1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id=
"sd-login">
27 <title>sd-login
</title>
28 <productname>systemd
</productname>
32 <contrib>Developer
</contrib>
33 <firstname>Lennart
</firstname>
34 <surname>Poettering
</surname>
35 <email>lennart@poettering.net
</email>
41 <refentrytitle>sd-login
</refentrytitle>
42 <manvolnum>7</manvolnum>
46 <refname>sd-login
</refname>
48 tracking logins
</refpurpose>
53 <funcsynopsisinfo>#include
<systemd/sd-login.h
></funcsynopsisinfo>
57 <command>pkg-config --cflags --libs libsystemd-login
</command>
62 <title>Description
</title>
64 <para><filename>sd-login.h
</filename> provides APIs to
65 introspect and monitor seat, login session and user
66 status information on the local system.
</para>
69 url=
"http://www.freedesktop.org/wiki/Software/systemd/multiseat">Multi-Seat
70 on Linux
</ulink> for an introduction into multi-seat
71 support on Linux, the background for this set of APIs.
</para>
73 <para>Note that these APIs only allow purely passive access
74 and monitoring of seats, sessions and users. To
75 actively make changes to the seat configuration,
76 terminate login sessions, or switch session on a seat
77 you need to utilize the D-Bus API of
78 systemd-logind, instead.
</para>
80 <para>These functions access data in
81 <filename>/proc
</filename>,
82 <filename>/sys/fs/cgroup
</filename> and
83 <filename>/run
</filename>. All of these are virtual
84 file systems, hence the runtime cost of the accesses
85 is relatively cheap.
</para>
87 <para>If the functions return string arrays, these are
88 generally NULL terminated and need to be freed by the
90 <citerefentry><refentrytitle>free
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
91 call after use, including the strings referenced
92 therein. Similar, individual strings returned need to
93 be freed, as well.
</para>
95 <para>As a special exception, instead of an empty
96 string array NULL may be returned, which should be
97 treated equivalent to an empty string array.
</para>
100 <citerefentry><refentrytitle>sd_pid_get_session
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
101 <citerefentry><refentrytitle>sd_uid_get_state
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
102 <citerefentry><refentrytitle>sd_session_is_active
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
103 <citerefentry><refentrytitle>sd_seat_get_active
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
104 <citerefentry><refentrytitle>sd_get_seats
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
105 <citerefentry><refentrytitle>sd_login_monitor_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
106 for more information about the functions
113 <para>These APIs are implemented as shared library,
114 which can be compiled and linked to with the
115 <literal>libsystemd-login
</literal>
116 <citerefentry><refentrytitle>pkg-config
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
121 <title>See Also
</title>
123 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
124 <citerefentry><refentrytitle>sd_pid_get_session
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
125 <citerefentry><refentrytitle>sd_uid_get_state
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
126 <citerefentry><refentrytitle>sd_session_is_active
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
127 <citerefentry><refentrytitle>sd_seat_get_active
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
128 <citerefentry><refentrytitle>sd_get_seats
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
129 <citerefentry><refentrytitle>sd_login_monitor_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
130 <citerefentry><refentrytitle>sd-daemon
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
131 <citerefentry><refentrytitle>sd-readahead
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
132 <citerefentry><refentrytitle>pkg-config
</refentrytitle><manvolnum>1</manvolnum></citerefentry>