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1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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8 Copyright 2014 Zbigniew Jędrzejewski-Szmek
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23
24 <refentry id="sd_bus_open_user" conditional="ENABLE_KDBUS">
25
26 <refentryinfo>
27 <title>sd_bus_open_user</title>
28 <productname>systemd</productname>
29
30 <authorgroup>
31 <author>
32 <contrib>A monkey with a typewriter</contrib>
33 <firstname>Zbigniew</firstname>
34 <surname>Jędrzejewski-Szmek</surname>
35 <email>zbyszek@in.waw.pl</email>
36 </author>
37 </authorgroup>
38 </refentryinfo>
39
40 <refmeta>
41 <refentrytitle>sd_bus_open_user</refentrytitle>
42 <manvolnum>3</manvolnum>
43 </refmeta>
44
45 <refnamediv>
46 <refname>sd_bus_open_user</refname>
47 <refname>sd_bus_open_system</refname>
48 <refname>sd_bus_open_system_remote</refname>
49 <refname>sd_bus_open_system_container</refname>
50
51 <refname>sd_bus_default_user</refname>
52 <refname>sd_bus_default_system</refname>
53
54 <refpurpose>Open a connection to the system or user bus</refpurpose>
55 </refnamediv>
56
57 <refsynopsisdiv>
58 <funcsynopsis>
59 <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
60
61 <funcprototype>
62 <funcdef>int <function>sd_bus_open_user</function></funcdef>
63 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
64 </funcprototype>
65
66 <funcprototype>
67 <funcdef>int <function>sd_bus_open_system</function></funcdef>
68 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
69 </funcprototype>
70
71 <funcprototype>
72 <funcdef>int <function>sd_bus_open_system_remote</function></funcdef>
73 <paramdef>const char *<parameter>host</parameter></paramdef>
74 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
75 </funcprototype>
76
77 <funcprototype>
78 <funcdef>int <function>sd_bus_open_system_container</function></funcdef>
79 <paramdef>const char *<parameter>machine</parameter></paramdef>
80 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
81 </funcprototype>
82
83 <funcprototype>
84 <funcdef>int <function>sd_bus_default_user</function></funcdef>
85 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
86 </funcprototype>
87
88 <funcprototype>
89 <funcdef>int <function>sd_bus_default_system</function></funcdef>
90 <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
91 </funcprototype>
92 </funcsynopsis>
93 </refsynopsisdiv>
94
95 <refsect1>
96 <title>Description</title>
97
98 <para><function>sd_bus_open_user()</function> creates a new bus
99 object and opens a connection to the user bus.
100 <function>sd_bus_open_system()</function> does the same, but
101 connects to the system bus.</para>
102
103 <para>If the <varname>$DBUS_SESSION_BUS_ADDRESS</varname> environment
104 variable is set
105 (cf. <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
106 it will be used as the address of the user bus. This variable can
107 contain multiple addresses separated by <literal>;</literal>. If
108 this variable is not set, a suitable default for the default user
109 D-Bus instance will be used.</para>
110
111 <para>If the <varname>$DBUS_SYSTEM_BUS_ADDRESS</varname> environment
112 variable is set, it will be used as the address of the system
113 bus. This variable uses the same syntax as
114 <varname>$DBUS_SESSION_BUS_ADDRESS</varname>/. If this variable is
115 not set, a suitable default for the default system D-Bus instance
116 will be used.</para>
117
118 <para><function>sd_bus_open_system_remote()</function> connects to
119 the system bus on the specified <parameter>host</parameter> using
120 SSH. <parameter>host</parameter> consists of an optional user name
121 followed by the <literal>@</literal> symbol, and the hostname.
122 </para>
123
124 <para><function>sd_bus_open_system_remote()</function> connects to
125 the system bus in the specified <parameter>machine</parameter>,
126 where <parameter>machine</parameter> is the name of a container.
127 See
128 <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
129 for more information about "machines".</para>
130
131 <para><function>sd_bus_default_user()</function> returns a bus
132 object connected to the user bus. Each thread has its own object, but it
133 may be passed around. It is created on the first invocation of
134 <function>sd_bus_default_user()</function>, and subsequent
135 invocations returns a reference to the same object.</para>
136
137 <para><function>sd_bus_default_system()</function> is similar to
138 <function>sd_bus_default_user()</function>, but connects to the
139 system bus.</para>
140 </refsect1>
141
142 <refsect1>
143 <title>Return Value</title>
144
145 <para>On success, these calls return 0 or a positive
146 integer. On failure, these calls return a negative
147 errno-style error code.</para>
148 </refsect1>
149
150 <refsect1>
151 <title>Reference ownership</title>
152 <para>Functions <function>sd_bus_open_user()</function>,
153 <function>sd_bus_open_system()</function>,
154 <function>sd_bus_open_system_remote()</function>, and
155 <function>sd_bus_open_system_machine()</function> return a new
156 object and the caller owns the sole reference. When not needed
157 anymore, this reference should be destroyed with
158 <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
159 </para>
160
161 <para>The functions <function>sd_bus_default_user()</function> and
162 <function>sd_bus_default_system()</function> do not create a new
163 reference.</para>
164 </refsect1>
165
166 <refsect1>
167 <title>Errors</title>
168
169 <para>Returned errors may indicate the following problems:</para>
170
171 <variablelist>
172
173 <varlistentry>
174 <term><varname>-EINVAL</varname></term>
175
176 <listitem><para>Specified parameter is invalid
177 (<constant>NULL</constant> in case of output
178 parameters).</para></listitem>
179 </varlistentry>
180
181 <varlistentry>
182 <term><varname>-ENOMEM</varname></term>
183
184 <listitem><para>Memory allocation failed.</para></listitem>
185 </varlistentry>
186
187 <para>In addition, any further connection-related errors may be
188 by returned. See <citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
189 </variablelist>
190 </refsect1>
191
192 <refsect1>
193 <title>Notes</title>
194
195 <para><function>sd_bus_open_user()</function> and other functions
196 described here are available as a shared library, which can be
197 compiled and linked to with the
198 <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
199 file.</para>
200 </refsect1>
201
202 <refsect1>
203 <title>See Also</title>
204
205 <para>
206 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
207 <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
208 <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
209 <citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
210 <citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
211 <citerefentry><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
212 <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
213 <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
214 </para>
215 </refsect1>
216
217 </refentry>