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">
6 This file is part of elogind.
8 Copyright 2010 Lennart Poettering
10 elogind is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 elogind is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with elogind; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_get_seats" conditional='HAVE_PAM'>
27 <title>sd_get_seats</title>
28 <productname>elogind</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_get_seats</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_get_seats</refname>
47 <refname>sd_get_sessions</refname>
48 <refname>sd_get_uids</refname>
49 <refname>sd_get_machine_names</refname>
50 <refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers</refpurpose>
55 <funcsynopsisinfo>#include <elogind/sd-login.h></funcsynopsisinfo>
58 <funcdef>int <function>sd_get_seats</function></funcdef>
59 <paramdef>char ***<parameter>seats</parameter></paramdef>
63 <funcdef>int <function>sd_get_sessions</function></funcdef>
64 <paramdef>char ***<parameter>sessions</parameter></paramdef>
68 <funcdef>int <function>sd_get_uids</function></funcdef>
69 <paramdef>uid_t **<parameter>users</parameter></paramdef>
73 <funcdef>int <function>sd_get_machine_names</function></funcdef>
74 <paramdef>char ***<parameter>machines</parameter></paramdef>
81 <title>Description</title>
83 <para><function>sd_get_seats()</function> may be used to determine
84 all currently available local seats. Returns a
85 <constant>NULL</constant> terminated array of seat identifiers.
86 The returned array and all strings it references need to be freed
88 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
89 call after use. Note that instead of an empty array
90 <constant>NULL</constant> may be returned and should be considered
91 equivalent to an empty array.</para>
93 <para>Similarly, <function>sd_get_sessions()</function> may be
94 used to determine all current login sessions.</para>
96 <para>Similarly, <function>sd_get_uids()</function> may be used to
97 determine all Unix users who currently have login sessions.</para>
99 <para>Similarly, <function>sd_get_machine_names()</function> may
100 be used to determine all current virtual machines and containers
101 on the system.</para>
103 <para>Note that the returned lists are not sorted and in an
104 undefined order.</para>
108 <title>Return Value</title>
110 <para>On success, <function>sd_get_seats()</function>,
111 <function>sd_get_sessions()</function>,
112 <function>sd_get_uids()</function> and
113 <function>sd_get_machine_names()</function> return the number of
114 entries in the arrays. On failure, these calls return a negative
115 errno-style error code.</para>
120 <title>Errors</title>
122 <para>Returned errors may indicate the following problems:</para>
127 <term><constant>-EINVAL</constant></term>
129 <listitem><para>An input parameter was invalid (out of range,
130 or NULL, where that is not accepted).</para></listitem>
134 <term><constant>-ENOMEM</constant></term>
136 <listitem><para>Memory allocation failed.</para></listitem>
144 <para>The <function>sd_get_seats()</function>,
145 <function>sd_get_sessions()</function>,
146 <function>sd_get_uids()</function> and
147 <function>sd_get_machine_names()</function> interfaces are
148 available as a shared library, which can be compiled and linked to
150 <constant>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
155 <title>See Also</title>
158 <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
159 <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
160 <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>