option>emerg</option>,
 581                                 <option>alert</option>,
 582                                 <option>crit</option>,
 583                                 <option>err</option>,
 584                                 <option>warning</option>,
 585                                 <option>notice</option>,
 586                                 <option>info</option>,
 587                                 <option>debug</option>. See
 588                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 589                                 for details. This option is only
 590                                 useful when
 591                                 <varname>StandardOutput=</varname> or
 592                                 <varname>StandardError=</varname> are
 593                                 set to <option>syslog</option> or
 594                                 <option>kmsg</option>. Note that
 595                                 individual lines output by the daemon
 596                                 might be prefixed with a different log
 597                                 level which can be used to override
 598                                 the default log level specified
 599                                 here. The interpretation of these
 600                                 prefixes may be disabled with
 601                                 <varname>SyslogLevelPrefix=</varname>,
 602                                 see below. For details see
 603                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 604
 605                                 Defaults to
 606                                 <option>info</option>.</para></listitem>
 607                         </varlistentry>
 608
 609                         <varlistentry>
 610                                 <term><varname>SyslogLevelPrefix=</varname></term>
 611                                 <listitem><para>Takes a boolean
 612                                 argument. If true and
 613                                 <varname>StandardOutput=</varname> or
 614                                 <varname>StandardError=</varname> are
 615                                 set to <option>syslog</option>,
 616                                 <option>kmsg</option> or
 617                                 <option>journal</option>, log lines
 618                                 written by the executed process that
 619                                 are prefixed with a log level will be
 620                                 passed on to syslog with this log
 621                                 level set but the prefix removed. If
 622                                 set to false, the interpretation of
 623                                 these prefixes is disabled and the
 624                                 logged lines are passed on as-is. For
 625                                 details about this prefixing see
 626                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 627                                 Defaults to true.</para></listitem>
 628                         </varlistentry>
 629
 630                         <varlistentry>
 631                                 <term><varname>TimerSlackNSec=</varname></term>
 632                                 <listitem><para>Sets the timer slack
 633                                 in nanoseconds for the executed
 634                                 processes. The timer slack controls
 635                                 the accuracy of wake-ups triggered by
 636                                 timers. See
 637                                 <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 638                                 for more information. Note that in
 639                                 contrast to most other time span
 640                                 definitions this parameter takes an
 641                                 integer value in nano-seconds if no
 642                                 unit is specified. The usual time
 643                                 units are understood
 644                                 too.</para></listitem>
 645                         </varlistentry>
 646
 647                         <varlistentry>
 648                                 <term><varname>LimitCPU=</varname></term>
 649                                 <term><varname>LimitFSIZE=</varname></term>
 650                                 <term><varname>LimitDATA=</varname></term>
 651                                 <term><varname>LimitSTACK=</varname></term>
 652                                 <term><varname>LimitCORE=</varname></term>
 653                                 <term><varname>LimitRSS=</varname></term>
 654                                 <term><varname>LimitNOFILE=</varname></term>
 655                                 <term><varname>LimitAS=</varname></term>
 656                                 <term><varname>LimitNPROC=</varname></term>
 657                                 <term><varname>LimitMEMLOCK=</varname></term>
 658                                 <term><varname>LimitLOCKS=</varname></term>
 659                                 <term><varname>LimitSIGPENDING=</varname></term>
 660                                 <term><varname>LimitMSGQUEUE=</varname></term>
 661                                 <term><varname>LimitNICE=</varname></term>
 662                                 <term><varname>LimitRTPRIO=</varname></term>
 663                                 <term><varname>LimitRTTIME=</varname></term>
 664                                 <listitem><para>These settings control
 665                                 various resource limits for executed
 666                                 processes. See
 667                                 <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 668                                 for details. Use the string
 669                                 <varname>infinity</varname> to
 670                                 configure no limit on a specific
 671                                 resource.</para></listitem>
 672                         </varlistentry>
 673
 674                         <varlistentry>
 675                                 <term><varname>PAMName=</varname></term>
 676                                 <listitem><para>Sets the PAM service
 677                                 name to set up a session as. If set,
 678                                 the executed process will be
 679                                 registered as a PAM session under the
 680                                 specified service name. This is only
 681                                 useful in conjunction with the
