man/sd_notify.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   5
   6 <refentry id="sd_notify"
   7   xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>sd_notify</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>sd_notify</refentrytitle>
  16     <manvolnum>3</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>sd_notify</refname>
  21     <refname>sd_notifyf</refname>
  22     <refname>sd_pid_notify</refname>
  23     <refname>sd_pid_notifyf</refname>
  24     <refname>sd_pid_notify_with_fds</refname>
  25     <refname>sd_notify_barrier</refname>
  26     <refpurpose>Notify service manager about start-up completion and other service status changes</refpurpose>
  27   </refnamediv>
  28
  29   <refsynopsisdiv>
  30     <funcsynopsis>
  31       <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  32
  33       <funcprototype>
  34         <funcdef>int <function>sd_notify</function></funcdef>
  35         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  36         <paramdef>const char *<parameter>state</parameter></paramdef>
  37       </funcprototype>
  38
  39       <funcprototype>
  40         <funcdef>int <function>sd_notifyf</function></funcdef>
  41         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  42         <paramdef>const char *<parameter>format</parameter></paramdef>
  43         <paramdef>…</paramdef>
  44       </funcprototype>
  45
  46       <funcprototype>
  47         <funcdef>int <function>sd_pid_notify</function></funcdef>
  48         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  49         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  50         <paramdef>const char *<parameter>state</parameter></paramdef>
  51       </funcprototype>
  52
  53       <funcprototype>
  54         <funcdef>int <function>sd_pid_notifyf</function></funcdef>
  55         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  56         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  57         <paramdef>const char *<parameter>format</parameter></paramdef>
  58         <paramdef>…</paramdef>
  59       </funcprototype>
  60
  61       <funcprototype>
  62         <funcdef>int <function>sd_pid_notify_with_fds</function></funcdef>
  63         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  64         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  65         <paramdef>const char *<parameter>state</parameter></paramdef>
  66         <paramdef>const int *<parameter>fds</parameter></paramdef>
  67         <paramdef>unsigned <parameter>n_fds</parameter></paramdef>
  68       </funcprototype>
  69
  70       <funcprototype>
  71         <funcdef>int <function>sd_notify_barrier</function></funcdef>
  72         <paramdef>int <parameter>unset_environment</parameter></paramdef>
  73         <paramdef>uint64_t <parameter>timeout</parameter></paramdef>
  74       </funcprototype>
  75     </funcsynopsis>
  76   </refsynopsisdiv>
  77
  78   <refsect1>
  79     <title>Description</title>
  80     <para><function>sd_notify()</function> may be called by a service
  81     to notify the service manager about state changes. It can be used
  82     to send arbitrary information, encoded in an
  83     environment-block-like string. Most importantly, it can be used for
  84     start-up completion notification.</para>
  85
  86     <para>If the <parameter>unset_environment</parameter> parameter is
  87     non-zero, <function>sd_notify()</function> will unset the
  88     <varname>$NOTIFY_SOCKET</varname> environment variable before
  89     returning (regardless of whether the function call itself
  90     succeeded or not). Further calls to
  91     <function>sd_notify()</function> will then fail, but the variable
  92     is no longer inherited by child processes.</para>
  93
  94     <para>The <parameter>state</parameter> parameter should contain a
  95     newline-separated list of variable assignments, similar in style
  96     to an environment block. A trailing newline is implied if none is
  97     specified. The string may contain any kind of variable
  98     assignments, but the following shall be considered
  99     well-known:</para>
 100
 101     <variablelist>
 102       <varlistentry>
 103         <term>READY=1</term>
 104
 105         <listitem><para>Tells the service manager that service startup is finished, or the service finished
 106         re-loading its configuration. This is only used by systemd if the service definition file has
 107         <varname>Type=notify</varname> or <varname>Type=notify-reload</varname> set. Since there is little
 108         value in signaling non-readiness, the only value services should send is <literal>READY=1</literal>
 109         (i.e.  <literal>READY=0</literal> is not defined).</para></listitem>
 110       </varlistentry>
 111
 112       <varlistentry>
 113         <term>RELOADING=1</term>
 114
 115         <listitem><para>Tells the service manager that the service is beginning to reload its
 116         configuration. This is useful to allow the service manager to track the service's internal state, and
 117         present it to the user. Note that a service that sends this notification must also send a
 118         <literal>READY=1</literal> notification when it completed reloading its configuration. Reloads the
 119         service manager is notified about with this mechanisms are propagated in the same way as they are
