systemd/man/sd_session_is_active.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "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>
                <refname>sd_session_get_service</refname>
                <refname>sd_session_get_type</refname>
                <refname>sd_session_get_class</refname>
                <refname>sd_session_get_display</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>

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

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

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

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

                <para><function>sd_session_get_service()</function>
                may be used to determine the name of the service (as
                passed during PAM session setup) that registered the
                session identified by the specified session
                identifier. 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_session_get_type()</function> may
                be used to determine the type of the session
                identified by the specified session identifier. The
                returned string is one of <literal>x11</literal>,
                <literal>tty</literal> or
                <literal>unspecified</literal> and needs to be freed
                with the libc
                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_class()</function> may
                be used to determine the class of the session
                identified by the specified session identifier. The
                returned string is one of <literal>user</literal>,
                <literal>greeter</literal> or
                <literal>lock-screen</literal> and needs to be freed
                with the libc
                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_display()</function>
                may be used to determine the X11 display of the
                session identified by the specified session
                identifier. The returned string is one of needs to be
                freed with the libc
                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para>If the <literal>session</literal> parameter of
                any of these functions is passed as NULL the operation
                is executed for the session the calling process is a
                member of, if there is any.</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>,
                <function>sd_session_get_service()</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>,
                <function>sd_session_get_service()</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>