 682                                 <varname>User=</varname> setting. If
 683                                 not set, no PAM session will be opened
 684                                 for the executed processes. See
 685                                 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 686                                 for details.</para></listitem>
 687                         </varlistentry>
 688
 689                         <varlistentry>
 690                                 <term><varname>TCPWrapName=</varname></term>
 691                                 <listitem><para>If this is a
 692                                 socket-activated service, this sets the
 693                                 tcpwrap service name to check the
 694                                 permission for the current connection
 695                                 with. This is only useful in
 696                                 conjunction with socket-activated
 697                                 services, and stream sockets (TCP) in
 698                                 particular. It has no effect on other
 699                                 socket types (e.g. datagram/UDP) and
 700                                 on processes unrelated to socket-based
 701                                 activation. If the tcpwrap
 702                                 verification fails, daemon start-up
 703                                 will fail and the connection is
 704                                 terminated. See
 705                                 <citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 706                                 for details. Note that this option may
 707                                 be used to do access control checks
 708                                 only. Shell commands and commands
 709                                 described in
 710                                 <citerefentry><refentrytitle>hosts_options</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 711                                 are not supported.</para></listitem>
 712                         </varlistentry>
 713
 714                         <varlistentry>
 715                                 <term><varname>CapabilityBoundingSet=</varname></term>
 716
 717                                 <listitem><para>Controls which
 718                                 capabilities to include in the
 719                                 capability bounding set for the
 720                                 executed process. See
 721                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 722                                 for details. Takes a whitespace-separated
 723                                 list of capability names as read by
 724                                 <citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 725                                 e.g. <constant>CAP_SYS_ADMIN</constant>,
 726                                 <constant>CAP_DAC_OVERRIDE</constant>,
 727                                 <constant>CAP_SYS_PTRACE</constant>.
 728                                 Capabilities listed will be included
 729                                 in the bounding set, all others are
 730                                 removed. If the list of capabilities
 731                                 is prefixed with <literal>~</literal>,
 732                                 all but the listed capabilities will
 733                                 be included, the effect of the
 734                                 assignment inverted. Note that this
 735                                 option also affects the respective
 736                                 capabilities in the effective,
 737                                 permitted and inheritable capability
 738                                 sets, on top of what
 739                                 <varname>Capabilities=</varname>
 740                                 does. If this option is not used, the
 741                                 capability bounding set is not
 742                                 modified on process execution, hence
 743                                 no limits on the capabilities of the
 744                                 process are enforced. This option may
 745                                 appear more than once in which case
 746                                 the bounding sets are merged. If the
 747                                 empty string is assigned to this
 748                                 option, the bounding set is reset to
 749                                 the empty capability set, and all
 750                                 prior settings have no effect. If set
 751                                 to <literal>~</literal> (without any
 752                                 further argument), the bounding set is
 753                                 reset to the full set of available
 754                                 capabilities, also undoing any
 755                                 previous settings.</para></listitem>
 756                         </varlistentry>
 757
 758                         <varlistentry>
 759                                 <term><varname>SecureBits=</varname></term>
 760                                 <listitem><para>Controls the secure
 761                                 bits set for the executed process. See
 762                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 763                                 for details. Takes a list of strings:
 764                                 <option>keep-caps</option>,
 765                                 <option>keep-caps-locked</option>,
 766                                 <option>no-setuid-fixup</option>,
 767                                 <option>no-setuid-fixup-locked</option>,
 768                                 <option>noroot</option> and/or
 769                                 <option>noroot-locked</option>. This
 770                                 option may appear more than once in
 771                                 which case the secure bits are
 772                                 ORed. If the empty string is assigned
 773                                 to this option, the bits are reset to
 774                                 0.</para></listitem>
 775                         </varlistentry>
 776
 777                         <varlistentry>
 778                                 <term><varname>Capabilities=</varname></term>
 779                                 <listitem><para>Controls the
 780                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 781                                 set for the executed process. Take a
