man/systemd.xml

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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="systemd"
  25     xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>systemd</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd</refentrytitle>
  43     <manvolnum>1</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd</refname>
  48     <refname>init</refname>
  49     <refpurpose>systemd system and service manager</refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <cmdsynopsis>
  54       <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command>
  55     </cmdsynopsis>
  56     <cmdsynopsis>
  57       <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
  58     </cmdsynopsis>
  59   </refsynopsisdiv>
  60
  61   <refsect1>
  62     <title>Description</title>
  63
  64     <para>systemd is a system and service manager for Linux operating
  65     systems. When run as first process on boot (as PID 1), it acts as
  66     init system that brings up and maintains userspace
  67     services.</para>
  68
  69     <para>For compatibility with SysV, if systemd is called as
  70     <command>init</command> and a PID that is not 1, it will execute
  71     <command>telinit</command> and pass all command line arguments
  72     unmodified. That means <command>init</command> and
  73     <command>telinit</command> are mostly equivalent when invoked from
  74     normal login sessions. See
  75     <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  76     for more information.</para>
  77
  78     <para>When run as a system instance, systemd interprets the
  79     configuration file <filename>system.conf</filename> and the files
  80     in <filename>system.conf.d</filename> directories; when run as a
  81     user instance, systemd interprets the configuration file
  82     <filename>user.conf</filename> and the files in
  83     <filename>user.conf.d</filename> directories. See
  84     <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  85     for more information.</para>
  86   </refsect1>
  87
  88   <refsect1>
  89     <title>Options</title>
  90
  91     <para>The following options are understood:</para>
  92
  93     <variablelist>
  94       <varlistentry>
  95         <term><option>--test</option></term>
  96
  97         <listitem><para>Determine startup sequence, dump it and exit.
  98         This is an option useful for debugging only.</para></listitem>
  99       </varlistentry>
 100       <varlistentry>
 101         <term><option>--dump-configuration-items</option></term>
 102
 103         <listitem><para>Dump understood unit configuration items. This
 104         outputs a terse but complete list of configuration items
 105         understood in unit definition files.</para></listitem>
 106       </varlistentry>
 107       <varlistentry>
 108         <term><option>--unit=</option></term>
 109
 110         <listitem><para>Set default unit to activate on startup. If
 111         not specified, defaults to
 112         <filename>default.target</filename>.</para></listitem>
 113       </varlistentry>
 114       <varlistentry>
 115         <term><option>--system</option></term>
 116         <term><option>--user</option></term>
 117
 118         <listitem><para>For <option>--system</option>, tell systemd to
 119         run a system instance, even if the process ID is not 1, i.e.
 120         systemd is not run as init process. <option>--user</option>
 121         does the opposite, running a user instance even if the process
 122         ID is 1. Normally, it should not be necessary to pass these
 123         options, as systemd automatically detects the mode it is
 124         started in. These options are hence of little use except for
 125         debugging. Note that it is not supported booting and
 126         maintaining a full system with systemd running in
 127         <option>--system</option> mode, but PID not 1. In practice,
 128         passing <option>--system</option> explicitly is only useful in
 129         conjunction with <option>--test</option>.</para></listitem>
 130       </varlistentry>
 131       <varlistentry>
 132         <term><option>--dump-core</option></term>
 133
 134         <listitem><para>Enable core dumping on crash. This switch has
 135         no effect when running as user instance. This setting may also
 136         be enabled during boot on the kernel command line via the
 137         <varname>systemd.dump_core=</varname> option, see
 138         below.</para></listitem>
 139       </varlistentry>
 140
 141       <varlistentry>
 142         <term><option>--crash-vt=</option><replaceable>VT</replaceable></term>
 143
 144         <listitem><para>Switch to a specific virtual console (VT) on
 145         crash. Takes a positive integer in the range 1–63, or a
 146         boolean argument. If an integer is passed, selects which VT to
 147         switch to. If <constant>yes</constant>, the VT kernel messages
 148         are written to is selected. If <constant>no</constant>, no VT
 149         switch is attempted. This switch has no effect when running as
 150         user instance. This setting may also be enabled during boot,
 151         on the kernel command line via the
 152         <varname>systemd.crash_vt=</varname> option, see
 153         below.</para></listitem>
 154       </varlistentry>
 155
 156       <varlistentry>
 157         <term><option>--crash-shell</option></term>
 158
 159         <listitem><para>Run a shell on crash. This switch has no
 160         effect when running as user instance. This setting may also be
 161         enabled during boot, on the kernel command line via the
 162         <varname>systemd.crash_shell=</varname> option, see
 163         below.</para></listitem>
 164       </varlistentry>
 165
 166       <varlistentry>
 167         <term><option>--crash-reboot</option></term>
 168
 169         <listitem><para>Automatically reboot the system on crash. This
 170         switch has no effect when running as user instance. This
 171         setting may also be enabled during boot, on the kernel command
 172         line via the <varname>systemd.crash_reboot=</varname> option,
 173         see below.</para></listitem>
 174       </varlistentry>
 175
 176       <varlistentry>
 177         <term><option>--confirm-spawn</option></term>
 178
 179         <listitem><para>Ask for confirmation when spawning processes.
