1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-id128" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-id128</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-id128</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-id128</refname>
<refpurpose>Generate and print sd-128 identifiers</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">new</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">machine-id</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">boot-id</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">invocation-id</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">var-partition-uuid</arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-id128</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">show</arg>
<arg choice="opt" rep="repeat">NAME|UUID</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>id128</command> may be used to conveniently print
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>
UUIDs. What identifier is printed depends on the specific verb.</para>
<para>With <command>new</command>, a new random identifier will be generated.</para>
<para>With <command>machine-id</command>, the identifier of the current machine will be
printed. See
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>With <command>boot-id</command>, the identifier of the current boot will be
printed.</para>
<para>With <command>invocation-id</command>, the identifier of the current service invocation
will be printed. This is available in systemd services. See
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>With <command>show</command>, well-known IDs are printed (for now, only GPT partition type UUIDs),
along with brief identifier strings. When no arguments are specified, all known IDs are shown. When
arguments are specified, they may be the identifiers or ID values of one or more known IDs, which are
then printed with their name, or arbitrary IDs, which are then printed with a placeholder name. Combine
with <option>--uuid</option> to list the IDs in UUID style, i.e. the way GPT partition type UUIDs are
usually shown.</para>
<para><command>machine-id</command>, <command>boot-id</command>, and <command>show</command> may be
combined with the <option>--app-specific=<replaceable>app-id</replaceable></option> switch to generate
application-specific IDs. See
<citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for the discussion when this is useful. Support for <command>show --app-specific=</command> was added in
version 255.</para>
<para><command>var-partition-uuid</command> prints a UUID which, following the <ulink
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">UAPI.2 Discoverable
Partitions Specification</ulink>, should be used as the GPT partition UUID for
<filename>/var/</filename>, being derived from the GPT partition type, keyed by the local
<filename>/etc/machine-id</filename>. Added in version 257.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>-p</option></term>
<term><option>--pretty</option></term>
<listitem><para>Generate output as programming language snippets.</para>
<xi:include href="version-info.xml" xpointer="v240"/></listitem>
</varlistentry>
<varlistentry>
<term><option>-P</option></term>
<term><option>--value</option></term>
<listitem><para>Only print the value. May be combined with
<option>-u</option>/<option>--uuid</option>.</para>
<xi:include href="version-info.xml" xpointer="v255"/></listitem>
</varlistentry>
<varlistentry>
<term><option>-a <replaceable>app-id</replaceable></option></term>
<term><option>--app-specific=<replaceable>app-id</replaceable></option></term>
<listitem><para>With this option, identifiers will be printed that are the result of hashing the
application identifier <replaceable>app-id</replaceable> and another ID. The
<replaceable>app-id</replaceable> argument must be a valid sd-id128 string identifying the
application. When used with <command>machine-id</command>, the other ID will be the machine ID as
described in
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>, when
used with <command>boot-id</command>, the other ID will be the boot ID, and when used with
<command>show</command>, the other ID or IDs should be specified via the positional arguments.</para>
<xi:include href="version-info.xml" xpointer="v240"/>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-u</option></term>
<term><option>--uuid</option></term>
<listitem><para>Generate output as a UUID formatted in the "canonical representation", with five
groups of digits separated by hyphens. See the Wikipedia entry for
<ulink url="https://en.wikipedia.org/wiki/Universally_unique_identifier#Format">Universally Unique Identifiers</ulink>
for more discussion.</para>
<xi:include href="version-info.xml" xpointer="v244"/></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="no-pager" />
<xi:include href="standard-options.xml" xpointer="no-legend" />
<xi:include href="standard-options.xml" xpointer="json" />
<xi:include href="standard-options.xml" xpointer="j" />
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success 0 is returned, and a non-zero failure code otherwise.</para>
</refsect1>
<refsect1>
<title>Examples</title>
<example>
<title>Show a well-known UUID</title>
<programlisting>
$ systemd-id128 show --value user-home
773f91ef66d449b5bd83d683bf40ad16
$ systemd-id128 show --value --uuid user-home
773f91ef-66d4-49b5-bd83-d683bf40ad16
$ systemd-id128 show 773f91ef-66d4-49b5-bd83-d683bf40ad16
NAME ID
user-home 773f91ef66d449b5bd83d683bf40ad16
</programlisting>
</example>
<example>
<title>Generate an application-specific UUID</title>
<programlisting>
$ systemd-id128 machine-id -u
3a9d668b-4db7-4939-8a4a-5e78a03bffb7
$ systemd-id128 new -u
1fb8f24b-02df-458d-9659-cc8ace68e28a
$ systemd-id128 machine-id -u -a 1fb8f24b-02df-458d-9659-cc8ace68e28a
47b82cb1-5339-43da-b2a6-1c350aef1bd1
$ systemd-id128 -Pu show 3a9d668b-4db7-4939-8a4a-5e78a03bffb7 \
-a 1fb8f24b-02df-458d-9659-cc8ace68e28a
47b82cb1-5339-43da-b2a6-1c350aef1bd1
</programlisting>
<para>On a given machine with the ID 3a9d668b-4db7-4939-8a4a-5e78a03bffb7, for the application
1fb8f24b-02df-458d-9659-cc8ace68e28a, we generate an application-specific machine ID
(47b82cb1-5339-43da-b2a6-1c350aef1bd1). If we want to later recreate the same calculation on a
different machine, we need to specify both IDs explicitly as parameters to <command>show</command>.
</para>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
|
