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c5abba08 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
c5abba08 | 5 | |
dfdebb1b | 6 | <refentry id="systemd-notify" |
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7 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
8 | ||
9 | <refentryinfo> | |
10 | <title>systemd-notify</title> | |
11 | <productname>systemd</productname> | |
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12 | </refentryinfo> |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>systemd-notify</refentrytitle> | |
16 | <manvolnum>1</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>systemd-notify</refname> | |
21 | <refpurpose>Notify service manager about start-up completion and other daemon status changes</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
25 | <cmdsynopsis> | |
26 | <command>systemd-notify <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">VARIABLE=VALUE</arg></command> | |
27 | </cmdsynopsis> | |
28 | </refsynopsisdiv> | |
29 | ||
30 | <refsect1> | |
31 | <title>Description</title> | |
32 | ||
33 | <para><command>systemd-notify</command> may be called by daemon | |
34 | scripts to notify the init system about status changes. It can be | |
35 | used to send arbitrary information, encoded in an | |
b938cb90 | 36 | environment-block-like list of strings. Most importantly, it can be |
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37 | used for start-up completion notification.</para> |
38 | ||
39 | <para>This is mostly just a wrapper around | |
40 | <function>sd_notify()</function> and makes this functionality | |
41 | available to shell scripts. For details see | |
42 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
43 | </para> | |
44 | ||
45 | <para>The command line may carry a list of environment variables | |
46 | to send as part of the status update.</para> | |
47 | ||
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48 | <para>Note that systemd will refuse reception of status updates from this command unless |
49 | <varname>NotifyAccess=</varname> is set for the service unit this command is called from.</para> | |
50 | ||
51 | <para>Note that <function>sd_notify()</function> notifications may be attributed to units correctly only if either | |
52 | the sending process is still around at the time PID 1 processes the message, or if the sending process is | |
53 | explicitly runtime-tracked by the service manager. The latter is the case if the service manager originally forked | |
54 | off the process, i.e. on all processes that match <varname>NotifyAccess=</varname><option>main</option> or | |
55 | <varname>NotifyAccess=</varname><option>exec</option>. Conversely, if an auxiliary process of the unit sends an | |
56 | <function>sd_notify()</function> message and immediately exits, the service manager might not be able to properly | |
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57 | attribute the message to the unit, and thus will ignore it, even if <varname>NotifyAccess=</varname><option>all |
58 | </option> is set for it. When <option>--no-block</option> is used, all synchronization for reception of notifications | |
59 | is disabled, and hence the aforementioned race may occur if the invoking process is not the service manager or spawned | |
60 | by the service manager.</para> | |
61 | ||
62 | <para>Hence, <command>systemd-notify</command> will first attempt to invoke <function>sd_notify()</function> | |
63 | pretending to have the PID of the invoking process. This will only succeed when invoked with sufficient privileges. | |
64 | On failure, it will then fall back to invoking it under its own PID. This behaviour is useful in order that when | |
65 | the tool is invoked from a shell script the shell process — and not the <command>systemd-notify</command> process | |
66 | — appears as sender of the message, which in turn is helpful if the shell process is the main process of a service, | |
67 | due to the limitations of <varname>NotifyAccess=</varname><option>all</option>. Use the <option>--pid=</option> | |
68 | switch to tweak this behaviour.</para> | |
69 | ||
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70 | </refsect1> |
71 | ||
72 | <refsect1> | |
73 | <title>Options</title> | |
74 | ||
75 | <para>The following options are understood:</para> | |
76 | ||
77 | <variablelist> | |
78 | <varlistentry> | |
79 | <term><option>--ready</option></term> | |
80 | ||
81 | <listitem><para>Inform the init system about service start-up | |
82 | completion. This is equivalent to <command>systemd-notify | |
83 | READY=1</command>. For details about the semantics of this | |
84 | option see | |
85 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> | |
86 | </varlistentry> | |
87 | ||
88 | <varlistentry> | |
89 | <term><option>--pid=</option></term> | |
90 | ||
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91 | <listitem><para>Inform the service manager about the main PID of the daemon. Takes a PID as |
92 | argument. If the argument is specified as <literal>auto</literal> or omitted, the PID of the process | |
93 | that invoked <command>systemd-notify</command> is used, except if that's the service manager. If the | |
94 | argument is specified as <literal>self</literal>, the PID of the <command>systemd-notify</command> | |
