man/sd-login.xml

   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">
   4
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   6   This file is part of systemd.
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="sd-login">
  25
  26         <refentryinfo>
  27                 <title>sd-login</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd-login</refentrytitle>
  42                 <manvolnum>7</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd-login</refname>
  47                 <refpurpose>APIs for
  48                 tracking logins</refpurpose>
  49         </refnamediv>
  50
  51         <refsynopsisdiv>
  52                 <funcsynopsis>
  53                         <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  54                 </funcsynopsis>
  55
  56                 <cmdsynopsis>
  57                         <command>pkg-config --cflags --libs libsystemd-login</command>
  58                 </cmdsynopsis>
  59         </refsynopsisdiv>
  60
  61         <refsect1>
  62                 <title>Description</title>
  63
  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>
  67
  68                 <para>See <ulink
  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>
  72
  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>
  79
  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>
  86
  87                 <para>If the functions return string arrays, these are
  88                 generally NULL terminated and need to be freed by the
  89                 caller with the libc
  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>
  94
  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>
  98
  99                 <para>See
 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
 107                 implemented.</para>
 108         </refsect1>
 109
 110         <refsect1>
 111                 <title>Notes</title>
 112
 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>
 117                 file.</para>
 118         </refsect1>
 119
 120         <refsect1>
 121                 <title>See Also</title>
 122                 <para>
 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>
 133                 </para>
 134         </refsect1>
 135
 136 </refentry>