man: various updates

[thirdparty/systemd.git] / man / sd-login.xml

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

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<refentry id="sd-login">

        <refentryinfo>
                <title>sd-login</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-login</refentrytitle>
                <manvolnum>7</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>sd-login</refname>
                <refpurpose>APIs for
                tracking logins</refpurpose>
        </refnamediv>

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

                <cmdsynopsis>
                        <command>pkg-config --cflags --libs libsystemd-login</command>
                </cmdsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><filename>sd-login.h</filename> provides APIs to
                introspect and monitor seat, login session and user
                status information on the local system. </para>

                <para>See <ulink
                url="http://www.freedesktop.org/wiki/Software/systemd/multiseat">Multi-Seat
                on Linux</ulink> for an introduction into multi-seat
                support on Linux, the background for this set of APIs.</para>

                <para>Note that these APIs only allow purely passive access
                and monitoring of seats, sessions and users. To
                actively make changes to the seat configuration,
                terminate login sessions, or switch session on a seat
                you need to utilize the D-Bus API of
                systemd-logind, instead.</para>

                <para>These functions access data in
                <filename>/proc</filename>,
                <filename>/sys/fs/cgroup</filename> and
                <filename>/run</filename>. All of these are virtual
                file systems, hence the runtime cost of the accesses
                is relatively cheap.</para>

                <para>If the functions return string arrays, these are
                generally NULL terminated and need to be freed by the
                caller with the libc
                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use, including the strings referenced
                therein. Similar, individual strings returned need to
                be freed, as well.</para>

                <para>As a special exception, instead of an empty
                string array NULL may be returned, which should be
                treated equivalent to an empty string array.</para>

                <para>See
                <citerefentry><refentrytitle>sd_pid_get_session</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                <citerefentry><refentrytitle>sd_uid_get_state</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                <citerefentry><refentrytitle>sd_seat_get_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                <citerefentry><refentrytitle>sd_login_monitor_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                for more information about the functions
                implemented.</para>
        </refsect1>

        <refsect1>
                <title>Notes</title>

                <para>These APIs are implemented 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_pid_get_session</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_uid_get_state</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_seat_get_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_login_monitor_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>