Systemd/man/sd_session_is_active.xml

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="sd_session_is_active" conditional='HAVE_PAM'>

        <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_is_remote</refname>
                <refname>sd_session_get_state</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_desktop</refname>
                <refname>sd_session_get_display</refname>
                <refname>sd_session_get_tty</refname>
                <refname>sd_session_get_vt</refname>
                <refname>sd_session_get_remote_host</refname>
                <refname>sd_session_get_remote_user</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_is_remote</function></funcdef>
                                <paramdef>const char *<parameter>session</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_session_get_state</function></funcdef>
                                <paramdef>const char *<parameter>session</parameter></paramdef>
                                <paramdef>char **<parameter>state</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_desktop</function></funcdef>
                                <paramdef>const char *<parameter>session</parameter></paramdef>
                                <paramdef>char **<parameter>desktop</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>

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

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

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

                        <funcprototype>
                                <funcdef>int <function>sd_session_get_vt</function></funcdef>
                                <paramdef>const char *<parameter>session</parameter></paramdef>
                                <paramdef>unsigned int *<parameter>vt</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_is_remote()</function> may
                be used to determine whether the session identified by
                the specified session identifier is a remote session
                (i.e. its remote host is known) or not.</para>

                <para><function>sd_session_get_state()</function> may
                be used to determine the state of the session
                identified by the specified session identifier. The
                following states are currently known:
                <literal>online</literal> (session logged in, but
                session not active, i.e. not in the foreground),
                <literal>active</literal> (session logged in and
                active, i.e. in the foreground),
                <literal>closing</literal> (session nominally logged
                out, but some processes belonging to it 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. This function is a more generic version of
                <function>sd_session_is_active()</function>. The returned
                string needs to be freed with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</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 project='man-pages'><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 project='man-pages'><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>wayland</literal>, <literal>tty</literal>,
                <literal>mir</literal> or <literal>unspecified</literal> and
                needs to be freed with the libc
                <citerefentry project='man-pages'><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>,
                <literal>lock-screen</literal>, or
                <literal>background</literal> and needs to be freed
                with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_desktop()</function> may
                be used to determine the brand of the desktop running on
                the session identified by the specified session identifier.
                This field can be set freely by desktop environments and
                does not follow any special formatting. However, desktops
                are strongly recommended to use the same identifiers and
                capitalization as for
                <varname>$XDG_CURRENT_DESKTOP</varname>, as defined by
                the <ulink
                url="http://standards.freedesktop.org/desktop-entry-spec/latest/">Desktop
                Entry
                Specification</ulink>. The returned string needs to be
                freed with the libc
                <citerefentry project='man-pages'><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 needs to be
                freed with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_remote_host()</function>
                may be used to determine the remote hostname of the
                session identified by the specified session
                identifier. The returned string needs to be
                freed with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_remote_user()</function>
                may be used to determine the remote username of the
                session identified by the specified session
                identifier. The returned string needs to be
                freed with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use. Note that this value is rarely known
                to the system, and even then should not be relied on.</para>

                <para><function>sd_session_get_tty()</function>
                may be used to determine the TTY device of the
                session identified by the specified session
                identifier. The returned string needs to be
                freed with the libc
                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call after use.</para>

                <para><function>sd_session_get_vt()</function>
                may be used to determine the VT number of the
                session identified by the specified session
                identifier. This function will return an error if
                the seat does not support VTs.</para>

                <para>If the <varname>session</varname> parameter of
                any of these functions is passed as
                <constant>NULL</constant>, 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> and
                <function>sd_session_is_remote()</function> return a
                positive integer; if it fails, 0.  On success,
                <function>sd_session_get_state()</function>,
                <function>sd_session_get_uid()</function>,
                <function>sd_session_get_seat()</function>,
                <function>sd_session_get_service()</function>,
                <function>sd_session_get_type()</function>,
                <function>sd_session_get_class()</function>,
                <function>sd_session_get_display()</function>,
                <function>sd_session_get_remote_user()</function>,
                <function>sd_session_get_remote_host()</function> and
                <function>sd_session_get_tty()</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_state()</function>,
                <function>sd_session_get_uid()</function>,
                <function>sd_session_get_seat()</function>,
                <function>sd_session_get_service()</function>,
                <function>sd_session_get_type()</function>,
                <function>sd_session_get_class()</function>,
                <function>sd_session_get_display()</function>,
                <function>sd_session_get_remote_host()</function>,
                <function>sd_session_get_remote_user()</function> and
                <function>sd_session_get_tty()</function>
                interfaces are available as a shared library, which can
                be compiled and linked to with the
                <constant>libsystemd</constant> <citerefentry project='die-net'><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>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_pid_get_session</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>