 180         This switch 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>Takes a boolean argument or the special value <constant>auto</constant>. If on, terse unit
 187         status information is shown on the console during boot-up and shutdown. If off, no such status information is
 188         shown. If set to <constant>auto</constant> behavior is similar to off, except that it is automatically switched
 189         to on, as soon as the first unit failure or significant boot delay is encountered. This switch has no effect
 190         when invoked as user instance. If specified, overrides both the kernel command line setting
 191         <varname>systemd.show_status=</varname> (see below) and the configuration file option
 192         <option>ShowStatus=</option>, see
 193         <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 194       </varlistentry>
 195       <varlistentry>
 196         <term><option>--log-target=</option></term>
 197
 198         <listitem><para>Set log target. Argument must be one of
 199         <option>console</option>,
 200         <option>journal</option>,
 201         <option>kmsg</option>,
 202         <option>journal-or-kmsg</option>,
 203         <option>null</option>.</para></listitem>
 204       </varlistentry>
 205       <varlistentry>
 206         <term><option>--log-level=</option></term>
 207
 208         <listitem><para>Set log level. As
 209         argument this accepts a numerical log
 210         level or the well-known <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 211         symbolic names (lowercase):
 212         <option>emerg</option>,
 213         <option>alert</option>,
 214         <option>crit</option>,
 215         <option>err</option>,
 216         <option>warning</option>,
 217         <option>notice</option>,
 218         <option>info</option>,
 219         <option>debug</option>.</para></listitem>
 220       </varlistentry>
 221       <varlistentry>
 222         <term><option>--log-color=</option></term>
 223
 224         <listitem><para>Highlight important log messages. Argument is
 225         a boolean value. If the argument is omitted, it defaults to
 226         <option>true</option>.</para></listitem>
 227       </varlistentry>
 228       <varlistentry>
 229         <term><option>--log-location=</option></term>
 230
 231         <listitem><para>Include code location in log messages. This is
 232         mostly relevant for debugging purposes. Argument is a boolean
 233         value. If the argument is omitted it defaults to
 234         <option>true</option>.</para></listitem>
 235       </varlistentry>
 236       <varlistentry>
 237         <term><option>--default-standard-output=</option></term>
 238         <term><option>--default-standard-error=</option></term>
 239
 240         <listitem><para>Sets the default output or error output for
 241         all services and sockets, respectively. That is, controls the
 242         default for <option>StandardOutput=</option> and
 243         <option>StandardError=</option> (see
 244         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 245         for details). Takes one of
 246         <option>inherit</option>,
 247         <option>null</option>,
 248         <option>tty</option>,
 249         <option>journal</option>,
 250         <option>journal+console</option>,
 251         <option>syslog</option>,
 252         <option>syslog+console</option>,
 253         <option>kmsg</option>,
 254         <option>kmsg+console</option>.  If the
 255         argument is omitted
 256         <option>--default-standard-output=</option> defaults to
 257         <option>journal</option> and
 258         <option>--default-standard-error=</option> to
 259         <option>inherit</option>.</para></listitem>
 260       </varlistentry>
 261
 262       <varlistentry>
 263         <term><option>--machine-id=</option></term>
 264
 265         <listitem><para>Override the machine-id set on the hard drive,
 266         useful for network booting or for containers. May not be set
 267         to all zeros.</para></listitem>
 268       </varlistentry>
 269
 270       <xi:include href="standard-options.xml" xpointer="help" />
 271       <xi:include href="standard-options.xml" xpointer="version" />
 272     </variablelist>
 273   </refsect1>
 274
 275   <refsect1>
 276     <title>Concepts</title>
 277
 278     <para>systemd provides a dependency system between various
 279     entities called "units" of 11 different types. Units encapsulate
 280     various objects that are relevant for system boot-up and
 281     maintenance. The majority of units are configured in unit
 282     configuration files, whose syntax and basic set of options is
 283     described in
 284     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 285     however some are created automatically from other configuration,
 286     dynamically from system state or programmatically at runtime.
 287     Units may be "active" (meaning started, bound, plugged in, …,
 288     depending on the unit type, see below), or "inactive" (meaning
 289     stopped, unbound, unplugged, …), as well as in the process of
 290     being activated or deactivated, i.e. between the two states (these
 291     states are called "activating", "deactivating"). A special
 292     "failed" state is available as well, which is very similar to
 293     "inactive" and is entered when the service failed in some way
 294     (process returned error code on exit, or crashed, or an operation
 295     timed out). If this state is entered, the cause will be logged,
 296     for later reference. Note that the various unit types may have a
 297     number of additional substates, which are mapped to the five
 298     generalized unit states described here.</para>
 299
 300     <para>The following unit types are available:</para>
 301
 302     <orderedlist>
 303       <listitem><para>Service units, which start and control daemons
 304       and the processes they consist of. For details, see
 305       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 306
 307       <listitem><para>Socket units, which encapsulate local IPC or
 308       network sockets in the system, useful for socket-based
 309       activation. For details about socket units, see
 310       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 311       for details on socket-based activation and other forms of
 312       activation, see
 313       <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
 314
 315       <listitem><para>Target units are useful to group units, or
 316       provide well-known synchronization points during boot-up, see
 317       <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 318
 319       <listitem><para>Device units expose kernel devices in systemd
 320       and may be used to implement device-based activation. For
 321       details, see
 322       <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 323
 324       <listitem><para>Mount units control mount points in the file
 325       system, for details see
 326       <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 327
 328       <listitem><para>Automount units provide automount capabilities,
 329       for on-demand mounting of file systems as well as parallelized
 330       boot-up. See
 331       <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 332
 333       <listitem><para>Timer units are useful for triggering activation
 334       of other units based on timers. You may find details in
 335       <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 336
 337       <listitem><para>Swap units are very similar to mount units and
 338       encapsulate memory swap partitions or files of the operating
 339       system. They are described in
 340       <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 341
 342       <listitem><para>Path units may be used to activate other
 343       services when file system objects change or are modified. See
 344       <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 345
 346       <listitem><para>Slice units may be used to group units which
 347       manage system processes (such as service and scope units) in a
 348       hierarchical tree for resource management purposes. See
 349       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 350
 351       <listitem><para>Scope units are similar to service units, but
 352       manage foreign processes instead of starting them as well. See
 353       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 354
 355     </orderedlist>
 356
 357     <para>Units are named as their configuration files. Some units
 358     have special semantics. A detailed list is available in
 359     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 360
 361     <para>systemd knows various kinds of dependencies, including
 362     positive and negative requirement dependencies (i.e.
