mirror of
https://github.com/systemd/systemd.git
synced 2024-12-23 21:35:11 +03:00
283 lines
15 KiB
XML
283 lines
15 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/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</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg>
|
|
</cmdsynopsis>
|
|
<cmdsynopsis>
|
|
<command>systemd-notify</command> <arg>--exec</arg> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg> <arg>;</arg> <arg rep="repeat">CMDLINE</arg>
|
|
</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. <option>--pid=auto</option> 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=<replaceable>USER</replaceable></option></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><simplelist type="inline">
|
|
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
</refentry>
|