 120         when originally initiated through the service manager. This message is particularly relevant for
 121         <varname>Type=notify-reload</varname> services, to inform the service manager that the request to
 122         reload the service has been received and is now being processed.</para></listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term>MONOTONIC_USEC=…</term>
 127
 128         <listitem><para>A field carrying the monotonic timestamp (as per
 129         <constant>CLOCK_MONOTONIC</constant>) formatted in decimal in µs, when the notification message was
 130         generated by the client. This is typically used in combination with <literal>RELOADING=1</literal>,
 131         to allow the service manager to properly synchronize reload cycles. See
 132         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 133         for details, specifically <literal>Type=notify-reload</literal>.</para></listitem>
 134       </varlistentry>
 135
 136       <varlistentry>
 137         <term>STOPPING=1</term>
 138
 139         <listitem><para>Tells the service manager that the service is
 140         beginning its shutdown. This is useful to allow the service
 141         manager to track the service's internal state, and present it
 142         to the user.</para></listitem>
 143       </varlistentry>
 144
 145       <varlistentry>
 146         <term>STATUS=…</term>
 147
 148         <listitem><para>Passes a single-line UTF-8 status string back
 149         to the service manager that describes the service state. This
 150         is free-form and can be used for various purposes: general
 151         state feedback, fsck-like programs could pass completion
 152         percentages and failing programs could pass a human-readable
 153         error message. Example: <literal>STATUS=Completed 66% of file
 154         system check…</literal></para></listitem>
 155       </varlistentry>
 156
 157       <varlistentry>
 158         <term>ERRNO=…</term>
 159
 160         <listitem><para>If a service fails, the errno-style error
 161         code, formatted as string. Example: <literal>ERRNO=2</literal>
 162         for ENOENT.</para></listitem>
 163       </varlistentry>
 164
 165       <varlistentry>
 166         <term>BUSERROR=…</term>
 167
 168         <listitem><para>If a service fails, the D-Bus error-style
 169         error code. Example:
 170         <literal>BUSERROR=org.freedesktop.DBus.Error.TimedOut</literal></para></listitem>
 171       </varlistentry>
 172
 173       <varlistentry>
 174         <term>MAINPID=…</term>
 175
 176         <listitem><para>The main process ID (PID) of the service, in
 177         case the service manager did not fork off the process itself.
 178         Example: <literal>MAINPID=4711</literal></para></listitem>
 179       </varlistentry>
 180
 181       <varlistentry>
 182         <term>WATCHDOG=1</term>
 183
 184         <listitem><para>Tells the service manager to update the
 185         watchdog timestamp. This is the keep-alive ping that services
 186         need to issue in regular intervals if
 187         <varname>WatchdogSec=</varname> is enabled for it. See
 188         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 189         for information how to enable this functionality and
 190         <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 191         for the details of how the service can check whether the
 192         watchdog is enabled. </para></listitem>
 193       </varlistentry>
 194
 195       <varlistentry>
 196         <term>WATCHDOG=trigger</term>
 197
 198         <listitem><para>Tells the service manager that the service detected an internal error that should be handled by
 199         the configured watchdog options. This will trigger the same behaviour as if <varname>WatchdogSec=</varname> is
 200         enabled and the service did not send <literal>WATCHDOG=1</literal> in time. Note that
 201         <varname>WatchdogSec=</varname> does not need to be enabled for <literal>WATCHDOG=trigger</literal> to trigger
 202         the watchdog action. See
 203         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 204         information about the watchdog behavior. </para></listitem>
 205       </varlistentry>
 206
 207       <varlistentry>
 208         <term>WATCHDOG_USEC=…</term>
 209
 210         <listitem><para>Reset <varname>watchdog_usec</varname> value during runtime.
 211         Notice that this is not available when using <function>sd_event_set_watchdog()</function>
 212         or <function>sd_watchdog_enabled()</function>.
 213         Example : <literal>WATCHDOG_USEC=20000000</literal></para></listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term>EXTEND_TIMEOUT_USEC=…</term>
 218
 219         <listitem><para>Tells the service manager to extend the startup, runtime or shutdown service timeout
 220         corresponding the current state. The value specified is a time in microseconds during which the service must
 221         send a new message. A service timeout will occur if the message isn't received, but only if the runtime of the
 222         current state is beyond the original maximum times of <varname>TimeoutStartSec=</varname>, <varname>RuntimeMaxSec=</varname>,
 223         and <varname>TimeoutStopSec=</varname>.
