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| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
| "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
| |
| <refentry id="systemd-notify" |
| xmlns:xi="http://www.w3.org/2001/XInclude"> |
| |
| <refentryinfo> |
| <title>systemd-notify</title> |
| <productname>systemd</productname> |
| </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 service scripts to notify the invoking service |
| manager 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=</varname> is appropriately set for the service unit this command is called |
| from. See |
| <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> for |
| details.</para> |
| |
| <para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only |
| if either the sending process is still around at the time the service manager processes the message, or |
| if the sending process is explicitly runtime-tracked by the service manager. The latter is the case if |
| the service manager originally forked off the process, i.e. on all processes that match |
| <varname>NotifyAccess=</varname><option>main</option> or |
| <varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit |
| sends an <function>sd_notify()</function> message and immediately exits, the service manager might not be |
| able to properly attribute the message to the unit, and thus will ignore it, even if |
| <varname>NotifyAccess=</varname><option>all</option> is set for it. To address this |
| <command>systemd-notify</command> will wait until the notification message has been processed by the |
| service manager. When <option>--no-block</option> is used, this synchronization for reception of |
| notifications is disabled, and hence the aforementioned race may occur if the invoking process is not the |
| service manager or spawned by the service manager.</para> |
| |
| <para><command>systemd-notify</command> will first attempt to invoke <function>sd_notify()</function> |
| pretending to have the PID of the parent process of <command>systemd-notify</command> (i.e. the invoking |
| process). This will only succeed when invoked with sufficient privileges. On failure, it will then fall |
| back to invoking it under its own PID. This behaviour is useful in order that when the tool is invoked |
| from a shell script the shell process — and not the <command>systemd-notify</command> process — appears |
| as sender of the message, which in turn is helpful if the shell process is the main process of a service, |
| due to the limitations of <varname>NotifyAccess=</varname><option>all</option>. Use the |
| <option>--pid=</option> switch to tweak this behaviour.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Options</title> |
| |
| <para>The following options are understood:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><option>--ready</option></term> |
| |
| <listitem><para>Inform the invoking service manager about service start-up or configuration reload |
| 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>--reloading</option></term> |
| |
| <listitem><para>Inform the invoking service manager about the beginning of a configuration reload |
| cycle. This is equivalent to <command>systemd-notify RELOADING=1</command> (but implicitly also sets |
| a <varname>MONOTONIC_USEC=</varname> field as required for <varname>Type=notify-reload</varname> |
| services, see |
| <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
| for details). For details about the semantics of this option see |
| <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--stopping</option></term> |
| |
| <listitem><para>Inform the invoking service manager about the beginning of the shutdown phase of the |
| service. This is equivalent to <command>systemd-notify STOPPING=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 service manager about the main PID of the service. Takes a PID as |
| argument. If the argument is specified as <literal>auto</literal> or omitted, the PID of the process |
| that invoked <command>systemd-notify</command> is used, except if that's the service manager. If the |
| argument is specified as <literal>self</literal>, the PID of the <command>systemd-notify</command> |
| command itself is used, and if <literal>parent</literal> is specified the calling process' PID is |
| used — even if it is the service manager. The latter 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> |
| |
| <para>If this switch is used in an <command>systemd-notify</command> invocation from a process that |
| shall become the new main process of a service — and which is not the process forked off by the |
| service manager (or the current main process) —, then it is essential to set |
| <varname>NotifyAccess=all</varname> in the service unit file, or otherwise the notification will be |
| ignored for security reasons. See |
| <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--uid=</option><replaceable>USER</replaceable></term> |
| |
| <listitem><para>Set the user ID to send the notification from. Takes a UNIX user name or numeric UID. When |
| specified the notification message will be sent with the specified UID as sender, in place of the user the |
| command was invoked as. This option requires sufficient privileges in order to be able manipulate the user |
| identity of the process.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><option>--status=</option></term> |
| |
| <listitem><para>Send a free-form human readable status string for the daemon to the service |
| manager. 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>. This |
| information is shown in |
| <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s |
| <command>status</command> output, among other places.</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 |
| alternate 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> |
| |
| <varlistentry> |
| <term><option>--no-block</option></term> |
| |
| <listitem><para>Do not synchronously wait for the requested operation to finish. Use of this option |
| is only recommended when <command>systemd-notify</command> is spawned by the service manager, or when |
| the invoking process is directly spawned by the service manager and has enough privileges to allow |
| <command>systemd-notify</command> to send the notification on its behalf. Sending notifications with |
| this option set is prone to race conditions in all other cases.</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/sh |
| |
| mkfifo /tmp/waldo |
| systemd-notify --ready --status="Waiting for data…" |
| |
| while : ; do |
| read -r a < /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>systemd.service</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> |