 782                                 capability string describing the
 783                                 effective, permitted and inherited
 784                                 capability sets as documented in
 785                                 <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 786                                 Note that these capability sets are
 787                                 usually influenced by the capabilities
 788                                 attached to the executed file. Due to
 789                                 that
 790                                 <varname>CapabilityBoundingSet=</varname>
 791                                 is probably the much more useful
 792                                 setting.</para></listitem>
 793                         </varlistentry>
 794
 795                         <varlistentry>
 796                                 <term><varname>ReadWriteDirectories=</varname></term>
 797                                 <term><varname>ReadOnlyDirectories=</varname></term>
 798                                 <term><varname>InaccessibleDirectories=</varname></term>
 799
 800                                 <listitem><para>Sets up a new
 801                                 file system namespace for executed
 802                                 processes. These options may be used
 803                                 to limit access a process might have
 804                                 to the main file system
 805                                 hierarchy. Each setting takes a
 806                                 space-separated list of absolute
 807                                 directory paths. Directories listed in
 808                                 <varname>ReadWriteDirectories=</varname>
 809                                 are accessible from within the
 810                                 namespace with the same access rights
 811                                 as from outside. Directories listed in
 812                                 <varname>ReadOnlyDirectories=</varname>
 813                                 are accessible for reading only,
 814                                 writing will be refused even if the
 815                                 usual file access controls would
 816                                 permit this. Directories listed in
 817                                 <varname>InaccessibleDirectories=</varname>
 818                                 will be made inaccessible for
 819                                 processes inside the namespace. Note
 820                                 that restricting access with these
 821                                 options does not extend to submounts
 822                                 of a directory. You must list
 823                                 submounts separately in these settings
 824                                 to ensure the same limited
 825                                 access. These options may be specified
 826                                 more than once in which case all
 827                                 directories listed will have limited
 828                                 access from within the namespace. If
 829                                 the empty string is assigned to this
 830                                 option, the specific list is reset, and
 831                                 all prior assignments have no
 832                                 effect.</para>
 833                                 <para>Paths in
 834                                 <varname>ReadOnlyDirectories=</varname>
 835                                 and
 836                                 <varname>InaccessibleDirectories=</varname>
 837                                 may be prefixed with
 838                                 <literal>-</literal>, in which case
 839                                 they will be ignored when they do not
 840                                 exist.</para></listitem>
 841                         </varlistentry>
 842
 843                         <varlistentry>
 844                                 <term><varname>PrivateTmp=</varname></term>
 845
 846                                 <listitem><para>Takes a boolean
 847                                 argument. If true, sets up a new file
 848                                 system namespace for the executed
 849                                 processes and mounts private
 850                                 <filename>/tmp</filename> and
 851                                 <filename>/var/tmp</filename>
 852                                 directories inside it that is not
 853                                 shared by processes outside of the
 854                                 namespace. This is useful to secure
 855                                 access to temporary files of the
 856                                 process, but makes sharing between
 857                                 processes via
 858                                 <filename>/tmp</filename> or
 859                                 <filename>/var/tmp</filename>
 860                                 impossible. All temporary data created
 861                                 by service will be removed after
 862                                 the service is stopped. Defaults to
 863                                 false. Note that it is possible to run
 864                                 two or more units within the same
 865                                 private <filename>/tmp</filename> and
 866                                 <filename>/var/tmp</filename>
 867                                 namespace by using the
 868                                 <varname>JoinsNamespaceOf=</varname>
 869                                 directive, see
 870                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 871                                 for details.</para></listitem>
 872                         </varlistentry>
 873
 874                         <varlistentry>
 875                                 <term><varname>PrivateNetwork=</varname></term>
 876
 877                                 <listitem><para>Takes a boolean
 878                                 argument. If true, sets up a new
 879                                 network namespace for the executed
 880                                 processes and configures only the
 881                                 loopback network device
 882                                 <literal>lo</literal> inside it. No
 883                                 other network devices will be
 884                                 available to the executed process.
