man/systemd-notify.xml

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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>--version</option></term>
  99
 100                                 <listitem><para>Prints a short version
 101                                 string and exits.</para></listitem>
 102                         </varlistentry>
 103
 104                         <varlistentry>
 105                                 <term><option>--ready</option></term>
 106
 107                                 <listitem><para>Inform the init system
 108                                 about service start-up
 109                                 completion. This is equivalent to
 110                                 <command>systemd-notify
 111                                 READY=1</command>. For details about
 112                                 the semantics of this option see
 113                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 114                         </varlistentry>
 115
 116                         <varlistentry>
 117                                 <term><option>--pid=</option></term>
 118
 119                                 <listitem><para>Inform the init system
 120                                 about the main PID of the
 121                                 daemon. Takes a PID as argument. If
 122                                 the argument is omitted the PID of the
 123                                 process that invoked
 124                                 <command>systemd-notify</command> is
 125                                 used. This is equivalent to
 126                                 <command>systemd-notify
 127                                 MAINPID=$PID</command>. For details
 128                                 about the semantics of this option see
 129                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 130                         </varlistentry>
 131
 132                         <varlistentry>
 133                                 <term><option>--status=</option></term>
 134
 135                                 <listitem><para>Send a free-form
 136                                 status string for the daemon to the
 137                                 init systemd. This option takes the
 138                                 status string as argument. This is
 139                                 equivalent to <command>systemd-notify
 140                                 STATUS=...</command>. For details
 141                                 about the semantics of this option see
 142                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 143                         </varlistentry>
 144
 145                         <varlistentry>
 146                                 <term><option>--booted</option></term>
 147
 148                                 <listitem><para>Returns 0 if the
 149                                 system was booted up with systemd,
 150                                 non-zero otherwise. If this option is
 151                                 passed no message is sent. This option
 152                                 is hence unrelated to the other
 153                                 options. For details about the
 154                                 semantics of this option see
 155                                 <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 156                         </varlistentry>
 157
 158                         <varlistentry>
 159                                 <term><option>--readahead=</option></term>
 160
 161                                 <listitem><para>Controls disk
 162                                 read-ahead operations. The argument
 163                                 must be a string, and either "cancel",
 164                                 "done" or "noreplay". For details
 165                                 about the semantics of this option see
 166                                 <citerefentry><refentrytitle>sd_readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 167                         </varlistentry>
 168                 </variablelist>
 169
 170         </refsect1>
 171
 172         <refsect1>
 173                 <title>Exit status</title>
 174
 175                 <para>On success 0 is returned, a non-zero failure
 176                 code otherwise.</para>
 177         </refsect1>
 178
 179         <refsect1>
 180                 <title>Example</title>
 181
 182                 <example>
 183                         <title>Start-up Notification and Status Updates</title>
 184
 185                         <para>A simple shell daemon that sends
 186                         start-up notifications after having set up its
 187                         communication channel. During runtime it sends
 188                         further status updates to the init
 189                         system:</para>
 190
 191                         <programlisting>#!/bin/bash
 192
 193 mkfifo /tmp/waldo
 194 systemd-notify --ready --status="Waiting for data..."
 195
 196 while : ; do
 197         read a &lt; /tmp/waldo
 198         systemd-notify --status="Processing $a"
 199
 200         # Do something with $a ...
 201
 202         systemd-notify --status="Waiting for data..."
 203 done</programlisting>
 204                 </example>
 205         </refsect1>
 206
 207         <refsect1>
 208                 <title>See Also</title>
 209                 <para>
 210                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 211                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 212                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 213                         <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 214                         <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 215                 </para>
 216         </refsect1>
 217
 218 </refentry>