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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 202</span><hr><div class="refentry"><a name="sd_seat_get_active"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_seat_get_active, sd_seat_get_sessions, sd_seat_can_multi_session — Determine state of a specific seat</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_seat_get_active</b>(</code></td><td>const char* <var class="pdparam">seat</var>, </td></tr><tr><td> </td><td>char** <var class="pdparam">session</var>, </td></tr><tr><td> </td><td>uid_t* <var class="pdparam">uid</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_seat_get_sessions</b>(</code></td><td>const char* <var class="pdparam">seat</var>, </td></tr><tr><td> </td><td>char*** <var class="pdparam">sessions</var>, </td></tr><tr><td> </td><td>uid_t** <var class="pdparam">uid</var>, </td></tr><tr><td> </td><td>unsigned* <var class="pdparam">n_uids</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_seat_can_multi_session</b>(</code></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_seat_can_tty</b>(</code></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_seat_can_graphical</b>(</code></td><td>const char* <var class="pdparam">seat</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idp26160"></a><h2>Description</h2><p><code class="function">sd_seat_get_active()</code> may be

used to determine which session is currently active on

a seat, if there is any. Returns the session

identifier and the user identifier of the Unix user

the session is belonging to. Either the session or the

user identifier parameter can be passed NULL, in

case only one of the parameters shall be queried. The

returned string needs to be freed with the libc

call after use.</p><p><code class="function">sd_seat_get_sessions()</code> may

be used to determine all sessions on the specified

seat. Returns two arrays, one (NULL terminated) with

the session identifiers of the sessions and one with

the user identifiers of the Unix users the sessions

belong to. An additional parameter may be used to

return the number of entries in the latter array. The

two arrays and the latter parameter may be passed as

NULL in case these values need not to be

determined. The arrays and the strings referenced by

them need to be freed with the libc

call after use. Note that instead of an empty array

NULL may be returned and should be considered

equivalent to an empty array.</p><p><code class="function">sd_seat_can_multi_session()</code>

may be used to determine whether a specific seat is

capable of multi-session, i.e. allows multiple login

sessions in parallel (with only one being active at a

time).</p><p><code class="function">sd_seat_can_tty()</code> may be

used to determine whether a specific seat provides TTY

functionality, i.e. is useful as a text console.</p><p><code class="function">sd_seat_can_graphical()</code> may

be used to determine whether a specific seat provides

graphics functionality, i.e. is useful as a graphics

display.</p><p>If the <code class="literal">seat</code> parameter of any

of these functions is passed as NULL the operation is

executed for the seat of the session of the calling

process, if there is any.</p></div><div class="refsect1"><a name="idp36592"></a><h2>Return Value</h2><p> On success

<code class="function">sd_seat_get_active()</code>

returns 0 or a positive integer. On success

<code class="function">sd_seat_get_sessions()</code> returns

the number of entries in the session identifier

array. If the test succeeds

<code class="function">sd_seat_can_multi_session</code>,

<code class="function">sd_seat_can_tty</code> and

<code class="function">sd_seat_can_graphical</code> return a

positive integer, if it fails 0. On failure, these

calls return a negative errno-style error code.</p></div><div class="refsect1"><a name="idp49008"></a><h2>Notes</h2><p>The <code class="function">sd_seat_get_active()</code>,

<code class="function">sd_seat_get_sessions()</code>,

<code class="function">sd_seat_can_multi_session()</code>,

<code class="function">sd_seat_can_tty()</code> and

<code class="function">sd_seat_can_grapical()</code> interfaces

are available as shared library, which can be compiled

and linked to with the

<code class="literal">libsystemd-login</code>

<a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>

file.</p></div><div class="refsect1"><a name="idp55488"></a><h2>See Also</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_session_get_seat.html"><span class="citerefentry"><span class="refentrytitle">sd_session_get_seat</span>(3)</span></a>

</p></div></div></body></html>

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