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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_get_seats" conditional='HAVE_PAM'>
<refentryinfo>
<title>sd_get_seats</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_get_seats</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_get_seats</refname>
<refname>sd_get_sessions</refname>
<refname>sd_get_uids</refname>
<refname>sd_get_machine_names</refname>
<refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_get_seats</function></funcdef>
<paramdef>char*** <parameter>seats</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_get_sessions</function></funcdef>
<paramdef>char*** <parameter>sessions</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_get_uids</function></funcdef>
<paramdef>uid_t** <parameter>users</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_get_machine_names</function></funcdef>
<paramdef>char*** <parameter>machines</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_get_seats()</function> may be used
to determine all currently available local
seats. Returns a <constant>NULL</constant> terminated array of seat
identifiers. The returned array and all strings it
references need to be freed with the libc
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use. Note that instead of an empty array
<constant>NULL</constant> may be returned and should be considered
equivalent to an empty array.</para>
<para>Similar, <function>sd_get_sessions()</function> may
be used to determine all current login sessions.</para>
<para>Similar, <function>sd_get_uids()</function> may
be used to determine all Unix users who currently have login sessions.</para>
<para>Similar,
<function>sd_get_machine_names()</function> may be
used to determine all current virtual machines and
containers on the system.</para>
<para>Note that the returned lists are not sorted and in an undefined order.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success <function>sd_get_seats()</function>,
<function>sd_get_sessions()</function>,
<function>sd_get_uids()</function> and
<function>sd_get_machine_names()</function> return the
number of entries in the arrays. On failure, these
calls return a negative errno-style error code.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_get_seats()</function>,
<function>sd_get_sessions()</function>,
<function>sd_get_uids()</function> and
<function>sd_get_machine_names()</function> interfaces
are available as shared library, which can be compiled
and linked to with the
<constant>libsystemd-login</constant>
<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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