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systemd/man/machine-id.xml
Lennart Poettering 811ad2b3a4 man: minor fixes
2011-04-21 01:18:23 +02:00

107 lines
4.5 KiB
XML

<?xml version='1.0'?> <!--*-nxml-*-->
<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
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Copyright 2010 Lennart Poettering
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<refentry id="machine-id">
<refentryinfo>
<title>/etc/machine-id</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>machine-id</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>machine-id</refname>
<refpurpose>local machine ID configuration file</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/etc/machine-id</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>The <filename>/etc/machine-id</filename> file
configures the unique machine id of the local system
that is set during installation. It should contain a
single newline-terminated, hexadecimal, lowercase 16
character machine ID string.</para>
<para>The machine ID is usually generated from a
random source during system installation and stays
constant for all subsequent boots. Optionally, for
stateless systems it is generated during runtime at
boot if it is found to be empty.</para>
<para>The machine ID does not change based on user
configuration, or when hardware is replaced.</para>
<para>This machine id follows the same format and
logic as the D-Bus machine ID.</para>
<para>Programs may use this ID to identify the host
with a globally unique ID in the network, that does
not change even if the local network configuration
changes. Due to this and its greater length it is
a more useful replacement for the
<citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call POSIX specifies.</para>
</refsect1>
<refsect1>
<title>History</title>
<para>The simple configuration file format of
<filename>/etc/machine-id</filename> originates in the
<filename>/var/lib/dbus/machine-id</filename> file
introduced by D-Bus. In fact this latter file might be a
symlink to the
<varname>/etc/machine-id</varname>.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>