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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" >
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="org.freedesktop.LogControl1"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>org.freedesktop.LogControl1</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>org.freedesktop.LogControl1</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>org.freedesktop.LogControl1</refname>
<refpurpose>D-Bus interface to query and set logging configuration</refpurpose>
</refnamediv>
<refsect1>
<title>Introduction</title>
<para><interfacename>org.freedesktop.LogControl1</interfacename> is a generic interface that is intended
to be used by any daemon which allows the log level and target to be set over D-Bus. It is implemented by
various daemons that are part of the
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> suite.</para>
<para>It is assumed that those settings are global for the whole program, so a fixed object path is
used. The interface should always be available under the path
<filename>/org/freedesktop/LogControl1</filename>.</para>
</refsect1>
<refsect1>
<title>Description</title>
<para>The following interface is exposed:</para>
<programlisting executable="systemd" node="/org/freedesktop/LogControl1" interface="org.freedesktop.LogControl1">
node /org/freedesktop/LogControl1 {
interface org.freedesktop.LogControl1 {
properties:
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
@org.freedesktop.systemd1.Privileged("true")
readwrite s LogLevel = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
@org.freedesktop.systemd1.Privileged("true")
readwrite s LogTarget = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
readonly s SyslogIdentifier = '...';
};
interface org.freedesktop.DBus.Peer { ... };
interface org.freedesktop.DBus.Introspectable { ... };
interface org.freedesktop.DBus.Properties { ... };
};
</programlisting>
<!--Autogenerated cross-references for systemd.directives, do not edit-->
<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.LogControl1"/>
<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.LogControl1"/>
<variablelist class="dbus-property" generated="True" extra-ref="LogLevel"/>
<variablelist class="dbus-property" generated="True" extra-ref="LogTarget"/>
<variablelist class="dbus-property" generated="True" extra-ref="SyslogIdentifier"/>
<!--End of Autogenerated section-->
<refsect2>
<title>Properties</title>
<para><varname>LogLevel</varname> describes the
<citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>-style
log-level, and should be one of <literal>emerg</literal>, <literal>alert</literal>,
<literal>crit</literal>, <literal>err</literal>, <literal>warning</literal>, <literal>notice</literal>,
<literal>info</literal>, <literal>debug</literal>, in order of increasing verbosity.</para>
<para><varname>LogTarget</varname> describes the log target (mechanism). It should be one of
<literal>console</literal> (log to the console or standard output),
<literal>kmsg</literal> (log to the kernel ring buffer),
<literal>journal</literal> (log to the journal natively, see
<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>),
<literal>syslog</literal> (log using the
<citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> call).
</para>
<para>Those two properties are writable, so they may be set by sufficiently privileged users.</para>
<para><varname>SyslogIdentifier</varname> is a read-only property that shows the "syslog identifier".
It is a short string that identifies the program that is the source of log messages that is passed to
the <citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> call.
</para>
</refsect2>
</refsect1>
<refsect1>
<title>Tools</title>
<para><command>journalctl</command> option <option>-p</option>/<option>--priority=</option> may be used
to filter log messages by log level, option <option>-t</option>/<option>--identifier=</option> may be
used to by the syslog identifier, and filters like <literal>_TRANSPORT=syslog</literal>,
<literal>_TRANSPORT=journal</literal>, and <literal>_TRANSPORT=kernel</literal> may be used to filter
messages by the mechanism through which they reached <command>systemd-journald</command>.</para>
<para><command>systemctl log-level</command> and <command>systemctl log-target</command> verbs may be
used to query and set the <varname>LogLevel</varname> and <varname>LogTarget</varname> properties of the
service manager. <command>systemctl service-log-level</command> and <command>systemctl
service-log-target</command> may similarly be used for individual services. (Services must have the
<varname>BusName=</varname> property set and must implement the interface described here. See
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details about <varname>BusName=</varname>.)</para>
</refsect1>
<refsect1>
<title>Example</title>
<example>
<title>Create a simple listener on the bus that implements LogControl1</title>
<programlisting><xi:include href="logcontrol-example.c" parse="text"/></programlisting>
<para>This creates a simple server on the bus. It implements the LogControl1 interface by providing
the required properties and allowing to set the writable ones. It logs at the configured log level using
<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project="man-pages"><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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