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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_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 — 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></div></div><div class="refsect1"><a name="idp26160"></a><h2>Description</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

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

NULL 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

call after use, including all the strings

referenced. If the string array parameter is passed as

NULL 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 NULL may

be returned and should be considered equivalent to an

empty array.</p><p>Similar, <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></div><div class="refsect1"><a name="idp49552"></a><h2>Return Value</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. On failure,

these calls return a negative errno-style error

code.</p></div><div class="refsect1"><a name="idp53744"></a><h2>Notes</h2><p>The <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> 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="idp59520"></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_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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