man/systemd-notify.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="systemd-notify">
  25
  26         <refentryinfo>
  27                 <title>systemd-notify</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-notify</refentrytitle>
  42                 <manvolnum>1</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd-notify</refname>
  47                 <refpurpose>Notify init system about start-up completion and other daemon status changes</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <cmdsynopsis>
  52                         <command>systemd-notify <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg></command>
  53                 </cmdsynopsis>
  54         </refsynopsisdiv>
  55
  56         <refsect1>
  57                 <title>Description</title>
  58
  59                 <para><command>systemd-notify</command> may be
  60                 called by daemon scripts to notify the init system
  61                 about status changes. It can be used to send arbitrary
  62                 information, encoded in an environment-block-like list
  63                 of strings. Most importantly it can be used for
  64                 start-up completion notification.</para>
  65
  66                 <para>This is mostly just a wrapper around
  67                 <function>sd_notify()</function> and makes this
  68                 functionality available to shell scripts. For details
  69                 see
  70                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  71
  72                 <para>The command line may carry a list of
  73                 environment variables to send as part of the status
  74                 update.</para>
  75
  76                 <para>Note that systemd will refuse reception of
  77                 status updates from this command unless
  78                 <varname>NotifyAccess=all</varname> is set for the
  79                 service unit this command is called from.</para>
  80
  81         </refsect1>
  82
  83         <refsect1>
  84                 <title>Options</title>
  85
  86                 <para>The following options are understood:</para>
  87
  88                 <variablelist>
  89                         <varlistentry>
  90                                 <term><option>--h</option></term>
  91                                 <term><option>--help</option></term>
  92
  93                                 <listitem><para>Prints a short help
  94                                 text and exits.</para></listitem>
  95                         </varlistentry>
  96
  97                         <varlistentry>
  98                                 <term><option>--ready</option></term>
  99
 100                                 <listitem><para>Inform the init system
 101                                 about service start-up
 102                                 completion. This is equivalent to
 103                                 <command>systemd-notify
 104                                 READY=1</command>. For details about
 105                                 the semantics of this option see
 106                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 107                         </varlistentry>
 108
 109                         <varlistentry>
 110                                 <term><option>--pid=</option></term>
 111
 112                                 <listitem><para>Inform the init system
 113                                 about the main PID of the
 114                                 daemon. Takes a PID as argument. If
 115                                 the argument is omitted the PID of the
 116                                 process that invoked
 117                                 <command>systemd-notify</command> is
 118                                 used. This is equivalent to
 119                                 <command>systemd-notify
 120                                 MAINPID=$PID</command>. For details
 121                                 about the semantics of this option see
 122                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 123                         </varlistentry>
 124
 125                         <varlistentry>
 126                                 <term><option>--status=</option></term>
 127
 128                                 <listitem><para>Send a free-form
 129                                 status string for the daemon to the
 130                                 init systemd. This option takes the
 131                                 status string as argument. This is
 132                                 equivalent to <command>systemd-notify
 133                                 STATUS=...</command>. For details
 134                                 about the semantics of this option see
 135                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 136                         </varlistentry>
 137
 138                         <varlistentry>
 139                                 <term><option>--booted</option></term>
 140
 141                                 <listitem><para>Returns 0 if the
 142                                 system was booted up with systemd,
 143                                 non-zero otherwise. If this option is
 144                                 passed no message is sent. This option
 145                                 is hence unrelated to the other
 146                                 options. For details about the
 147                                 semantics of this option see
 148                                 <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 149                         </varlistentry>
 150
 151                         <varlistentry>
 152                                 <term><option>--readahead=</option></term>
 153
 154                                 <listitem><para>Controls disk
 155                                 read-ahead operations. The argument
 156                                 must be a string, and either "cancel",
 157                                 "done" or "noreplay". For details
 158                                 about the semantics of this option see
 159                                 <citerefentry><refentrytitle>sd_readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 160                         </varlistentry>
 161                 </variablelist>
 162
 163         </refsect1>
 164
 165         <refsect1>
 166                 <title>Exit status</title>
 167
 168                 <para>On success 0 is returned, a non-zero failure
 169                 code otherwise.</para>
 170         </refsect1>
 171
 172         <refsect1>
 173                 <title>Example</title>
 174
 175                 <example>
 176                         <title>Start-up Notification and Status Updates</title>
 177
 178                         <para>A simple shell daemon that sends
 179                         start-up notifications after having set up its
 180                         communication channel. During runtime it sends
 181                         further status updates to the init
 182                         system:</para>
 183
 184                         <programlisting>#!/bin/bash
 185
 186 mkfifo /tmp/waldo
 187 systemd-notify --ready --status="Waiting for data..."
 188
 189 while : ; do
 190         read a &lt; /tmp/waldo
 191         systemd-notify --status="Processing $a"
 192
 193         # Do something with $a ...
 194
 195         systemd-notify --status="Waiting for data..."
 196 done</programlisting>
 197                 </example>
 198         </refsect1>
 199
 200         <refsect1>
 201                 <title>See Also</title>
 202                 <para>
 203                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 204                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 205                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 206                         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 207                         <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 208                 </para>
 209         </refsect1>
 210
 211 </refentry>