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5d13a15b1d
Double newlines (i.e. one empty lines) are great to structure code. But let's avoid triple newlines (i.e. two empty lines), quadruple newlines, quintuple newlines, …, that's just spurious whitespace. It's an easy way to drop 121 lines of code, and keeps the coding style of our sources a bit tigther.
148 lines
4.7 KiB
XML
148 lines
4.7 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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SPDX-License-Identifier: LGPL-2.1+
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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-->
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<refentry id="sd_get_seats" conditional='HAVE_PAM'>
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<refentryinfo>
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<title>sd_get_seats</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_get_seats</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_get_seats</refname>
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<refname>sd_get_sessions</refname>
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<refname>sd_get_uids</refname>
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<refname>sd_get_machine_names</refname>
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<refpurpose>Determine available seats, sessions, logged in users and virtual machines/containers</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_get_seats</function></funcdef>
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<paramdef>char ***<parameter>seats</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_get_sessions</function></funcdef>
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<paramdef>char ***<parameter>sessions</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_get_uids</function></funcdef>
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<paramdef>uid_t **<parameter>users</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_get_machine_names</function></funcdef>
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<paramdef>char ***<parameter>machines</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_get_seats()</function> may be used to determine
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all currently available local seats. Returns the number of seat
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identifiers and if the input pointer is non-NULL, a
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<constant>NULL</constant>-terminated array of seat identifiers
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is stored at the address.
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The returned array and all strings it references need to be freed
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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. Note that instead of an empty array
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<constant>NULL</constant> may be returned and should be considered
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equivalent to an empty array.</para>
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<para>Similarly, <function>sd_get_sessions()</function> may be
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used to determine all current login sessions.</para>
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<para>Similarly, <function>sd_get_uids()</function> may be used to
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determine all Unix users who currently have login sessions.</para>
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<para>Similarly, <function>sd_get_machine_names()</function> may
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be used to determine all current virtual machines and containers
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on the system.</para>
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<para>Note that the returned lists are not sorted and in an
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undefined order.</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_get_seats()</function>,
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<function>sd_get_sessions()</function>,
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<function>sd_get_uids()</function> and
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<function>sd_get_machine_names()</function> return the number of
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entries in the arrays. On failure, these calls return a negative
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errno-style error code.</para>
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</refsect1>
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<refsect1>
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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>-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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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_get_seats()</function>,
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<function>sd_get_sessions()</function>,
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<function>sd_get_uids()</function> and
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<function>sd_get_machine_names()</function> interfaces are
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available as a shared library, which can be compiled and linked to
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with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</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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