man/systemd.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  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
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="systemd">
  25
  26         <refentryinfo>
  27                 <title>systemd</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd</refentrytitle>
  42                 <manvolnum>1</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd</refname>
  47                 <refname>init</refname>
  48                 <refpurpose>systemd System and Service Manager</refpurpose>
  49         </refnamediv>
  50
  51         <refsynopsisdiv>
  52                 <cmdsynopsis>
  53                         <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command>
  54                 </cmdsynopsis>
  55                 <cmdsynopsis>
  56                         <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
  57                 </cmdsynopsis>
  58         </refsynopsisdiv>
  59
  60         <refsect1>
  61                 <title>Description</title>
  62
  63                 <para>systemd is a system and service manager for
  64                 Linux operating systems. When run as first process on
  65                 boot (as PID 1), it acts as init system that brings
  66                 up and maintains userspace services.</para>
  67
  68                 <para>For compatibility with SysV, if systemd is called
  69                 as <command>init</command> and a PID that is not
  70                 1, it will execute <command>telinit</command> and pass
  71                 all command line arguments unmodified. That means
  72                 <command>init</command> and <command>telinit</command>
  73                 are mostly equivalent when invoked from normal login sessions. See
  74                 <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  75                 for more information.</para>
  76
  77                 <para>When run as system instance, systemd interprets
  78                 the configuration file
  79                 <filename>system.conf</filename>, otherwise
  80                 <filename>user.conf</filename>. See
  81                 <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  82                 for more information.</para>
  83         </refsect1>
  84
  85         <refsect1>
  86                 <title>Options</title>
  87
  88                 <para>The following options are understood:</para>
  89
  90                 <variablelist>
  91                         <varlistentry>
  92                                 <term><option>-h</option></term>
  93                                 <term><option>--help</option></term>
  94
  95                                 <listitem><para>Prints a short help
  96                                 text and exits.</para></listitem>
  97                         </varlistentry>
  98                         <varlistentry>
  99                                 <term><option>--test</option></term>
 100
 101                                 <listitem><para>Determine startup
 102                                 sequence, dump it and exit. This is an
 103                                 option useful for debugging
 104                                 only.</para></listitem>
 105                         </varlistentry>
 106                         <varlistentry>
 107                                 <term><option>--dump-configuration-items</option></term>
 108
 109                                 <listitem><para>Dump understood unit
 110                                 configuration items. This outputs a
 111                                 terse but complete list of
 112                                 configuration items understood in unit
 113                                 definition files.</para></listitem>
 114                         </varlistentry>
 115                         <varlistentry>
 116                                 <term><option>--introspect=</option></term>
 117
 118                                 <listitem><para>Extract D-Bus
 119                                 interface introspection data. This is
 120                                 mostly useful at install time
 121                                 to generate data suitable for the
 122                                 D-Bus interfaces
 123                                 repository. Optionally the interface
 124                                 name for the introspection data may be
 125                                 specified. If omitted, the
 126                                 introspection data for all interfaces
 127                                 is dumped.</para></listitem>
 128                         </varlistentry>
 129                         <varlistentry>
 130                                 <term><option>--unit=</option></term>
 131
 132                                 <listitem><para>Set default unit to
 133                                 activate on startup. If not specified
 134                                 defaults to
 135                                 <filename>default.target</filename>.</para></listitem>
 136                         </varlistentry>
 137                         <varlistentry>
 138                                 <term><option>--system</option></term>
 139                                 <term><option>--user</option></term>
 140
 141                                 <listitem><para>Tell systemd to run a
 142                                 system instance (resp. user
 143                                 instance), even if the process ID is
 144                                 not 1 (resp. is 1), i.e. systemd is
 145                                 not (resp. is) run as init process.
 146                                 Normally it should not be necessary to
 147                                 pass these options, as systemd
 148                                 automatically detects the mode it is
 149                                 started in. These options are hence of
 150                                 little use except for debugging. Note
 151                                 that it is not supported booting and
 152                                 maintaining a full system with systemd
 153                                 running in <option>--system</option>
 154                                 mode, but PID not 1. In practice,
 155                                 passing <option>--system</option> explicitly is
 156                                 only useful in conjunction with
 157                                 <option>--test</option>.</para></listitem>
 158                         </varlistentry>
 159                         <varlistentry>
 160                                 <term><option>--dump-core</option></term>
 161
 162                                 <listitem><para>Dump core on
 163                                 crash. This switch has no effect when
 164                                 run as user
 165                                 instance.</para></listitem>
 166                         </varlistentry>
 167                         <varlistentry>
 168                                 <term><option>--crash-shell</option></term>
 169
 170                                 <listitem><para>Run shell on
 171                                 crash. This switch has no effect when
 172                                 run as user
 173                                 instance.</para></listitem>
 174                         </varlistentry>
 175                         <varlistentry>
 176                                 <term><option>--confirm-spawn</option></term>
 177
 178                                 <listitem><para>Ask for confirmation
 179                                 when spawning processes. This switch
 180                                 has no effect when run as user
 181                                 instance.</para></listitem>
 182                         </varlistentry>
 183                         <varlistentry>
 184                                 <term><option>--show-status=</option></term>
 185
 186                                 <listitem><para>Show terse service
 187                                 status information while booting. This
 188                                 switch has no effect when run as user
 189                                 instance. Takes a boolean argument
 190                                 which may be omitted which is