 363     <varname>Requires=</varname> and <varname>Conflicts=</varname>) as
 364     well as ordering dependencies (<varname>After=</varname> and
 365     <varname>Before=</varname>). NB: ordering and requirement
 366     dependencies are orthogonal. If only a requirement dependency
 367     exists between two units (e.g. <filename>foo.service</filename>
 368     requires <filename>bar.service</filename>), but no ordering
 369     dependency (e.g. <filename>foo.service</filename> after
 370     <filename>bar.service</filename>) and both are requested to start,
 371     they will be started in parallel. It is a common pattern that both
 372     requirement and ordering dependencies are placed between two
 373     units. Also note that the majority of dependencies are implicitly
 374     created and maintained by systemd. In most cases, it should be
 375     unnecessary to declare additional dependencies manually, however
 376     it is possible to do this.</para>
 377
 378     <para>Application programs and units (via dependencies) may
 379     request state changes of units. In systemd, these requests are
 380     encapsulated as 'jobs' and maintained in a job queue. Jobs may
 381     succeed or can fail, their execution is ordered based on the
 382     ordering dependencies of the units they have been scheduled
 383     for.</para>
 384
 385     <para>On boot systemd activates the target unit
 386     <filename>default.target</filename> whose job is to activate
 387     on-boot services and other on-boot units by pulling them in via
 388     dependencies. Usually, the unit name is just an alias (symlink) for
 389     either <filename>graphical.target</filename> (for fully-featured
 390     boots into the UI) or <filename>multi-user.target</filename> (for
 391     limited console-only boots for use in embedded or server
 392     environments, or similar; a subset of graphical.target). However,
 393     it is at the discretion of the administrator to configure it as an
 394     alias to any other target unit. See
 395     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 396     for details about these target units.</para>
 397
 398     <para>Processes systemd spawns are placed in individual Linux
 399     control groups named after the unit which they belong to in the
 400     private systemd hierarchy. (see <ulink
 401     url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
 402     for more information about control groups, or short "cgroups").
 403     systemd uses this to effectively keep track of processes. Control
 404     group information is maintained in the kernel, and is accessible
 405     via the file system hierarchy (beneath
 406     <filename>/sys/fs/cgroup/systemd/</filename>), or in tools such as
 407     <citerefentry project='man-pages'><refentrytitle>systemd-cgls</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 408     or
 409     <citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 410     (<command>ps xawf -eo pid,user,cgroup,args</command> is
 411     particularly useful to list all processes and the systemd units
 412     they belong to.).</para>
 413
 414     <para>systemd is compatible with the SysV init system to a large
 415     degree: SysV init scripts are supported and simply read as an
 416     alternative (though limited) configuration file format. The SysV
 417     <filename>/dev/initctl</filename> interface is provided, and
 418     compatibility implementations of the various SysV client tools are
 419     available. In addition to that, various established Unix
 420     functionality such as <filename>/etc/fstab</filename> or the
 421     <filename>utmp</filename> database are supported.</para>
 422
 423     <para>systemd has a minimal transaction system: if a unit is
 424     requested to start up or shut down it will add it and all its
 425     dependencies to a temporary transaction. Then, it will verify if
 426     the transaction is consistent (i.e. whether the ordering of all
 427     units is cycle-free). If it is not, systemd will try to fix it up,
 428     and removes non-essential jobs from the transaction that might
 429     remove the loop. Also, systemd tries to suppress non-essential
 430     jobs in the transaction that would stop a running service. Finally
 431     it is checked whether the jobs of the transaction contradict jobs
 432     that have already been queued, and optionally the transaction is
 433     aborted then. If all worked out and the transaction is consistent
 434     and minimized in its impact it is merged with all already
 435     outstanding jobs and added to the run queue. Effectively this
 436     means that before executing a requested operation, systemd will
 437     verify that it makes sense, fixing it if possible, and only
 438     failing if it really cannot work.</para>
 439
 440     <para>Systemd contains native implementations of various tasks
 441     that need to be executed as part of the boot process. For example,
 442     it sets the hostname or configures the loopback network device. It
 443     also sets up and mounts various API file systems, such as
 444     <filename>/sys</filename> or <filename>/proc</filename>.</para>
 445
 446     <para>For more information about the concepts and
 447     ideas behind systemd, please refer to the
 448     <ulink url="http://0pointer.de/blog/projects/systemd.html">Original Design Document</ulink>.</para>
 449
 450     <para>Note that some but not all interfaces provided
 451     by systemd are covered by the
 452     <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
 453     Stability Promise</ulink>.</para>
 454
 455     <para>Units may be generated dynamically at boot and system
 456     manager reload time, for example based on other configuration
 457     files or parameters passed on the kernel command line. For details, see
 458     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 459
 460     <para>Systems which invoke systemd in a container or initrd
 461     environment should implement the
 462     <ulink url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container Interface</ulink> or
 463     <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InitrdInterface">initrd Interface</ulink>
 464     specifications, respectively.</para>
 465   </refsect1>
 466
 467   <refsect1>
 468     <title>Directories</title>
 469
 470     <variablelist>
 471       <varlistentry>
 472         <term>System unit directories</term>
 473
