man/sd_uid_get_state.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">
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   8   Copyright 2010 Lennart Poettering
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  23
  24 <refentry id="sd_uid_get_state" conditional='HAVE_PAM'>
  25
  26         <refentryinfo>
  27                 <title>sd_uid_get_state</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_uid_get_state</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd_uid_get_state</refname>
  47                 <refname>sd_uid_is_on_seat</refname>
  48                 <refname>sd_uid_get_sessions</refname>
  49                 <refname>sd_uid_get_seats</refname>
  50                 <refpurpose>Determine login state of a specific Unix user ID</refpurpose>
  51         </refnamediv>
  52
  53         <refsynopsisdiv>
  54                 <funcsynopsis>
  55                         <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  56
  57                         <funcprototype>
  58                                 <funcdef>int <function>sd_uid_get_state</function></funcdef>
  59                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  60                                 <paramdef>char** <parameter>state</parameter></paramdef>
  61                         </funcprototype>
  62
  63                         <funcprototype>
  64                                 <funcdef>int <function>sd_uid_is_on_seat</function></funcdef>
  65                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  66                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  67                                 <paramdef>const char* <parameter>seat</parameter></paramdef>
  68                         </funcprototype>
  69
  70                         <funcprototype>
  71                                 <funcdef>int <function>sd_uid_get_sessions</function></funcdef>
  72                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  73                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  74                                 <paramdef>char*** <parameter>sessions</parameter></paramdef>
  75                         </funcprototype>
  76
  77                         <funcprototype>
  78                                 <funcdef>int <function>sd_uid_get_seats</function></funcdef>
  79                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  80                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  81                                 <paramdef>char*** <parameter>seats</parameter></paramdef>
  82                         </funcprototype>
  83                 </funcsynopsis>
  84         </refsynopsisdiv>
  85
  86         <refsect1>
  87                 <title>Description</title>
  88
  89                 <para><function>sd_uid_get_state()</function> may be
  90                 used to determine the login state of a specific Unix
  91                 user identifier. The following states are currently
  92                 known: <literal>offline</literal> (user not logged in
  93                 at all), <literal>lingering</literal> (user not logged
  94                 in, but some user services running),
  95                 <literal>online</literal> (user logged in, but not
  96                 active, i.e. has no session in the foreground),
  97                 <literal>active</literal> (user logged in, and has at
  98                 least one active session, i.e. one session in the
  99                 foreground), <literal>closing</literal> (user not
 100                 logged in, and not lingering, but some processes are
 101                 still around). In the future additional states might
 102                 be defined, client code should be written to be robust
 103                 in regards to additional state strings being
 104                 returned. The returned string needs to be freed with
 105                 the libc
 106                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 107                 call after use.</para>
 108
 109                 <para><function>sd_uid_is_on_seat()</function> may be
 110                 used to determine whether a specific user is logged in
 111                 or active on a specific seat. Accepts a Unix user
 112                 identifier and a seat identifier string as
 113                 parameters. The <parameter>require_active</parameter>
 114                 parameter is a boolean value. If non-zero (true), this
 115                 function will test if the user is active (i.e. has a
 116                 session that is in the foreground and accepting user
 117                 input) on the specified seat, otherwise (false) only
 118                 if the user is logged in (and possibly inactive) on
 119                 the specified seat.</para>
 120
 121                 <para><function>sd_uid_get_sessions()</function> may
 122                 be used to determine the current sessions of the
 123                 specified user. Accepts a Unix user identifier as
 124                 parameter. The <parameter>require_active</parameter>
 125                 parameter controls whether the returned list shall
 126                 consist of only those sessions where the user is
 127                 currently active (&gt; 0), where the user is currently
 128                 online but possibly inactive (= 0), or
 129                 logged in at all but possibly closing the session (&lt; 0). The call returns a
 130                 <constant>NULL</constant> terminated string array of session identifiers in
 131                 <parameter>sessions</parameter> which needs to be
 132                 freed by the caller with the libc
 133                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 134                 call after use, including all the strings
 135                 referenced. If the string array parameter is passed as
 136                 <constant>NULL</constant>, the array will not be filled in, but the return
 137                 code still indicates the number of current
 138                 sessions. Note that instead of an empty array <constant>NULL</constant> may
 139                 be returned and should be considered equivalent to an
 140                 empty array.</para>
 141
 142                 <para>Similar, <function>sd_uid_get_seats()</function>
 143                 may be used to determine the list of seats on which
 144                 the user currently has sessions. Similar semantics
 145                 apply, however note that the user may have
 146                 multiple sessions on the same seat as well as sessions
 147                 with no attached seat and hence the number of entries
 148                 in the returned array may differ from the one returned
 149                 by <function>sd_uid_get_sessions()</function>.</para>
 150         </refsect1>
 151
 152         <refsect1>
 153                 <title>Return Value</title>
 154
 155                 <para>On success
 156                 <function>sd_uid_get_state()</function> returns 0 or a
 157                 positive integer. If the test succeeds,
 158                 <function>sd_uid_is_on_seat()</function> returns a
 159                 positive integer, if it fails
 160                 0. <function>sd_uid_get_sessions()</function> and
 161                 <function>sd_uid_get_seats()</function> return the
 162                 number of entries in the returned arrays. On failure,
 163                 these calls return a negative errno-style error
 164                 code.</para>
 165         </refsect1>
 166
 167         <refsect1>
 168                 <title>Notes</title>
 169
 170                 <para>The <function>sd_uid_get_state()</function>,
 171                 <function>sd_uid_is_on_seat()</function>,
 172                 <function>sd_uid_get_sessions()</function>, and
 173                 <function>sd_uid_get_seats()</function> interfaces are
 174                 available as shared library, which can be compiled and
 175                 linked to with the <constant>libsystemd-login</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 176                 file.</para>
 177         </refsect1>
 178
 179         <refsect1>
 180                 <title>See Also</title>
 181
 182                 <para>
 183                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 184                         <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 185                         <citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 186                 </para>
 187         </refsect1>
 188
 189 </refentry>