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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> | |
3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
4 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
5 | ||
6 | <!-- | |
7 | This file is part of systemd. | |
8 | ||
9 | Copyright 2010 Lennart Poettering | |
10 | ||
11 | systemd is free software; you can redistribute it and/or modify it | |
12 | under the terms of the GNU General Public License as published by | |
13 | the Free Software Foundation; either version 2 of the License, or | |
14 | (at your option) any later version. | |
15 | ||
16 | systemd is distributed in the hope that it will be useful, but | |
17 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | General Public License for more details. | |
20 | ||
21 | You should have received a copy of the GNU General Public License | |
22 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
23 | --> | |
24 | ||
25 | <refentry id="machine-id"> | |
26 | <refentryinfo> | |
27 | <title>/etc/machine-id</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>machine-id</refentrytitle> | |
42 | <manvolnum>5</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>machine-id</refname> | |
47 | <refpurpose>local machine ID configuration file</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <para><filename>/etc/machine-id</filename></para> | |
52 | </refsynopsisdiv> | |
53 | ||
54 | <refsect1> | |
55 | <title>Description</title> | |
56 | ||
57 | <para>The <filename>/etc/machine-id</filename> file | |
58 | configures the unique machine id of the local system | |
59 | that is set during installation. It should contain a | |
60 | single newline-terminated, hexadecimal, lowercase 16 | |
61 | character machine ID string.</para> | |
62 | ||
63 | <para>The machine ID is usually generated from a | |
64 | random source during system installation and stays | |
65 | constant for all subsequent boots. Optionally, for | |
66 | stateless systems it is generated during runtime at | |
67 | boot.</para> | |
68 | ||
69 | <para>The machine ID does not change based on user | |
70 | configuration, or when hardware is replaced.</para> | |
71 | ||
72 | <para>This machine id follows the same format and | |
73 | logic as the D-Bus machine ID.</para> | |
74 | ||
75 | <para>Programs may use this ID to identify the host | |
76 | with a globally unique ID in the network, that does | |
77 | not change even if the local network configuration | |
78 | changes. Due to this and its greater length it is | |
7640a5de | 79 | a more useful replacement for the |
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80 | <citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
81 | call POSIX specifies.</para> | |
82 | </refsect1> | |
83 | ||
84 | <refsect1> | |
85 | <title>History</title> | |
86 | ||
87 | <para>The simple configuration file format of | |
88 | <filename>/etc/machine-id</filename> originates in the | |
89 | <filename>/var/lib/dbus/machine-id</filename> file | |
90 | introduced by D-Bus. In fact this latter file might be a | |
91 | symlink to the | |
92 | <varname>/etc/machine-id</varname>.</para> | |
93 | </refsect1> | |
94 | ||
95 | <refsect1> | |
96 | <title>See Also</title> | |
97 | <para> | |
98 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
99 | <citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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100 | <citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
101 | <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
102 | <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
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103 | </para> |
104 | </refsect1> | |
105 | ||
106 | </refentry> |