 191                                 interpreted as
 192                                 <option>true</option>.</para></listitem>
 193                         </varlistentry>
 194                         <varlistentry>
 195                                 <term><option>--log-target=</option></term>
 196
 197                                 <listitem><para>Set log
 198                                 target. Argument must be one of
 199                                 <option>console</option>,
 200                                 <option>journal</option>,
 201                                 <option>syslog</option>,
 202                                 <option>kmsg</option>,
 203                                 <option>journal-or-kmsg</option>,
 204                                 <option>syslog-or-kmsg</option>,
 205                                 <option>null</option>.</para></listitem>
 206                         </varlistentry>
 207                         <varlistentry>
 208                                 <term><option>--log-level=</option></term>
 209
 210                                 <listitem><para>Set log level. As
 211                                 argument this accepts a numerical log
 212                                 level or the well-known <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 213                                 symbolic names (lowercase):
 214                                 <option>emerg</option>,
 215                                 <option>alert</option>,
 216                                 <option>crit</option>,
 217                                 <option>err</option>,
 218                                 <option>warning</option>,
 219                                 <option>notice</option>,
 220                                 <option>info</option>,
 221                                 <option>debug</option>.</para></listitem>
 222                         </varlistentry>
 223                         <varlistentry>
 224                                 <term><option>--log-color=</option></term>
 225
 226                                 <listitem><para>Highlight important
 227                                 log messages. Argument is a boolean
 228                                 value. If the argument is omitted it
 229                                 defaults to
 230                                 <option>true</option>.</para></listitem>
 231                         </varlistentry>
 232                         <varlistentry>
 233                                 <term><option>--log-location=</option></term>
 234
 235                                 <listitem><para>Include code location
 236                                 in log messages. This is mostly
 237                                 relevant for debugging
 238                                 purposes. Argument is a boolean
 239                                 value. If the argument is omitted
 240                                 it defaults to
 241                                 <option>true</option>.</para></listitem>
 242                         </varlistentry>
 243                         <varlistentry>
 244                                 <term><option>--default-standard-output=</option></term>
 245                                 <term><option>--default-standard-error=</option></term>
 246
 247                                 <listitem><para>Sets the default
 248                                 output resp. error output for all
 249                                 services and sockets, i.e. controls
 250                                 the default for
 251                                 <option>StandardOutput=</option>
 252                                 resp. <option>StandardError=</option>
 253                                 (see
 254                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 255                                 for details). Takes one of
 256                                 <option>inherit</option>,
 257                                 <option>null</option>,
 258                                 <option>tty</option>,
 259                                 <option>journal</option>,
 260                                 <option>journal+console</option>,
 261                                 <option>syslog</option>,
 262                                 <option>syslog+console</option>,
 263                                 <option>kmsg</option>,
 264                                 <option>kmsg+console</option>.  If the
 265                                 argument is omitted
 266                                 <option>--default-standard-output=</option>
 267                                 defaults to <option>journal</option>
 268                                 and
 269                                 <option>--default-standard-error=</option>
 270                                 to
 271                                 <option>inherit</option>.</para></listitem>
 272                         </varlistentry>
 273                 </variablelist>
 274         </refsect1>
 275
 276         <refsect1>
 277                 <title>Concepts</title>
 278
 279                 <para>systemd provides a dependency system between
 280                 various entities called "units". Units encapsulate
 281                 various objects that are relevant for system boot-up
 282                 and maintenance. The majority of units are configured
 283                 in unit configuration files, whose syntax and basic
 284                 set of options is described in
 285                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 286                 however some are created automatically from other
 287                 configuration or dynamically from system state. Units
 288                 may be 'active' (meaning started, bound, plugged in,
 289                 ...  depending on the unit type, see below), or
 290                 'inactive' (meaning stopped, unbound, unplugged, ...),
 291                 as well as in the process of being activated or
 292                 deactivated, i.e. between the two states (these states
 293                 are called 'activating', 'deactivating'). A special
 294                 'failed' state is available as well which is very
 295                 similar to 'inactive' and is entered when the service
 296                 failed in some way (process returned error code on
 297                 exit, or crashed, or an operation timed out). If this
 298                 state is entered the cause will be logged, for later
 299                 reference. Note that the various unit types may have a
 300                 number of additional substates, which are mapped to
 301                 the five generalized unit states described
 302                 here.</para>
 303
 304                 <para>The following unit types are available:</para>
 305
 306                 <orderedlist>
 307                         <listitem><para>Service units, which control
 308                         daemons and the processes they consist of. For
 309                         details see
 310                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 311
 312                         <listitem><para>Socket units, which
 313                         encapsulate local IPC or network sockets in
 314                         the system, useful for socket-based
 315                         activation. For details about socket units see
 316                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 317                         for details on socket-based activation and
 318                         other forms of activation, see
 319                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
 320
 321                         <listitem><para>Target units are useful to
 322                         group units, or provide well-known
 323                         synchronization points during boot-up, see
 324                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 325
 326                         <listitem><para>Device units expose kernel
 327                         devices in systemd and may be used to
 328                         implement device-based activation. For details
 329                         see
 330                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 331
 332                         <listitem><para>Mount units control mount
