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
  13   (at your option) any later version.
  14
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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 (more
 344                                 specifically, after all
 345                                 processes from a previous unit state
 346                                 terminated. This means you can
 347                                 generate these files in one unit
 348                                 state, and read it with this option in
 349                                 the next). Settings from these files
 350                                 override settings made with
 351                                 <varname>Environment=</varname>. If
 352                                 the same variable is set twice from
 353                                 these files, the files will be read in
 354                                 the order they are specified and the
 355                                 later setting will override the
 356                                 earlier setting.</para></listitem>
 357                         </varlistentry>
 358
 359                         <varlistentry>
 360                                 <term><varname>StandardInput=</varname></term>
 361                                 <listitem><para>Controls where file
 362                                 descriptor 0 (STDIN) of the executed
 363                                 processes is connected to. Takes one
 364                                 of <option>null</option>,
 365                                 <option>tty</option>,
 366                                 <option>tty-force</option>,
 367                                 <option>tty-fail</option> or
 368                                 <option>socket</option>. If
 369                                 <option>null</option> is selected,
 370                                 standard input will be connected to
 371                                 <filename>/dev/null</filename>,
 372                                 i.e. all read attempts by the process
 373                                 will result in immediate EOF. If
 374                                 <option>tty</option> is selected,
 375                                 standard input is connected to a TTY
 376                                 (as configured by
 377                                 <varname>TTYPath=</varname>, see
 378                                 below) and the executed process
 379                                 becomes the controlling process of the
 380                                 terminal. If the terminal is already
 381                                 being controlled by another process, the
 382                                 executed process waits until the current
 383                                 controlling process releases the
 384                                 terminal.
 385                                 <option>tty-force</option>
 386                                 is similar to <option>tty</option>,
 387                                 but the executed process is forcefully
 388                                 and immediately made the controlling
 389                                 process of the terminal, potentially
 390                                 removing previous controlling
 391                                 processes from the
 392                                 terminal. <option>tty-fail</option> is
 393                                 similar to <option>tty</option> but if
 394                                 the terminal already has a controlling
 395                                 process start-up of the executed
 396                                 process fails.  The
 397                                 <option>socket</option> option is only
 398                                 valid in socket-activated services,
 399                                 and only when the socket configuration
 400                                 file (see
 401                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 402                                 for details) specifies a single socket
 403                                 only. If this option is set, standard
 404                                 input will be connected to the socket
 405                                 the service was activated from, which
 406                                 is primarily useful for compatibility
 407                                 with daemons designed for use with the
 408                                 traditional
 409                                 <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 410                                 daemon. This setting defaults to
 411                                 <option>null</option>.</para></listitem>
 412                         </varlistentry>
 413                         <varlistentry>
 414                                 <term><varname>StandardOutput=</varname></term>
 415                                 <listitem><para>Controls where file
 416                                 descriptor 1 (STDOUT) of the executed
 417                                 processes is connected to. Takes one
 418                                 of <option>inherit</option>,
 419                                 <option>null</option>,
 420                                 <option>tty</option>,
 421                                 <option>syslog</option>,
 422                                 <option>kmsg</option>,
 423                                 <option>journal</option>,
 424                                 <option>syslog+console</option>,
 425                                 <option>kmsg+console</option>,
 426                                 <option>journal+console</option> or
 427                                 <option>socket</option>. If set to
 428                                 <option>inherit</option>, the file
 429                                 descriptor of standard input is
 430                                 duplicated for standard output. If set
 431                                 to <option>null</option>, standard
 432                                 output will be connected to
 433                                 <filename>/dev/null</filename>,
 434                                 i.e. everything written to it will be
 435                                 lost. If set to <option>tty</option>,
 436                                 standard output will be connected to a
 437                                 tty (as configured via
 438                                 <varname>TTYPath=</varname>, see
 439                                 below). If the TTY is used for output
 440                                 only, the executed process will not
 441                                 become the controlling process of the
 442                                 terminal, and will not fail or wait
 443                                 for other processes to release the
 444                                 terminal. <option>syslog</option>
 445                                 connects standard output to the
 446                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 447                                 system syslog
 448                                 service. <option>kmsg</option>
 449                                 connects it with the kernel log buffer
 450                                 which is accessible via
 451                                 <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>journal</option>
 452                                 connects it with the journal which is
 453                                 accessible via
 454                                 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 455                                 (Note that everything that is written
 456                                 to syslog or kmsg is implicitly stored
 457                                 in the journal as well, those options
 458                                 are hence supersets of this
 459                                 one). <option>syslog+console</option>,
 460                                 <option>journal+console</option> and
 461                                 <option>kmsg+console</option> work
 462                                 similarly but copy the output to the
 463                                 system console as
 464                                 well. <option>socket</option> connects
 465                                 standard output to a socket from
 466                                 socket activation, semantics are
 467                                 similar to the respective option of
 468                                 <varname>StandardInput=</varname>.
 469                                 This setting defaults to the value set
 470                                 with
 471                                 <option>DefaultStandardOutput=</option>
 472                                 in
 473                                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 474                                 which defaults to
 475                                 <option>journal</option>.</para></listitem>
 476                         </varlistentry>
 477                         <varlistentry>
 478                                 <term><varname>StandardError=</varname></term>
 479                                 <listitem><para>Controls where file
 480                                 descriptor 2 (STDERR) of the
 481                                 executed processes is connected to.
