systemd/man/sd_session_is_active.xml

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        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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<refentry id="sd_session_is_active">

        <refentryinfo>
                <title>sd_session_is_active</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_session_is_active</refentrytitle>
                <manvolnum>3</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>sd_session_is_active</refname>
                <refname>sd_session_get_uid</refname>
                <refname>sd_session_get_seat</refname>
                <refpurpose>Determine state of a specific session</refpurpose>
        </refnamediv>

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

                        <funcprototype>
                                <funcdef>int <function>sd_session_is_active</function></funcdef>
                                <paramdef>const char* <parameter>session</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_session_get_uid</function></funcdef>
                                <paramdef>const char* <parameter>session</parameter></paramdef>
                                <paramdef>uid_t* <parameter>uid</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_session_get_seat</function></funcdef>
                                <paramdef>const char* <parameter>session</parameter></paramdef>
                                <paramdef>char** <parameter>seat</parameter></paramdef>
                        </funcprototype>
                </funcsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><function>sd_session_is_active()</function> may
                be used to determine whether the session identified by
                the specified session identifier is currently active
                (i.e. currently in the foreground and available for
                user input) or not.</para>

                <para><function>sd_session_get_uid()</function> may be
                used to determine the user identifier of the Unix user the session
                identified by the specified session identifier belongs
                to.</para>

                <para><function>sd_session_get_seat()</function> may
                be used to determine the seat identifier of the seat
                the session identified by the specified session
                identifier belongs to. Note that not all sessions are
                attached to a seat, this call will fail for them. The
                returned string needs to be freed with the libc
                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>
        </refsect1>

        <refsect1>
                <title>Return Value</title>

                <para>If the test succeeds
                <function>sd_session_is_active()</function> returns a
                positive integer, if it fails 0.  On success
                <function>sd_session_get_uid()</function> and
                <function>sd_session_get_seat()</function> return 0 or
                a positive integer. On failure, these calls return a
                negative errno-style error code.</para>
        </refsect1>

        <refsect1>
                <title>Notes</title>

                <para>The <function>sd_session_is_active()</function>,
                <function>sd_session_get_uid()</function>, and
                <function>sd_session_get_seat()</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_session</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>