 474         <listitem><para>The systemd system manager reads unit
 475         configuration from various directories. Packages that want to
 476         install unit files shall place them in the directory returned
 477         by <command>pkg-config systemd
 478         --variable=systemdsystemunitdir</command>. Other directories
 479         checked are <filename>/usr/local/lib/systemd/system</filename>
 480         and <filename>/usr/lib/systemd/system</filename>. User
 481         configuration always takes precedence. <command>pkg-config
 482         systemd --variable=systemdsystemconfdir</command> returns the
 483         path of the system configuration directory. Packages should
 484         alter the content of these directories only with the
 485         <command>enable</command> and <command>disable</command>
 486         commands of the
 487         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 488         tool. Full list of directories is provided in
 489         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 490         </para></listitem>
 491       </varlistentry>
 492     </variablelist>
 493
 494     <variablelist>
 495       <varlistentry>
 496         <term>User unit directories</term>
 497
 498         <listitem><para>Similar rules apply for the user unit
 499         directories. However, here the
 500         <ulink url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 501         Base Directory specification</ulink> is followed to find
 502         units. Applications should place their unit files in the
 503         directory returned by <command>pkg-config systemd
 504         --variable=systemduserunitdir</command>. Global configuration
 505         is done in the directory reported by <command>pkg-config
 506         systemd --variable=systemduserconfdir</command>. The
 507         <command>enable</command> and <command>disable</command>
 508         commands of the
 509         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 510         tool can handle both global (i.e. for all users) and private
 511         (for one user) enabling/disabling of units. Full list of
 512         directories is provided in
 513         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 514         </para></listitem>
 515       </varlistentry>
 516     </variablelist>
 517
 518     <variablelist>
 519       <varlistentry>
 520         <term>SysV init scripts directory</term>
 521
 522         <listitem><para>The location of the SysV init script directory
 523         varies between distributions. If systemd cannot find a native
 524         unit file for a requested service, it will look for a SysV
 525         init script of the same name (with the
 526         <filename>.service</filename> suffix
 527         removed).</para></listitem>
 528       </varlistentry>
 529     </variablelist>
 530
 531     <variablelist>
 532       <varlistentry>
 533         <term>SysV runlevel link farm directory</term>
 534
 535         <listitem><para>The location of the SysV runlevel link farm
 536         directory varies between distributions. systemd will take the
 537         link farm into account when figuring out whether a service
 538         shall be enabled. Note that a service unit with a native unit
 539         configuration file cannot be started by activating it in the
 540         SysV runlevel link farm.</para></listitem>
 541       </varlistentry>
 542     </variablelist>
 543   </refsect1>
 544
 545   <refsect1>
 546     <title>Signals</title>
 547
 548     <variablelist>
 549       <varlistentry>
 550         <term><constant>SIGTERM</constant></term>
 551
 552         <listitem><para>Upon receiving this signal the systemd system
 553         manager serializes its state, reexecutes itself and
 554         deserializes the saved state again. This is mostly equivalent
 555         to <command>systemctl daemon-reexec</command>.</para>
 556
 557         <para>systemd user managers will start the
 558         <filename>exit.target</filename> unit when this signal is
 559         received. This is mostly equivalent to <command>systemctl
 560         --user start exit.target</command>.</para></listitem>
 561       </varlistentry>
 562
 563       <varlistentry>
 564         <term><constant>SIGINT</constant></term>
 565
 566         <listitem><para>Upon receiving this signal the systemd system
 567         manager will start the
 568         <filename>ctrl-alt-del.target</filename> unit. This is mostly
 569         equivalent to <command>systemctl start
 570         ctl-alt-del.target</command>. If this signal is received more
 571         than 7 times per 2s, an immediate reboot is triggered.
 572         Note that pressing Ctrl-Alt-Del on the console will trigger
 573         this signal. Hence, if a reboot is hanging, pressing
 574         Ctrl-Alt-Del more than 7 times in 2s is a relatively safe way
 575         to trigger an immediate reboot.</para>
 576
 577         <para>systemd user managers treat this signal the same way as
 578         <constant>SIGTERM</constant>.</para></listitem>
 579       </varlistentry>
 580
 581       <varlistentry>
 582         <term><constant>SIGWINCH</constant></term>
 583
 584         <listitem><para>When this signal is received the systemd
 585         system manager will start the
 586         <filename>kbrequest.target</filename> unit. This is mostly
 587         equivalent to <command>systemctl start
 588         kbrequest.target</command>.</para>
 589
 590         <para>This signal is ignored by systemd user
 591         managers.</para></listitem>
 592       </varlistentry>
 593
 594       <varlistentry>
 595         <term><constant>SIGPWR</constant></term>
 596
 597         <listitem><para>When this signal is received the systemd
 598         manager will start the <filename>sigpwr.target</filename>
 599         unit. This is mostly equivalent to <command>systemctl start
 600         sigpwr.target</command>.</para></listitem>
 601       </varlistentry>
 602
 603       <varlistentry>
 604         <term><constant>SIGUSR1</constant></term>
 605
 606         <listitem><para>When this signal is received the systemd
 607         manager will try to reconnect to the D-Bus
 608         bus.</para></listitem>
 609       </varlistentry>
 610
 611       <varlistentry>
 612         <term><constant>SIGUSR2</constant></term>
 613
 614         <listitem><para>When this signal is received the systemd
 615         manager will log its complete state in human-readable form.