 482                                 The available options are identical to
 483                                 those of
 484                                 <varname>StandardOutput=</varname>,
 485                                 with one exception: if set to
 486                                 <option>inherit</option> the file
 487                                 descriptor used for standard output is
 488                                 duplicated for standard error. This
 489                                 setting defaults to the value set with
 490                                 <option>DefaultStandardError=</option>
 491                                 in
 492                                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 493                                 which defaults to
 494                                 <option>inherit</option>.</para></listitem>
 495                         </varlistentry>
 496                         <varlistentry>
 497                                 <term><varname>TTYPath=</varname></term>
 498                                 <listitem><para>Sets the terminal
 499                                 device node to use if standard input, output,
 500                                 or error are connected to a
 501                                 TTY (see above). Defaults to
 502                                 <filename>/dev/console</filename>.</para></listitem>
 503                         </varlistentry>
 504                         <varlistentry>
 505                                 <term><varname>TTYReset=</varname></term>
 506                                 <listitem><para>Reset the terminal
 507                                 device specified with
 508                                 <varname>TTYPath=</varname> before and
 509                                 after execution. Defaults to
 510                                 <literal>no</literal>.</para></listitem>
 511                         </varlistentry>
 512                         <varlistentry>
 513                                 <term><varname>TTYVHangup=</varname></term>
 514                                 <listitem><para>Disconnect all clients
 515                                 which have opened the terminal device
 516                                 specified with
 517                                 <varname>TTYPath=</varname>
 518                                 before and after execution. Defaults
 519                                 to
 520                                 <literal>no</literal>.</para></listitem>
 521                         </varlistentry>
 522                         <varlistentry>
 523                                 <term><varname>TTYVTDisallocate=</varname></term>
 524                                 <listitem><para>If the terminal
 525                                 device specified with
 526                                 <varname>TTYPath=</varname> is a
 527                                 virtual console terminal, try to
 528                                 deallocate the TTY before and after
 529                                 execution. This ensures that the
 530                                 screen and scrollback buffer is
 531                                 cleared. Defaults to
 532                                 <literal>no</literal>.</para></listitem>
 533                         </varlistentry>
 534                         <varlistentry>
 535                                 <term><varname>SyslogIdentifier=</varname></term>
 536                                 <listitem><para>Sets the process name
 537                                 to prefix log lines sent to syslog or
 538                                 the kernel log buffer with. If not set,
 539                                 defaults to the process name of the
 540                                 executed process. This option is only
 541                                 useful when
 542                                 <varname>StandardOutput=</varname> or
 543                                 <varname>StandardError=</varname> are
 544                                 set to <option>syslog</option> or
 545                                 <option>kmsg</option>.</para></listitem>
 546                         </varlistentry>
 547                         <varlistentry>
 548                                 <term><varname>SyslogFacility=</varname></term>
 549                                 <listitem><para>Sets the syslog
 550                                 facility to use when logging to
 551                                 syslog. One of <option>kern</option>,
 552                                 <option>user</option>,
 553                                 <option>mail</option>,
 554                                 <option>daemon</option>,
 555                                 <option>auth</option>,
 556                                 <option>syslog</option>,
 557                                 <option>lpr</option>,
 558                                 <option>news</option>,
 559                                 <option>uucp</option>,
 560                                 <option>cron</option>,
 561                                 <option>authpriv</option>,
 562                                 <option>ftp</option>,
 563                                 <option>local0</option>,
 564                                 <option>local1</option>,
 565                                 <option>local2</option>,
 566                                 <option>local3</option>,
 567                                 <option>local4</option>,
 568                                 <option>local5</option>,
 569                                 <option>local6</option> or
 570                                 <option>local7</option>. See
 571                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 572                                 for details. This option is only
 573                                 useful when
 574                                 <varname>StandardOutput=</varname> or
 575                                 <varname>StandardError=</varname> are
 576                                 set to <option>syslog</option>.
