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 systemd.
8 Copyright 2010 Lennart Poettering
10 systemd 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 systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_seat_get_active" conditional='HAVE_PAM'>
27 <title>sd_seat_get_active</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_seat_get_active</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_seat_get_active</refname>
47 <refname>sd_seat_get_sessions</refname>
48 <refname>sd_seat_can_multi_session</refname>
49 <refpurpose>Determine state of a specific seat</refpurpose>
54 <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
57 <funcdef>int <function>sd_seat_get_active</function></funcdef>
58 <paramdef>const char* <parameter>seat</parameter></paramdef>
59 <paramdef>char** <parameter>session</parameter></paramdef>
60 <paramdef>uid_t* <parameter>uid</parameter></paramdef>
64 <funcdef>int <function>sd_seat_get_sessions</function></funcdef>
65 <paramdef>const char* <parameter>seat</parameter></paramdef>
66 <paramdef>char*** <parameter>sessions</parameter></paramdef>
67 <paramdef>uid_t** <parameter>uid</parameter></paramdef>
68 <paramdef>unsigned* <parameter>n_uids</parameter></paramdef>
72 <funcdef>int <function>sd_seat_can_multi_session</function></funcdef>
73 <paramdef>const char* <parameter>seat</parameter></paramdef>
77 <funcdef>int <function>sd_seat_can_tty</function></funcdef>
78 <paramdef>const char* <parameter>seat</parameter></paramdef>
82 <funcdef>int <function>sd_seat_can_graphical</function></funcdef>
83 <paramdef>const char* <parameter>seat</parameter></paramdef>
89 <title>Description</title>
91 <para><function>sd_seat_get_active()</function> may be
92 used to determine which session is currently active on
93 a seat, if there is any. Returns the session
94 identifier and the user identifier of the Unix user
95 the session is belonging to. Either the session or the
96 user identifier parameter can be passed NULL, in
97 case only one of the parameters shall be queried. The
98 returned string needs to be freed with the libc
99 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
100 call after use.</para>
102 <para><function>sd_seat_get_sessions()</function> may
103 be used to determine all sessions on the specified
104 seat. Returns two arrays, one (<constant>NULL</constant> terminated) with
105 the session identifiers of the sessions and one with
106 the user identifiers of the Unix users the sessions
107 belong to. An additional parameter may be used to
108 return the number of entries in the latter array. The
109 two arrays and the latter parameter may be passed as
110 <constant>NULL</constant> in case these values need not to be
111 determined. The arrays and the strings referenced by
112 them need to be freed with the libc
113 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
114 call after use. Note that instead of an empty array
115 <constant>NULL</constant> may be returned and should be considered
116 equivalent to an empty array.</para>
118 <para><function>sd_seat_can_multi_session()</function>
119 may be used to determine whether a specific seat is
120 capable of multi-session, i.e. allows multiple login
121 sessions in parallel (with only one being active at a
124 <para><function>sd_seat_can_tty()</function> may be
125 used to determine whether a specific seat provides TTY
126 functionality, i.e. is useful as a text console.</para>
128 <para><function>sd_seat_can_graphical()</function> may
129 be used to determine whether a specific seat provides
130 graphics functionality, i.e. is useful as a graphics
133 <para>If the <varname>seat</varname> parameter of any
134 of these functions is passed as
135 <constant>NULL</constant> the operation is executed
136 for the seat of the session of the calling process, if
141 <title>Return Value</title>
144 <function>sd_seat_get_active()</function>
145 returns 0 or a positive integer. On success
146 <function>sd_seat_get_sessions()</function> returns
147 the number of entries in the session identifier
148 array. If the test succeeds
149 <function>sd_seat_can_multi_session</function>,
150 <function>sd_seat_can_tty</function> and
151 <function>sd_seat_can_graphical</function> return a
152 positive integer, if it fails 0. On failure, these
153 calls return a negative errno-style error code.</para>
159 <para>The <function>sd_seat_get_active()</function>,
160 <function>sd_seat_get_sessions()</function>,
161 <function>sd_seat_can_multi_session()</function>,
162 <function>sd_seat_can_tty()</function> and
163 <function>sd_seat_can_grapical()</function> interfaces
164 are available as shared library, which can be compiled
165 and linked to with the
166 <constant>libsystemd-login</constant>
167 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
172 <title>See Also</title>
175 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
176 <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
177 <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>