 616         The data logged is the same as printed by
 617         <command>systemd-analyze dump</command>.</para></listitem>
 618       </varlistentry>
 619
 620       <varlistentry>
 621         <term><constant>SIGHUP</constant></term>
 622
 623         <listitem><para>Reloads the complete daemon configuration.
 624         This is mostly equivalent to <command>systemctl
 625         daemon-reload</command>.</para></listitem>
 626       </varlistentry>
 627
 628       <varlistentry>
 629         <term><constant>SIGRTMIN+0</constant></term>
 630
 631         <listitem><para>Enters default mode, starts the
 632         <filename>default.target</filename> unit. This is mostly
 633         equivalent to <command>systemctl start
 634         default.target</command>.</para></listitem>
 635       </varlistentry>
 636
 637       <varlistentry>
 638         <term><constant>SIGRTMIN+1</constant></term>
 639
 640         <listitem><para>Enters rescue mode, starts the
 641         <filename>rescue.target</filename> unit. This is mostly
 642         equivalent to <command>systemctl isolate
 643         rescue.target</command>.</para></listitem>
 644       </varlistentry>
 645
 646       <varlistentry>
 647         <term><constant>SIGRTMIN+2</constant></term>
 648
 649         <listitem><para>Enters emergency mode, starts the
 650         <filename>emergency.service</filename> unit. This is mostly
 651         equivalent to <command>systemctl isolate
 652         emergency.service</command>.</para></listitem>
 653       </varlistentry>
 654
 655       <varlistentry>
 656         <term><constant>SIGRTMIN+3</constant></term>
 657
 658         <listitem><para>Halts the machine, starts the
 659         <filename>halt.target</filename> unit. This is mostly
 660         equivalent to <command>systemctl start
 661         halt.target</command>.</para></listitem>
 662       </varlistentry>
 663
 664       <varlistentry>
 665         <term><constant>SIGRTMIN+4</constant></term>
 666
 667         <listitem><para>Powers off the machine, starts the
 668         <filename>poweroff.target</filename> unit. This is mostly
 669         equivalent to <command>systemctl start
 670         poweroff.target</command>.</para></listitem>
 671       </varlistentry>
 672
 673       <varlistentry>
 674         <term><constant>SIGRTMIN+5</constant></term>
 675
 676         <listitem><para>Reboots the machine, starts the
 677         <filename>reboot.target</filename> unit. This is mostly
 678         equivalent to <command>systemctl start
 679         reboot.target</command>.</para></listitem>
 680       </varlistentry>
 681
 682       <varlistentry>
 683         <term><constant>SIGRTMIN+6</constant></term>
 684
 685         <listitem><para>Reboots the machine via kexec, starts the
 686         <filename>kexec.target</filename> unit. This is mostly
 687         equivalent to <command>systemctl start
 688         kexec.target</command>.</para></listitem>
 689       </varlistentry>
 690
 691       <varlistentry>
 692         <term><constant>SIGRTMIN+13</constant></term>
 693
 694         <listitem><para>Immediately halts the machine.</para></listitem>
 695       </varlistentry>
 696
 697       <varlistentry>
 698         <term><constant>SIGRTMIN+14</constant></term>
 699
 700         <listitem><para>Immediately powers off the machine.</para></listitem>
 701       </varlistentry>
 702
 703       <varlistentry>
 704         <term><constant>SIGRTMIN+15</constant></term>
 705
 706         <listitem><para>Immediately reboots the machine.</para></listitem>
 707       </varlistentry>
 708
 709       <varlistentry>
 710         <term><constant>SIGRTMIN+16</constant></term>
 711
 712         <listitem><para>Immediately reboots the machine with kexec.</para></listitem>
 713       </varlistentry>
 714
 715       <varlistentry>
 716         <term><constant>SIGRTMIN+20</constant></term>
 717
 718         <listitem><para>Enables display of status messages on the
 719         console, as controlled via
 720         <varname>systemd.show_status=1</varname> on the kernel command
 721         line.</para></listitem>
 722       </varlistentry>
 723
 724       <varlistentry>
 725         <term><constant>SIGRTMIN+21</constant></term>
 726
 727         <listitem><para>Disables display of
 728         status messages on the console, as
 729         controlled via
 730         <varname>systemd.show_status=0</varname>
 731         on the kernel command
 732         line.</para></listitem>
 733       </varlistentry>
 734
 735       <varlistentry>
 736         <term><constant>SIGRTMIN+22</constant></term>
 737         <term><constant>SIGRTMIN+23</constant></term>
 738
 739         <listitem><para>Sets the log level to <literal>debug</literal>
 740         (or <literal>info</literal> on
 741         <constant>SIGRTMIN+23</constant>), as controlled via
 742         <varname>systemd.log_level=debug</varname> (or
 743         <varname>systemd.log_level=info</varname> on
 744         <constant>SIGRTMIN+23</constant>) on the kernel command
 745         line.</para></listitem>
 746       </varlistentry>
 747
 748       <varlistentry>
 749         <term><constant>SIGRTMIN+24</constant></term>
 750
 751         <listitem><para>Immediately exits the manager (only available
 752         for --user instances).</para></listitem>
 753       </varlistentry>
 754
 755       <varlistentry>
 756         <term><constant>SIGRTMIN+26</constant></term>
 757         <term><constant>SIGRTMIN+27</constant></term>
 758         <term><constant>SIGRTMIN+28</constant></term>
 759
 760         <listitem><para>Sets the log level to
