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Diffstat (limited to 'src/libsystemd/sd_id128_get_machine.xml')
| -rw-r--r-- | src/libsystemd/sd_id128_get_machine.xml | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/src/libsystemd/sd_id128_get_machine.xml b/src/libsystemd/sd_id128_get_machine.xml new file mode 100644 index 0000000000..9a86c24aed --- /dev/null +++ b/src/libsystemd/sd_id128_get_machine.xml @@ -0,0 +1,139 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<!-- + This file is part of systemd. + + Copyright 2012 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +--> + +<refentry id="sd_id128_get_machine"> + + <refentryinfo> + <title>sd_id128_get_machine</title> + <productname>systemd</productname> + + <authorgroup> + <author> + <contrib>Developer</contrib> + <firstname>Lennart</firstname> + <surname>Poettering</surname> + <email>lennart@poettering.net</email> + </author> + </authorgroup> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_id128_get_machine</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_id128_get_machine</refname> + <refname>sd_id128_get_boot</refname> + <refname>sd_id128_get_invocation</refname> + <refpurpose>Retrieve 128-bit IDs</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_id128_get_machine</function></funcdef> + <paramdef>sd_id128_t *<parameter>ret</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_id128_get_boot</function></funcdef> + <paramdef>sd_id128_t *<parameter>ret</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_id128_get_invocation</function></funcdef> + <paramdef>sd_id128_t *<parameter>ret</parameter></paramdef> + </funcprototype> + + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_id128_get_machine()</function> returns the + machine ID of the executing host. This reads and parses the + <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> + file. This function caches the machine ID internally to make + retrieving the machine ID a cheap operation.</para> + + <para><function>sd_id128_get_boot()</function> returns the boot ID + of the executing kernel. This reads and parses the + <filename>/proc/sys/kernel/random/boot_id</filename> file exposed + by the kernel. It is randomly generated early at boot and is + unique for every running kernel instance. See + <citerefentry project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> + for more information. This function also internally caches the + returned ID to make this call a cheap operation.</para> + + <para><function>sd_id128_get_invocation()</function> returns the invocation ID of the currently executed + service. In its current implementation, this reads and parses the <varname>$INVOCATION_ID</varname> environment + variable that the service manager sets when activating a service, see + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The + ID is cached internally. In future a different mechanism to determine the invocation ID may be added.</para> + + <para>Note that <function>sd_id128_get_boot()</function> and <function>sd_id128_get_invocation()</function> always + return UUID v4 compatible IDs. <function>sd_id128_get_machine()</function> will also return a UUID v4-compatible + ID on new installations but might not on older. It is possible to convert the machine ID into a UUID v4-compatible + one. For more information, see + <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <para>For more information about the <literal>sd_id128_t</literal> + type see + <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>The two calls return 0 on success (in which case + <parameter>ret</parameter> is filled in), or a negative + errno-style error code.</para> + </refsect1> + + <refsect1> + <title>Notes</title> + + <para>The <function>sd_id128_get_machine()</function>, <function>sd_id128_get_boot()</function> and + <function>sd_id128_get_invocation()</function> interfaces are available as a shared library, which can be compiled + and linked to with the <literal>libsystemd</literal> <citerefentry + project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</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>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |