man/systemd-notify.xml

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<refentry id="systemd-notify"
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-notify</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-notify</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-notify</refname>
    <refpurpose>Notify service manager about start-up completion and other daemon status changes</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>systemd-notify <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg></command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>systemd-notify</command> may be called by daemon
    scripts to notify the init system about status changes. It can be
    used to send arbitrary information, encoded in an
    environment-block-like list of strings. Most importantly it can be
    used for start-up completion notification.</para>

    <para>This is mostly just a wrapper around
    <function>sd_notify()</function> and makes this functionality
    available to shell scripts. For details see
    <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <para>The command line may carry a list of environment variables
    to send as part of the status update.</para>

    <para>Note that systemd will refuse reception of status updates
    from this command unless <varname>NotifyAccess=all</varname> is
    set for the service unit this command is called from.</para>

  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>

    <variablelist>
      <varlistentry>
        <term><option>--ready</option></term>

        <listitem><para>Inform the init system about service start-up
        completion. This is equivalent to <command>systemd-notify
        READY=1</command>. For details about the semantics of this
        option see
        <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--pid=</option></term>

        <listitem><para>Inform the init system about the main PID of
        the daemon. Takes a PID as argument. If the argument is
        omitted, the PID of the process that invoked
        <command>systemd-notify</command> is used. This is equivalent
        to <command>systemd-notify MAINPID=$PID</command>. For details
        about the semantics of this option see
        <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--status=</option></term>

        <listitem><para>Send a free-form status string for the daemon
        to the init systemd. This option takes the status string as
        argument. This is equivalent to <command>systemd-notify
        STATUS=...</command>. For details about the semantics of this
        option see
        <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--booted</option></term>

        <listitem><para>Returns 0 if the system was booted up with
        systemd, non-zero otherwise. If this option is passed, no
        message is sent. This option is hence unrelated to the other
        options. For details about the semantics of this option, see
        <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>. An
        alternative way to check for this state is to call
        <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
        with the <command>is-system-running</command> command. It will
        return <literal>offline</literal> if the system was not booted
        with systemd.  </para></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>

  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure code
    otherwise.</para>
  </refsect1>

  <refsect1>
    <title>Example</title>

    <example>
      <title>Start-up Notification and Status Updates</title>

      <para>A simple shell daemon that sends start-up notifications
      after having set up its communication channel. During runtime it
      sends further status updates to the init system:</para>

      <programlisting>#!/bin/bash

mkfifo /tmp/waldo
systemd-notify --ready --status="Waiting for data..."

while : ; do
        read a &lt; /tmp/waldo
        systemd-notify --status="Processing $a"

        # Do something with $a ...

        systemd-notify --status="Waiting for data..."
done</programlisting>
    </example>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>