man/sd_get_seats.xml

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  10   Copyright 2010 Lennart Poettering
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  25
  26 <refentry id="sd_get_seats" conditional='HAVE_PAM'>
  27
  28   <refentryinfo>
  29     <title>sd_get_seats</title>
  30     <productname>systemd</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Lennart</firstname>
  36         <surname>Poettering</surname>
  37         <email>lennart@poettering.net</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>sd_get_seats</refentrytitle>
  44     <manvolnum>3</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>sd_get_seats</refname>
  49     <refname>sd_get_sessions</refname>
  50     <refname>sd_get_uids</refname>
  51     <refname>sd_get_machine_names</refname>
  52     <refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers</refpurpose>
  53   </refnamediv>
  54
  55   <refsynopsisdiv>
  56     <funcsynopsis>
  57       <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  58
  59       <funcprototype>
  60         <funcdef>int <function>sd_get_seats</function></funcdef>
  61         <paramdef>char ***<parameter>seats</parameter></paramdef>
  62       </funcprototype>
  63
  64       <funcprototype>
  65         <funcdef>int <function>sd_get_sessions</function></funcdef>
  66         <paramdef>char ***<parameter>sessions</parameter></paramdef>
  67       </funcprototype>
  68
  69       <funcprototype>
  70         <funcdef>int <function>sd_get_uids</function></funcdef>
  71         <paramdef>uid_t **<parameter>users</parameter></paramdef>
  72       </funcprototype>
  73
  74       <funcprototype>
  75         <funcdef>int <function>sd_get_machine_names</function></funcdef>
  76         <paramdef>char ***<parameter>machines</parameter></paramdef>
  77       </funcprototype>
  78
  79     </funcsynopsis>
  80   </refsynopsisdiv>
  81
  82   <refsect1>
  83     <title>Description</title>
  84
  85     <para><function>sd_get_seats()</function> may be used to determine
  86     all currently available local seats. Returns the number of seat
  87     identifiers and if the input pointer is non-NULL, a
  88     <constant>NULL</constant>-terminated array of seat identifiers
  89     is stored at the address.
  90     The returned array and all strings it references need to be freed
  91     with the libc
  92     <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  93     call after use. Note that instead of an empty array
  94     <constant>NULL</constant> may be returned and should be considered
  95     equivalent to an empty array.</para>
  96
  97     <para>Similarly, <function>sd_get_sessions()</function> may be
  98     used to determine all current login sessions.</para>
  99
 100     <para>Similarly, <function>sd_get_uids()</function> may be used to
 101     determine all Unix users who currently have login sessions.</para>
 102
 103     <para>Similarly, <function>sd_get_machine_names()</function> may
 104     be used to determine all current virtual machines and containers
 105     on the system.</para>
 106
 107     <para>Note that the returned lists are not sorted and in an
 108     undefined order.</para>
 109   </refsect1>
 110
 111   <refsect1>
 112     <title>Return Value</title>
 113
 114     <para>On success, <function>sd_get_seats()</function>,
 115     <function>sd_get_sessions()</function>,
 116     <function>sd_get_uids()</function> and
 117     <function>sd_get_machine_names()</function> return the number of
 118     entries in the arrays. On failure, these calls return a negative
 119     errno-style error code.</para>
 120   </refsect1>
 121
 122
 123   <refsect1>
 124     <title>Errors</title>
 125
 126     <para>Returned errors may indicate the following problems:</para>
 127
 128     <variablelist>
 129
 130       <varlistentry>
 131         <term><constant>-ENOMEM</constant></term>
 132
 133         <listitem><para>Memory allocation failed.</para></listitem>
 134       </varlistentry>
 135     </variablelist>
 136   </refsect1>
 137
 138   <refsect1>
 139     <title>Notes</title>
 140
 141     <para>The <function>sd_get_seats()</function>,
 142     <function>sd_get_sessions()</function>,
 143     <function>sd_get_uids()</function> and
 144     <function>sd_get_machine_names()</function> interfaces are
 145     available as a shared library, which can be compiled and linked to
 146     with the
 147     <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 148     file.</para>
 149   </refsect1>
 150
 151   <refsect1>
 152     <title>See Also</title>
 153
 154     <para>
 155       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 156       <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 157       <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 158     </para>
 159   </refsect1>
 160
 161 </refentry>