mirror of
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fe45f8dc9b
In the troff output, this doesn't seem to make any difference. But in the html output, the whitespace is sometimes preserved, creating an additional gap before the following content. Drop it everywhere to avoid this.
151 lines
7.4 KiB
XML
151 lines
7.4 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" >
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="org.freedesktop.LogControl1"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>org.freedesktop.LogControl1</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>org.freedesktop.LogControl1</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>org.freedesktop.LogControl1</refname>
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<refpurpose>D-Bus interface to query and set logging configuration</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Introduction</title>
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<para><interfacename>org.freedesktop.LogControl1</interfacename> is a generic interface that is intended
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to be used by any daemon which allows the log level and target to be set over D-Bus. It is implemented by
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various daemons that are part of the
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> suite.</para>
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<para>It is assumed that those settings are global for the whole program, so a fixed object path is
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used. The interface should always be available under the path
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<filename>/org/freedesktop/LogControl1</filename>.</para>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<para>The following interface is exposed:</para>
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<programlisting executable="systemd" node="/org/freedesktop/LogControl1" interface="org.freedesktop.LogControl1">
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node /org/freedesktop/LogControl1 {
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interface org.freedesktop.LogControl1 {
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properties:
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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@org.freedesktop.systemd1.Privileged("true")
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readwrite s LogLevel = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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@org.freedesktop.systemd1.Privileged("true")
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readwrite s LogTarget = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s SyslogIdentifier = '...';
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};
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interface org.freedesktop.DBus.Peer { ... };
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interface org.freedesktop.DBus.Introspectable { ... };
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interface org.freedesktop.DBus.Properties { ... };
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};
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</programlisting>
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<!--Autogenerated cross-references for systemd.directives, do not edit-->
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<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.LogControl1"/>
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<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.LogControl1"/>
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<variablelist class="dbus-property" generated="True" extra-ref="LogLevel"/>
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<variablelist class="dbus-property" generated="True" extra-ref="LogTarget"/>
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<variablelist class="dbus-property" generated="True" extra-ref="SyslogIdentifier"/>
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<!--End of Autogenerated section-->
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<refsect2>
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<title>Properties</title>
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<para><varname>LogLevel</varname> describes the
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<citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>-style
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log-level, and should be one of <literal>emerg</literal>, <literal>alert</literal>,
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<literal>crit</literal>, <literal>err</literal>, <literal>warning</literal>, <literal>notice</literal>,
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<literal>info</literal>, <literal>debug</literal>, in order of increasing verbosity.</para>
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<para><varname>LogTarget</varname> describes the log target (mechanism). It should be one of
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<literal>console</literal> (log to the console or standard output),
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<literal>kmsg</literal> (log to the kernel ring buffer),
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<literal>journal</literal> (log to the journal natively, see
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<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>),
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<literal>syslog</literal> (log using the
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<citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> call).
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</para>
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<caution><title>Write Access</title><para>The <varname>LogLevel</varname> and
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<varname>LogTarget</varname> properties are supposed to be writable. Care should be taken to ensure
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that only appropriately privileged clients can modify them.</para></caution>
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<para><varname>SyslogIdentifier</varname> is a read-only property that shows the "syslog identifier".
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It is a short string that identifies the program that is the source of log messages that is passed to
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the <citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> call.
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</para>
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</refsect2>
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</refsect1>
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<refsect1>
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<title>Tools</title>
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<para><command>journalctl</command> option <option>-p</option>/<option>--priority=</option> may be used
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to filter log messages by log level, option <option>-t</option>/<option>--identifier=</option> may be
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used to by the syslog identifier, and filters like <literal>_TRANSPORT=syslog</literal>,
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<literal>_TRANSPORT=journal</literal>, and <literal>_TRANSPORT=kernel</literal> may be used to filter
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messages by the mechanism through which they reached <command>systemd-journald</command>.</para>
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<para><command>systemctl log-level</command> and <command>systemctl log-target</command> verbs may be
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used to query and set the <varname>LogLevel</varname> and <varname>LogTarget</varname> properties of the
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service manager. <command>systemctl service-log-level</command> and <command>systemctl
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service-log-target</command> may similarly be used for individual services. (Services must have the
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<varname>BusName=</varname> property set and must implement the interface described here. See
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details about <varname>BusName=</varname>.)</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>Create a simple listener on the bus that implements LogControl1</title>
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<programlisting><xi:include href="logcontrol-example.c" parse="text"/></programlisting>
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<para>This creates a simple server on the bus. It implements the LogControl1 interface by providing
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the required properties and allowing to set the writable ones. It logs at the configured log level using
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<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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<para>Note that when porting this example to other D-Bus libraries it might be necessary to add manual
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client privilege checks, as they typically do not default to the restrictive defaults of sd-bus, where
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unprivileged access to properties is controlled via the <constant>SD_BUS_VTABLE_UNPRIVILEGED</constant>
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flag that is opt-in rather than opt-out.</para>
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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><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
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<member><citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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