 577                                 Defaults to
 578                                 <option>daemon</option>.</para></listitem>
 579                         </varlistentry>
 580                         <varlistentry>
 581                                 <term><varname>SyslogLevel=</varname></term>
 582                                 <listitem><para>Default syslog level
 583                                 to use when logging to syslog or the
 584                                 kernel log buffer. One of
 585                                 <option>emerg</option>,
 586                                 <option>alert</option>,
 587                                 <option>crit</option>,
 588                                 <option>err</option>,
 589                                 <option>warning</option>,
 590                                 <option>notice</option>,
 591                                 <option>info</option>,
 592                                 <option>debug</option>. See
 593                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 594                                 for details. This option is only
 595                                 useful when
 596                                 <varname>StandardOutput=</varname> or
 597                                 <varname>StandardError=</varname> are
 598                                 set to <option>syslog</option> or
 599                                 <option>kmsg</option>. Note that
 600                                 individual lines output by the daemon
 601                                 might be prefixed with a different log
 602                                 level which can be used to override
 603                                 the default log level specified
 604                                 here. The interpretation of these
 605                                 prefixes may be disabled with
 606                                 <varname>SyslogLevelPrefix=</varname>,
 607                                 see below. For details see
 608                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 609
 610                                 Defaults to
 611                                 <option>info</option>.</para></listitem>
 612                         </varlistentry>
 613
 614                         <varlistentry>
 615                                 <term><varname>SyslogLevelPrefix=</varname></term>
 616                                 <listitem><para>Takes a boolean
 617                                 argument. If true and
 618                                 <varname>StandardOutput=</varname> or
 619                                 <varname>StandardError=</varname> are
 620                                 set to <option>syslog</option>,
 621                                 <option>kmsg</option> or
 622                                 <option>journal</option>, log lines
 623                                 written by the executed process that
 624                                 are prefixed with a log level will be
 625                                 passed on to syslog with this log
 626                                 level set but the prefix removed. If
 627                                 set to false, the interpretation of
 628                                 these prefixes is disabled and the
 629                                 logged lines are passed on as-is. For
 630                                 details about this prefixing see
 631                                 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 632                                 Defaults to true.</para></listitem>
 633                         </varlistentry>
 634
 635                         <varlistentry>
 636                                 <term><varname>TimerSlackNSec=</varname></term>
 637                                 <listitem><para>Sets the timer slack
 638                                 in nanoseconds for the executed
 639                                 processes. The timer slack controls
 640                                 the accuracy of wake-ups triggered by
 641                                 timers. See
 642                                 <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 643                                 for more information. Note that in
 644                                 contrast to most other time span
 645                                 definitions this parameter takes an
 646                                 integer value in nano-seconds if no
 647                                 unit is specified. The usual time
 648                                 units are understood
 649                                 too.</para></listitem>
 650                         </varlistentry>
 651
 652                         <varlistentry>
 653                                 <term><varname>LimitCPU=</varname></term>
 654                                 <term><varname>LimitFSIZE=</varname></term>
 655                                 <term><varname>LimitDATA=</varname></term>
 656                                 <term><varname>LimitSTACK=</varname></term>
 657                                 <term><varname>LimitCORE=</varname></term>
 658                                 <term><varname>LimitRSS=</varname></term>
 659                                 <term><varname>LimitNOFILE=</varname></term>
 660                                 <term><varname>LimitAS=</varname></term>
 661                                 <term><varname>LimitNPROC=</varname></term>
 662                                 <term><varname>LimitMEMLOCK=</varname></term>
 663                                 <term><varname>LimitLOCKS=</varname></term>
 664                                 <term><varname>LimitSIGPENDING=</varname></term>
 665                                 <term><varname>LimitMSGQUEUE=</varname></term>
 666                                 <term><varname>LimitNICE=</varname></term>
 667                                 <term><varname>LimitRTPRIO=</varname></term>
 668                                 <term><varname>LimitRTTIME=</varname></term>
 669                                 <listitem><para>These settings control
 670                                 various resource limits for executed
 671                                 processes. See
 672                                 <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 673                                 for details. Use the string
 674                                 <varname>infinity</varname> to
 675                                 configure no limit on a specific
 676                                 resource.</para></listitem>
 677                         </varlistentry>
 678
 679                         <varlistentry>
 680                                 <term><varname>PAMName=</varname></term>
 681                                 <listitem><para>Sets the PAM service
 682                                 name to set up a session as. If set,
 683                                 the executed process will be
 684                                 registered as a PAM session under the
 685                                 specified service name. This is only
 686                                 useful in conjunction with the
 687                                 <varname>User=</varname> setting. If
 688                                 not set, no PAM session will be opened
 689                                 for the executed processes. See
 690                                 <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 691                                 for details.</para></listitem>
 692                         </varlistentry>
 693
 694                         <varlistentry>
 695                                 <term><varname>CapabilityBoundingSet=</varname></term>
 696
 697                                 <listitem><para>Controls which
 698                                 capabilities to include in the
 699                                 capability bounding set for the
 700                                 executed process. See
 701                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 702                                 for details. Takes a whitespace-separated
 703                                 list of capability names as read by
 704                                 <citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 705                                 e.g. <constant>CAP_SYS_ADMIN</constant>,
 706                                 <constant>CAP_DAC_OVERRIDE</constant>,
 707                                 <constant>CAP_SYS_PTRACE</constant>.