 224         See <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 225         for effects on the service timeouts.</para></listitem>
 226       </varlistentry>
 227
 228       <varlistentry>
 229         <term>FDSTORE=1</term>
 230
 231         <listitem><para>Stores additional file descriptors in the service manager. File descriptors sent this way will
 232         be maintained per-service by the service manager and will later be handed back using the usual file descriptor
 233         passing logic at the next invocation of the service (e.g. when it is restarted), see
 234         <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.  This is
 235         useful for implementing services that can restart after an explicit request or a crash without losing
 236         state. Any open sockets and other file descriptors which should not be closed during the restart may be stored
 237         this way. Application state can either be serialized to a file in <filename>/run/</filename>, or better, stored
 238         in a <citerefentry><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry> memory
 239         file descriptor. Note that the service manager will accept messages for a service only if its
 240         <varname>FileDescriptorStoreMax=</varname> setting is non-zero (defaults to zero, see
 241         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
 242         <varname>FDPOLL=0</varname> is not set and the file descriptors sent are pollable (see
 243         <citerefentry><refentrytitle>epoll_ctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>), then any
 244         <constant>EPOLLHUP</constant> or <constant>EPOLLERR</constant> event seen on them will result in their
 245         automatic removal from the store. Multiple arrays of file descriptors may be sent in separate messages, in
 246         which case the arrays are combined. Note that the service manager removes duplicate (pointing to the same
 247         object) file descriptors before passing them to the service. When a service is stopped, its file descriptor
 248         store is discarded and all file descriptors in it are closed. Use <function>sd_pid_notify_with_fds()</function>
 249         to send messages with <literal>FDSTORE=1</literal>, see below.</para></listitem>
 250       </varlistentry>
 251
 252       <varlistentry>
 253         <term>FDSTOREREMOVE=1</term>
 254
 255         <listitem><para>Removes file descriptors from the file descriptor store. This field needs to be combined with
 256         <varname>FDNAME=</varname> to specify the name of the file descriptors to remove.</para></listitem>
 257       </varlistentry>
 258
 259       <varlistentry>
 260         <term>FDNAME=…</term>
 261
 262         <listitem><para>When used in combination with <varname>FDSTORE=1</varname>, specifies a name for the submitted
 263         file descriptors. When used with <varname>FDSTOREREMOVE=1</varname>, specifies the name for the file
 264         descriptors to remove. This name is passed to the service during activation, and may be queried using
 265         <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>. File
 266         descriptors submitted without this field set, will implicitly get the name <literal>stored</literal>
 267         assigned. Note that, if multiple file descriptors are submitted at once, the specified name will be assigned to
 268         all of them. In order to assign different names to submitted file descriptors, submit them in separate
 269         invocations of <function>sd_pid_notify_with_fds()</function>. The name may consist of arbitrary ASCII
 270         characters except control characters or <literal>:</literal>. It may not be longer than 255 characters. If a
 271         submitted name does not follow these restrictions, it is ignored.</para></listitem>
 272       </varlistentry>
 273
 274       <varlistentry>
 275         <term>FDPOLL=0</term>
 276
 277         <listitem><para>When used in combination with <varname>FDSTORE=1</varname>, disables polling of the stored
 278         file descriptors regardless of whether or not they are pollable. As this option disables automatic cleanup
 279         of the stored file descriptors on EPOLLERR and EPOLLHUP, care must be taken to ensure proper manual cleanup.
