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11a1589223
Files which are installed as-is (any .service and other unit files, .conf files, .policy files, etc), are left as is. My assumption is that SPDX identifiers are not yet that well known, so it's better to retain the extended header to avoid any doubt. I also kept any copyright lines. We can probably remove them, but it'd nice to obtain explicit acks from all involved authors before doing that.
229 lines
9.7 KiB
XML
229 lines
9.7 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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SPDX-License-Identifier: LGPL-2.1+
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This file is part of systemd.
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Copyright 2013 Lennart Poettering
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-->
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<refentry id="sd_bus_request_name">
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<refentryinfo>
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<title>sd_bus_request_name</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>sd_bus_request_name</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_request_name</refname>
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<refname>sd_bus_request_name_async</refname>
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<refname>sd_bus_release_name</refname>
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<refname>sd_bus_release_name_async</refname>
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<refpurpose>Request or release a well-known service name on a bus</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_bus_request_name</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>uint64_t <parameter>flags</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_request_name_async</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>uint64_t <parameter>flags</parameter></paramdef>
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<paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef>
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<paramdef>void *<parameter>userdata</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_release_name</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_release_name_async</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef>
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<paramdef>void *<parameter>userdata</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_request_name()</function> requests a well-known service name on a bus. It takes a bus
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connection, a valid bus name and a flags parameter. The flags parameter is a combination of the following
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flags:</para>
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<variablelist>
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<varlistentry>
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<term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
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<listitem><para>After acquiring the name successfully, permit other peers to take over the name when they try
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to acquire it with the <varname>SD_BUS_NAME_REPLACE_EXISTING</varname> flag set. If
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<varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> is not set on the original request, such a request by other
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peers will be denied.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
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<listitem><para>Take over the name if it is already acquired by another peer, and that other peer has permitted
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takeover by setting <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> while acquiring it.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SD_BUS_NAME_QUEUE</varname></term>
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<listitem><para>Queue the acquisition of the name when the name is already taken.</para></listitem>
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</varlistentry>
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</variablelist>
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<para><function>sd_bus_request_name()</function> operates in a synchronous fashion: a message requesting the name
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is sent to the bus broker, and the call waits until the broker responds.</para>
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<para><function>sd_bus_request_name_async()</function> is an asynchronous version of of
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<function>sd_bus_release_name()</function>. Instead of waiting for the request to complete, the request message is
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enqueued. The specified <parameter>callback</parameter> will be called when the broker's response is received. If
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the parameter is specified as <constant>NULL</constant> a default implementation is used instead which will
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terminate the connection when the name cannot be acquired. The function returns a slot object in its
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<parameter>slot</parameter> parameter — if it is passed as non-<constant>NULL</constant> — which may be used as a
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reference to the name request operation. Use
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<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> to destroy
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this reference. Note that destroying the reference will not unregister the name, but simply ensure the specified
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callback is no longer called.</para>
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<para><function>sd_bus_release_name()</function> releases an acquired well-known name. It takes a bus connection
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and a valid bus name as parameters. This function operates synchronously, sending a release request message to the
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bus broker and waiting for it to reply.</para>
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<para><function>sd_bus_release_name_async()</function> is an asynchronous version of
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<function>sd_bus_release_name()</function>. The specified <parameter>callback</parameter> function is called when
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the name has been released successfully. If specified as <constant>NULL</constant> a generic implementation is used
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that ignores the result of the operation. As above, the <parameter>slot</parameter> (if
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non-<constant>NULL</constant>) is set to an object that may be used to reference the operation.</para>
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<para>These functions are supported only on bus connections, i.e. connections to a bus broker and not on direct
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connections.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, these calls return 0 or a positive integer. On failure, these calls return a negative errno-style
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error code.</para>
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<para>If <varname>SD_BUS_NAME_QUEUE</varname> is specified, <function>sd_bus_request_name()</function> will return
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0 when the name is already taken by another peer and the client has been added to the queue for the name. In that
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case, the caller can subscribe to <literal>NameOwnerChanged</literal> signals to be notified when the name is
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successfully acquired. <function>sd_bus_request_name()</function> returns > 0 when the name has immediately
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been acquired successfully.</para>
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</refsect1>
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<refsect1>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EALREADY</constant></term>
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<listitem><para>The caller already is the owner of the specified name.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EEXIST</constant></term>
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<listitem><para>The name has already been acquired by a different peer, and SD_BUS_NAME_REPLACE_EXISTING was
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not specified or the other peer did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
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name.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ESRCH</constant></term>
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<listitem><para>It was attempted to release a name that is currently not registered on the
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bus.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EADDRINUSE</constant></term>
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<listitem><para>It was attempted to release a name that is owned by a different peer on the
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bus.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>A specified parameter is invalid. This is also generated when the requested name is a special
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service name reserved by the D-Bus specification, or when the operation is requested on a connection that does
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not refer to a bus.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOTCONN</constant></term>
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<listitem><para>The bus connection has been disconnected.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The bus connection has been created in a different process than the current
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one.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_bus_acquire_name()</function> and the other interfaces described here are available as a
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shared library, which can be compiled and linked to with the <constant>libsystemd</constant> <citerefentry
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project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
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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>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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