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3b3d7d069d
Shift the asterisks in the documentation's prototypes such that they are consistent among each other. Use the right side to match what is used in source code. Addendum to commit v209~82.
138 lines
6.0 KiB
XML
138 lines
6.0 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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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_id128_get_machine">
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<refentryinfo>
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<title>sd_id128_get_machine</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_id128_get_machine</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_id128_get_machine</refname>
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<refname>sd_id128_get_boot</refname>
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<refpurpose>Retrieve 128-bit IDs</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_id128_get_machine</function></funcdef>
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<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_id128_get_boot</function></funcdef>
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<paramdef>sd_id128_t *<parameter>ret</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_id128_get_machine()</function>
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returns the machine ID of the executing host. This
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reads and parses the
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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file. This function caches the machine ID internally
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to make retrieving the machine ID a cheap
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operation.</para>
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<para><function>sd_id128_get_boot()</function> returns
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the boot ID of the executing kernel. This reads and
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parses the
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<filename>/proc/sys/kernel/random/boot_id</filename>
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file exposed by the kernel. It is randomly generated
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early at boot and is unique for every running kernel
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instance. See
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<citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>
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for more information. This function also internally
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caches the returned ID to make this call a cheap
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operation.</para>
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<para>Note that
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<function>sd_id128_get_boot()</function> always returns
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a UUID v4 compatible
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ID. <function>sd_id128_get_machine()</function> will
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also return a UUID v4-compatible ID on new
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installations but might not on older. It is possible
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to convert the machine ID into a UUID v4-compatible
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one. For more information, see
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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<para>For more information about the
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<literal>sd_id128_t</literal> type see
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<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>The two calls return 0 on success (in which
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case <parameter>ret</parameter> is filled in), or a
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negative errno-style error code.</para>
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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_id128_get_machine()</function>
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and <function>sd_id128_get_boot()</function>
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interfaces are available as a shared library, which can
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be compiled and linked to with the
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<literal>libsystemd</literal> <citerefentry><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-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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