 280         Use of this option is not generally recommended except for when automatic cleanup has unwanted behavior such
 281         as prematurely discarding file descriptors from the store.</para></listitem>
 282       </varlistentry>
 283
 284       <varlistentry>
 285         <term>BARRIER=1</term>
 286
 287         <listitem><para>Tells the service manager that the client is explicitly requesting synchronization by
 288         means of closing the file descriptor sent with this command. The service manager guarantees that the
 289         processing of a <varname>BARRIER=1</varname> command will only happen after all previous notification
 290         messages sent before this command have been processed. Hence, this command accompanied with a single
 291         file descriptor can be used to synchronize against reception of all previous status messages. Note
 292         that this command cannot be mixed with other notifications, and has to be sent in a separate message
 293         to the service manager, otherwise all assignments will be ignored. Note that sending 0 or more than 1
 294         file descriptor with this command is a violation of the protocol.</para></listitem>
 295       </varlistentry>
 296     </variablelist>
 297
 298     <para>It is recommended to prefix variable names that are not
 299     listed above with <varname>X_</varname> to avoid namespace
 300     clashes.</para>
 301
 302     <para>Note that systemd will accept status data sent from a
 303     service only if the <varname>NotifyAccess=</varname> option is
 304     correctly set in the service definition file. See
 305     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 306     for details.</para>
 307
 308     <para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only if either
 309     the sending process is still around at the time PID 1 processes the message, or if the sending process is
 310     explicitly runtime-tracked by the service manager. The latter is the case if the service manager originally forked
 311     off the process, i.e. on all processes that match <varname>NotifyAccess=</varname><option>main</option> or
 312     <varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit sends an
 313     <function>sd_notify()</function> message and immediately exits, the service manager might not be able to properly
 314     attribute the message to the unit, and thus will ignore it, even if
 315     <varname>NotifyAccess=</varname><option>all</option> is set for it.</para>
 316
 317     <para>Hence, to eliminate all race conditions involving lookup of the client's unit and attribution of notifications
 318     to units correctly, <function>sd_notify_barrier()</function> may be used. This call acts as a synchronization point
 319     and ensures all notifications sent before this call have been picked up by the service manager when it returns
 320     successfully. Use of <function>sd_notify_barrier()</function> is needed for clients which are not invoked by the
 321     service manager, otherwise this synchronization mechanism is unnecessary for attribution of notifications to the
 322     unit.</para>
 323
 324     <para><function>sd_notifyf()</function> is similar to
 325     <function>sd_notify()</function> but takes a
 326     <function>printf()</function>-like format string plus
 327     arguments.</para>
 328
 329     <para><function>sd_pid_notify()</function> and
 330     <function>sd_pid_notifyf()</function> are similar to
 331     <function>sd_notify()</function> and
 332     <function>sd_notifyf()</function> but take a process ID (PID) to
 333     use as originating PID for the message as first argument. This is
 334     useful to send notification messages on behalf of other processes,
 335     provided the appropriate privileges are available. If the PID
 336     argument is specified as 0, the process ID of the calling process
 337     is used, in which case the calls are fully equivalent to
 338     <function>sd_notify()</function> and
 339     <function>sd_notifyf()</function>.</para>
 340
 341     <para><function>sd_pid_notify_with_fds()</function> is similar to
 342     <function>sd_pid_notify()</function> but takes an additional array
 343     of file descriptors. These file descriptors are sent along the
 344     notification message to the service manager. This is particularly
 345     useful for sending <literal>FDSTORE=1</literal> messages, as
 346     described above. The additional arguments are a pointer to the
 347     file descriptor array plus the number of file descriptors in the
 348     array. If the number of file descriptors is passed as 0, the call
 349     is fully equivalent to <function>sd_pid_notify()</function>, i.e.
 350     no file descriptors are passed. Note that sending file descriptors
 351     to the service manager on messages that do not expect them (i.e.
 352     without <literal>FDSTORE=1</literal>) they are immediately closed
 353     on reception.</para>
 354
 355     <para><function>sd_notify_barrier()</function> allows the caller to
 356     synchronize against reception of previously sent notification messages
 357     and uses the <varname>BARRIER=1</varname> command. It takes a relative
 358     <varname>timeout</varname> value in microseconds which is passed to
 359     <citerefentry><refentrytitle>ppoll</refentrytitle><manvolnum>2</manvolnum>
 360     </citerefentry>. A value of UINT64_MAX is interpreted as infinite timeout.
