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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
264 lines
10 KiB
XML
264 lines
10 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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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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This file is part of systemd.
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Copyright 2014 Zbigniew Jędrzejewski-Szmek
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_bus_default">
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<refentryinfo>
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<title>sd_bus_default</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>A monkey with a typewriter</contrib>
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<firstname>Zbigniew</firstname>
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<surname>Jędrzejewski-Szmek</surname>
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<email>zbyszek@in.waw.pl</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_default</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_default</refname>
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<refname>sd_bus_default_user</refname>
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<refname>sd_bus_default_system</refname>
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<refname>sd_bus_open</refname>
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<refname>sd_bus_open_user</refname>
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<refname>sd_bus_open_system</refname>
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<refname>sd_bus_open_system_remote</refname>
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<refname>sd_bus_open_system_machine</refname>
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<refpurpose>Acquire a connection to a system or user 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_default</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_default_user</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_default_system</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_open</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_open_user</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_open_system</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_open_system_remote</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>host</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_open_system_machine</function></funcdef>
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<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
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<paramdef>const char *<parameter>machine</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_default()</function> acquires a bus
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connection object to the user bus when invoked in user context or
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to the system bus otherwise. The connection object is associated
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to the calling thread. Each time the function is invoked from the
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same thread the same object is returned, but its reference count
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increased by one, as long as at least one reference is kept. When
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the last reference to the connection is dropped (using the
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<function>sd_bus_unref()</function> call), the connection is
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terminated. Note that the connection is not automatically
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terminated when the associated thread ends. It is important to
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drop the last reference to the bus connection explicitly before
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the thread ends or otherwise the connection will be leaked.</para>
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<para><function>sd_bus_default_user()</function> returns a user
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bus connection object associated to the calling thread.
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<function>sd_bus_default_system()</function> is similar, but
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connects to the system bus.</para>
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<para><function>sd_bus_open()</function> creates a new,
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independent bus connection to the user bus when invoked in user
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context or the system bus
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otherwise. <function>sd_bus_open_user()</function> is similar, but
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connects only to the user bus.
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<function>sd_bus_open_system()</function> does the same, but
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connects to the system bus. In contrast to
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<function>sd_bus_default()</function>,
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<function>sd_bus_default_user()</function>,
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<function>sd_bus_default_system()</function> these calls return
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new, independent connection objects that are not associated with
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the invoking thread and are not shared between multiple
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invocations. It is recommended to share connections per thread to
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efficiently make use the available resources. Thus, it is
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recommended to use <function>sd_bus_default()</function>,
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<function>sd_bus_default_user()</function>,
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<function>sd_bus_default_system()</function> to connect to the
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user or system buses.</para>
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<para>If the <varname>$DBUS_SESSION_BUS_ADDRESS</varname> environment
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variable is set
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(cf. <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
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it will be used as the address of the user bus. This variable can
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contain multiple addresses separated by <literal>;</literal>. If
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this variable is not set, a suitable default for the default user
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D-Bus instance will be used.</para>
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<para>If the <varname>$DBUS_SYSTEM_BUS_ADDRESS</varname>
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environment variable is set, it will be used as the address of the
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system bus. This variable uses the same syntax as
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<varname>$DBUS_SESSION_BUS_ADDRESS</varname>. If this variable is
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not set, a suitable default for the default system D-Bus instance
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will be used.</para>
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<para><function>sd_bus_open_system_remote()</function> connects to
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the system bus on the specified <parameter>host</parameter> using
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SSH. <parameter>host</parameter> consists of an optional user name
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followed by the <literal>@</literal> symbol, and the hostname.
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</para>
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<para><function>sd_bus_open_system_container()</function> connects
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to the system bus in the specified <parameter>machine</parameter>,
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where <parameter>machine</parameter> is the name of a local
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container. See
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for more information about "machines".</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
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integer. On failure, these calls return a negative
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errno-style error code.</para>
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</refsect1>
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<refsect1>
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<title>Reference ownership</title>
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<para>The functions <function>sd_bus_open_user()</function>,
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<function>sd_bus_open()</function>,
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<function>sd_bus_open_system()</function>,
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<function>sd_bus_open_system_remote()</function>, and
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<function>sd_bus_open_system_machine()</function> return a new
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object and the caller owns the sole reference. When not needed
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anymore, this reference should be destroyed with
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<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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</para>
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<para>The functions <function>sd_bus_default()</function>,
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<function>sd_bus_default_user()</function> and
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<function>sd_bus_default_system()</function> do not necessarily
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create a new object, but increase the connection reference by
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one. Use
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<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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to drop the reference.</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>-EINVAL</constant></term>
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<listitem><para>The specified parameters are invalid.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ESOCKTNOSUPPORT</constant></term>
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<listitem><para>The protocol version required to connect to the selected bus is not supported.</para></listitem>
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</varlistentry>
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</variablelist>
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<para>In addition, any further connection-related errors may be
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by returned. See <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para><function>sd_bus_open_user()</function> and the other
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functions described here are available as a shared library, which
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can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry
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project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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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_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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