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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_uid_get_state</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<span style="float:right">systemd 221</span><hr><div class="refentry"><a name="sd_uid_get_state"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_uid_get_state, sd_uid_is_on_seat, sd_uid_get_sessions, sd_uid_get_seats, sd_uid_get_display — Determine login state of a specific Unix user ID</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-login.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_uid_get_state</b>(</code></td><td>uid_t <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">state</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_uid_is_on_seat</b>(</code></td><td>uid_t <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">require_active</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">seat</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_uid_get_sessions</b>(</code></td><td>uid_t <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">require_active</var>, </td></tr><tr><td> </td><td>char ***<var class="pdparam">sessions</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_uid_get_seats</b>(</code></td><td>uid_t <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">require_active</var>, </td></tr><tr><td> </td><td>char ***<var class="pdparam">seats</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_uid_get_display</b>(</code></td><td>uid_t <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">session</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm47054849194608"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_uid_get_state()</code> may be used to
determine the login state of a specific Unix user identifier. The
following states are currently known: "<code class="literal">offline</code>"
(user not logged in at all), "<code class="literal">lingering</code>" (user
not logged in, but some user services running),
"<code class="literal">online</code>" (user logged in, but not active, i.e.
has no session in the foreground), "<code class="literal">active</code>" (user
logged in, and has at least one active session, i.e. one session
in the foreground), "<code class="literal">closing</code>" (user not logged
in, and not lingering, but some processes are still around). In
the future additional states might be defined, client code should
be written to be robust in regards to additional state strings
being returned. The returned string needs to be freed with the
libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use.</p><p><code class="function">sd_uid_is_on_seat()</code> may be used to
determine whether a specific user is logged in or active on a
specific seat. Accepts a Unix user identifier and a seat
identifier string as parameters. The
<em class="parameter"><code>require_active</code></em> parameter is a boolean
value. If non-zero (true), this function will test if the user is
active (i.e. has a session that is in the foreground and accepting
user input) on the specified seat, otherwise (false) only if the
user is logged in (and possibly inactive) on the specified
seat.</p><p><code class="function">sd_uid_get_sessions()</code> may be used to
determine the current sessions of the specified user. Accepts a
Unix user identifier as parameter. The
<em class="parameter"><code>require_active</code></em> parameter controls whether
the returned list shall consist of only those sessions where the
user is currently active (> 0), where the user is currently
online but possibly inactive (= 0), or logged in at all but
possibly closing the session (< 0). The call returns a
<code class="constant">NULL</code> terminated string array of session
identifiers in <em class="parameter"><code>sessions</code></em> which needs to be
freed by the caller with the libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use, including all the strings referenced. If the
string array parameter is passed as <code class="constant">NULL</code>, the
array will not be filled in, but the return code still indicates
the number of current sessions. Note that instead of an empty
array <code class="constant">NULL</code> may be returned and should be
considered equivalent to an empty array.</p><p>Similarly, <code class="function">sd_uid_get_seats()</code> may be
used to determine the list of seats on which the user currently
has sessions. Similar semantics apply, however note that the user
may have multiple sessions on the same seat as well as sessions
with no attached seat and hence the number of entries in the
returned array may differ from the one returned by
<code class="function">sd_uid_get_sessions()</code>.</p><p><code class="function">sd_uid_get_display()</code> returns the name
of the "primary" session of a user. If the user has graphical
sessions, it will be the oldest graphical session. Otherwise, it
will be the oldest open session.</p></div><div class="refsect1"><a name="idm47054849177632"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, <code class="function">sd_uid_get_state()</code> returns
0 or a positive integer. If the test succeeds,
<code class="function">sd_uid_is_on_seat()</code> returns a positive
integer; if it fails, 0.
<code class="function">sd_uid_get_sessions()</code> and
<code class="function">sd_uid_get_seats()</code> return the number of
entries in the returned arrays.
<code class="function">sd_uid_get_display()</code> returns a non-negative
code on success. On failure, these calls return a negative
errno-style error code.</p></div><div class="refsect1"><a name="idm47054849173232"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>Functions described here are available as a shared library,
and can be compiled and linked to using the
<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
entry.</p></div><div class="refsect1"><a name="idm47054849170560"></a><h2 id="History">History<a class="headerlink" title="Permalink to this headline" href="#History">¶</a></h2><p><code class="function">sd_uid_get_state()</code>,
<code class="function">sd_uid_is_on_seat()</code>,
<code class="function">sd_uid_get_sessions()</code>, and
<code class="function">sd_uid_get_seats()</code> functions were added in
systemd-31.</p><p><code class="function">sd_uid_get_display()</code> was added in
systemd-213.</p></div><div class="refsect1"><a name="idm47054849166160"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-login.html"><span class="citerefentry"><span class="refentrytitle">sd-login</span>(3)</span></a>,
<a href="sd_pid_get_owner_uid.html"><span class="citerefentry"><span class="refentrytitle">sd_pid_get_owner_uid</span>(3)</span></a>
</p></div></div></body></html>
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