 761         <literal>journal-or-kmsg</literal> (or
 762         <literal>console</literal> on
 763         <constant>SIGRTMIN+27</constant>, <literal>kmsg</literal> on
 764         <constant>SIGRTMIN+28</constant>), as controlled via
 765         <varname>systemd.log_target=journal-or-kmsg</varname> (or
 766         <varname>systemd.log_target=console</varname> on
 767         <constant>SIGRTMIN+27</constant> or
 768         <varname>systemd.log_target=kmsg</varname> on
 769         <constant>SIGRTMIN+28</constant>) on the kernel command
 770         line.</para></listitem>
 771       </varlistentry>
 772     </variablelist>
 773   </refsect1>
 774
 775   <refsect1>
 776     <title>Environment</title>
 777
 778     <variablelist class='environment-variables'>
 779       <varlistentry>
 780         <term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
 781         <listitem><para>systemd reads the log level from this
 782         environment variable. This can be overridden with
 783         <option>--log-level=</option>.</para></listitem>
 784       </varlistentry>
 785
 786       <varlistentry>
 787         <term><varname>$SYSTEMD_LOG_TARGET</varname></term>
 788         <listitem><para>systemd reads the log target from this
 789         environment variable. This can be overridden with
 790         <option>--log-target=</option>.</para></listitem>
 791       </varlistentry>
 792
 793       <varlistentry>
 794         <term><varname>$SYSTEMD_LOG_COLOR</varname></term>
 795         <listitem><para>Controls whether systemd highlights important
 796         log messages. This can be overridden with
 797         <option>--log-color=</option>.</para></listitem>
 798       </varlistentry>
 799
 800       <varlistentry>
 801         <term><varname>$SYSTEMD_LOG_LOCATION</varname></term>
 802         <listitem><para>Controls whether systemd prints the code
 803         location along with log messages. This can be overridden with
 804         <option>--log-location=</option>.</para></listitem>
 805       </varlistentry>
 806
 807       <varlistentry>
 808         <term><varname>$XDG_CONFIG_HOME</varname></term>
 809         <term><varname>$XDG_CONFIG_DIRS</varname></term>
 810         <term><varname>$XDG_DATA_HOME</varname></term>
 811         <term><varname>$XDG_DATA_DIRS</varname></term>
 812
 813         <listitem><para>The systemd user manager uses these variables
 814         in accordance to the <ulink
 815         url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 816         Base Directory specification</ulink> to find its
 817         configuration.</para></listitem>
 818       </varlistentry>
 819
 820       <varlistentry>
 821         <term><varname>$SYSTEMD_UNIT_PATH</varname></term>
 822
 823         <listitem><para>Controls where systemd looks for unit
 824         files.</para></listitem>
 825       </varlistentry>
 826
 827       <varlistentry>
 828         <term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term>
 829
 830         <listitem><para>Controls where systemd looks for SysV init
 831         scripts.</para></listitem>
 832       </varlistentry>
 833
 834       <varlistentry>
 835         <term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term>
 836
 837         <listitem><para>Controls where systemd looks for SysV init
 838         script runlevel link farms.</para></listitem>
 839       </varlistentry>
 840
 841       <varlistentry>
 842         <term><varname>$SYSTEMD_COLORS</varname></term>
 843
 844         <listitem><para>The value must be a boolean. Controls whether colorized output should be
 845         generated. This can be specified to override the decision that <command>systemd</command>
 846         makes based on <varname>$TERM</varname> and what the console is connected to.</para>
 847         </listitem>
 848       </varlistentry>
 849
 850       <varlistentry>
 851         <term><varname>$LISTEN_PID</varname></term>
 852         <term><varname>$LISTEN_FDS</varname></term>
 853         <term><varname>$LISTEN_FDNAMES</varname></term>
 854
 855         <listitem><para>Set by systemd for supervised processes during
 856         socket-based activation. See
 857         <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 858         for more information.</para></listitem>
 859       </varlistentry>
 860
 861       <varlistentry>
 862         <term><varname>$NOTIFY_SOCKET</varname></term>
 863
 864         <listitem><para>Set by systemd for supervised processes for
 865         status and start-up completion notification. See
 866         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 867         for more information.</para></listitem>
 868       </varlistentry>
 869     </variablelist>
 870   </refsect1>
 871
 872   <refsect1>
 873     <title>Kernel Command Line</title>
 874
 875     <para>When run as system instance systemd parses a number of
 876     kernel command line arguments<footnote><para>If run inside a Linux
 877     container these arguments may be passed as command line arguments
 878     to systemd itself, next to any of the command line options listed
 879     in the Options section above. If run outside of Linux containers,
 880     these arguments are parsed from <filename>/proc/cmdline</filename>
 881     instead.</para></footnote>:</para>
 882
 883     <variablelist class='kernel-commandline-options'>
 884       <varlistentry>
 885         <term><varname>systemd.unit=</varname></term>
 886         <term><varname>rd.systemd.unit=</varname></term>
 887
 888         <listitem><para>Overrides the unit to activate on boot.