 361     </para>
 362   </refsect1>
 363
 364   <refsect1>
 365     <title>Return Value</title>
 366
 367     <para>On failure, these calls return a negative errno-style error code. If <varname>$NOTIFY_SOCKET</varname> was
 368     not set and hence no status message could be sent, 0 is returned. If the status was sent, these functions return a
 369     positive value. In order to support both service managers that implement this scheme and those which do not, it is
 370     generally recommended to ignore the return value of this call. Note that the return value simply indicates whether
 371     the notification message was enqueued properly, it does not reflect whether the message could be processed
 372     successfully. Specifically, no error is returned when a file descriptor is attempted to be stored using
 373     <varname>FDSTORE=1</varname> but the service is not actually configured to permit storing of file descriptors (see
 374     above).</para>
 375   </refsect1>
 376
 377   <refsect1>
 378     <title>Notes</title>
 379
 380     <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 381
 382     <para>These functions send a single datagram with the
 383     state string as payload to the socket referenced in the
 384     <varname>$NOTIFY_SOCKET</varname> environment variable. If the
 385     first character of <varname>$NOTIFY_SOCKET</varname> is
 386     <literal>/</literal> or <literal>@</literal>, the string is understood
 387     as an <constant>AF_UNIX</constant> or Linux abstract namespace socket
 388     (respectively), and in both cases the datagram is accompanied by the
 389     process credentials of the sending service, using SCM_CREDENTIALS. If
 390     the string starts with <literal>vsock:</literal> then the string is
 391     understood as an <constant>AF_VSOCK</constant> address, which is useful
 392     for hypervisors/VMMs or other processes on the host to receive a
 393     notification when a virtual machine has finished booting. Note that in
 394     case the hypervisor does not support <constant>SOCK_DGRAM</constant>
 395     over <constant>AF_VSOCK</constant>, <constant>SOCK_SEQPACKET</constant>
 396     will be used instead. The address should be in the form:
 397     <literal>vsock:CID:PORT</literal>. Note that unlike other uses of vsock,
 398     the CID is mandatory and cannot be <literal>VMADDR_CID_ANY</literal>.
 399     Note that PID1 will send the VSOCK packets from a privileged port
 400     (i.e.: lower than 1024), as an attempt to address concerns that unprivileged
 401     processes in the guest might try to send malicious notifications to the
 402     host, driving it to make destructive decisions based on them.</para>
 403   </refsect1>
 404
 405   <refsect1>
 406     <title>Environment</title>
 407
 408     <variablelist class='environment-variables'>
 409       <varlistentry>
 410         <term><varname>$NOTIFY_SOCKET</varname></term>
 411
 412         <listitem><para>Set by the service manager for supervised
 413         processes for status and start-up completion notification.
 414         This environment variable specifies the socket
 415         <function>sd_notify()</function> talks to. See above for
 416         details.</para></listitem>
 417       </varlistentry>
 418     </variablelist>
 419   </refsect1>
 420
 421   <refsect1>
 422     <title>Examples</title>
 423
 424     <example>
 425       <title>Start-up Notification</title>
 426
 427       <para>When a service finished starting up, it might issue the
 428       following call to notify the service manager:</para>
 429
 430       <programlisting>sd_notify(0, "READY=1");</programlisting>
 431     </example>
 432
 433     <example>
 434       <title>Extended Start-up Notification</title>
 435
 436       <para>A service could send the following after completing
 437       initialization:</para>
 438
 439       <programlisting>
 440 sd_notifyf(0, "READY=1\n"
 441            "STATUS=Processing requests…\n"
 442            "MAINPID=%lu",
 443            (unsigned long) getpid());</programlisting>
 444     </example>
 445
 446     <example>
 447       <title>Error Cause Notification</title>
 448
 449       <para>A service could send the following shortly before exiting, on failure:</para>
 450
 451       <programlisting>
 452 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
 453            "ERRNO=%i",
 454            strerror_r(errnum, (char[1024]){}, 1024),
 455            errnum);</programlisting>
 456     </example>
 457
 458     <example>
 459       <title>Store a File Descriptor in the Service Manager</title>
 460
 461       <para>To store an open file descriptor in the service manager,
 462       in order to continue operation after a service restart without
 463       losing state, use <literal>FDSTORE=1</literal>:</para>
 464
 465       <programlisting>sd_pid_notify_with_fds(0, 0, "FDSTORE=1\nFDNAME=foobar", &amp;fd, 1);</programlisting>
 466     </example>
 467
 468     <example>
 469       <title>Eliminating race conditions</title>
 470
 471       <para>When the client sending the notifications is not spawned
 472       by the service manager, it may exit too quickly and the service
 473       manager may fail to attribute them correctly to the unit. To
 474       prevent such races, use <function>sd_notify_barrier()</function>
 475       to synchronize against reception of all notifications sent before
 476       this call is made.</para>
 477
 478       <programlisting>
 479 sd_notify(0, "READY=1");
 480 /* set timeout to 5 seconds */
 481 sd_notify_barrier(0, 5 * 1000000);
 482       </programlisting>
 483     </example>
 484   </refsect1>
 485
 486   <refsect1>
 487     <title>See Also</title>
 488     <para>
 489       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 490       <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 491       <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 492       <citerefentry><refentrytitle>sd_listen_fds_with_names</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 493       <citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 494       <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 495       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 496     </para>
 497   </refsect1>
 498
 499 </refentry>