 333                         points in the file system, for details see
 334                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 335
 336                         <listitem><para>Automount units provide
 337                         automount capabilities, for on-demand mounting
 338                         of file systems as well as parallelized
 339                         boot-up. See
 340                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 341
 342                         <listitem><para>Snapshot units can be used to
 343                         temporarily save the state of the set of
 344                         systemd units, which later may be restored by
 345                         activating the saved snapshot unit. For more
 346                         information see
 347                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 348
 349                         <listitem><para>Timer units are useful for
 350                         triggering activation of other units based on
 351                         timers. You may find details in
 352                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 353
 354                         <listitem><para>Swap units are very similar to
 355                         mount units and encapsulate memory swap
 356                         partitions or files of the operating
 357                         system. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 358
 359                         <listitem><para>Path units may be used
 360                         to activate other services when file system
 361                         objects change or are modified. See
 362                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 363
 364                 </orderedlist>
 365
 366                 <para>Units are named as their configuration
 367                 files. Some units have special semantics. A detailed
 368                 list is available in
 369                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 370
 371                 <para>systemd knows various kinds of dependencies,
 372                 including positive and negative requirement
 373                 dependencies (i.e. <varname>Requires=</varname> and
 374                 <varname>Conflicts=</varname>) as well as ordering
 375                 dependencies (<varname>After=</varname> and
 376                 <varname>Before=</varname>). NB: ordering and
 377                 requirement dependencies are orthogonal. If only a
 378                 requirement dependency exists between two units
 379                 (e.g. <filename>foo.service</filename> requires
 380                 <filename>bar.service</filename>), but no ordering
 381                 dependency (e.g. <filename>foo.service</filename>
 382                 after <filename>bar.service</filename>) and both are
 383                 requested to start, they will be started in
 384                 parallel. It is a common pattern that both requirement
 385                 and ordering dependencies are placed between two
 386                 units. Also note that the majority of dependencies are
 387                 implicitly created and maintained by systemd. In most
 388                 cases it should be unnecessary to declare additional
 389                 dependencies manually, however it is possible to do
 390                 this.</para>
 391
 392                 <para>Application programs and units (via
 393                 dependencies) may request state changes of units. In
 394                 systemd, these requests are encapsulated as 'jobs' and
 395                 maintained in a job queue. Jobs may succeed or can
 396                 fail, their execution is ordered based on the ordering
 397                 dependencies of the units they have been scheduled
 398                 for.</para>
 399
 400                 <para>On boot systemd activates the target unit
 401                 <filename>default.target</filename> whose job is to
 402                 activate on-boot services and other on-boot units by
 403                 pulling them in via dependencies. Usually the unit
 404                 name is just an alias (symlink) for either
 405                 <filename>graphical.target</filename> (for
 406                 fully-featured boots into the UI) or
 407                 <filename>multi-user.target</filename> (for limited
 408                 console-only boots for use in embedded or server
 409                 environments, or similar; a subset of
 410                 graphical.target). However it is at the discretion of
 411                 the administrator to configure it as an alias to any
 412                 other target unit. See
 413                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 414                 for details about these target units.</para>
 415
 416                 <para>Processes systemd spawns are placed in
 417                 individual Linux control groups named after the unit
 418                 which they belong to in the private systemd
 419                 hierarchy. (see <ulink
 420                 url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
 421                 for more information about control groups, or short
 422                 "cgroups"). systemd uses this to effectively keep
 423                 track of processes. Control group information is
 424                 maintained in the kernel, and is accessible via the
 425                 file system hierarchy (beneath
 426                 <filename>/sys/fs/cgroup/systemd/</filename>), or in tools
 427                 such as
 428                 <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 429                 (<command>ps xawf -eo pid,user,cgroup,args</command>
 430                 is particularly useful to list all processes and the
 431                 systemd units they belong to.).</para>
 432
 433                 <para>systemd is compatible with the SysV init system
 434                 to a large degree: SysV init scripts are supported and
 435                 simply read as an alternative (though limited)
 436                 configuration file format. The SysV
 437                 <filename>/dev/initctl</filename> interface is
 438                 provided, and compatibility implementations of the
 439                 various SysV client tools are available. In addition to
 440                 that, various established Unix functionality such as
 441                 <filename>/etc/fstab</filename> or the
 442                 <filename>utmp</filename> database are
 443                 supported.</para>
 444
 445                 <para>systemd has a minimal transaction system: if a
 446                 unit is requested to start up or shut down it will add
 447                 it and all its dependencies to a temporary
 448                 transaction. Then, it will verify if the transaction
 449                 is consistent (i.e. whether the ordering of all units
 450                 is cycle-free). If it is not, systemd will try to fix
 451                 it up, and removes non-essential jobs from the
 452                 transaction that might remove the loop. Also, systemd
 453                 tries to suppress non-essential jobs in the
 454                 transaction that would stop a running service. Finally
 455                 it is checked whether the jobs of the transaction
 456                 contradict jobs that have already been queued, and
 457                 optionally the transaction is aborted then. If all
 458                 worked out and the transaction is consistent and
 459                 minimized in its impact it is merged with all already
 460                 outstanding jobs and added to the run
 461                 queue. Effectively this means that before executing a
 462                 requested operation, systemd will verify that it makes
 463                 sense, fixing it if possible, and only failing if it
 464                 really cannot work.</para>
 465
 466                 <para>Systemd contains native implementations of
 467                 various tasks that need to be executed as part of the
 468                 boot process. For example, it sets the host name or
 469                 configures the loopback network device. It also sets