 708                                 Capabilities listed will be included
 709                                 in the bounding set, all others are
 710                                 removed. If the list of capabilities
 711                                 is prefixed with <literal>~</literal>,
 712                                 all but the listed capabilities will
 713                                 be included, the effect of the
 714                                 assignment inverted. Note that this
 715                                 option also affects the respective
 716                                 capabilities in the effective,
 717                                 permitted and inheritable capability
 718                                 sets, on top of what
 719                                 <varname>Capabilities=</varname>
 720                                 does. If this option is not used, the
 721                                 capability bounding set is not
 722                                 modified on process execution, hence
 723                                 no limits on the capabilities of the
 724                                 process are enforced. This option may
 725                                 appear more than once in which case
 726                                 the bounding sets are merged. If the
 727                                 empty string is assigned to this
 728                                 option, the bounding set is reset to
 729                                 the empty capability set, and all
 730                                 prior settings have no effect. If set
 731                                 to <literal>~</literal> (without any
 732                                 further argument), the bounding set is
 733                                 reset to the full set of available
 734                                 capabilities, also undoing any
 735                                 previous settings.</para></listitem>
 736                         </varlistentry>
 737
 738                         <varlistentry>
 739                                 <term><varname>SecureBits=</varname></term>
 740                                 <listitem><para>Controls the secure
 741                                 bits set for the executed process. See
 742                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 743                                 for details. Takes a list of strings:
 744                                 <option>keep-caps</option>,
 745                                 <option>keep-caps-locked</option>,
 746                                 <option>no-setuid-fixup</option>,
 747                                 <option>no-setuid-fixup-locked</option>,
 748                                 <option>noroot</option> and/or
 749                                 <option>noroot-locked</option>. This
 750                                 option may appear more than once in
 751                                 which case the secure bits are
 752                                 ORed. If the empty string is assigned
 753                                 to this option, the bits are reset to
 754                                 0.</para></listitem>
 755                         </varlistentry>
 756
 757                         <varlistentry>
 758                                 <term><varname>Capabilities=</varname></term>
 759                                 <listitem><para>Controls the
 760                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 761                                 set for the executed process. Take a
 762                                 capability string describing the
 763                                 effective, permitted and inherited
 764                                 capability sets as documented in
 765                                 <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 766                                 Note that these capability sets are
 767                                 usually influenced by the capabilities
 768                                 attached to the executed file. Due to
 769                                 that
 770                                 <varname>CapabilityBoundingSet=</varname>
 771                                 is probably the much more useful
 772                                 setting.</para></listitem>
 773                         </varlistentry>
 774
 775                         <varlistentry>
 776                                 <term><varname>ReadWriteDirectories=</varname></term>
 777                                 <term><varname>ReadOnlyDirectories=</varname></term>
 778                                 <term><varname>InaccessibleDirectories=</varname></term>
 779
 780                                 <listitem><para>Sets up a new
 781                                 file system namespace for executed
 782                                 processes. These options may be used
 783                                 to limit access a process might have
 784                                 to the main file system
 785                                 hierarchy. Each setting takes a
 786                                 space-separated list of absolute
 787                                 directory paths. Directories listed in
 788                                 <varname>ReadWriteDirectories=</varname>
 789                                 are accessible from within the
 790                                 namespace with the same access rights
 791                                 as from outside. Directories listed in
 792                                 <varname>ReadOnlyDirectories=</varname>
 793                                 are accessible for reading only,
 794                                 writing will be refused even if the
 795                                 usual file access controls would
 796                                 permit this. Directories listed in
 797                                 <varname>InaccessibleDirectories=</varname>
 798                                 will be made inaccessible for
 799                                 processes inside the namespace. Note
 800                                 that restricting access with these
 801                                 options does not extend to submounts
 802                                 of a directory. You must list
 803                                 submounts separately in these settings
 804                                 to ensure the same limited
 805                                 access. These options may be specified
 806                                 more than once in which case all
 807                                 directories listed will have limited
 808                                 access from within the namespace. If
 809                                 the empty string is assigned to this
 810                                 option, the specific list is reset, and
 811                                 all prior assignments have no
 812                                 effect.</para>
 813                                 <para>Paths in
 814                                 <varname>ReadOnlyDirectories=</varname>
 815                                 and
 816                                 <varname>InaccessibleDirectories=</varname>
 817                                 may be prefixed with
 818                                 <literal>-</literal>, in which case
 819                                 they will be ignored when they do not
 820                                 exist. Note that using this
 821                                 setting will disconnect propagation of
 822                                 mounts from the service to the host
 823                                 (propagation in the opposite direction
 824                                 continues to work). This means that
 825                                 this setting may not be used for
 826                                 services which shall be able to
 827                                 install mount points in the main mount
 828                                 namespace.</para></listitem>
 829                         </varlistentry>
 830
 831                         <varlistentry>
 832                                 <term><varname>PrivateTmp=</varname></term>
 833
 834                                 <listitem><para>Takes a boolean
 835                                 argument. If true, sets up a new file
 836                                 system namespace for the executed
 837                                 processes and mounts private
 838                                 <filename>/tmp</filename> and
 839                                 <filename>/var/tmp</filename>
 840                                 directories inside it that is not
 841                                 shared by processes outside of the
 842                                 namespace. This is useful to secure
 843                                 access to temporary files of the
 844                                 process, but makes sharing between
 845                                 processes via
 846                                 <filename>/tmp</filename> or
 847                                 <filename>/var/tmp</filename>
 848                                 impossible. If this is enabled, all
 849                                 temporary files created by a service
 850                                 in these directories will be removed
 851                                 after the service is stopped. Defaults
 852                                 to false. It is possible to run two or
 853                                 more units within the same private
 854                                 <filename>/tmp</filename> and
 855                                 <filename>/var/tmp</filename>
 856                                 namespace by using the
 857                                 <varname>JoinsNamespaceOf=</varname>
 858                                 directive, see
 859                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 860                                 for details. Note that using this
 861                                 setting will disconnect propagation of
 862                                 mounts from the service to the host
 863                                 (propagation in the opposite direction
 864                                 continues to work). This means that
 865                                 this setting may not be used for
 866                                 services which shall be able to install
 867                                 mount points in the main mount
 868                                 namespace.</para></listitem>
 869                         </varlistentry>
 870
 871                         <varlistentry>
 872                                 <term><varname>PrivateDevices=</varname></term>
 873
 874                                 <listitem><para>Takes a boolean
 875                                 argument. If true, sets up a new /dev
 876                                 namespace for the executed processes
 877                                 and only adds API pseudo devices such
 878                                 as <filename>/dev/null</filename>,
 879                                 <filename>/dev/zero</filename> or
 880                                 <filename>/dev/random</filename> (as
 881                                 well as the pseudo TTY subsystem) to
 882                                 it, but no physical devices such as
 883                                 <filename>/dev/sda</filename>. This is
 884                                 useful to securely turn off physical
 885                                 device access by the executed
 886                                 process. Defaults to false. Enabling
 887                                 this option will also remove
 888                                 <constant>CAP_MKNOD</constant> from
 889                                 the capability bounding set for the
 890                                 unit (see above), and set
 891                                 <varname>DevicePolicy=closed</varname>
 892                                 (see
 893                                 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 894                                 for details). Note that using this
 895                                 setting will disconnect propagation of
 896                                 mounts from the service to the host
 897                                 (propagation in the opposite direction
 898                                 continues to work). This means that
 899                                 this setting may not be used for
 900                                 services which shall be able to
 901                                 install mount points in the main mount
 902                                 namespace.</para></listitem>
 903                         </varlistentry>
 904
 905                         <varlistentry>
 906                                 <term><varname>PrivateNetwork=</varname></term>
 907
 908                                 <listitem><para>Takes a boolean
 909                                 argument. If true, sets up a new
 910                                 network namespace for the executed
 911                                 processes and configures only the
 912                                 loopback network device
 913                                 <literal>lo</literal> inside it. No
 914                                 other network devices will be
 915                                 available to the executed process.
