man/sd_get_seats.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
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright 2010 Lennart Poettering
   9 -->
  10
  11 <refentry id="sd_get_seats" conditional='HAVE_PAM'
  12           xmlns:xi="http://www.w3.org/2001/XInclude">
  13
  14   <refentryinfo>
  15     <title>sd_get_seats</title>
  16     <productname>systemd</productname>
  17
  18     <authorgroup>
  19       <author>
  20         <contrib>Developer</contrib>
  21         <firstname>Lennart</firstname>
  22         <surname>Poettering</surname>
  23         <email>lennart@poettering.net</email>
  24       </author>
  25     </authorgroup>
  26   </refentryinfo>
  27
  28   <refmeta>
  29     <refentrytitle>sd_get_seats</refentrytitle>
  30     <manvolnum>3</manvolnum>
  31   </refmeta>
  32
  33   <refnamediv>
  34     <refname>sd_get_seats</refname>
  35     <refname>sd_get_sessions</refname>
  36     <refname>sd_get_uids</refname>
  37     <refname>sd_get_machine_names</refname>
  38     <refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <funcsynopsis>
  43       <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  44
  45       <funcprototype>
  46         <funcdef>int <function>sd_get_seats</function></funcdef>
  47         <paramdef>char ***<parameter>seats</parameter></paramdef>
  48       </funcprototype>
  49
  50       <funcprototype>
  51         <funcdef>int <function>sd_get_sessions</function></funcdef>
  52         <paramdef>char ***<parameter>sessions</parameter></paramdef>
  53       </funcprototype>
  54
  55       <funcprototype>
  56         <funcdef>int <function>sd_get_uids</function></funcdef>
  57         <paramdef>uid_t **<parameter>users</parameter></paramdef>
  58       </funcprototype>
  59
  60       <funcprototype>
  61         <funcdef>int <function>sd_get_machine_names</function></funcdef>
  62         <paramdef>char ***<parameter>machines</parameter></paramdef>
  63       </funcprototype>
  64
  65     </funcsynopsis>
  66   </refsynopsisdiv>
  67
  68   <refsect1>
  69     <title>Description</title>
  70
  71     <para><function>sd_get_seats()</function> may be used to determine
  72     all currently available local seats. Returns the number of seat
  73     identifiers and if the input pointer is non-NULL, a
  74     <constant>NULL</constant>-terminated array of seat identifiers
  75     is stored at the address.
  76     The returned array and all strings it references need to be freed
  77     with the libc
  78     <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  79     call after use. Note that instead of an empty array
  80     <constant>NULL</constant> may be returned and should be considered
  81     equivalent to an empty array.</para>
  82
  83     <para>Similarly, <function>sd_get_sessions()</function> may be
  84     used to determine all current login sessions.</para>
  85
  86     <para>Similarly, <function>sd_get_uids()</function> may be used to
  87     determine all Unix users who currently have login sessions.</para>
  88
  89     <para>Similarly, <function>sd_get_machine_names()</function> may
  90     be used to determine all current virtual machines and containers
  91     on the system.</para>
  92
  93     <para>Note that the returned lists are not sorted and in an
  94     undefined order.</para>
  95   </refsect1>
  96
  97   <refsect1>
  98     <title>Return Value</title>
  99
 100     <para>On success, <function>sd_get_seats()</function>,
 101     <function>sd_get_sessions()</function>,
 102     <function>sd_get_uids()</function> and
 103     <function>sd_get_machine_names()</function> return the number of
 104     entries in the arrays. On failure, these calls return a negative
 105     errno-style error code.</para>
 106   </refsect1>
 107
 108   <refsect1>
 109     <title>Errors</title>
 110
 111     <para>Returned errors may indicate the following problems:</para>
 112
 113     <variablelist>
 114
 115       <varlistentry>
 116         <term><constant>-ENOMEM</constant></term>
 117
 118         <listitem><para>Memory allocation failed.</para></listitem>
 119       </varlistentry>
 120     </variablelist>
 121   </refsect1>
 122
 123   <xi:include href="libsystemd-pkgconfig.xml" />
 124
 125   <refsect1>
 126     <title>See Also</title>
 127
 128     <para>
 129       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 130       <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 131       <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 132     </para>
 133   </refsect1>
 134
 135 </refentry>