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d7ccca2e3f
This is supposed to play the same roles /var/lib/dbus/machine-id, however fixes a couple of problems: - It is available during early boot since it is stored in /etc - Removes the ID from the D-Bus context and moves it into a system context, thus hopefully lowering hesitation by people to use it. - It is generated at installation time. If the file is empty at boot time it will be mounted over with a randomly generated ID, which is not saved to disk. This is useful to support state-less machines with no transient or writable /etc configuration.
105 lines
4.2 KiB
XML
105 lines
4.2 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="machine-id">
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<refentryinfo>
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<title>/etc/machine-id</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>machine-id</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>machine-id</refname>
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<refpurpose>local machine ID configuration file</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/etc/machine-id</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>The <filename>/etc/machine-id</filename> file
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configures the unique machine id of the local system
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that is set during installation. It should contain a
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single newline-terminated, hexadecimal, lowercase 16
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character machine ID string.</para>
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<para>The machine ID is usually generated from a
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random source during system installation and stays
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constant for all subsequent boots. Optionally, for
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stateless systems it is generated during runtime at
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boot.</para>
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<para>The machine ID does not change based on user
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configuration, or when hardware is replaced.</para>
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<para>This machine id follows the same format and
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logic as the D-Bus machine ID.</para>
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<para>Programs may use this ID to identify the host
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with a globally unique ID in the network, that does
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not change even if the local network configuration
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changes. Due to this and its greater length it is
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a more useful replacement than the
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<citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call POSIX specifies.</para>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para>The simple configuration file format of
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<filename>/etc/machine-id</filename> originates in the
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<filename>/var/lib/dbus/machine-id</filename> file
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introduced by D-Bus. In fact this latter file might be a
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symlink to the
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<varname>/etc/machine-id</varname>.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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