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The new --uid= switch allows selecting the UID from which the notificaiton messages shall originate. This is primarily useful for testing purposes, but might have other uses.
211 lines
8.7 KiB
XML
211 lines
8.7 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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SPDX-License-Identifier: LGPL-2.1+
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-notify"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-notify</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-notify</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-notify</refname>
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<refpurpose>Notify service manager about start-up completion and other daemon status changes</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>systemd-notify <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg></command>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>systemd-notify</command> may be called by daemon
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scripts to notify the init system about status changes. It can be
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used to send arbitrary information, encoded in an
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environment-block-like list of strings. Most importantly, it can be
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used for start-up completion notification.</para>
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<para>This is mostly just a wrapper around
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<function>sd_notify()</function> and makes this functionality
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available to shell scripts. For details see
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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</para>
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<para>The command line may carry a list of environment variables
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to send as part of the status update.</para>
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<para>Note that systemd will refuse reception of status updates from this command unless
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<varname>NotifyAccess=</varname> is set for the service unit this command is called from.</para>
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<para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only if either
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the sending process is still around at the time PID 1 processes the message, or if the sending process is
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explicitly runtime-tracked by the service manager. The latter is the case if the service manager originally forked
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off the process, i.e. on all processes that match <varname>NotifyAccess=</varname><option>main</option> or
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<varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit sends an
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<function>sd_notify()</function> message and immediately exits, the service manager might not be able to properly
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attribute the message to the unit, and thus will ignore it, even if
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<varname>NotifyAccess=</varname><option>all</option> is set for it.</para>
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<para><command>systemd-notify</command> will first attempt to invoke <function>sd_notify()</function> pretending to
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have the PID of the invoking process. This will only succeed when invoked with sufficient privileges. On failure,
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it will then fall back to invoking it under its own PID. This behaviour is useful in order that when the tool is
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invoked from a shell script the shell process — and not the <command>systemd-notify</command> process — appears as
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sender of the message, which in turn is helpful if the shell process is the main process of a service, due to the
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limitations of <varname>NotifyAccess=</varname><option>all</option> described above.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The following options are understood:</para>
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<variablelist>
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<varlistentry>
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<term><option>--ready</option></term>
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<listitem><para>Inform the init system about service start-up
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completion. This is equivalent to <command>systemd-notify
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READY=1</command>. For details about the semantics of this
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option see
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--pid=</option></term>
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<listitem><para>Inform the init system about the main PID of
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the daemon. Takes a PID as argument. If the argument is
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omitted, the PID of the process that invoked
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<command>systemd-notify</command> is used. This is equivalent
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to <command>systemd-notify MAINPID=$PID</command>. For details
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about the semantics of this option see
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--uid=</option><replaceable>USER</replaceable></term>
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<listitem><para>Set the user ID to send the notification from. Takes a UNIX user name or numeric UID. When
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specified the notification message will be sent with the specified UID as sender, in place of the user the
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command was invoked as. This option requires sufficient privileges in order to be able manipulate the user
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identity of the process.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--status=</option></term>
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<listitem><para>Send a free-form status string for the daemon
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to the init systemd. This option takes the status string as
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argument. This is equivalent to <command>systemd-notify
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STATUS=…</command>. For details about the semantics of this
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option see
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--booted</option></term>
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<listitem><para>Returns 0 if the system was booted up with
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systemd, non-zero otherwise. If this option is passed, no
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message is sent. This option is hence unrelated to the other
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options. For details about the semantics of this option, see
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<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>. An
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alternate way to check for this state is to call
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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with the <command>is-system-running</command> command. It will
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return <literal>offline</literal> if the system was not booted
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with systemd. </para></listitem>
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</varlistentry>
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<xi:include href="standard-options.xml" xpointer="help" />
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<xi:include href="standard-options.xml" xpointer="version" />
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Exit status</title>
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<para>On success, 0 is returned, a non-zero failure code
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otherwise.</para>
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</refsect1>
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<refsect1>
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<title>Example</title>
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<example>
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<title>Start-up Notification and Status Updates</title>
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<para>A simple shell daemon that sends start-up notifications
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after having set up its communication channel. During runtime it
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sends further status updates to the init system:</para>
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<programlisting>#!/bin/bash
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mkfifo /tmp/waldo
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systemd-notify --ready --status="Waiting for data…"
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while : ; do
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read a < /tmp/waldo
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systemd-notify --status="Processing $a"
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# Do something with $a …
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systemd-notify --status="Waiting for data…"
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done</programlisting>
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</example>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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