 885                                 This is useful to securely turn off
 886                                 network access by the executed
 887                                 process. Defaults to false. Note that
 888                                 it is possible to run two or more
 889                                 units within the same private network
 890                                 namespace by using the
 891                                 <varname>JoinsNamespaceOf=</varname>
 892                                 directive, see
 893                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 894                                 for details.</para></listitem>
 895                         </varlistentry>
 896
 897                         <varlistentry>
 898                                 <term><varname>PrivateDevices=</varname></term>
 899
 900                                 <listitem><para>Takes a boolean
 901                                 argument. If true, sets up a new /dev
 902                                 namespace for the executed processes
 903                                 and only adds API pseudo devices such
 904                                 as <filename>/dev/null</filename>,
 905                                 <filename>/dev/zero</filename> or
 906                                 <filename>/dev/random</filename> to
 907                                 it, but no physical devices such as
 908                                 <filename>/dev/sda</filename>. This is
 909                                 useful to securely turn off physical
 910                                 device access by the executed
 911                                 process. Defaults to
 912                                 false.</para></listitem>
 913                         </varlistentry>
 914
 915                         <varlistentry>
 916                                 <term><varname>MountFlags=</varname></term>
 917
 918                                 <listitem><para>Takes a mount
 919                                 propagation flag:
 920                                 <option>shared</option>,
 921                                 <option>slave</option> or
 922                                 <option>private</option>, which
 923                                 control whether the file system
 924                                 namespace set up for this unit's
 925                                 processes will receive or propagate
 926                                 new mounts. See
 927                                 <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 928                                 for details. Default to
 929                                 <option>shared</option>.</para></listitem>
 930                         </varlistentry>
 931
 932                         <varlistentry>
 933                                 <term><varname>UtmpIdentifier=</varname></term>
 934
 935                                 <listitem><para>Takes a four
 936                                 character identifier string for an
 937                                 utmp/wtmp entry for this service. This
 938                                 should only be set for services such
 939                                 as <command>getty</command>
 940                                 implementations where utmp/wtmp
 941                                 entries must be created and cleared
 942                                 before and after execution. If the
 943                                 configured string is longer than four
 944                                 characters, it is truncated and the
 945                                 terminal four characters are
 946                                 used. This setting interprets %I style
 947                                 string replacements. This setting is
 948                                 unset by default, i.e. no utmp/wtmp
 949                                 entries are created or cleaned up for
 950                                 this service.</para></listitem>
 951                         </varlistentry>
 952
 953                         <varlistentry>
 954                                 <term><varname>SELinuxContext=</varname></term>
 955
 956                                 <listitem><para>Set the SELinux
 957                                 security context of the executed
 958                                 process. If set, this will override
 959                                 the automated domain
 960                                 transition. However, the policy still
 961                                 needs to autorize the transition. This
 962                                 directive is ignored if SELinux is
 963                                 disabled. If prefixed by
 964                                 <literal>-</literal>, all errors will
 965                                 be ignored. See
 966                                 <citerefentry><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 967                                 for details.</para></listitem>
 968                         </varlistentry>
 969
 970                         <varlistentry>
 971                                 <term><varname>AppArmorProfile=</varname></term>
 972
 973                                 <listitem><para>Take a profile name as argument.
 974                                 The process executed by the unit will switch to
 975                                 this profile when started. Profiles must already
 976                                 be loaded in the kernel, or the unit will fail.
 977                                 This result in a non operation if AppArmor is not
 978                                 enabled. If prefixed by <literal>-</literal>, all errors
 979                                 will be ignored.
 980                                 </para></listitem>
 981                         </varlistentry>
 982
 983                         <varlistentry>
 984                                 <term><varname>IgnoreSIGPIPE=</varname></term>
 985
 986                                 <listitem><para>Takes a boolean
 987                                 argument. If true, causes <constant>SIGPIPE</constant> to be
 988                                 ignored in the executed
 989                                 process. Defaults to true because
 990                                 <constant>SIGPIPE</constant> generally is useful only in
 991                                 shell pipelines.</para></listitem>
 992                         </varlistentry>
 993
 994                         <varlistentry>
 995                                 <term><varname>NoNewPrivileges=</varname></term>
 996
 997                                 <listitem><para>Takes a boolean
 998                                 argument. If true, ensures that the
 999                                 service process and all its children
1000                                 can never gain new privileges. This
1001                                 option is more powerful than the respective
1002                                 secure bits flags (see above), as it
1003                                 also prohibits UID changes of any
1004                                 kind. This is the simplest, most
1005                                 effective way to ensure that a process
1006                                 and its children can never elevate
1007                                 privileges again.</para></listitem>
1008                         </varlistentry>
1009
1010                         <varlistentry>
1011                                 <term><varname>SystemCallFilter=</varname></term>
1012
1013                                 <listitem><para>Takes a
1014                                 space-separated list of system call
