man/sd_id128_randomize.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2012 Lennart Poettering
  11 -->
  12
  13 <refentry id="sd_id128_randomize">
  14
  15   <refentryinfo>
  16     <title>sd_id128_randomize</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>Developer</contrib>
  22         <firstname>Lennart</firstname>
  23         <surname>Poettering</surname>
  24         <email>lennart@poettering.net</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>sd_id128_randomize</refentrytitle>
  31     <manvolnum>3</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>sd_id128_randomize</refname>
  36     <refpurpose>Generate 128-bit IDs</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <funcsynopsis>
  41       <funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
  42
  43       <funcprototype>
  44         <funcdef>int <function>sd_id128_randomize</function></funcdef>
  45         <paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
  46       </funcprototype>
  47
  48     </funcsynopsis>
  49   </refsynopsisdiv>
  50
  51   <refsect1>
  52     <title>Description</title>
  53
  54     <para><function>sd_id128_randomize()</function> generates a new
  55     randomized 128-bit ID and returns it in
  56     <parameter>ret</parameter>. Every invocation returns a new
  57     randomly generated ID. This uses the
  58     <filename>/dev/urandom</filename> kernel random number
  59     generator.</para>
  60
  61     <para>Note that <function>sd_id128_randomize()</function> always
  62     returns a UUID v4-compatible ID.</para>
  63
  64     <para>For more information about the <literal>sd_id128_t</literal>
  65     type, see
  66     <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  67
  68     <para><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  69     <option>--new-id128</option> option may be used as a command line
  70     front-end for <function>sd_id128_randomize()</function>.</para>
  71   </refsect1>
  72
  73   <refsect1>
  74     <title>Return Value</title>
  75
  76     <para>The call returns 0 on success (in which case
  77     <parameter>ret</parameter> is filled in), or a negative
  78     errno-style error code.</para>
  79   </refsect1>
  80
  81   <refsect1>
  82     <title>Notes</title>
  83
  84     <para>The <function>sd_id128_randomize()</function> interface is
  85     available as a shared library, which can be compiled and linked to
  86     with the
  87     <literal>libsystemd</literal> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  88     file.</para>
  89   </refsect1>
  90
  91   <refsect1>
  92     <title>See Also</title>
  93
  94     <para>
  95       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  96       <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  97       <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  98       <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
  99       <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 100     </para>
 101   </refsect1>
 102
 103 </refentry>