 916                                 This is useful to securely turn off
 917                                 network access by the executed
 918                                 process. Defaults to false. It is
 919                                 possible to run two or more units
 920                                 within the same private network
 921                                 namespace by using the
 922                                 <varname>JoinsNamespaceOf=</varname>
 923                                 directive, see
 924                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 925                                 for details. Note that this option
 926                                 will disconnect all socket families
 927                                 from the host, this includes
 928                                 AF_NETLINK and AF_UNIX. The latter has
 929                                 the effect that AF_UNIX sockets in the
 930                                 abstract socket namespace will become
 931                                 unavailable to the processes (however,
 932                                 those located in the file system will
 933                                 continue to be
 934                                 accessible).</para></listitem>
 935                         </varlistentry>
 936
 937                         <varlistentry>
 938                                 <term><varname>MountFlags=</varname></term>
 939
 940                                 <listitem><para>Takes a mount
 941                                 propagation flag:
 942                                 <option>shared</option>,
 943                                 <option>slave</option> or
 944                                 <option>private</option>, which
 945                                 control whether mounts in the file
 946                                 system namespace set up for this
 947                                 unit's processes will receive or
 948                                 propagate mounts or unmounts. See
 949                                 <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 950                                 for details. Defaults to
 951                                 <option>shared</option>. Use
 952                                 <option>shared</option> to ensure that
 953                                 mounts and unmounts are propagated
 954                                 from the host to the container and
 955                                 vice versa. Use <option>slave</option>
 956                                 to run processes so that none of their
 957                                 mounts and unmounts will propagate to
 958                                 the host. Use <option>private</option>
 959                                 to also ensure that no mounts and
 960                                 unmounts from the host will propagate
 961                                 into the unit processes'
 962                                 namespace. Note that
 963                                 <option>slave</option> means that file
 964                                 systems mounted on the host might stay
 965                                 mounted continously in the unit's
 966                                 namespace, and thus keep the device
 967                                 busy. Note that the file system
 968                                 namespace related options
 969                                 (<varname>PrivateTmp=</varname>,
 970                                 <varname>PrivateDevices=</varname>,
 971                                 <varname>ReadOnlyDirectories=</varname>,
 972                                 <varname>InaccessibleDirectories=</varname>
 973                                 and
 974                                 <varname>ReadWriteDirectories=</varname>)
 975                                 require that mount and unmount
 976                                 propagation from the unit's file
 977                                 system namespace is disabled, and
 978                                 hence downgrade
 979                                 <option>shared</option> to
 980                                 <option>slave</option>.
 981                                 </para></listitem>
 982                         </varlistentry>
 983
 984                         <varlistentry>
 985                                 <term><varname>UtmpIdentifier=</varname></term>
 986
 987                                 <listitem><para>Takes a four
 988                                 character identifier string for an
 989                                 utmp/wtmp entry for this service. This
 990                                 should only be set for services such
 991                                 as <command>getty</command>
 992                                 implementations where utmp/wtmp
 993                                 entries must be created and cleared
 994                                 before and after execution. If the
 995                                 configured string is longer than four
 996                                 characters, it is truncated and the
 997                                 terminal four characters are
 998                                 used. This setting interprets %I style
 999                                 string replacements. This setting is
1000                                 unset by default, i.e. no utmp/wtmp
1001                                 entries are created or cleaned up for
1002                                 this service.</para></listitem>
1003                         </varlistentry>
1004
1005                         <varlistentry>
1006                                 <term><varname>SELinuxContext=</varname></term>
1007
1008                                 <listitem><para>Set the SELinux
1009                                 security context of the executed
1010                                 process. If set, this will override
1011                                 the automated domain
1012                                 transition. However, the policy still
1013                                 needs to autorize the transition. This
1014                                 directive is ignored if SELinux is
1015                                 disabled. If prefixed by
1016                                 <literal>-</literal>, all errors will
1017                                 be ignored. See
1018                                 <citerefentry><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
1019                                 for details.</para></listitem>
1020                         </varlistentry>
1021
1022                         <varlistentry>
1023                                 <term><varname>AppArmorProfile=</varname></term>
1024
1025                                 <listitem><para>Takes a profile name as argument.
