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diff --git a/man/systemd-notify.xml b/man/systemd-notify.xml new file mode 100644 index 0000000..0222978 --- /dev/null +++ b/man/systemd-notify.xml @@ -0,0 +1,282 @@ +<?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> + <cmdsynopsis> + <command>systemd-notify --exec <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg> ; <arg rep="repeat">CMDLINE</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> + + <xi:include href="version-info.xml" xpointer="v253"/></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> + + <xi:include href="version-info.xml" xpointer="v253"/></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> + + <xi:include href="version-info.xml" xpointer="v237"/></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> + + <xi:include href="version-info.xml" xpointer="v246"/></listitem> + </varlistentry> + + <varlistentry> + <term><option>--exec</option></term> + + <listitem><para>If specified <command>systemd-notify</command> will execute another command line + after it completed its operation, replacing its own process. If used, the list of assignments to + include in the message sent must be followed by a <literal>;</literal> character (as separate + argument), followed by the command line to execute. This permits "chaining" of commands, i.e. issuing + one operation, followed immediately by another, without changing PIDs.</para> + + <para>Note that many shells interpret <literal>;</literal> as their own separator for command lines, + hence when <command>systemd-notify</command> is invoked from a shell the semicolon must usually be + escaped as <literal>\;</literal>.</para> + + <xi:include href="version-info.xml" xpointer="v254"/></listitem> + </varlistentry> + + <varlistentry> + <term><option>--fd=</option></term> + + <listitem><para>Send a file descriptor along with the notification message. This is useful when + invoked in services that have the <varname>FileDescriptorStoreMax=</varname> setting enabled, see + <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for details. The specified file descriptor must be passed to <command>systemd-notify</command> when + invoked. This option may be used multiple times to pass multiple file descriptors in a single + notification message.</para> + + <para>To use this functionality from a + <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry> + shell, use an expression like the following:</para> + <programlisting>systemd-notify --fd=4 --fd=5 4</some/file 5</some/other/file</programlisting> + + <xi:include href="version-info.xml" xpointer="v254"/></listitem> + </varlistentry> + + <varlistentry> + <term><option>--fdname=</option></term> + + <listitem><para>Set a name to assign to the file descriptors passed via <option>--fd=</option> (see + above). This controls the <literal>FDNAME=</literal> field. This setting may only be specified once, + and applies to all file descriptors passed. Invoke this tool multiple times in case multiple file + descriptors with different file descriptor names shall be submitted.</para> + + <xi:include href="version-info.xml" xpointer="v254"/></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> |