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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" conditional='HAVE_PAM'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_session_is_active</title>
<productname>systemd</productname>
</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 <systemd/sd-login.h></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 (returning
<constant>-ENODATA</constant>) 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>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-ENXIO</constant></term>
<listitem><para>The specified session does not exist.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENODATA</constant></term>
<listitem><para>The given field is not specified for the described
session.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>An input parameter was invalid (out of range,
or NULL, where that is not accepted).</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<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>