 470                 up and mounts various API file systems, such as
 471                 <filename>/sys</filename> or
 472                 <filename>/proc</filename>.</para>
 473
 474                 <para>For more information about the concepts and
 475                 ideas behind systemd please refer to the <ulink
 476                 url="http://0pointer.de/blog/projects/systemd.html">Original
 477                 Design Document</ulink>.</para>
 478
 479                 <para>Note that some but not all interfaces provided
 480                 by systemd are covered by the <ulink
 481                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
 482                 Stability Promise</ulink>.</para>
 483         </refsect1>
 484
 485         <refsect1>
 486                 <title>Directories</title>
 487
 488                 <variablelist>
 489                         <varlistentry>
 490                                 <term>System unit directories</term>
 491
 492                                 <listitem><para>The systemd system
 493                                 manager reads unit configuration from
 494                                 various directories. Packages that
 495                                 want to install unit files shall place
 496                                 them in the directory returned by
 497                                 <command>pkg-config systemd
 498                                 --variable=systemdsystemunitdir</command>. Other
 499                                 directories checked are
 500                                 <filename>/usr/local/lib/systemd/system</filename>
 501                                 and
 502                                 <filename>/usr/lib/systemd/system</filename>. User
 503                                 configuration always takes
 504                                 precedence. <command>pkg-config
 505                                 systemd
 506                                 --variable=systemdsystemconfdir</command>
 507                                 returns the path of the system
 508                                 configuration directory. Packages
 509                                 should alter the content of these
 510                                 directories only with the
 511                                 <command>enable</command> and
 512                                 <command>disable</command> commands of
 513                                 the
 514                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 515                                 tool.</para></listitem>
 516                         </varlistentry>
 517                 </variablelist>
 518
 519                 <variablelist>
 520                         <varlistentry>
 521                                 <term>User unit directories</term>
 522
 523                                 <listitem><para>Similar rules apply
 524                                 for the user unit
 525                                 directories. However, here the <ulink
 526                                 url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 527                                 Base Directory specification</ulink>
 528                                 is followed to find
 529                                 units. Applications should place their
 530                                 unit files in the directory returned
 531                                 by <command>pkg-config systemd
 532                                 --variable=systemduserunitdir</command>. Global
 533                                 configuration is done in the directory
 534                                 reported by <command>pkg-config
 535                                 systemd
 536                                 --variable=systemduserconfdir</command>. The
 537                                 <command>enable</command> and
 538                                 <command>disable</command> commands of
 539                                 the
 540                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 541                                 tool can handle both global (i.e. for
 542                                 all users) and private (for one user)
 543                                 enabling/disabling of
 544                                 units.</para></listitem>
 545                         </varlistentry>
 546                 </variablelist>
 547
 548                 <variablelist>
 549                         <varlistentry>
 550                                 <term>SysV init scripts directory</term>
 551
 552                                 <listitem><para>The location of the
 553                                 SysV init script directory varies
 554                                 between distributions. If systemd
 555                                 cannot find a native unit file for a
 556                                 requested service, it will look for a
 557                                 SysV init script of the same name
 558                                 (with the
 559                                 <filename>.service</filename> suffix
 560                                 removed).</para></listitem>
 561                         </varlistentry>
 562                 </variablelist>
 563
 564                 <variablelist>
 565                         <varlistentry>
 566                                 <term>SysV runlevel link farm directory</term>
 567
 568                                 <listitem><para>The location of the
 569                                 SysV runlevel link farm directory
 570                                 varies between distributions. systemd
 571                                 will take the link farm into account
 572                                 when figuring out whether a service
 573                                 shall be enabled. Note that a service
 574                                 unit with a native unit configuration
 575                                 file cannot be started by activating it
 576                                 in the SysV runlevel link
 577                                 farm.</para></listitem>
 578                         </varlistentry>
 579                 </variablelist>
 580         </refsect1>
 581
 582         <refsect1>
 583                 <title>Signals</title>
 584
 585                 <variablelist>
 586                         <varlistentry>
 587                                 <term>SIGTERM</term>
 588
 589                                 <listitem><para>Upon receiving this
 590                                 signal the systemd system manager
 591                                 serializes its state, reexecutes
 592                                 itself and deserializes the saved
 593                                 state again. This is mostly equivalent
 594                                 to <command>systemctl
 595                                 daemon-reexec</command>.</para>
 596
 597                                 <para>systemd user managers will
 598                                 start the
 599                                 <filename>exit.target</filename> unit
 600                                 when this signal is received. This is
 601                                 mostly equivalent to
 602                                 <command>systemctl --user start
 603                                 exit.target</command>.</para></listitem>
 604                         </varlistentry>
 605
 606                         <varlistentry>
 607                                 <term>SIGINT</term>
 608
 609                                 <listitem><para>Upon receiving this
 610                                 signal the systemd system manager will
 611                                 start the
 612                                 <filename>ctrl-alt-del.target</filename> unit. This
 613                                 is mostly equivalent to
 614                                 <command>systemctl start
 615                                 ctl-alt-del.target</command>.</para>
 616
 617                                 <para>systemd user managers
 618                                 treat this signal the same way as
 619                                 SIGTERM.</para></listitem>
 620                         </varlistentry>
 621
 622                         <varlistentry>
 623                                 <term>SIGWINCH</term>