1015                                 names. If this setting is used, all
1016                                 system calls executed by the unit
1017                                 processes except for the listed ones
1018                                 will result in immediate process
1019                                 termination with the
1020                                 <constant>SIGSYS</constant> signal
1021                                 (whitelisting). If the first character
1022                                 of the list is <literal>~</literal>,
1023                                 the effect is inverted: only the
1024                                 listed system calls will result in
1025                                 immediate process termination
1026                                 (blacklisting). If running in user
1027                                 mode and this option is used,
1028                                 <varname>NoNewPrivileges=yes</varname>
1029                                 is implied. This feature makes use of the
1030                                 Secure Computing Mode 2 interfaces of
1031                                 the kernel ('seccomp filtering') and
1032                                 is useful for enforcing a minimal
1033                                 sandboxing environment. Note that the
1034                                 <function>execve</function>,
1035                                 <function>rt_sigreturn</function>,
1036                                 <function>sigreturn</function>,
1037                                 <function>exit_group</function>,
1038                                 <function>exit</function> system calls
1039                                 are implicitly whitelisted and do not
1040                                 need to be listed explicitly. This
1041                                 option may be specified more than once
1042                                 in which case the filter masks are
1043                                 merged. If the empty string is
1044                                 assigned, the filter is reset, all
1045                                 prior assignments will have no
1046                                 effect.</para>
1047
1048                                 <para>If you specify both types of
1049                                 this option (i.e. whitelisting and
1050                                 blacklisting), the first encountered
1051                                 will take precedence and will dictate
1052                                 the default action (termination or
1053                                 approval of a system call). Then the
1054                                 next occurrences of this option will
1055                                 add or delete the listed system calls
1056                                 from the set of the filtered system
1057                                 calls, depending of its type and the
1058                                 default action. (For example, if you have started
1059                                 with a whitelisting of
1060                                 <function>read</function> and
1061                                 <function>write</function>, and right
1062                                 after it add a blacklisting of
1063                                 <function>write</function>, then
1064                                 <function>write</function> will be
1065                                 removed from the set.)
1066                                 </para></listitem>
1067                         </varlistentry>
1068
1069                         <varlistentry>
1070                                 <term><varname>SystemCallErrorNumber=</varname></term>
1071
1072                                 <listitem><para>Takes an
1073                                 <literal>errno</literal> error number
1074                                 name to return when the system call
1075                                 filter configured with
1076                                 <varname>SystemCallFilter=</varname>
1077                                 is triggered, instead of terminating
1078                                 the process immediately. Takes an
1079                                 error name such as
1080                                 <constant>EPERM</constant>,
1081                                 <constant>EACCES</constant> or
1082                                 <constant>EUCLEAN</constant>. When this
1083                                 setting is not used, or when the empty
1084                                 string is assigned, the process will be
1085                                 terminated immediately when the filter
1086                                 is triggered.</para></listitem>
1087                         </varlistentry>
1088
1089                         <varlistentry>
1090                                 <term><varname>SystemCallArchitectures=</varname></term>
1091
1092                                 <listitem><para>Takes a space
1093                                 separated list of architecture
1094                                 identifiers to include in the system
1095                                 call filter. The known architecture
1096                                 identifiers are
1097                                 <constant>x86</constant>,
1098                                 <constant>x86-64</constant>,
1099                                 <constant>x32</constant>,
1100                                 <constant>arm</constant> as well as
1101                                 the special identifier
1102                                 <constant>native</constant>. Only
1103                                 system calls of the specified
1104                                 architectures will be permitted to
1105                                 processes of this unit. This is an
1106                                 effective way to disable compatibility
1107                                 with non-native architectures for
1108                                 processes, for example to prohibit
1109                                 execution of 32-bit x86 binaries on
1110                                 64-bit x86-64 systems. The special
1111                                 <constant>native</constant> identifier
1112                                 implicitly maps to the native
1113                                 architecture of the system (or more
1114                                 strictly: to the architecture the
1115                                 system manager is compiled for). If
1116                                 running in user mode and this option
1117                                 is used,
1118                                 <varname>NoNewPrivileges=yes</varname>
1119                                 is implied. Note that setting this
1120                                 option to a non-empty list implies
1121                                 that <constant>native</constant> is
1122                                 included too. By default, this option
1123                                 is set to the empty list, i.e. no
1124                                 architecture system call filtering is
1125                                 applied.</para></listitem>
1126                         </varlistentry>
1127
1128                         <varlistentry>
1129                                 <term><varname>RestrictAddressFamilies=</varname></term>
1130
1131                                 <listitem><para>Restricts the set of
1132                                 socket address families accessible to
1133                                 the processes of this unit. Takes a
1134                                 space-separated list of address family
