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), <literal>active</literal> (user logged in on
  97                 an active seat). In the future additional states might
  98                 be defined, client code should be written to be robust
  99                 in regards to additional state strings being
 100                 returned. The returned string needs to be freed with
 101                 the libc
 102                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 103                 call after use.</para>
 104
 105                 <para><function>sd_uid_is_on_seat()</function> may be
 106                 used to determine whether a specific user is logged in
 107                 or active on a specific seat. Accepts a Unix user
 108                 identifier and a seat identifier string as
 109                 parameters. The <parameter>require_active</parameter>
 110                 parameter is a boolean. If non-zero (true) this
 111                 function will test if the user is active (i.e. has a
 112                 session that is in the foreground and accepting user
 113                 input) on the specified seat, otherwise (false) only
 114                 if the user is logged in (and possibly inactive) on
 115                 the specified seat.</para>
 116
 117                 <para><function>sd_uid_get_sessions()</function> may
 118                 be used to determine the current sessions of the
 119                 specified user. Acceptes a Unix user identifier as
 120                 parameter. The <parameter>require_active</parameter>
 121                 boolean parameter controls whether the returned list
 122                 shall consist of only those sessions where the user is
 123                 currently active (true) or where the user is currently
 124                 logged in at all, possibly inactive (false). The call
 125                 returns a NULL terminated string array of session
 126                 identifiers in <parameter>sessions</parameter> which
 127                 needs to be freed by the caller with the libc
 128                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 129                 call after use, including all the strings
 130                 referenced. If the string array parameter is passed as
 131                 NULL the array will not be filled in, but the return
 132                 code still indicates the number of current
 133                 sessions. Note that instead of an empty array NULL may
 134                 be returned and should be considered equivalent to an
 135                 empty array.</para>
 136
 137                 <para>Similar, <function>sd_uid_get_seats()</function>
 138                 may be used to determine the list of seats on which
 139                 the user currently has sessions. Similar semantics
 140                 apply, however note that the user may have
 141                 multiple sessions on the same seat as well as sessions
 142                 with no attached seat and hence the number of entries
 143                 in the returned array may differ from the one returned
 144                 by <function>sd_uid_get_sessions()</function>.</para>
 145         </refsect1>
 146
 147         <refsect1>
 148                 <title>Return Value</title>
 149
 150                 <para>On success
 151                 <function>sd_uid_get_state()</function> returns 0 or a
 152                 positive integer. If the test succeeds
 153                 <function>sd_uid_is_on_seat()</function> returns a
 154                 positive integer, if it fails
 155                 0. <function>sd_uid_get_sessions()</function> and
 156                 <function>sd_uid_get_seats()</function> return the
 157                 number of entries in the returned arrays. On failure,
 158                 these calls return a negative errno-style error
 159                 code.</para>
 160         </refsect1>
 161
 162         <refsect1>
 163                 <title>Notes</title>
 164
 165                 <para>The <function>sd_uid_get_state()</function>,
 166                 <function>sd_uid_is_on_seat()</function>,
 167                 <function>sd_uid_get_sessions()</function>, and
 168                 <function>sd_uid_get_seats()</function> interfaces are
 169                 available as shared library, which can be compiled and
 170                 linked to with the <literal>libsystemd-login</literal>
 171                 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 172                 file.</para>
 173         </refsect1>
 174
 175         <refsect1>
 176                 <title>See Also</title>
 177
 178                 <para>
 179                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 180                         <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 181                         <citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 182                 </para>
 183         </refsect1>
 184
 185 </refentry>