<?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>