man/sd_uid_get_state.xml

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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                 <refname>sd_uid_get_display</refname>
  51                 <refpurpose>Determine login state of a specific Unix user ID</refpurpose>
  52         </refnamediv>
  53
  54         <refsynopsisdiv>
  55                 <funcsynopsis>
  56                         <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  57
  58                         <funcprototype>
  59                                 <funcdef>int <function>sd_uid_get_state</function></funcdef>
  60                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  61                                 <paramdef>char **<parameter>state</parameter></paramdef>
  62                         </funcprototype>
  63
  64                         <funcprototype>
  65                                 <funcdef>int <function>sd_uid_is_on_seat</function></funcdef>
  66                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  67                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  68                                 <paramdef>const char *<parameter>seat</parameter></paramdef>
  69                         </funcprototype>
  70
  71                         <funcprototype>
  72                                 <funcdef>int <function>sd_uid_get_sessions</function></funcdef>
  73                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  74                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  75                                 <paramdef>char ***<parameter>sessions</parameter></paramdef>
  76                         </funcprototype>
  77
  78                         <funcprototype>
  79                                 <funcdef>int <function>sd_uid_get_seats</function></funcdef>
  80                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  81                                 <paramdef>int <parameter>require_active</parameter></paramdef>
  82                                 <paramdef>char ***<parameter>seats</parameter></paramdef>
  83                         </funcprototype>
  84
  85                         <funcprototype>
  86                                 <funcdef>int <function>sd_uid_get_display</function></funcdef>
  87                                 <paramdef>uid_t <parameter>uid</parameter></paramdef>
  88                                 <paramdef>char **<parameter>session</parameter></paramdef>
  89                         </funcprototype>
  90                 </funcsynopsis>
  91         </refsynopsisdiv>
  92
  93         <refsect1>
  94                 <title>Description</title>
  95
  96                 <para><function>sd_uid_get_state()</function> may be
  97                 used to determine the login state of a specific Unix
  98                 user identifier. The following states are currently
  99                 known: <literal>offline</literal> (user not logged in
 100                 at all), <literal>lingering</literal> (user not logged
 101                 in, but some user services running),
 102                 <literal>online</literal> (user logged in, but not
 103                 active, i.e. has no session in the foreground),
 104                 <literal>active</literal> (user logged in, and has at
 105                 least one active session, i.e. one session in the
 106                 foreground), <literal>closing</literal> (user not
 107                 logged in, and not lingering, but some processes are
 108                 still around). In the future additional states might
 109                 be defined, client code should be written to be robust
 110                 in regards to additional state strings being
 111                 returned. The returned string needs to be freed with
 112                 the libc
 113                 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 114                 call after use.</para>
 115
 116                 <para><function>sd_uid_is_on_seat()</function> may be
 117                 used to determine whether a specific user is logged in
 118                 or active on a specific seat. Accepts a Unix user
 119                 identifier and a seat identifier string as
 120                 parameters. The <parameter>require_active</parameter>
 121                 parameter is a boolean value. If non-zero (true), this
 122                 function will test if the user is active (i.e. has a
 123                 session that is in the foreground and accepting user
 124                 input) on the specified seat, otherwise (false) only
 125                 if the user is logged in (and possibly inactive) on
 126                 the specified seat.</para>
 127
 128                 <para><function>sd_uid_get_sessions()</function> may
 129                 be used to determine the current sessions of the
 130                 specified user. Accepts a Unix user identifier as
 131                 parameter. The <parameter>require_active</parameter>
 132                 parameter controls whether the returned list shall
 133                 consist of only those sessions where the user is
 134                 currently active (&gt; 0), where the user is currently
 135                 online but possibly inactive (= 0), or
 136                 logged in at all but possibly closing the session (&lt; 0). The call returns a
 137                 <constant>NULL</constant> terminated string array of session identifiers in
 138                 <parameter>sessions</parameter> which needs to be
 139                 freed by the caller with the libc
 140                 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 141                 call after use, including all the strings
 142                 referenced. If the string array parameter is passed as
 143                 <constant>NULL</constant>, the array will not be filled in, but the return
 144                 code still indicates the number of current
 145                 sessions. Note that instead of an empty array <constant>NULL</constant> may
 146                 be returned and should be considered equivalent to an
 147                 empty array.</para>
 148
 149                 <para>Similarly, <function>sd_uid_get_seats()</function>
 150                 may be used to determine the list of seats on which
 151                 the user currently has sessions. Similar semantics
 152                 apply, however note that the user may have
 153                 multiple sessions on the same seat as well as sessions
 154                 with no attached seat and hence the number of entries
 155                 in the returned array may differ from the one returned
 156                 by <function>sd_uid_get_sessions()</function>.</para>
 157
 158                 <para><function>sd_uid_get_display()</function>
 159                 returns the name of the "primary" session of a user.
 160                 If the user has graphical sessions, it will be the
 161                 oldest graphical session. Otherwise, it will be the
 162                 oldest open session.</para>
 163         </refsect1>
 164
 165         <refsect1>
 166                 <title>Return Value</title>
 167
 168                 <para>On success,
 169                 <function>sd_uid_get_state()</function> returns 0 or a
 170                 positive integer. If the test succeeds,
 171                 <function>sd_uid_is_on_seat()</function> returns a
 172                 positive integer; if it fails,
 173                 0. <function>sd_uid_get_sessions()</function> and
 174                 <function>sd_uid_get_seats()</function> return the
 175                 number of entries in the returned arrays.
 176                 <function>sd_uid_get_display()</function> returns
 177                 a non-negative code on success. On failure,
 178                 these calls return a negative errno-style error
 179                 code.</para>
 180         </refsect1>
 181
 182         <refsect1>
 183                 <title>Notes</title>
 184
 185                 <para>Functions described here are available as a
 186                 shared library, and can be compiled and linked to
 187                 using the
 188                 <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 189                 entry.</para>
 190         </refsect1>
 191
 192         <refsect1>
 193                 <title>History</title>
 194
 195                 <function>sd_uid_get_state()</function>,
 196                 <function>sd_uid_is_on_seat()</function>,
 197                 <function>sd_uid_get_sessions()</function>,
 198                 and <function>sd_uid_get_seats()</function> functions
 199                 were added in systemd-31.
 200
 201                 <para><function>sd_uid_get_display()</function> was
 202                 added in systemd-213.</para>
 203         </refsect1>
 204
 205         <refsect1>
 206                 <title>See Also</title>
 207
 208                 <para>
 209                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 210                         <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 211                         <citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 212                 </para>
 213         </refsect1>
 214
 215 </refentry>