1135                                 names to whitelist, such as
1136                                 <constant>AF_UNIX</constant>,
1137                                 <constant>AF_INET</constant> or
1138                                 <constant>AF_INET6</constant>. When
1139                                 prefixed with <constant>~</constant>
1140                                 the listed address families will be
1141                                 applied as blacklist, otherwise as
1142                                 whitelist. Note that this restricts
1143                                 access to the
1144                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1145                                 system call only. Sockets passed into
1146                                 the process by other means (for
1147                                 example, by using socket activation
1148                                 with socket units, see
1149                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1150                                 are unaffected. Also, sockets created
1151                                 with <function>socketpair()</function>
1152                                 (which creates connected AF_UNIX
1153                                 sockets only) are unaffected. Note
1154                                 that this option has no effect on
1155                                 32bit x86 and is ignored (but works
1156                                 correctly on x86-64). If running in user
1157                                 mode and this option is used,
1158                                 <varname>NoNewPrivileges=yes</varname>
1159                                 is implied. By default no
1160                                 restriction applies, all address
1161                                 families are accessible to
1162                                 processes. If assigned the empty
1163                                 string any previous list changes are
1164                                 undone.</para>
1165
1166                                 <para>Use this option to limit
1167                                 exposure of processes to remote
1168                                 systems, in particular via exotic
1169                                 network protocols. Note that in most
1170                                 cases the local
1171                                 <constant>AF_UNIX</constant> address
1172                                 family should be included in the
1173                                 configured whitelist as it is
1174                                 frequently used for local
1175                                 communication, including for
1176                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1177                                 logging.</para></listitem>
1178                         </varlistentry>
1179
1180                         <varlistentry>
1181                                 <term><varname>Personality=</varname></term>
1182
1183                                 <listitem><para>Controls which
1184                                 kernel architecture
1185                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1186                                 shall report, when invoked by unit
1187                                 processes. Takes one of
1188                                 <constant>x86</constant> and
1189                                 <constant>x86-64</constant>. This is
1190                                 useful when running 32bit services on
1191                                 a 64bit host system. If not specified
1192                                 the personality is left unmodified and
1193                                 thus reflects the personality of the
1194                                 host system's
1195                                 kernel.</para></listitem>
1196                         </varlistentry>
1197
1198                         <varlistentry>
1199                                 <term><varname>RuntimeDirectory=</varname></term>
1200                                 <term><varname>RuntimeDirectoryMode=</varname></term>
1201
1202                                 <listitem><para>Takes a list of
1203                                 directory names. If set one or more
1204                                 directories by the specified names
1205                                 will be created below
1206                                 <filename>/run</filename> (for system
1207                                 services) or below
1208                                 <varname>$XDG_RUNTIME_DIR</varname>
1209                                 (for user services) when the unit is
1210                                 started and removed when the unit is
1211                                 stopped. The directories will have the
1212                                 access mode specified in
1213                                 <varname>RuntimeDirectoryMode=</varname>,
1214                                 and will be owned by the user and
1215                                 group specified in
1216                                 <varname>User=</varname> and
1217                                 <varname>Group=</varname>. Use this to
1218                                 manage one or more runtime directories
1219                                 of the unit and bind their lifetime to
1220                                 the daemon runtime. The specified
1221                                 directory names must be relative, and
1222                                 may not include a
1223                                 <literal>/</literal>, i.e. must refer
1224                                 to simple directories to create or
1225                                 remove. This is particularly useful
1226                                 for unpriviliges daemons that cannot
1227                                 create runtime directories in
1228                                 <filename>/run</filename> due to lack
1229                                 of privileges, and to make sure the
1230                                 runtime directory is cleaned up
1231                                 automatically after use. For runtime
1232                                 directories that require more complex
1233                                 or different configuration or lifetime
1234                                 guarantees, please consider using
1235                                 <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
1236                         </varlistentry>
1237
1238                 </variablelist>
1239         </refsect1>
1240
1241         <refsect1>
1242                 <title>Environment variables in spawned processes</title>
1243
1244                 <para>Processes started by the system are executed in
1245                 a clean environment in which select variables
1246                 listed below are set. System processes started by systemd
1247                 do not inherit variables from PID 1, but processes
1248                 started by user systemd instances inherit all
1249                 environment variables from the user systemd instance.
1250                 </para>
1251
1252                 <variablelist class='environment-variables'>
1253                         <varlistentry>
1254                                 <term><varname>$PATH</varname></term>
1255
1256                                 <listitem><para>Colon-separated list
1257                                 of directiories to use when launching
1258                                 executables. Systemd uses a fixed
1259                                 value of
1260                                 <filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>.
