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   This file is part of systemd.
   7
   8   Copyright 2012 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  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> generates a new
  66     randomized 128-bit ID and returns it in
  67     <parameter>ret</parameter>. Every invocation returns a new
  68     randomly generated ID. This uses the
  69     <filename>/dev/urandom</filename> kernel random number
  70     generator.</para>
  71
  72     <para>Note that <function>sd_id128_randomize()</function> always
  73     returns a UUID v4-compatible ID.</para>
  74
  75     <para>For more information about the <literal>sd_id128_t</literal>
  76     type, see
  77     <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  78
  79     <para><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
  80     <option>--new-id</option> option may be used as a command line
  81     front-end for <function>sd_id128_randomize()</function>.</para>
  82   </refsect1>
  83
  84   <refsect1>
  85     <title>Return Value</title>
  86
  87     <para>The call returns 0 on success (in which case
  88     <parameter>ret</parameter> is filled in), or a negative
  89     errno-style error code.</para>
  90   </refsect1>
  91
  92   <refsect1>
  93     <title>Notes</title>
  94
  95     <para>The <function>sd_id128_randomize()</function> interface is
  96     available as a shared library, which can be compiled and linked to
  97     with the
  98     <literal>libsystemd</literal> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  99     file.</para>
 100   </refsect1>
 101
 102   <refsect1>
 103     <title>See Also</title>
 104
 105     <para>
 106       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 107       <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 108       <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 109       <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
 110       <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 111     </para>
 112   </refsect1>
 113
 114 </refentry>