 624
 625                                 <listitem><para>When this signal is
 626                                 received the systemd system manager
 627                                 will start the
 628                                 <filename>kbrequest.target</filename>
 629                                 unit. This is mostly equivalent to
 630                                 <command>systemctl start
 631                                 kbrequest.target</command>.</para>
 632
 633                                 <para>This signal is ignored by
 634                                 systemd user
 635                                 managers.</para></listitem>
 636                         </varlistentry>
 637
 638                         <varlistentry>
 639                                 <term>SIGPWR</term>
 640
 641                                 <listitem><para>When this signal is
 642                                 received the systemd manager
 643                                 will start the
 644                                 <filename>sigpwr.target</filename>
 645                                 unit. This is mostly equivalent to
 646                                 <command>systemctl start
 647                                 sigpwr.target</command>.</para></listitem>
 648                         </varlistentry>
 649
 650                         <varlistentry>
 651                                 <term>SIGUSR1</term>
 652
 653                                 <listitem><para>When this signal is
 654                                 received the systemd manager will try
 655                                 to reconnect to the D-Bus
 656                                 bus.</para></listitem>
 657                         </varlistentry>
 658
 659                         <varlistentry>
 660                                 <term>SIGUSR2</term>
 661
 662                                 <listitem><para>When this signal is
 663                                 received the systemd manager will log
 664                                 its complete state in human readable
 665                                 form. The data logged is the same as
 666                                 printed by <command>systemctl
 667                                 dump</command>.</para></listitem>
 668                         </varlistentry>
 669
 670                         <varlistentry>
 671                                 <term>SIGHUP</term>
 672
 673                                 <listitem><para>Reloads the complete
 674                                 daemon configuration. This is mostly
 675                                 equivalent to <command>systemctl
 676                                 daemon-reload</command>.</para></listitem>
 677                         </varlistentry>
 678
 679                         <varlistentry>
 680                                 <term>SIGRTMIN+0</term>
 681
 682                                 <listitem><para>Enters default mode, starts the
 683                                 <filename>default.target</filename>
 684                                 unit. This is mostly equivalent to
 685                                 <command>systemctl start
 686                                 default.target</command>.</para></listitem>
 687                         </varlistentry>
 688
 689                         <varlistentry>
 690                                 <term>SIGRTMIN+1</term>
 691
 692                                 <listitem><para>Enters rescue mode,
 693                                 starts the
 694                                 <filename>rescue.target</filename>
 695                                 unit. This is mostly equivalent to
 696                                 <command>systemctl isolate
 697                                 rescue.target</command>.</para></listitem>
 698                         </varlistentry>
 699
 700                         <varlistentry>
 701                                 <term>SIGRTMIN+2</term>
 702
 703                                 <listitem><para>Enters emergency mode,
 704                                 starts the
 705                                 <filename>emergency.service</filename>
 706                                 unit. This is mostly equivalent to
 707                                 <command>systemctl isolate
 708                                 emergency.service</command>.</para></listitem>
 709                         </varlistentry>
 710
 711                         <varlistentry>
 712                                 <term>SIGRTMIN+3</term>
 713
 714                                 <listitem><para>Halts the machine,
 715                                 starts the
 716                                 <filename>halt.target</filename>
 717                                 unit. This is mostly equivalent to
 718                                 <command>systemctl start
 719                                 halt.target</command>.</para></listitem>
 720                         </varlistentry>
 721
 722                         <varlistentry>
 723                                 <term>SIGRTMIN+4</term>
 724
 725                                 <listitem><para>Powers off the machine,
 726                                 starts the
 727                                 <filename>poweroff.target</filename>
 728                                 unit. This is mostly equivalent to
 729                                 <command>systemctl start
 730                                 poweroff.target</command>.</para></listitem>
 731                         </varlistentry>
 732
 733                         <varlistentry>
 734                                 <term>SIGRTMIN+5</term>
 735
 736                                 <listitem><para>Reboots the machine,
 737                                 starts the
 738                                 <filename>reboot.target</filename>
 739                                 unit. This is mostly equivalent to
 740                                 <command>systemctl start
 741                                 reboot.target</command>.</para></listitem>
 742                         </varlistentry>
 743
 744                         <varlistentry>
 745                                 <term>SIGRTMIN+6</term>
 746
 747                                 <listitem><para>Reboots the machine via kexec,
 748                                 starts the
 749                                 <filename>kexec.target</filename>
 750                                 unit. This is mostly equivalent to
 751                                 <command>systemctl start
 752                                 kexec.target</command>.</para></listitem>
 753                         </varlistentry>
 754
 755                         <varlistentry>
 756                                 <term>SIGRTMIN+13</term>
 757
 758                                 <listitem><para>Immediately halts the machine.</para></listitem>
 759                         </varlistentry>
 760
 761                         <varlistentry>
 762                                 <term>SIGRTMIN+14</term>
 763
 764                                 <listitem><para>Immediately powers off the machine.</para></listitem>
 765                         </varlistentry>
 766
 767                         <varlistentry>
 768                                 <term>SIGRTMIN+15</term>
 769
 770                                 <listitem><para>Immediately reboots the machine.</para></listitem>
 771                         </varlistentry>
 772
 773                         <varlistentry>
 774                                 <term>SIGRTMIN+16</term>
 775
 776                                 <listitem><para>Immediately reboots the machine with kexec.</para></listitem>
 777                         </varlistentry>
 778
 779                         <varlistentry>
 780                                 <term>SIGRTMIN+20</term>
 781
 782                                 <listitem><para>Enables display of
 783                                 status messages on the console, as
 784                                 controlled via
 785                                 <varname>systemd.show_status=1</varname>
 786                                 on the kernel command
 787                                 line.</para></listitem>
 788                         </varlistentry>
 789
 790                         <varlistentry>
 791                                 <term>SIGRTMIN+21</term>
 792
 793                                 <listitem><para>Disables display of
 794                                 status messages on the console, as
 795                                 controlled via
 796                                 <varname>systemd.show_status=0</varname>
 797                                 on the kernel command
 798                                 line.</para></listitem>
 799                         </varlistentry>
 800
 801                         <varlistentry>
 802                                 <term>SIGRTMIN+22</term>
 803                                 <term>SIGRTMIN+23</term>
 804
 805                                 <listitem><para>Sets the log level to
 806                                 <literal>debug</literal>
 807                                 (resp. <literal>info</literal> on
 808                                 <literal>SIGRTMIN+23</literal>), as
 809                                 controlled via
 810                                 <varname>systemd.log_level=debug</varname>
 811                                 (resp. <varname>systemd.log_level=info</varname>
 812                                 on <literal>SIGRTMIN+23</literal>) on
 813                                 the kernel command
 814                                 line.</para></listitem>
 815                         </varlistentry>
 816
 817                         <varlistentry>
 818                                 <term>SIGRTMIN+26</term>
 819                                 <term>SIGRTMIN+27</term>
 820                                 <term>SIGRTMIN+28</term>
 821                                 <term>SIGRTMIN+29</term>
 822
 823                                 <listitem><para>Sets the log level to
 824                                 <literal>journal-or-kmsg</literal>
 825                                 (resp. <literal>console</literal> on
 826                                 <literal>SIGRTMIN+27</literal>;
 827                                 resp. <literal>kmsg</literal> on
 828                                 <literal>SIGRTMIN+28</literal>;
 829                                 resp. <literal>syslog-or-kmsg</literal>
 830                                 on <literal>SIGRTMIN+29</literal>), as
 831                                 controlled via
 832                                 <varname>systemd.log_target=journal-or-kmsg</varname>
 833                                 (resp. <varname>systemd.log_target=console</varname>
 834                                 on <literal>SIGRTMIN+27</literal>;
 835                                 resp. <varname>systemd.log_target=kmsg</varname>
 836                                 on <literal>SIGRTMIN+28</literal>;
 837                                 resp
 838                                 <varname>systemd.log_target=syslog-or-kmsg</varname>
 839                                 on <literal>SIGRTMIN+29</literal>) on
 840                                 the kernel command
 841                                 line.</para></listitem>
 842                         </varlistentry>
 843                 </variablelist>
 844         </refsect1>
 845
 846         <refsect1>
 847                 <title>Environment</title>
 848
 849                 <variablelist>
 850                         <varlistentry>
 851                                 <term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
 852                                 <listitem><para>systemd reads the
 853                                 log level from this environment
 854                                 variable. This can be overridden with
 855                                 <option>--log-level=</option>.</para></listitem>
 856                         </varlistentry>
 857
 858                         <varlistentry>
 859                                 <term><varname>$SYSTEMD_LOG_TARGET</varname></term>
 860                                 <listitem><para>systemd reads the
 861                                 log target from this environment
 862                                 variable. This can be overridden with
 863                                 <option>--log-target=</option>.</para></listitem>
 864                         </varlistentry>
 865
 866                         <varlistentry>
 867                                 <term><varname>$SYSTEMD_LOG_COLOR</varname></term>
 868                                 <listitem><para>Controls whether
 869                                 systemd highlights important log
 870                                 messages. This can be overridden with
 871                                 <option>--log-color=</option>.</para></listitem>
 872                         </varlistentry>
 873
 874                         <varlistentry>
 875                                 <term><varname>$SYSTEMD_LOG_LOCATION</varname></term>
 876                                 <listitem><para>Controls whether
 877                                 systemd prints the code location along
 878                                 with log messages. This can be
 879                                 overridden with
 880                                 <option>--log-location=</option>.</para></listitem>
 881                         </varlistentry>
 882
 883                         <varlistentry>
 884                                 <term><varname>$XDG_CONFIG_HOME</varname></term>
 885                                 <term><varname>$XDG_CONFIG_DIRS</varname></term>
 886                                 <term><varname>$XDG_DATA_HOME</varname></term>
 887                                 <term><varname>$XDG_DATA_DIRS</varname></term>
 888
 889                                 <listitem><para>The systemd user
 890                                 manager uses these variables in
 891                                 accordance to the <ulink
 892                                 url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 893                                 Base Directory specification</ulink>
 894                                 to find its configuration.</para></listitem>
 895                         </varlistentry>
 896
 897                         <varlistentry>
 898                                 <term><varname>$SYSTEMD_UNIT_PATH</varname></term>
 899
 900                                 <listitem><para>Controls where systemd
 901                                 looks for unit
 902                                 files.</para></listitem>
 903                         </varlistentry>
 904
 905                         <varlistentry>
 906                                 <term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term>
 907
 908                                 <listitem><para>Controls where systemd
 909                                 looks for SysV init scripts.</para></listitem>
 910                         </varlistentry>
 911
 912                         <varlistentry>
 913                                 <term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term>
 914
 915                                 <listitem><para>Controls where systemd
 916                                 looks for SysV init script runlevel link
 917                                 farms.</para></listitem>
 918                         </varlistentry>
 919
 920                         <varlistentry>
 921                                 <term><varname>$LISTEN_PID</varname></term>
 922                                 <term><varname>$LISTEN_FDS</varname></term>
 923
 924                                 <listitem><para>Set by systemd for
 925                                 supervised processes during
 926                                 socket-based activation. See
 927                                 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 928                                 for more information.
 929                                 </para></listitem>
 930                         </varlistentry>
 931
 932                         <varlistentry>
 933                                 <term><varname>$NOTIFY_SOCKET</varname></term>
 934
 935                                 <listitem><para>Set by systemd for
 936                                 supervised processes for status and
 937                                 start-up completion notification. See
 938                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 939                                 for more information.
