man/sd_seat_get_active.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 218</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, sd_seat_can_tty, sd_seat_can_graphical — Determine state of a specific seat</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include &lt;systemd/sd-login.h&gt;</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 int *<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="idm139917953911264"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_seat_get_active()</code> may be
  23                 used to determine which session is currently active on
  24                 a seat, if there is any. Returns the session
  25                 identifier and the user identifier of the Unix user
  26                 the session is belonging to. Either the session or the
  27                 user identifier parameter can be passed
  28                 <code class="constant">NULL</code>, in case only one of the
  29                 parameters shall be queried. The returned string needs
  30                 to be freed with the libc
  31                 <a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
  32                 call after use.</p><p><code class="function">sd_seat_get_sessions()</code> may
  33                 be used to determine all sessions on the specified
  34                 seat. Returns two arrays, one (<code class="constant">NULL</code> terminated) with
  35                 the session identifiers of the sessions and one with
  36                 the user identifiers of the Unix users the sessions
  37                 belong to. An additional parameter may be used to
  38                 return the number of entries in the latter array. The
  39                 two arrays and the latter parameter may be passed as
  40                 <code class="constant">NULL</code> in case these values need not to be
  41                 determined. The arrays and the strings referenced by
  42                 them need to be freed with the libc
  43                 <a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
  44                 call after use. Note that instead of an empty array
  45                 <code class="constant">NULL</code> may be returned and should be considered
  46                 equivalent to an empty array.</p><p><code class="function">sd_seat_can_multi_session()</code>
  47                 may be used to determine whether a specific seat is
  48                 capable of multi-session, i.e. allows multiple login
  49                 sessions in parallel (with only one being active at a
  50                 time).</p><p><code class="function">sd_seat_can_tty()</code> may be
  51                 used to determine whether a specific seat provides TTY
  52                 functionality, i.e. is useful as a text console.</p><p><code class="function">sd_seat_can_graphical()</code> may
  53                 be used to determine whether a specific seat provides
  54                 graphics functionality, i.e. is useful as a graphics
  55                 display.</p><p>If the <code class="varname">seat</code> parameter of any
  56                 of these functions is passed as
  57                 <code class="constant">NULL</code>, the operation is executed
  58                 for the seat of the session of the calling process, if
  59                 there is any.</p></div><div class="refsect1"><a name="idm139917953898624"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p> On success,
  60                 <code class="function">sd_seat_get_active()</code>
  61                 returns 0 or a positive integer. On success,
  62                 <code class="function">sd_seat_get_sessions()</code> returns
  63                 the number of entries in the session identifier
  64                 array. If the test succeeds,
  65                 <code class="function">sd_seat_can_multi_session</code>,
  66                 <code class="function">sd_seat_can_tty</code> and
  67                 <code class="function">sd_seat_can_graphical</code> return a
  68                 positive integer, if it fails 0. On failure, these
  69                 calls return a negative errno-style error code.</p></div><div class="refsect1"><a name="idm139917953886240"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_seat_get_active()</code>,
  70                 <code class="function">sd_seat_get_sessions()</code>,
  71                 <code class="function">sd_seat_can_multi_session()</code>,
  72                 <code class="function">sd_seat_can_tty()</code> and
  73                 <code class="function">sd_seat_can_grapical()</code> interfaces
  74                 are available as a shared library, which can be compiled
  75                 and linked to with the
  76                 <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>
  77                 file.</p></div><div class="refsect1"><a name="idm139917953879680"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  78                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  79                         <a href="sd-login.html"><span class="citerefentry"><span class="refentrytitle">sd-login</span>(3)</span></a>,
  80                         <a href="sd_session_get_seat.html"><span class="citerefentry"><span class="refentrytitle">sd_session_get_seat</span>(3)</span></a>
  81                 </p></div></div></body></html>