1261                                 </para></listitem>
1262                         </varlistentry>
1263
1264                         <varlistentry>
1265                                 <term><varname>$LANG</varname></term>
1266
1267                                 <listitem><para>Locale. Can be set in
1268                                 <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1269                                 or on the kernel command line (see
1270                                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1271                                 and
1272                                 <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
1273                                 </para></listitem>
1274                         </varlistentry>
1275
1276                         <varlistentry>
1277                                 <term><varname>$USER</varname></term>
1278                                 <term><varname>$LOGNAME</varname></term>
1279                                 <term><varname>$HOME</varname></term>
1280                                 <term><varname>$SHELL</varname></term>
1281
1282                                 <listitem><para>User name (twice), home
1283                                 directory, and the login shell.
1284                                 The variables are set for the units that
1285                                 have <varname>User=</varname> set,
1286                                 which includes user
1287                                 <command>systemd</command> instances.
1288                                 See
1289                                 <citerefentry><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1290                                 </para></listitem>
1291                         </varlistentry>
1292
1293                         <varlistentry>
1294                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
1295
1296                                 <listitem><para>The directory for volatile
1297                                 state. Set for the user <command>systemd</command>
1298                                 instance, and also in user sessions.
1299                                 See
1300                                 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
1301                                 </para></listitem>
1302                         </varlistentry>
1303
1304                         <varlistentry>
1305                                 <term><varname>$XDG_SESSION_ID</varname></term>
1306                                 <term><varname>$XDG_SEAT</varname></term>
1307                                 <term><varname>$XDG_VTNR</varname></term>
1308
1309                                 <listitem><para>The identifier of the
1310                                 session, the seat name, and
1311                                 virtual terminal of the session. Set
1312                                 by
1313                                 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1314                                 for login sessions.
1315                                 <varname>$XDG_SEAT</varname> and
1316                                 <varname>$XDG_VTNR</varname> will
1317                                 only be set when attached to a seat and a
1318                                 tty.</para></listitem>
1319                         </varlistentry>
1320
1321                         <varlistentry>
1322                                 <term><varname>$MAINPID</varname></term>
1323
1324                                 <listitem><para>The PID of the units
1325                                 main process if it is known. This is
1326                                 only set for control processes as
1327                                 invoked by
1328                                 <varname>ExecReload=</varname> and
1329                                 similar.  </para></listitem>
1330                         </varlistentry>
1331
1332                         <varlistentry>
1333                                 <term><varname>$MANAGERPID</varname></term>
1334
1335                                 <listitem><para>The PID of the user
1336                                 <command>systemd</command> instance,
1337                                 set for processes spawned by it.
1338                                 </para></listitem>
1339                         </varlistentry>
1340
1341                         <varlistentry>
1342                                 <term><varname>$LISTEN_FDS</varname></term>
1343                                 <term><varname>$LISTEN_PID</varname></term>
1344
1345                                 <listitem><para>Information about file
1346                                 descriptors passed to a service for
1347                                 socket activation.  See
1348                                 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1349                                 </para></listitem>
1350                         </varlistentry>
1351
1352                         <varlistentry>
1353                                 <term><varname>$TERM</varname></term>
1354
1355                                 <listitem><para>Terminal type, set
1356                                 only for units connected to a terminal
1357                                 (<varname>StandardInput=tty</varname>,
1358                                 <varname>StandardOutput=tty</varname>,
1359                                 or
1360                                 <varname>StandardError=tty</varname>).
1361                                 See
1362                                 <citerefentry><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1363                                 </para></listitem>
1364                         </varlistentry>
1365                 </variablelist>
1366
1367                 <para>Additional variables may be configured by the
1368                 following means: for processes spawned in specific
1369                 units, use the <varname>Environment=</varname> and
1370                 <varname>EnvironmentFile=</varname> options above; to
1371                 specify variables globally, use
1372                 <varname>DefaultEnvironment=</varname> (see
1373                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1374                 or the kernel option
1375                 <varname>systemd.setenv=</varname> (see
1376                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Additional
1377                 variables may also be set through PAM,
1378                 c.f. <citerefentry><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
1379         </refsect1>
1380
1381         <refsect1>
1382                   <title>See Also</title>
1383                   <para>
1384                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1385                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1386                           <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1387                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1388                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1389                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1390                           <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1391                           <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1392                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1393                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1394                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1395                           <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1396                           <citerefentry><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
1397                   </para>
1398         </refsect1>
1399
1400 </refentry>