 940                                 </para></listitem>
 941                         </varlistentry>
 942                 </variablelist>
 943         </refsect1>
 944
 945         <refsect1>
 946                 <title>Kernel Command Line</title>
 947
 948                 <para>When run as system instance systemd parses a
 949                 number of kernel command line
 950                 arguments<footnote><para>If run inside a Linux
 951                 container these arguments may be passed as command
 952                 line arguments to systemd itself, next to any of the
 953                 command line options listed in the Options section
 954                 above. If run outside of Linux containers, these
 955                 arguments are parsed from
 956                 <filename>/proc/cmdline</filename>
 957                 instead.</para></footnote>:</para>
 958
 959                 <variablelist>
 960                         <varlistentry>
 961                                 <term><varname>systemd.unit=</varname></term>
 962                                 <term><varname>rd.systemd.unit=</varname></term>
 963
 964                                 <listitem><para>Overrides the unit to
 965                                 activate on boot. Defaults to
 966                                 <filename>default.target</filename>. This
 967                                 may be used to temporarily boot into a
 968                                 different boot unit, for example
 969                                 <filename>rescue.target</filename> or
 970                                 <filename>emergency.service</filename>. See
 971                                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 972                                 for details about these units. The
 973                                 option prefixed with
 974                                 <literal>rd.</literal> is honoured
 975                                 only in the initial RAM disk (initrd),
 976                                 while the one that isn't prefixed only
 977                                 in the main system.</para></listitem>
 978                         </varlistentry>
 979
 980                         <varlistentry>
 981                                 <term><varname>systemd.dump_core=</varname></term>
 982
 983                                 <listitem><para>Takes a boolean
 984                                 argument. If <option>true</option>
 985                                 systemd dumps core when it
 986                                 crashes. Otherwise no core dump is
 987                                 created. Defaults to
 988                                 <option>true</option>.</para></listitem>
 989                         </varlistentry>
 990
 991                         <varlistentry>
 992                                 <term><varname>systemd.crash_shell=</varname></term>
 993
 994                                 <listitem><para>Takes a boolean
 995                                 argument. If <option>true</option>
 996                                 systemd spawns a shell when it
 997                                 crashes. Otherwise no shell is
 998                                 spawned. Defaults to
 999                                 <option>false</option>, for security
1000                                 reasons, as the shell is not protected
1001                                 by any password
1002                                 authentication.</para></listitem>
1003                         </varlistentry>
1004
1005                         <varlistentry>
1006                                 <term><varname>systemd.crash_chvt=</varname></term>
1007
1008                                 <listitem><para>Takes an integer
1009                                 argument. If positive systemd
1010                                 activates the specified virtual
1011                                 terminal when it crashes. Defaults to
1012                                 <literal>-1</literal>.</para></listitem>
1013                         </varlistentry>
1014
1015                         <varlistentry>
1016                                 <term><varname>systemd.confirm_spawn=</varname></term>
1017
1018                                 <listitem><para>Takes a boolean
1019                                 argument. If <option>true</option>
1020                                 asks for confirmation when spawning
1021                                 processes. Defaults to
1022                                 <option>false</option>.</para></listitem>
1023                         </varlistentry>
1024
1025                         <varlistentry>
1026                                 <term><varname>systemd.show_status=</varname></term>
1027
1028                                 <listitem><para>Takes a boolean
1029                                 argument. If <option>true</option>
1030                                 shows terse service status updates on
1031                                 the console during bootup. Defaults to
1032                                 <option>true</option>, unless
1033                                 <option>quiet</option> is passed as
1034                                 kernel command line option in which
1035                                 case it defaults to
1036                                 <option>false</option>.</para></listitem>
1037                         </varlistentry>
1038
1039                         <varlistentry>
1040                                 <term><varname>systemd.log_target=</varname></term>
1041                                 <term><varname>systemd.log_level=</varname></term>
1042                                 <term><varname>systemd.log_color=</varname></term>
1043                                 <term><varname>systemd.log_location=</varname></term>
1044
1045                                 <listitem><para>Controls log output,
1046                                 with the same effect as the
1047                                 <varname>$SYSTEMD_LOG_TARGET</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>, <varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LOCATION</varname>
1048                                 environment variables described above.</para></listitem>
1049                         </varlistentry>
1050
1051                         <varlistentry>
1052                                 <term><varname>systemd.default_standard_output=</varname></term>
1053                                 <term><varname>systemd.default_standard_error=</varname></term>
1054                                 <listitem><para>Controls default
1055                                 standard output/error output for
1056                                 services, with the same effect as the
1057                                 <option>--default-standard-output=</option>
1058                                 resp. <option>--default-standard-error=</option>
1059                                 command line arguments described
1060                                 above.</para></listitem>
1061                         </varlistentry>
1062
1063                         <varlistentry>
1064                                 <term><varname>systemd.setenv=</varname></term>
1065
1066                                 <listitem><para>Takes a string
1067                                 argument in the form
1068                                 VARIABLE=VALUE. May be used to set
1069                                 environment variables for the init
1070                                 process and all its children at boot
1071                                 time. May be used more than once to
1072                                 set multiple variables. If the equal
1073                                 sign and variable are missing unsets
1074                                 an environment variable which might be
1075                                 passed in from the initial ram
1076                                 disk.</para></listitem>
1077                         </varlistentry>
1078
1079                         <varlistentry>
1080                                 <term><varname>quiet</varname></term>
1081
1082                                 <listitem><para>If passed turns off
1083                                 status output at boot, much like
1084                                 <varname>systemd.show_status=false</varname>
1085                                 would. Note that this option is also
1086                                 read by the kernel itself and disables
1087                                 kernel log output to the
1088                                 kernel. Passing this option hence
1089                                 turns off the usual output from both