1026                                 The process executed by the unit will switch to
1027                                 this profile when started. Profiles must already
1028                                 be loaded in the kernel, or the unit will fail.
1029                                 This result in a non operation if AppArmor is not
1030                                 enabled. If prefixed by <literal>-</literal>, all errors
1031                                 will be ignored.
1032                                 </para></listitem>
1033                         </varlistentry>
1034
1035                         <varlistentry>
1036                                 <term><varname>IgnoreSIGPIPE=</varname></term>
1037
1038                                 <listitem><para>Takes a boolean
1039                                 argument. If true, causes <constant>SIGPIPE</constant> to be
1040                                 ignored in the executed
1041                                 process. Defaults to true because
1042                                 <constant>SIGPIPE</constant> generally is useful only in
1043                                 shell pipelines.</para></listitem>
1044                         </varlistentry>
1045
1046                         <varlistentry>
1047                                 <term><varname>NoNewPrivileges=</varname></term>
1048
1049                                 <listitem><para>Takes a boolean
1050                                 argument. If true, ensures that the
1051                                 service process and all its children
1052                                 can never gain new privileges. This
1053                                 option is more powerful than the respective
1054                                 secure bits flags (see above), as it
1055                                 also prohibits UID changes of any
1056                                 kind. This is the simplest, most
1057                                 effective way to ensure that a process
1058                                 and its children can never elevate
1059                                 privileges again.</para></listitem>
1060                         </varlistentry>
1061
1062                         <varlistentry>
1063                                 <term><varname>SystemCallFilter=</varname></term>
1064
1065                                 <listitem><para>Takes a
1066                                 space-separated list of system call
1067                                 names. If this setting is used, all
1068                                 system calls executed by the unit
1069                                 processes except for the listed ones
1070                                 will result in immediate process
1071                                 termination with the
1072                                 <constant>SIGSYS</constant> signal
1073                                 (whitelisting). If the first character
1074                                 of the list is <literal>~</literal>,
1075                                 the effect is inverted: only the
1076                                 listed system calls will result in
1077                                 immediate process termination
1078                                 (blacklisting). If running in user
1079                                 mode and this option is used,
1080                                 <varname>NoNewPrivileges=yes</varname>
1081                                 is implied. This feature makes use of the
1082                                 Secure Computing Mode 2 interfaces of
1083                                 the kernel ('seccomp filtering') and
1084                                 is useful for enforcing a minimal
1085                                 sandboxing environment. Note that the
1086                                 <function>execve</function>,
1087                                 <function>rt_sigreturn</function>,
1088                                 <function>sigreturn</function>,
1089                                 <function>exit_group</function>,
1090                                 <function>exit</function> system calls
1091                                 are implicitly whitelisted and do not
1092                                 need to be listed explicitly. This
1093                                 option may be specified more than once
1094                                 in which case the filter masks are
1095                                 merged. If the empty string is
1096                                 assigned, the filter is reset, all
1097                                 prior assignments will have no
1098                                 effect.</para>
1099
1100                                 <para>If you specify both types of
1101                                 this option (i.e. whitelisting and
1102                                 blacklisting), the first encountered
1103                                 will take precedence and will dictate
1104                                 the default action (termination or
1105                                 approval of a system call). Then the
1106                                 next occurrences of this option will
1107                                 add or delete the listed system calls
1108                                 from the set of the filtered system
1109                                 calls, depending of its type and the
1110                                 default action. (For example, if you have started
1111                                 with a whitelisting of
1112                                 <function>read</function> and
1113                                 <function>write</function>, and right
1114                                 after it add a blacklisting of
1115                                 <function>write</function>, then
1116                                 <function>write</function> will be
1117                                 removed from the set.)
