systemd/man/systemd-id128.xml
2020-01-23 23:32:13 +01:00

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XML

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<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>
</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>Both <command>machine-id</command> and <command>boot-id</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.</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 UUIDs are printed. When no arguments are specified, all
known UUIDs are shown. When arguments are specified, they must be the names or values of one or more
known UUIDs, which are then printed.</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></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, an identifier that is the result of hashing the
application identifier <replaceable>app-id</replaceable> and the machine identifier will be
printed. The <replaceable>app-id</replaceable> argument must be a valid sd-id128 string
identifying the application.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-u</option></term>
<term><option>--uuid</option></term>
<listitem><para>Generate output as an UUID formatted in the "canonical representation", with five
groups of digits separated by hyphens. See the
<ulink url="https://en.wikipedia.org/wiki/Universally_unique_identifier#Format">wikipedia</ulink>
for more discussion.</para></listitem>
</varlistentry>
<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, a non-zero failure code otherwise.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>