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systemd/man/sd_bus_open_user.xml
Lennart Poettering 3802a3d3d7 man: add emacs header to get correct indention in nxml-mode for the manpage XML files that use 2ch indenting
In the long run we really should figure out if we want to stick with 8ch
or 2ch indenting, and not continue with half-and-half. For now, just
make emacs aware of the files that use 2ch indenting.
2014-11-21 20:44:48 +01:00

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<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2014 Zbigniew Jędrzejewski-Szmek
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_open_user" conditional="ENABLE_KDBUS">
<refentryinfo>
<title>sd_bus_open_user</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>A monkey with a typewriter</contrib>
<firstname>Zbigniew</firstname>
<surname>Jędrzejewski-Szmek</surname>
<email>zbyszek@in.waw.pl</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_open_user</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_open_user</refname>
<refname>sd_bus_open_system</refname>
<refname>sd_bus_open_system_remote</refname>
<refname>sd_bus_open_system_container</refname>
<refname>sd_bus_default_user</refname>
<refname>sd_bus_default_system</refname>
<refpurpose>Open a connection to the system or user bus</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_open_user</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_remote</function></funcdef>
<paramdef>const char *<parameter>host</parameter></paramdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_open_system_container</function></funcdef>
<paramdef>const char *<parameter>machine</parameter></paramdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_user</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_default_system</function></funcdef>
<paramdef>sd_bus **<parameter>bus</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_open_user()</function> creates a new bus
object and opens a connection to the user bus.
<function>sd_bus_open_system()</function> does the same, but
connects to the system bus.</para>
<para>If the <varname>$DBUS_SESSION_BUS_ADDRESS</varname> environment
variable is set
(cf. <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
it will be used as the address of the user bus. This variable can
contain multiple addresses separated by <literal>;</literal>. If
this variable is not set, a suitable default for the default user
D-Bus instance will be used.</para>
<para>If the <varname>$DBUS_SYSTEM_BUS_ADDRESS</varname> environment
variable is set, it will be used as the address of the system
bus. This variable uses the same syntax as
<varname>$DBUS_SESSION_BUS_ADDRESS</varname>/. If this variable is
not set, a suitable default for the default system D-Bus instance
will be used.</para>
<para><function>sd_bus_open_system_remote()</function> connects to
the system bus on the specified <parameter>host</parameter> using
SSH. <parameter>host</parameter> consists of an optional user name
followed by the <literal>@</literal> symbol, and the hostname.
</para>
<para><function>sd_bus_open_system_container()</function> connects
to the system bus in the specified <parameter>machine</parameter>,
where <parameter>machine</parameter> is the name of a container.
See
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
for more information about "machines".</para>
<para><function>sd_bus_default_user()</function> returns a bus
object connected to the user bus. Each thread has its own object, but it
may be passed around. It is created on the first invocation of
<function>sd_bus_default_user()</function>, and subsequent
invocations returns a reference to the same object.</para>
<para><function>sd_bus_default_system()</function> is similar to
<function>sd_bus_default_user()</function>, but connects to the
system bus.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive
integer. On failure, these calls return a negative
errno-style error code.</para>
</refsect1>
<refsect1>
<title>Reference ownership</title>
<para>Functions <function>sd_bus_open_user()</function>,
<function>sd_bus_open_system()</function>,
<function>sd_bus_open_system_remote()</function>, and
<function>sd_bus_open_system_machine()</function> return a new
object and the caller owns the sole reference. When not needed
anymore, this reference should be destroyed with
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
<para>The functions <function>sd_bus_default_user()</function> and
<function>sd_bus_default_system()</function> do not create a new
reference.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>Specified parameter is invalid
(<constant>NULL</constant> in case of output
parameters).</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
<para>In addition, any further connection-related errors may be
by returned. See <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_open_user()</function> and other functions
described here are available as a shared library, which can be
compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>