 889         Defaults to <filename>default.target</filename>. This may be
 890         used to temporarily boot into a different boot unit, for
 891         example <filename>rescue.target</filename> or
 892         <filename>emergency.service</filename>. See
 893         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 894         for details about these units. The option prefixed with
 895         <literal>rd.</literal> is honored only in the initial RAM disk
 896         (initrd), while the one that is not prefixed only in the main
 897         system.</para></listitem>
 898       </varlistentry>
 899
 900       <varlistentry>
 901         <term><varname>systemd.dump_core=</varname></term>
 902
 903         <listitem><para>Takes a boolean argument. If
 904         <option>yes</option>, the systemd manager (PID 1) dumps core
 905         when it crashes.  Otherwise, no core dump is created. Defaults
 906         to <option>yes</option>.</para></listitem>
 907       </varlistentry>
 908
 909       <varlistentry>
 910         <term><varname>systemd.crash_chvt=</varname></term>
 911
 912         <listitem><para>Takes a positive integer, or a boolean
 913         argument. If a positive integer (in the range 1–63) is
 914         specified, the system manager (PID 1) will activate the specified
 915         virtual terminal (VT) when it crashes. Defaults to
 916         <constant>no</constant>, meaning that no such switch is
 917         attempted. If set to <constant>yes</constant>, the VT the
 918         kernel messages are written to is selected.</para></listitem>
 919       </varlistentry>
 920
 921       <varlistentry>
 922         <term><varname>systemd.crash_shell=</varname></term>
 923
 924         <listitem><para>Takes a boolean argument. If
 925         <option>yes</option>, the system manager (PID 1) spawns a
 926         shell when it crashes, after a 10s delay. Otherwise, no shell
 927         is spawned. Defaults to <option>no</option>, for security
 928         reasons, as the shell is not protected by password
 929         authentication.</para></listitem>
 930       </varlistentry>
 931
 932       <varlistentry>
 933         <term><varname>systemd.crash_reboot=</varname></term>
 934
 935         <listitem><para>Takes a boolean argument. If
 936         <option>yes</option>, the system manager (PID 1) will reboot
 937         the machine automatically when it crashes, after a 10s delay.
 938         Otherwise, the system will hang indefinitely. Defaults to
 939         <option>no</option>, in order to avoid a reboot loop. If
 940         combined with <varname>systemd.crash_shell=</varname>, the
 941         system is rebooted after the shell exits.</para></listitem>
 942       </varlistentry>
 943
 944       <varlistentry>
 945         <term><varname>systemd.confirm_spawn=</varname></term>
 946
 947         <listitem><para>Takes a boolean argument or a path to the
 948         virtual console where the confirmation messages should be
 949         emitted. If <option>yes</option>, the system manager (PID 1)
 950         asks for confirmation when spawning processes using
 951         <option>/dev/console</option>. If a path or a console name
 952         (such as <literal>ttyS0</literal>) is provided, the virtual
 953         console pointed to by this path or described by the give name
 954         will be used instead. Defaults to <option>no</option>.</para></listitem>
 955       </varlistentry>
 956
 957       <varlistentry>
 958         <term><varname>systemd.show_status=</varname></term>
 959
 960         <listitem><para>Takes a boolean argument or the constant <constant>auto</constant>. If <option>yes</option>,
 961         the systemd manager (PID 1) shows terse service status updates on the console during bootup.
 962         <constant>auto</constant> behaves like <option>false</option> until a unit fails or there is a significant
 963         delay in boot.  Defaults to <option>yes</option>, unless <option>quiet</option> is passed as kernel command
 964         line option, in which case it defaults to <constant>auto</constant>. If specified overrides the system manager
 965         configuration file option <option>ShowStatus=</option>, see
 966         <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. However,
 967         the process command line option <option>--show-status=</option> takes precedence over both this kernel command
 968         line option and the configuration file option.</para></listitem>
 969       </varlistentry>
 970
 971       <varlistentry>
 972         <term><varname>systemd.log_target=</varname></term>
 973         <term><varname>systemd.log_level=</varname></term>
 974         <term><varname>systemd.log_color=</varname></term>
 975         <term><varname>systemd.log_location=</varname></term>
 976
 977         <listitem><para>Controls log output, with the same effect as
 978         the <varname>$SYSTEMD_LOG_TARGET</varname>,
 979         <varname>$SYSTEMD_LOG_LEVEL</varname>,
 980         <varname>$SYSTEMD_LOG_COLOR</varname>,
 981         <varname>$SYSTEMD_LOG_LOCATION</varname> environment variables
 982         described above.</para></listitem>
 983       </varlistentry>
 984
 985       <varlistentry>
 986         <term><varname>systemd.default_standard_output=</varname></term>
 987         <term><varname>systemd.default_standard_error=</varname></term>
 988         <listitem><para>Controls default standard output and error
 989         output for services, with the same effect as the
 990         <option>--default-standard-output=</option> and
 991         <option>--default-standard-error=</option> command line
 992         arguments described above, respectively.</para></listitem>
 993       </varlistentry>
 994
 995       <varlistentry>
 996         <term><varname>systemd.setenv=</varname></term>
 997
 998         <listitem><para>Takes a string argument in the form
 999         VARIABLE=VALUE. May be used to set default environment
1000         variables to add to forked child processes. May be used more
1001         than once to set multiple variables.</para></listitem>
1002       </varlistentry>
1003
1004       <varlistentry>
1005         <term><varname>systemd.machine_id=</varname></term>
1006
1007         <listitem><para>Takes a 32 character hex value to be
1008         used for setting the machine-id. Intended mostly for
1009         network booting where the same machine-id is desired
1010         for every boot.</para></listitem>
1011       </varlistentry>
1012
1013       <varlistentry>
1014         <term><varname>quiet</varname></term>
1015
1016         <listitem><para>Turn off status output at boot, much like
1017         <varname>systemd.show_status=false</varname> would. Note that
1018         this option is also read by the kernel itself and disables
1019         kernel log output. Passing this option hence turns off the
1020         usual output from both the system manager and the kernel.
