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<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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<refentry id="sd_seat_get_active">
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<title>sd_seat_get_active</title>
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<productname>systemd</productname>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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<refentrytitle>sd_seat_get_active</refentrytitle>
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<manvolnum>3</manvolnum>
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<refname>sd_seat_get_active</refname>
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<refname>sd_seat_get_sessions</refname>
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<refname>sd_seat_can_multi_session</refname>
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<refpurpose>Determine state of a specific seat</refpurpose>
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<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
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<funcdef>int <function>sd_seat_get_active</function></funcdef>
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<paramdef>const char* <parameter>seat</parameter></paramdef>
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<paramdef>char** <parameter>session</parameter></paramdef>
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<paramdef>uid_t* <parameter>uid</parameter></paramdef>
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<funcdef>int <function>sd_seat_get_sessions</function></funcdef>
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<paramdef>const char* <parameter>seat</parameter></paramdef>
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<paramdef>char*** <parameter>sessions</parameter></paramdef>
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<paramdef>uid_t** <parameter>uid</parameter></paramdef>
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<paramdef>unsigned* <parameter>n_uids</parameter></paramdef>
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<funcdef>int <function>sd_seat_can_multi_session</function></funcdef>
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<paramdef>const char* <parameter>seat</parameter></paramdef>
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<title>Description</title>
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<para><function>sd_seat_get_active()</function> may be
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used to determine which session is currently active on
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a seat, if there is any. Returns the session
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identifier and the user identifier of the Unix user
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the session is belonging to. Either the session or the
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user identifier parameter can be be passed NULL, in
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case only one of the parameters shall be queried. The
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returned string needs to be freed with the libc
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<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_seat_get_sessions()</function> may
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be used to determine all sessions on the specified
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seat. Returns two arrays, one (NULL terminated) with
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the session identifiers of the sessions and one with
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the user identifiers of the Unix users the sessions
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belong to. An additional parameter may be used to
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return the number of entries in the latter array. The
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two arrays and the latter parameter may be passed as
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NULL in case these values need not to be
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determined. The arrays and the strings referenced by
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them need to be freed with the libc
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<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use. Note that instead of an empty array
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NULL may be returned and should be considered
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equivalent to an empty array.</para>
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<para><function>sd_seat_can_multi_session()</function>
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may be used to determine whether a specific seat is
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capable of multi-session, i.e. allows multiple login
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sessions in parallel (whith only one being active at a
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<para>If the <literal>seat</literal> parameter of any
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of these functions is passed as NULL the operation is
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executed for the seat of the session of the calling
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process, if there is any.</para>
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<title>Return Value</title>
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<function>sd_seat_get_active()</function> return
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return 0 or a positive integer. On success
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<function>sd_seat_get_sessions()</function> returns
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the number of entries in the session identifier
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array. If the test succeeds
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<function>sd_seat_can_multi_session</function> returns
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a positive integer, if it fails 0. On failure, these
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calls return a negative errno-style error code.</para>
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<para>The <function>sd_seat_get_active()</function>,
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<function>sd_seat_get_sessions()</function>, and
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<function>sd_seat_can_multi_session()</function> interfaces
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are available as shared library, which can be compiled
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and linked to with the
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<literal>libsystemd-login</literal>
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<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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<title>See Also</title>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>