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200 lines
8.1 KiB
XML
200 lines
8.1 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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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>--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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