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 SPDX-License-Identifier: LGPL-2.1+
8 This file is part of systemd.
10 Copyright 2010 Lennart Poettering
13 <refentry id=
"sd_get_seats" conditional='HAVE_PAM'
>
16 <title>sd_get_seats
</title>
17 <productname>systemd
</productname>
21 <contrib>Developer
</contrib>
22 <firstname>Lennart
</firstname>
23 <surname>Poettering
</surname>
24 <email>lennart@poettering.net
</email>
30 <refentrytitle>sd_get_seats
</refentrytitle>
31 <manvolnum>3</manvolnum>
35 <refname>sd_get_seats
</refname>
36 <refname>sd_get_sessions
</refname>
37 <refname>sd_get_uids
</refname>
38 <refname>sd_get_machine_names
</refname>
39 <refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers
</refpurpose>
44 <funcsynopsisinfo>#include
<systemd/sd-login.h
></funcsynopsisinfo>
47 <funcdef>int
<function>sd_get_seats
</function></funcdef>
48 <paramdef>char ***
<parameter>seats
</parameter></paramdef>
52 <funcdef>int
<function>sd_get_sessions
</function></funcdef>
53 <paramdef>char ***
<parameter>sessions
</parameter></paramdef>
57 <funcdef>int
<function>sd_get_uids
</function></funcdef>
58 <paramdef>uid_t **
<parameter>users
</parameter></paramdef>
62 <funcdef>int
<function>sd_get_machine_names
</function></funcdef>
63 <paramdef>char ***
<parameter>machines
</parameter></paramdef>
70 <title>Description
</title>
72 <para><function>sd_get_seats()
</function> may be used to determine
73 all currently available local seats. Returns the number of seat
74 identifiers and if the input pointer is non-NULL, a
75 <constant>NULL
</constant>-terminated array of seat identifiers
76 is stored at the address.
77 The returned array and all strings it references need to be freed
79 <citerefentry project='man-pages'
><refentrytitle>free
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
80 call after use. Note that instead of an empty array
81 <constant>NULL
</constant> may be returned and should be considered
82 equivalent to an empty array.
</para>
84 <para>Similarly,
<function>sd_get_sessions()
</function> may be
85 used to determine all current login sessions.
</para>
87 <para>Similarly,
<function>sd_get_uids()
</function> may be used to
88 determine all Unix users who currently have login sessions.
</para>
90 <para>Similarly,
<function>sd_get_machine_names()
</function> may
91 be used to determine all current virtual machines and containers
94 <para>Note that the returned lists are not sorted and in an
95 undefined order.
</para>
99 <title>Return Value
</title>
101 <para>On success,
<function>sd_get_seats()
</function>,
102 <function>sd_get_sessions()
</function>,
103 <function>sd_get_uids()
</function> and
104 <function>sd_get_machine_names()
</function> return the number of
105 entries in the arrays. On failure, these calls return a negative
106 errno-style error code.
</para>
110 <title>Errors
</title>
112 <para>Returned errors may indicate the following problems:
</para>
117 <term><constant>-ENOMEM
</constant></term>
119 <listitem><para>Memory allocation failed.
</para></listitem>
127 <para>The
<function>sd_get_seats()
</function>,
128 <function>sd_get_sessions()
</function>,
129 <function>sd_get_uids()
</function> and
130 <function>sd_get_machine_names()
</function> interfaces are
131 available as a shared library, which can be compiled and linked to
133 <constant>libsystemd
</constant> <citerefentry project='die-net'
><refentrytitle>pkg-config
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
138 <title>See Also
</title>
141 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
142 <citerefentry><refentrytitle>sd-login
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
143 <citerefentry><refentrytitle>sd_session_get_seat
</refentrytitle><manvolnum>3</manvolnum></citerefentry>