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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

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<refentry id="sd_uid_get_state">

<refentryinfo>

<title>sd_uid_get_state</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>Developer</contrib>

<firstname>Lennart</firstname>

<surname>Poettering</surname>

<email>lennart@poettering.net</email>

</author>

</authorgroup>

</refentryinfo>

<refmeta>

<refentrytitle>sd_uid_get_state</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_uid_get_state</refname>

<refname>sd_uid_is_on_seat</refname>

<refname>sd_uid_get_sessions</refname>

<refname>sd_uid_get_seats</refname>

<refpurpose>Determine login state of a specific Unix user ID</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>int <function>sd_uid_get_state</function></funcdef>

<paramdef>uid_t <parameter>uid</parameter></paramdef>

<paramdef>char** <parameter>state</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_uid_is_on_seat</function></funcdef>

<paramdef>uid_t <parameter>uid</parameter></paramdef>

<paramdef>int <parameter>require_active</parameter></paramdef>

<paramdef>const char* <parameter>seat</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_uid_get_sessions</function></funcdef>

<paramdef>uid_t <parameter>uid</parameter></paramdef>

<paramdef>int <parameter>require_active</parameter></paramdef>

<paramdef>char*** <parameter>sessions</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_uid_get_seats</function></funcdef>

<paramdef>uid_t <parameter>uid</parameter></paramdef>

<paramdef>int <parameter>require_active</parameter></paramdef>

<paramdef>char*** <parameter>seats</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_uid_get_state()</function> may be

used to determine the login state of a specific Unix

user identifier. The following states are currently

known: <literal>offline</literal> (user not logged in

at all), <literal>lingering</literal> (user not logged

in, but some user services running),

<literal>online</literal> (user logged in, but not

active), <literal>active</literal> (user logged in on

an active seat). 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

<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>

call after use.</para>

<para><function>sd_uid_is_on_seat()</function> 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 <parameter>require_active</parameter>

parameter is a boolean. 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.</para>

<para><function>sd_uid_get_sessions()</function> may

be used to determine the current sessions of the

specified user. Acceptes a Unix user identifier as

parameter. The <parameter>require_active</parameter>

boolean parameter controls whether the returned list

shall consist of only those sessions where the user is

currently active (true) or where the user is currently

logged in at all, possibly inactive (false). The call

returns a NULL terminated string array of session

identifiers in <parameter>sessions</parameter> which

needs to be freed by the caller with the libc

<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>

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.</para>

<para>Similar, <function>sd_uid_get_seats()</function>

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 <function>sd_uid_get_sessions()</function>.</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>On success

<function>sd_uid_get_state()</function> returns 0 or a

positive integer. If the test succeeds

<function>sd_uid_is_on_seat()</function> returns a

positive integer, if it fails

0. <function>sd_uid_get_sessions()</function> and

<function>sd_uid_get_seats()</function> return the

number of entries in the returned arrays. On failure,

these calls return a negative errno-style error

code.</para>

</refsect1>

<refsect1>

<title>Notes</title>

<para>The <function>sd_uid_get_state()</function>,

<function>sd_uid_is_on_seat()</function>,

<function>sd_uid_get_sessions()</function>, and

<function>sd_uid_get_seats()</function> interfaces are

available as shared library, which can be compiled and

linked to with the <literal>libsystemd-login</literal>

<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>

file.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>7</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>