163 lines
6.4 KiB
XML
163 lines
6.4 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_seat_get_active" conditional='HAVE_PAM'
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_seat_get_active</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_seat_get_active</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_seat_get_active</refname>
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<refname>sd_seat_get_sessions</refname>
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<refname>sd_seat_can_tty</refname>
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<refname>sd_seat_can_graphical</refname>
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<refpurpose>Determine state of a specific seat</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_seat_get_active</function></funcdef>
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<paramdef>const char *<parameter>seat</parameter></paramdef>
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<paramdef>char **<parameter>session</parameter></paramdef>
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<paramdef>uid_t *<parameter>uid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_seat_get_sessions</function></funcdef>
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<paramdef>const char *<parameter>seat</parameter></paramdef>
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<paramdef>char ***<parameter>ret_sessions</parameter></paramdef>
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<paramdef>uid_t **<parameter>ret_uids</parameter></paramdef>
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<paramdef>unsigned int *<parameter>ret_n_uids</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_seat_can_tty</function></funcdef>
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<paramdef>const char *<parameter>seat</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_seat_can_graphical</function></funcdef>
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<paramdef>const char *<parameter>seat</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_seat_get_active()</function> may be used to
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determine which session is currently active on a seat, if there is
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any. Returns the session identifier and the user identifier of the
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Unix user the session is belonging to. Either the session or the
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user identifier parameter can be passed <constant>NULL</constant>,
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in case only one of the parameters shall be queried. The returned
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string needs to be freed with the libc
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<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_seat_get_sessions()</function> may be used to determine all sessions on the specified
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seat. Returns two arrays, one (<constant>NULL</constant> terminated) with the session identifiers of the
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sessions and one with the user identifiers of the Unix users the sessions belong to. An additional
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parameter may be used to return the number of entries in the latter array. This value is the same as the
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return value if the return value is nonnegative. The output parameters may be passed as
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<constant>NULL</constant> in case these output values are not needed. The arrays and the strings
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referenced by them need to be freed with the libc <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry> call after
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use. Note that instead of an empty array <constant>NULL</constant> may be returned and should be
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considered equivalent to an empty array.</para>
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<para><function>sd_seat_can_tty()</function> may be used to
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determine whether a specific seat provides TTY functionality, i.e.
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is useful as a text console.</para>
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<para><function>sd_seat_can_graphical()</function> may be used to
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determine whether a specific seat provides graphics functionality,
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i.e. is useful as a graphics display.</para>
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<para>If the <varname>seat</varname> parameter of any of these
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functions is passed as <constant>NULL</constant>, the operation is
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executed for the seat of the session of the calling process, if
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there is any.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para> On success, <function>sd_seat_get_active()</function> returns 0 or a positive integer. On success,
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<function>sd_seat_get_sessions()</function> returns the number of entries in the session identifier
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array. If the test succeeds,
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<function>sd_seat_can_tty()</function> and <function>sd_seat_can_graphical()</function> return a positive
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integer, if it fails 0. On failure, these calls return a negative errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-ENODATA</constant></term>
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<listitem><para>The given field is not specified for the described seat.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENXIO</constant></term>
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<listitem><para>The specified seat is unknown.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>, where
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that is not accepted).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>History</title>
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<para>In the past, <function>sd_seat_can_multi_session()</function> was used to check whether the seat
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supports multiple sessions. All seats support that now, so that function has been deprecated and always
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returns true.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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