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[elogind.git] / 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">
4
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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>pid</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>pid</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>pid</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>pid</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>