95 | command itself is used, and if <literal>parent</literal> is specified the calling process' PID is | |
96 | used — even if it is the service manager. This is equivalent to <command>systemd-notify | |
97 | MAINPID=$PID</command>. For details about the semantics of this option see | |
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98 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> |
99 | </varlistentry> | |
100 | ||
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101 | <varlistentry> |
102 | <term><option>--uid=</option><replaceable>USER</replaceable></term> | |
103 | ||
104 | <listitem><para>Set the user ID to send the notification from. Takes a UNIX user name or numeric UID. When | |
105 | specified the notification message will be sent with the specified UID as sender, in place of the user the | |
106 | command was invoked as. This option requires sufficient privileges in order to be able manipulate the user | |
107 | identity of the process.</para></listitem> | |
108 | </varlistentry> | |
109 | ||
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110 | <varlistentry> |
111 | <term><option>--status=</option></term> | |
112 | ||
113 | <listitem><para>Send a free-form status string for the daemon | |
114 | to the init systemd. This option takes the status string as | |
115 | argument. This is equivalent to <command>systemd-notify | |
1eecafb8 | 116 | STATUS=…</command>. For details about the semantics of this |
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117 | option see |
118 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> | |
119 | </varlistentry> | |
120 | ||
121 | <varlistentry> | |
122 | <term><option>--booted</option></term> | |
123 | ||
124 | <listitem><para>Returns 0 if the system was booted up with | |
125 | systemd, non-zero otherwise. If this option is passed, no | |
126 | message is sent. This option is hence unrelated to the other | |
127 | options. For details about the semantics of this option, see | |
94f099d8 | 128 | <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>. An |
a8eaaee7 | 129 | alternate way to check for this state is to call |
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130 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
131 | with the <command>is-system-running</command> command. It will | |
132 | return <literal>offline</literal> if the system was not booted | |
133 | with systemd. </para></listitem> | |
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134 | </varlistentry> |
135 | ||
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136 | <varlistentry> |
137 | <term><option>--no-block</option></term> | |
138 | ||
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139 | <listitem><para>Do not synchronously wait for the requested operation to finish. Use of this option |
140 | is only recommended when <command>systemd-notify</command> is spawned by the service manager, or when | |
141 | the invoking process is directly spawned by the service manager and has enough privileges to allow | |
142 | <command>systemd-notify</command> to send the notification on its behalf. Sending notifications with | |
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143 | this option set is prone to race conditions in all other cases.</para></listitem> |
144 | </varlistentry> | |
145 | ||
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146 | <xi:include href="standard-options.xml" xpointer="help" /> |
147 | <xi:include href="standard-options.xml" xpointer="version" /> | |
148 | </variablelist> | |
149 | ||
150 | </refsect1> | |
151 | ||
152 | <refsect1> | |
153 | <title>Exit status</title> | |
154 | ||
155 | <para>On success, 0 is returned, a non-zero failure code | |
156 | otherwise.</para> | |
157 | </refsect1> | |
158 | ||
159 | <refsect1> | |
160 | <title>Example</title> | |
161 | ||
162 | <example> | |
163 | <title>Start-up Notification and Status Updates</title> | |
164 | ||
165 | <para>A simple shell daemon that sends start-up notifications | |
166 | after having set up its communication channel. During runtime it | |
167 | sends further status updates to the init system:</para> | |
168 | ||
169 | <programlisting>#!/bin/bash | |
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170 | |
171 | mkfifo /tmp/waldo | |
1eecafb8 | 172 | systemd-notify --ready --status="Waiting for data…" |
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173 | |
174 | while : ; do | |
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175 | read a < /tmp/waldo |
176 | systemd-notify --status="Processing $a" | |
c61fbdfc | 177 | |
1eecafb8 | 178 | # Do something with $a … |
c61fbdfc | 179 | |
1eecafb8 | 180 | systemd-notify --status="Waiting for data…" |
c61fbdfc | 181 | done</programlisting> |
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182 | </example> |
183 | </refsect1> | |
184 | ||
185 | <refsect1> | |
186 | <title>See Also</title> | |
187 | <para> | |
188 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
189 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
190 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
191 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
192 | <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
193 | </para> | |
194 | </refsect1> | |
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195 | |
196 | </refentry> |