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systemd/man/sd_id128_randomize.xml
2023-12-25 15:51:47 +01:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_id128_randomize" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_id128_randomize</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_id128_randomize</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_id128_randomize</refname>
<refpurpose>Generate 128-bit IDs</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_id128_randomize</function></funcdef>
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_id128_randomize()</function> generates a new randomized 128-bit ID and returns it in
<parameter>ret</parameter>. Every invocation returns a new randomly generated ID. This uses the
<citerefentry
project='man-pages'><refentrytitle>getrandom</refentrytitle><manvolnum>2</manvolnum></citerefentry>
kernel random number generator.</para>
<para>Note that <function>sd_id128_randomize()</function> always returns a UUID Variant 1 Version 4
compatible ID. It is hence guaranteed that this function will never return the ID consisting of all zero
or all one bits (<constant>SD_ID128_NULL</constant>, <constant>SD_ID128_ALLF</constant>).</para>
<para>For more information about the <literal>sd_id128_t</literal>
type, see
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para><citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>new</command> command may be used as a command line front-end for
<function>sd_id128_randomize()</function>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>The call returns 0 on success (in which case
<parameter>ret</parameter> is filled in), or a negative
errno-style error code.</para>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_id128_randomize()</function> was added in version 187.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>getrandom</refentrytitle><manvolnum>2</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>