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  <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 215</span><hr><div class="refentry"><a name="sd_get_seats"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_get_seats, sd_get_sessions, sd_get_uids, sd_get_machine_names — Determine available seats, sessions, logged in users and virtual machines/containers</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_get_seats</b>(</code></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_get_sessions</b>(</code></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_get_uids</b>(</code></td><td>uid_t **<var class="pdparam">users</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_get_machine_names</b>(</code></td><td>char ***<var class="pdparam">machines</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214188979664"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description"></a></h2><p><code class="function">sd_get_seats()</code> may be used
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                to determine all currently available local
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                seats. Returns a <code class="constant">NULL</code> terminated array of seat
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                identifiers. The returned array and all strings it
                references need to be freed with the libc
                <a href="free.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
                call after use. Note that instead of an empty array
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                <code class="constant">NULL</code> may be returned and should be considered
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                equivalent to an empty array.</p><p>Similarly, <code class="function">sd_get_sessions()</code> may
                be used to determine all current login sessions.</p><p>Similarly, <code class="function">sd_get_uids()</code> may
                be used to determine all Unix users who currently have login sessions.</p><p>Similarly,
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                <code class="function">sd_get_machine_names()</code> may be
                used to determine all current virtual machines and
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                containers on the system.</p><p>Note that the returned lists are not sorted and in an undefined order.</p></div><div class="refsect1"><a name="idm214188972032"></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_get_seats()</code>,
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                <code class="function">sd_get_sessions()</code>,
                <code class="function">sd_get_uids()</code> and
                <code class="function">sd_get_machine_names()</code> return the
                number of entries in the arrays. On failure, these
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                calls return a negative errno-style error code.</p></div><div class="refsect1"><a name="idm214188967808"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes"></a></h2><p>The <code class="function">sd_get_seats()</code>,
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                <code class="function">sd_get_sessions()</code>,
                <code class="function">sd_get_uids()</code> and
                <code class="function">sd_get_machine_names()</code> interfaces
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                are available as a shared library, which can be compiled
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                and linked to with the
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                <code class="constant">libsystemd</code> <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
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                file.</p></div><div class="refsect1"><a name="idm214192866880"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also"></a></h2><p>
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                        <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>