1090                                 the system manager and the
1091                                 kernel.</para></listitem>
1092                         </varlistentry>
1093
1094                         <varlistentry>
1095                                 <term><varname>emergency</varname></term>
1096
1097                                 <listitem><para>Boot into emergency
1098                                 mode. This is equivalent to
1099                                 <varname>systemd.unit=emergency.target</varname>
1100                                 and provided for compatibility
1101                                 reasons and to be easier to type.</para></listitem>
1102                         </varlistentry>
1103
1104                         <varlistentry>
1105                                 <term><varname>single</varname></term>
1106                                 <term><varname>s</varname></term>
1107                                 <term><varname>S</varname></term>
1108                                 <term><varname>1</varname></term>
1109
1110                                 <listitem><para>Boot into rescue
1111                                 mode. This is equivalent to
1112                                 <varname>systemd.unit=rescue.target</varname>
1113                                 and provided for compatibility reasons
1114                                 and to be easier to
1115                                 type.</para></listitem>
1116                         </varlistentry>
1117
1118                         <varlistentry>
1119                                 <term><varname>2</varname></term>
1120                                 <term><varname>3</varname></term>
1121                                 <term><varname>4</varname></term>
1122                                 <term><varname>5</varname></term>
1123
1124                                 <listitem><para>Boot into the
1125                                 specified legacy SysV runlevel. This
1126                                 is equivalent to
1127                                 <varname>systemd.unit=runlevel2.target</varname>,
1128                                 <varname>systemd.unit=runlevel3.target</varname>,
1129                                 <varname>systemd.unit=runlevel4.target</varname>,
1130                                 resp. <varname>systemd.unit=runlevel5.target</varname>
1131                                 and provided for compatibility reasons
1132                                 and to be easier to
1133                                 type.</para></listitem>
1134                         </varlistentry>
1135
1136                         <varlistentry>
1137                                 <term><varname>locale.LANG=</varname></term>
1138                                 <term><varname>locale.LANGUAGE=</varname></term>
1139                                 <term><varname>locale.LC_CTYPE=</varname></term>
1140                                 <term><varname>locale.LC_NUMERIC=</varname></term>
1141                                 <term><varname>locale.LC_TIME=</varname></term>
1142                                 <term><varname>locale.LC_COLLATE=</varname></term>
1143                                 <term><varname>locale.LC_MONETARY=</varname></term>
1144                                 <term><varname>locale.LC_MESSAGES=</varname></term>
1145                                 <term><varname>locale.LC_PAPER=</varname></term>
1146                                 <term><varname>locale.LC_NAME=</varname></term>
1147                                 <term><varname>locale.LC_ADDRESS=</varname></term>
1148                                 <term><varname>locale.LC_TELEPHONE=</varname></term>
1149                                 <term><varname>locale.LC_MEASUREMENT=</varname></term>
1150                                 <term><varname>locale.LC_IDENTIFICATION=</varname></term>
1151
1152                                 <listitem><para>Set the system locale
1153                                 to use. This overrides the settings in
1154                                 <filename>/etc/locale.conf</filename>. For
1155                                 more information see
1156                                 <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1157                                 and
1158                                 <citerefentry><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
1159                                 </para></listitem>
1160                         </varlistentry>
1161                 </variablelist>
1162
1163                 <para>For other kernel command line parameters
1164                 understood by components of the core OS, please refer
1165                 to
1166                 <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
1167         </refsect1>
1168
1169         <refsect1>
1170                 <title>Sockets and FIFOs</title>
1171
1172                 <variablelist>
1173                         <varlistentry>
1174                                 <term><filename>/run/systemd/notify</filename></term>
1175
1176                                 <listitem><para>Daemon status
1177                                 notification socket. This is an
1178                                 AF_UNIX datagram socket and is used to
1179                                 implement the daemon notification
1180                                 logic as implemented by
1181                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
1182
1183                         </varlistentry>
1184
1185                         <varlistentry>
1186                                 <term><filename>/run/systemd/shutdownd</filename></term>
1187
1188                                 <listitem><para>Used internally by the
1189                                 <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1190                                 tool to implement delayed
1191                                 shutdowns. This is an AF_UNIX datagram
1192                                 socket.</para></listitem>
1193                         </varlistentry>
1194
1195                         <varlistentry>
1196                                 <term><filename>/run/systemd/private</filename></term>
1197
1198                                 <listitem><para>Used internally as
1199                                 communication channel between
1200                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1201                                 and the systemd process. This is an
1202                                 AF_UNIX stream socket. This interface
1203                                 is private to systemd and should not
1204                                 be used in external
1205                                 projects.</para></listitem>
1206                         </varlistentry>
1207
1208                         <varlistentry>
1209                                 <term><filename>/dev/initctl</filename></term>
1210
1211                                 <listitem><para>Limited compatibility
1212                                 support for the SysV client interface,
1213                                 as implemented by the
1214                                 <filename>systemd-initctl.service</filename>
1215                                 unit. This is a named pipe in the file
1216                                 system. This interface is obsolete and
1217                                 should not be used in new
1218                                 applications.</para></listitem>
1219                         </varlistentry>
1220                 </variablelist>
1221         </refsect1>
1222
1223         <refsect1>
1224                 <title>See Also</title>
1225                 <para>
1226                         <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1227                         <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1228                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1229                         <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1230                         <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1231                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1232                         <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1233                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1234                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1235                         <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1236                         <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1237                         <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1238                 </para>
1239         </refsect1>
1240
1241 </refentry>