1118                                 </para></listitem>
1119                         </varlistentry>
1120
1121                         <varlistentry>
1122                                 <term><varname>SystemCallErrorNumber=</varname></term>
1123
1124                                 <listitem><para>Takes an
1125                                 <literal>errno</literal> error number
1126                                 name to return when the system call
1127                                 filter configured with
1128                                 <varname>SystemCallFilter=</varname>
1129                                 is triggered, instead of terminating
1130                                 the process immediately. Takes an
1131                                 error name such as
1132                                 <constant>EPERM</constant>,
1133                                 <constant>EACCES</constant> or
1134                                 <constant>EUCLEAN</constant>. When this
1135                                 setting is not used, or when the empty
1136                                 string is assigned, the process will be
1137                                 terminated immediately when the filter
1138                                 is triggered.</para></listitem>
1139                         </varlistentry>
1140
1141                         <varlistentry>
1142                                 <term><varname>SystemCallArchitectures=</varname></term>
1143
1144                                 <listitem><para>Takes a space
1145                                 separated list of architecture
1146                                 identifiers to include in the system
1147                                 call filter. The known architecture
1148                                 identifiers are
1149                                 <constant>x86</constant>,
1150                                 <constant>x86-64</constant>,
1151                                 <constant>x32</constant>,
1152                                 <constant>arm</constant> as well as
1153                                 the special identifier
1154                                 <constant>native</constant>. Only
1155                                 system calls of the specified
1156                                 architectures will be permitted to
1157                                 processes of this unit. This is an
1158                                 effective way to disable compatibility
1159                                 with non-native architectures for
1160                                 processes, for example to prohibit
1161                                 execution of 32-bit x86 binaries on
1162                                 64-bit x86-64 systems. The special
1163                                 <constant>native</constant> identifier
1164                                 implicitly maps to the native
1165                                 architecture of the system (or more
1166                                 strictly: to the architecture the
1167                                 system manager is compiled for). If
1168                                 running in user mode and this option
1169                                 is used,
1170                                 <varname>NoNewPrivileges=yes</varname>
1171                                 is implied. Note that setting this
1172                                 option to a non-empty list implies
1173                                 that <constant>native</constant> is
1174                                 included too. By default, this option
1175                                 is set to the empty list, i.e. no
1176                                 architecture system call filtering is
1177                                 applied.</para></listitem>
1178                         </varlistentry>
1179
1180                         <varlistentry>
1181                                 <term><varname>RestrictAddressFamilies=</varname></term>
1182
1183                                 <listitem><para>Restricts the set of
1184                                 socket address families accessible to
1185                                 the processes of this unit. Takes a
1186                                 space-separated list of address family
1187                                 names to whitelist, such as
1188                                 <constant>AF_UNIX</constant>,
1189                                 <constant>AF_INET</constant> or
1190                                 <constant>AF_INET6</constant>. When
1191                                 prefixed with <constant>~</constant>
1192                                 the listed address families will be
1193                                 applied as blacklist, otherwise as
1194                                 whitelist. Note that this restricts
1195                                 access to the
1196                                 <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1197                                 system call only. Sockets passed into
1198                                 the process by other means (for
1199                                 example, by using socket activation
1200                                 with socket units, see
1201                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1202                                 are unaffected. Also, sockets created
1203                                 with <function>socketpair()</function>
1204                                 (which creates connected AF_UNIX
1205                                 sockets only) are unaffected. Note
1206                                 that this option has no effect on
1207                                 32-bit x86 and is ignored (but works
1208                                 correctly on x86-64). If running in user
1209                                 mode and this option is used,
1210                                 <varname>NoNewPrivileges=yes</varname>
1211                                 is implied. By default, no
1212                                 restriction applies, all address
1213                                 families are accessible to
1214                                 processes. If assigned the empty
1215                                 string, any previous list changes are
1216                                 undone.</para>
1217
1218                                 <para>Use this option to limit
1219                                 exposure of processes to remote
1220                                 systems, in particular via exotic
1221                                 network protocols. Note that in most
1222                                 cases, the local
1223                                 <constant>AF_UNIX</constant> address
1224                                 family should be included in the
1225                                 configured whitelist as it is
1226                                 frequently used for local
1227                                 communication, including for
1228                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1229                                 logging.</para></listitem>
1230                         </varlistentry>
1231
1232                         <varlistentry>
1233                                 <term><varname>Personality=</varname></term>
1234
1235                                 <listitem><para>Controls which
1236                                 kernel architecture
1237                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1238                                 shall report, when invoked by unit
1239                                 processes. Takes one of
1240                                 <constant>x86</constant> and
1241                                 <constant>x86-64</constant>. This is
1242                                 useful when running 32-bit services on
1243                                 a 64-bit host system. If not specified,
1244                                 the personality is left unmodified and
1245                                 thus reflects the personality of the
1246                                 host system's
1247                                 kernel.</para></listitem>
1248                         </varlistentry>
1249
1250                         <varlistentry>
1251                                 <term><varname>RuntimeDirectory=</varname></term>
1252                                 <term><varname>RuntimeDirectoryMode=</varname></term>
1253
1254                                 <listitem><para>Takes a list of
1255                                 directory names. If set, one or more
1256                                 directories by the specified names
1257                                 will be created below
1258                                 <filename>/run</filename> (for system
1259                                 services) or below
1260                                 <varname>$XDG_RUNTIME_DIR</varname>
1261                                 (for user services) when the unit is
1262                                 started, and removed when the unit is
1263                                 stopped. The directories will have the
1264                                 access mode specified in
1265                                 <varname>RuntimeDirectoryMode=</varname>,
1266                                 and will be owned by the user and
1267                                 group specified in
1268                                 <varname>User=</varname> and
1269                                 <varname>Group=</varname>. Use this to
1270                                 manage one or more runtime directories
1271                                 of the unit and bind their lifetime to
1272                                 the daemon runtime. The specified
1273                                 directory names must be relative, and
1274                                 may not include a
1275                                 <literal>/</literal>, i.e. must refer
1276                                 to simple directories to create or
1277                                 remove. This is particularly useful
1278                                 for unprivileged daemons that cannot
1279                                 create runtime directories in
1280                                 <filename>/run</filename> due to lack
1281                                 of privileges, and to make sure the
1282                                 runtime directory is cleaned up
1283                                 automatically after use. For runtime
1284                                 directories that require more complex
1285                                 or different configuration or lifetime
1286                                 guarantees, please consider using
1287                                 <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
1288                         </varlistentry>
1289
1290                 </variablelist>
1291         </refsect1>
1292
1293         <refsect1>
1294                 <title>Environment variables in spawned processes</title>
1295
1296                 <para>Processes started by the system are executed in
1297                 a clean environment in which select variables
1298                 listed below are set. System processes started by systemd
1299                 do not inherit variables from PID 1, but processes
1300                 started by user systemd instances inherit all
1301                 environment variables from the user systemd instance.
