man/sd_id128_randomize.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8   Copyright 2012 Lennart Poettering
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  23
  24 <refentry id="sd_id128_randomize">
  25
  26         <refentryinfo>
  27                 <title>sd_id128_randomize</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd_id128_randomize</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd_id128_randomize</refname>
  47                 <refpurpose>Generate 128 bit IDs</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <funcsynopsis>
  52                         <funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
  53
  54                         <funcprototype>
  55                                 <funcdef>int <function>sd_id128_randomize</function></funcdef>
  56                                 <paramdef>sd_id128_t* <parameter>ret</parameter></paramdef>
  57                         </funcprototype>
  58
  59                 </funcsynopsis>
  60         </refsynopsisdiv>
  61
  62         <refsect1>
  63                 <title>Description</title>
  64
  65                 <para><function>sd_id128_randomize()</function>
  66                 generates a new randomized 128 bit ID and returns it
  67                 in <parameter>ret</parameter>. Every invocation
  68                 returns a new randomly generated ID. This uses the
  69                 <filename>/dev/urandom</filename> kernel random number
  70                 generator.</para>
  71
  72                 <para>Note that
  73                 <function>sd_id128_randomize()</function> always returns
  74                 a UUID v4 compatible
  75                 ID.</para>
  76
  77                 <para>For more information about the
  78                 <literal>sd_id128_t</literal> type see
  79                 <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  80
  81                 <para><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  82                 <literal>--new-id</literal> command may be used as
  83                 command line front-end for
  84                 <function>sd_id128_randomize()</function>.</para>
  85         </refsect1>
  86
  87         <refsect1>
  88                 <title>Return Value</title>
  89
  90                 <para>The call returns 0 on success (in which
  91                 case <parameter>ret</parameter> is filled in), or a
  92                 negative errno-style error code.</para>
  93         </refsect1>
  94
  95         <refsect1>
  96                 <title>Notes</title>
  97
  98                 <para>The <function>sd_id128_randomize()</function> interface
  99                 is available as shared library, which can be compiled
 100                 and linked to with the
 101                 <literal>libsystemd-id128</literal>
 102                 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 103                 file.</para>
 104         </refsect1>
 105
 106         <refsect1>
 107                 <title>See Also</title>
 108
 109                 <para>
 110                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 111                         <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 112                         <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 113                         <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
 114                         <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 115                 </para>
 116         </refsect1>
 117
 118 </refentry>