man/sd_uid_get_state.xml

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  23
  24 <refentry id="sd_uid_get_state">
  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. 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. Acceptes a Unix user identifier as
 124                 parameter. The <parameter>require_active</parameter>
 125                 boolean parameter controls whether the returned list
 126                 shall consist of only those sessions where the user is
 127                 currently active (true) or where the user is currently
 128                 logged in at all, possibly inactive (false). The call
 129                 returns a NULL terminated string array of session
 130                 identifiers in <parameter>sessions</parameter> which
 131                 needs to be freed by the caller with the libc
 132                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 133                 call after use, including all the strings
 134                 referenced. If the string array parameter is passed as
 135                 NULL the array will not be filled in, but the return
 136                 code still indicates the number of current
 137                 sessions. Note that instead of an empty array NULL may
 138                 be returned and should be considered equivalent to an
 139                 empty array.</para>
 140
 141                 <para>Similar, <function>sd_uid_get_seats()</function>
 142                 may be used to determine the list of seats on which
 143                 the user currently has sessions. Similar semantics
 144                 apply, however note that the user may have
 145                 multiple sessions on the same seat as well as sessions
 146                 with no attached seat and hence the number of entries
 147                 in the returned array may differ from the one returned
 148                 by <function>sd_uid_get_sessions()</function>.</para>
 149         </refsect1>
 150
 151         <refsect1>
 152                 <title>Return Value</title>
 153
 154                 <para>On success
 155                 <function>sd_uid_get_state()</function> returns 0 or a
 156                 positive integer. If the test succeeds
 157                 <function>sd_uid_is_on_seat()</function> returns a
 158                 positive integer, if it fails
 159                 0. <function>sd_uid_get_sessions()</function> and
 160                 <function>sd_uid_get_seats()</function> return the
 161                 number of entries in the returned arrays. On failure,
 162                 these calls return a negative errno-style error
 163                 code.</para>
 164         </refsect1>
 165
 166         <refsect1>
 167                 <title>Notes</title>
 168
 169                 <para>The <function>sd_uid_get_state()</function>,
 170                 <function>sd_uid_is_on_seat()</function>,
 171                 <function>sd_uid_get_sessions()</function>, and
 172                 <function>sd_uid_get_seats()</function> interfaces are
 173                 available as shared library, which can be compiled and
 174                 linked to with the <literal>libsystemd-login</literal>
 175                 <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>7</manvolnum></citerefentry>,
 185                         <citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 186                 </para>
 187         </refsect1>
 188
 189 </refentry>