1302                 </para>
1303
1304                 <variablelist class='environment-variables'>
1305                         <varlistentry>
1306                                 <term><varname>$PATH</varname></term>
1307
1308                                 <listitem><para>Colon-separated list
1309                                 of directiories to use when launching
1310                                 executables. Systemd uses a fixed
1311                                 value of
1312                                 <filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>.
1313                                 </para></listitem>
1314                         </varlistentry>
1315
1316                         <varlistentry>
1317                                 <term><varname>$LANG</varname></term>
1318
1319                                 <listitem><para>Locale. Can be set in
1320                                 <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1321                                 or on the kernel command line (see
1322                                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1323                                 and
1324                                 <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
1325                                 </para></listitem>
1326                         </varlistentry>
1327
1328                         <varlistentry>
1329                                 <term><varname>$USER</varname></term>
1330                                 <term><varname>$LOGNAME</varname></term>
1331                                 <term><varname>$HOME</varname></term>
1332                                 <term><varname>$SHELL</varname></term>
1333
1334                                 <listitem><para>User name (twice), home
1335                                 directory, and the login shell.
1336                                 The variables are set for the units that
1337                                 have <varname>User=</varname> set,
1338                                 which includes user
1339                                 <command>systemd</command> instances.
1340                                 See
1341                                 <citerefentry><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1342                                 </para></listitem>
1343                         </varlistentry>
1344
1345                         <varlistentry>
1346                                 <term><varname>$XDG_RUNTIME_DIR</varname></term>
1347
1348                                 <listitem><para>The directory for volatile
1349                                 state. Set for the user <command>systemd</command>
1350                                 instance, and also in user sessions.
1351                                 See
1352                                 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
1353                                 </para></listitem>
1354                         </varlistentry>
1355
1356                         <varlistentry>
1357                                 <term><varname>$XDG_SESSION_ID</varname></term>
1358                                 <term><varname>$XDG_SEAT</varname></term>
1359                                 <term><varname>$XDG_VTNR</varname></term>
1360
1361                                 <listitem><para>The identifier of the
1362                                 session, the seat name, and
1363                                 virtual terminal of the session. Set
1364                                 by
1365                                 <citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1366                                 for login sessions.
1367                                 <varname>$XDG_SEAT</varname> and
1368                                 <varname>$XDG_VTNR</varname> will
1369                                 only be set when attached to a seat and a
1370                                 tty.</para></listitem>
1371                         </varlistentry>
1372
1373                         <varlistentry>
1374                                 <term><varname>$MAINPID</varname></term>
1375
1376                                 <listitem><para>The PID of the units
1377                                 main process if it is known. This is
1378                                 only set for control processes as
1379                                 invoked by
1380                                 <varname>ExecReload=</varname> and
1381                                 similar.  </para></listitem>
1382                         </varlistentry>
1383
1384                         <varlistentry>
1385                                 <term><varname>$MANAGERPID</varname></term>
1386
1387                                 <listitem><para>The PID of the user
1388                                 <command>systemd</command> instance,
1389                                 set for processes spawned by it.
1390                                 </para></listitem>
1391                         </varlistentry>
1392
1393                         <varlistentry>
1394                                 <term><varname>$LISTEN_FDS</varname></term>
1395                                 <term><varname>$LISTEN_PID</varname></term>
1396
1397                                 <listitem><para>Information about file
1398                                 descriptors passed to a service for
1399                                 socket activation.  See
1400                                 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1401                                 </para></listitem>
1402                         </varlistentry>
1403
1404                         <varlistentry>
1405                                 <term><varname>$TERM</varname></term>
1406
1407                                 <listitem><para>Terminal type, set
1408                                 only for units connected to a terminal
1409                                 (<varname>StandardInput=tty</varname>,
1410                                 <varname>StandardOutput=tty</varname>,
1411                                 or
1412                                 <varname>StandardError=tty</varname>).
1413                                 See
1414                                 <citerefentry><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1415                                 </para></listitem>
1416                         </varlistentry>
1417                 </variablelist>
1418
1419                 <para>Additional variables may be configured by the
1420                 following means: for processes spawned in specific
1421                 units, use the <varname>Environment=</varname> and
1422                 <varname>EnvironmentFile=</varname> options above; to
1423                 specify variables globally, use
1424                 <varname>DefaultEnvironment=</varname> (see
1425                 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
1426                 or the kernel option
1427                 <varname>systemd.setenv=</varname> (see
1428                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Additional
1429                 variables may also be set through PAM,
1430                 cf. <citerefentry><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
1431         </refsect1>
1432
1433         <refsect1>
1434                   <title>See Also</title>
1435                   <para>
1436                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1437                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1438                           <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1439                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1440                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1441                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1442                           <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1443                           <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1444                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1445                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1446                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1447                           <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1448                           <citerefentry><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
1449                   </para>
1450         </refsect1>
1451
1452 </refentry>