]>
Commit | Line | Data |
---|---|---|
2a5a41e8 DR |
1 | <?xml version="1.0"?> |
2 | <!--*-nxml-*--> | |
12b42c76 | 3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
2a5a41e8 | 4 | <!-- |
572eb058 ZJS |
5 | SPDX-License-Identifier: LGPL-2.1+ |
6 | ||
96b2fb93 | 7 | Copyright © 2014 Didier Roche |
2a5a41e8 DR |
8 | --> |
9 | <refentry id="systemd-machine-id-commit.service"> | |
10 | ||
798d3a52 ZJS |
11 | <refentryinfo> |
12 | <title>systemd-machine-id-commit.service</title> | |
13 | <productname>systemd</productname> | |
798d3a52 ZJS |
14 | </refentryinfo> |
15 | ||
16 | <refmeta> | |
17 | <refentrytitle>systemd-machine-id-commit.service</refentrytitle> | |
18 | <manvolnum>8</manvolnum> | |
19 | </refmeta> | |
20 | ||
21 | <refnamediv> | |
22 | <refname>systemd-machine-id-commit.service</refname> | |
a8eaaee7 | 23 | <refpurpose>Commit a transient machine ID to disk</refpurpose> |
798d3a52 ZJS |
24 | </refnamediv> |
25 | ||
26 | <refsynopsisdiv> | |
27 | <para><filename>systemd-machine-id-commit.service</filename></para> | |
798d3a52 ZJS |
28 | </refsynopsisdiv> |
29 | ||
30 | <refsect1> | |
31 | <title>Description</title> | |
32 | ||
4a9b1dd4 | 33 | <para><filename>systemd-machine-id-commit.service</filename> is an |
b938cb90 | 34 | early boot service responsible for committing transient |
4a9b1dd4 | 35 | <filename>/etc/machine-id</filename> files to a writable disk file |
798d3a52 ZJS |
36 | system. See |
37 | <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
4a9b1dd4 LP |
38 | for more information about machine IDs.</para> |
39 | ||
40 | <para>This service is started after | |
41 | <filename>local-fs.target</filename> in case | |
42 | <filename>/etc/machine-id</filename> is a mount point of its own | |
43 | (usually from a memory file system such as | |
44 | <literal>tmpfs</literal>) and /etc is writable. The service will | |
45 | invoke <command>systemd-machine-id-setup --commit</command>, which | |
46 | writes the current transient machine ID to disk and unmount the | |
798d3a52 | 47 | <filename>/etc/machine-id</filename> file in a race-free manner to |
4a9b1dd4 LP |
48 | ensure that file is always valid and accessible for other |
49 | processes. See | |
50 | <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
51 | for details.</para> | |
52 | ||
53 | <para>The main use case of this service are systems where | |
54 | <filename>/etc/machine-id</filename> is read-only and initially | |
b938cb90 | 55 | not initialized. In this case, the system manager will generate a |
4a9b1dd4 LP |
56 | transient machine ID file on a memory file system, and mount it |
57 | over <filename>/etc/machine-id</filename>, during the early boot | |
58 | phase. This service is then invoked in a later boot phase, as soon | |
59 | as <filename>/etc</filename> has been remounted writable and the | |
60 | ID may thus be committed to disk to make it permanent.</para> | |
798d3a52 ZJS |
61 | </refsect1> |
62 | ||
63 | <refsect1> | |
64 | <title>See Also</title> | |
65 | <para> | |
66 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
798d3a52 ZJS |
67 | <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
68 | <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
69 | <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
70 | </para> | |
71 | </refsect1> | |
2a5a41e8 DR |
72 | |
73 | </refentry> |