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diff --git a/man/systemd-notify.xml b/man/systemd-notify.xml new file mode 100644 index 0000000..1327d23 --- /dev/null +++ b/man/systemd-notify.xml @@ -0,0 +1,196 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!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 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=</varname> is set for the service unit this command is called from.</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 PID 1 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. When <option>--no-block</option> is used, all 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>Hence, <command>systemd-notify</command> will first attempt to invoke <function>sd_notify()</function> + pretending to have the PID of 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 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 service manager about the main PID of the daemon. 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. 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>--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 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 + 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>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |