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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 General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_uid_get_state">
<refentryinfo>
<title>sd_uid_get_state</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_uid_get_state</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_uid_get_state</refname>
<refname>sd_uid_is_on_seat</refname>
<refname>sd_uid_get_sessions</refname>
<refname>sd_uid_get_seats</refname>
<refpurpose>Determine login state of a specific Unix user ID</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_uid_get_state</function></funcdef>
<paramdef>uid_t <parameter>uid</parameter></paramdef>
<paramdef>char** <parameter>state</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_uid_is_on_seat</function></funcdef>
<paramdef>uid_t <parameter>uid</parameter></paramdef>
<paramdef>int <parameter>require_active</parameter></paramdef>
<paramdef>const char* <parameter>seat</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_uid_get_sessions</function></funcdef>
<paramdef>uid_t <parameter>uid</parameter></paramdef>
<paramdef>int <parameter>require_active</parameter></paramdef>
<paramdef>char*** <parameter>sessions</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_uid_get_seats</function></funcdef>
<paramdef>uid_t <parameter>uid</parameter></paramdef>
<paramdef>int <parameter>require_active</parameter></paramdef>
<paramdef>char*** <parameter>seats</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_uid_get_state()</function> may be
used to determine the login state of a specific Unix
user identifier. The following states are currently
known: <literal>offline</literal> (user not logged in
at all), <literal>lingering</literal> (user not logged
in, but some user services running),
<literal>online</literal> (user logged in, but not
active), <literal>active</literal> (user logged in on
an active seat). In the future additional states might
be defined, client code should be written to be robust
in regards to additional state strings being
returned. The returned string needs to be freed with
the libc
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para><function>sd_uid_is_on_seat()</function> may be
used to determine whether a specific user is logged in
or active on a specific seat. Accepts a Unix user
identifier and a seat identifier string as
parameters. The <parameter>require_active</parameter>
parameter is a boolean. If non-zero (true) this
function will test if the user is active (i.e. has a
session that is in the foreground and accepting user
input) on the specified seat, otherwise (false) only
if the user is logged in (and possibly inactive) on
the specified seat.</para>
<para><function>sd_uid_get_sessions()</function> may
be used to determine the current sessions of the
specified user. Acceptes a Unix user identifier as
parameter. The <parameter>require_active</parameter>
boolean parameter controls whether the returned list
shall consist of only those sessions where the user is
currently active (true) or where the user is currently
logged in at all, possibly inactive (false). The call
returns a NULL terminated string array of session
identifiers in <parameter>sessions</parameter> which
needs to be freed by the caller with the libc
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use, including all the strings
referenced. If the string array parameter is passed as
NULL the array will not be filled in, but the return
code still indicates the number of current
sessions. Note that instead of an empty array NULL may
be returned and should be considered equivalent to an
empty array.</para>
<para>Similar, <function>sd_uid_get_seats()</function>
may be used to determine the list of seats on which
the user currently has sessions. Similar semantics
apply, however note that the user may have
multiple sessions on the same seat as well as sessions
with no attached seat and hence the number of entries
in the returned array may differ from the one returned
by <function>sd_uid_get_sessions()</function>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success
<function>sd_uid_get_state()</function> returns 0 or a
positive integer. If the test succeeds
<function>sd_uid_is_on_seat()</function> returns a
positive integer, if it fails
0. <function>sd_uid_get_sessions()</function> and
<function>sd_uid_get_seats()</function> return the
number of entries in the returned arrays. On failure,
these calls return a negative errno-style error
code.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_uid_get_state()</function>,
<function>sd_uid_is_on_seat()</function>,
<function>sd_uid_get_sessions()</function>, and
<function>sd_uid_get_seats()</function> interfaces are
available as shared library, which can be compiled and
linked to with the <literal>libsystemd-login</literal>
<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>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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