1021         </para></listitem>
1022       </varlistentry>
1023
1024       <varlistentry>
1025         <term><varname>debug</varname></term>
1026
1027         <listitem><para>Turn on debugging output. This is equivalent
1028         to <varname>systemd.log_level=debug</varname>. Note that this
1029         option is also read by the kernel itself and enables kernel
1030         debug output. Passing this option hence turns on the debug
1031         output from both the system manager and the
1032         kernel.</para></listitem>
1033       </varlistentry>
1034
1035       <varlistentry>
1036         <term><varname>emergency</varname></term>
1037         <term><varname>rd.emergency</varname></term>
1038         <term><varname>-b</varname></term>
1039
1040         <listitem><para>Boot into emergency mode. This is equivalent
1041         to <varname>systemd.unit=emergency.target</varname> or
1042         <varname>rd.systemd.unit=emergency.target</varname>, respectively, and
1043         provided for compatibility reasons and to be easier to type.</para></listitem>
1044       </varlistentry>
1045
1046       <varlistentry>
1047         <term><varname>rescue</varname></term>
1048         <term><varname>rd.rescue</varname></term>
1049         <term><varname>single</varname></term>
1050         <term><varname>s</varname></term>
1051         <term><varname>S</varname></term>
1052         <term><varname>1</varname></term>
1053
1054         <listitem><para>Boot into rescue mode. This is equivalent to
1055         <varname>systemd.unit=rescue.target</varname> or
1056         <varname>rd.systemd.unit=rescue.target</varname>, respectively, and
1057         provided for compatibility reasons and to be easier to type.</para></listitem>
1058       </varlistentry>
1059
1060       <varlistentry>
1061         <term><varname>2</varname></term>
1062         <term><varname>3</varname></term>
1063         <term><varname>4</varname></term>
1064         <term><varname>5</varname></term>
1065
1066         <listitem><para>Boot into the specified legacy SysV runlevel.
1067         These are equivalent to
1068         <varname>systemd.unit=runlevel2.target</varname>,
1069         <varname>systemd.unit=runlevel3.target</varname>,
1070         <varname>systemd.unit=runlevel4.target</varname>, and
1071         <varname>systemd.unit=runlevel5.target</varname>,
1072         respectively, and provided for compatibility reasons and to be
1073         easier to type.</para></listitem>
1074       </varlistentry>
1075
1076       <varlistentry>
1077         <term><varname>locale.LANG=</varname></term>
1078         <term><varname>locale.LANGUAGE=</varname></term>
1079         <term><varname>locale.LC_CTYPE=</varname></term>
1080         <term><varname>locale.LC_NUMERIC=</varname></term>
1081         <term><varname>locale.LC_TIME=</varname></term>
1082         <term><varname>locale.LC_COLLATE=</varname></term>
1083         <term><varname>locale.LC_MONETARY=</varname></term>
1084         <term><varname>locale.LC_MESSAGES=</varname></term>
1085         <term><varname>locale.LC_PAPER=</varname></term>
1086         <term><varname>locale.LC_NAME=</varname></term>
1087         <term><varname>locale.LC_ADDRESS=</varname></term>
1088         <term><varname>locale.LC_TELEPHONE=</varname></term>
1089         <term><varname>locale.LC_MEASUREMENT=</varname></term>
1090         <term><varname>locale.LC_IDENTIFICATION=</varname></term>
1091
1092         <listitem><para>Set the system locale to use. This overrides
1093         the settings in <filename>/etc/locale.conf</filename>. For
1094         more information, see
1095         <citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1096         and
1097         <citerefentry project='man-pages'><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
1098         </para></listitem>
1099       </varlistentry>
1100     </variablelist>
1101
1102     <para>For other kernel command line parameters understood by
1103     components of the core OS, please refer to
1104     <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
1105   </refsect1>
1106
1107   <refsect1>
1108     <title>Sockets and FIFOs</title>
1109
1110     <variablelist>
1111       <varlistentry>
1112         <term><filename>/run/systemd/notify</filename></term>
1113
1114         <listitem><para>Daemon status notification socket. This is an
1115         <constant>AF_UNIX</constant> datagram socket and is used to
1116         implement the daemon notification logic as implemented by
1117         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
1118
1119       </varlistentry>
1120
1121       <varlistentry>
1122         <term><filename>/run/systemd/private</filename></term>
1123
1124         <listitem><para>Used internally as communication channel
1125         between
1126         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1127         and the systemd process. This is an
1128         <constant>AF_UNIX</constant> stream socket. This interface is
1129         private to systemd and should not be used in external
1130         projects.</para></listitem>
1131       </varlistentry>
1132
1133       <varlistentry>
1134         <term><filename>/dev/initctl</filename></term>
1135
1136         <listitem><para>Limited compatibility support for the SysV
1137         client interface, as implemented by the
1138         <filename>systemd-initctl.service</filename> unit. This is a
1139         named pipe in the file system. This interface is obsolete and
1140         should not be used in new applications.</para></listitem>
1141       </varlistentry>
1142     </variablelist>
1143   </refsect1>
1144
1145   <refsect1>
1146     <title>See Also</title>
1147     <para>
1148       The <ulink url="http://www.freedesktop.org/wiki/Software/systemd/">systemd Homepage</ulink>,
1149       <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1150       <citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1151       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1152       <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1153       <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1154       <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1155       <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
1156       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1157       <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1158       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1159       <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1160       <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1161       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1162     </para>
1163   </refsect1>
1164
1165 </refentry>