man/sd_id128_get_machine.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 208</span><hr><div class="refentry"><a name="sd_id128_get_machine"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_id128_get_machine, sd_id128_get_boot — Retrieve 128-bit IDs</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include &lt;systemd/sd-id128.h&gt;</pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_id128_get_machine</b>(</code></td><td>sd_id128_t* <var class="pdparam">ret</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_id128_get_boot</b>(</code></td><td>sd_id128_t* <var class="pdparam">ret</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm274685871200"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_id128_get_machine()</code>
  23                 returns the machine ID of the executing host. This
  24                 reads and parses the
  25                 <a href="machine-id.html"><span class="citerefentry"><span class="refentrytitle">machine-id</span>(5)</span></a>
  26                 file. This function caches the machine ID internally
  27                 to make retrieving the machine ID a cheap
  28                 operation.</p><p><code class="function">sd_id128_get_boot()</code> returns
  29                 the boot ID of the executing kernel. This reads and
  30                 parses the
  31                 <code class="filename">/proc/sys/kernel/random/boot_id</code>
  32                 file exposed by the kernel. It is randomly generated
  33                 early at boot and is unique for every running kernel
  34                 instance. See
  35                 <a href="random.html"><span class="citerefentry"><span class="refentrytitle">random</span>(4)</span></a>
  36                 for more information. This function also internally
  37                 caches the returned ID to make this call a cheap
  38                 operation.</p><p>Note that
  39                 <code class="function">sd_id128_get_boot()</code> always returns
  40                 a UUID v4 compatible
  41                 ID. <code class="function">sd_id128_get_machine()</code> will
  42                 also return a UUID v4-compatible ID on new
  43                 installations but might not on older. It is possible
  44                 to convert the machine ID into a UUID v4-compatible
  45                 one. For more information, see
  46                 <a href="machine-id.html"><span class="citerefentry"><span class="refentrytitle">machine-id</span>(5)</span></a>.</p><p>For more information about the
  47                 "<code class="literal">sd_id128_t</code>" type see
  48                 <a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>.</p></div><div class="refsect1"><a name="idm274689814576"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>The two calls return 0 on success (in which
  49                 case <em class="parameter"><code>ret</code></em> is filled in), or a
  50                 negative errno-style error code.</p></div><div class="refsect1"><a name="idm274689812736"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_id128_get_machine()</code>
  51                 and <code class="function">sd_id128_get_boot()</code>
  52                 interfaces are available as shared library, which can
  53                 be compiled and linked to with the
  54                 "<code class="literal">libsystemd-id128</code>" <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
  55                 file.</p></div><div class="refsect1"><a name="idm274689808400"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  56                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  57                         <a href="sd-id128.html"><span class="citerefentry"><span class="refentrytitle">sd-id128</span>(3)</span></a>,
  58                         <a href="machine-id.html"><span class="citerefentry"><span class="refentrytitle">machine-id</span>(5)</span></a>,
  59                         <a href="random.html"><span class="citerefentry"><span class="refentrytitle">random</span>(4)</span></a>,
  60                         <a href="sd_id128_randomize.html"><span class="citerefentry"><span class="refentrytitle">sd_id128_randomize</span>(3)</span></a>
  61                 </p></div></div></body></html>