1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"sd_get_seats" conditional='HAVE_PAM'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>sd_get_seats
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>sd_get_seats
</refentrytitle>
16 <manvolnum>3</manvolnum>
20 <refname>sd_get_seats
</refname>
21 <refname>sd_get_sessions
</refname>
22 <refname>sd_get_uids
</refname>
23 <refname>sd_get_machine_names
</refname>
24 <refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers
</refpurpose>
29 <funcsynopsisinfo>#include
<systemd/sd-login.h
></funcsynopsisinfo>
32 <funcdef>int
<function>sd_get_seats
</function></funcdef>
33 <paramdef>char ***
<parameter>seats
</parameter></paramdef>
37 <funcdef>int
<function>sd_get_sessions
</function></funcdef>
38 <paramdef>char ***
<parameter>sessions
</parameter></paramdef>
42 <funcdef>int
<function>sd_get_uids
</function></funcdef>
43 <paramdef>uid_t **
<parameter>users
</parameter></paramdef>
47 <funcdef>int
<function>sd_get_machine_names
</function></funcdef>
48 <paramdef>char ***
<parameter>machines
</parameter></paramdef>
55 <title>Description
</title>
57 <para><function>sd_get_seats()
</function> may be used to determine
58 all currently available local seats. Returns the number of seat
59 identifiers and if the input pointer is non-
<constant>NULL
</constant>, a
60 <constant>NULL
</constant>-terminated array of seat identifiers
61 is stored at the address.
62 The returned array and all strings it references need to be freed
64 <citerefentry project='man-pages'
><refentrytitle>free
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
65 call after use. Note that instead of an empty array
66 <constant>NULL
</constant> may be returned and should be considered
67 equivalent to an empty array.
</para>
69 <para>Similarly,
<function>sd_get_sessions()
</function> may be
70 used to determine all current login sessions.
</para>
72 <para>Similarly,
<function>sd_get_uids()
</function> may be used to
73 determine all Unix users who currently have login sessions.
</para>
75 <para>Similarly,
<function>sd_get_machine_names()
</function> may
76 be used to determine all current virtual machines and containers
79 <para>Note that the returned lists are not sorted and in an
80 undefined order.
</para>
84 <title>Return Value
</title>
86 <para>On success,
<function>sd_get_seats()
</function>,
<function>sd_get_sessions()
</function>,
87 <function>sd_get_uids()
</function> and
<function>sd_get_machine_names()
</function> return the number of
88 entries in the arrays. On failure, these calls return a negative errno-style error code.
</para>
93 <para>Returned errors may indicate the following problems:
</para>
98 <term><constant>-ENOMEM
</constant></term>
100 <listitem><para>Memory allocation failed.
</para></listitem>
106 <xi:include href=
"libsystemd-pkgconfig.xml" />
109 <title>See Also
</title>
112 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
113 <citerefentry><refentrytitle>sd-login
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
114 <citerefentry><refentrytitle>sd_session_get_seat
</refentrytitle><manvolnum>3</manvolnum></citerefentry>