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+<?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" [
+<!ENTITY % entities SYSTEM "custom-entities.ent" >
+%entities;
+]>
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="org.freedesktop.hostname1" conditional='ENABLE_HOSTNAMED'
+ xmlns:xi="http://www.w3.org/2001/XInclude">
+ <refentryinfo>
+ <title>org.freedesktop.hostname1</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>org.freedesktop.hostname1</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>org.freedesktop.hostname1</refname>
+ <refpurpose>The D-Bus interface of systemd-hostnamed</refpurpose>
+ </refnamediv>
+
+ <refsect1>
+ <title>Introduction</title>
+
+ <para>
+ <citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ is a system service that can be used to control the hostname and related machine metadata from user
+ programs. This page describes the hostname semantics and the D-Bus interface.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>The D-Bus API</title>
+
+ <para>The service exposes the following interfaces on the bus:</para>
+
+ <programlisting executable="systemd-hostnamed" node="/org/freedesktop/hostname1" interface="org.freedesktop.hostname1">
+node /org/freedesktop/hostname1 {
+ interface org.freedesktop.hostname1 {
+ methods:
+ SetHostname(in s hostname,
+ in b interactive);
+ SetStaticHostname(in s hostname,
+ in b interactive);
+ SetPrettyHostname(in s hostname,
+ in b interactive);
+ SetIconName(in s icon,
+ in b interactive);
+ SetChassis(in s chassis,
+ in b interactive);
+ SetDeployment(in s deployment,
+ in b interactive);
+ SetLocation(in s location,
+ in b interactive);
+ GetProductUUID(in b interactive,
+ out ay uuid);
+ GetHardwareSerial(out s serial);
+ Describe(out s json);
+ properties:
+ readonly s Hostname = '...';
+ readonly s StaticHostname = '...';
+ readonly s PrettyHostname = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s DefaultHostname = '...';
+ readonly s HostnameSource = '...';
+ readonly s IconName = '...';
+ readonly s Chassis = '...';
+ readonly s Deployment = '...';
+ readonly s Location = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s KernelName = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s KernelRelease = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s KernelVersion = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s OperatingSystemPrettyName = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s OperatingSystemCPEName = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s HomeURL = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s HardwareVendor = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s HardwareModel = '...';
+ @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+ readonly s FirmwareVersion = '...';
+ };
+ interface org.freedesktop.DBus.Peer { ... };
+ interface org.freedesktop.DBus.Introspectable { ... };
+ interface org.freedesktop.DBus.Properties { ... };
+};
+ </programlisting>
+
+ <!--method GetHardwareSerial is not documented!-->
+
+ <!--property HardwareVendor is not documented!-->
+
+ <!--property HardwareModel is not documented!-->
+
+ <!--property FirmwareVersion is not documented!-->
+
+ <!--Autogenerated cross-references for systemd.directives, do not edit-->
+
+ <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.hostname1"/>
+
+ <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.hostname1"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetHostname()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetStaticHostname()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetPrettyHostname()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetIconName()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetChassis()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetDeployment()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="SetLocation()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="GetProductUUID()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="GetHardwareSerial()"/>
+
+ <variablelist class="dbus-method" generated="True" extra-ref="Describe()"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="Hostname"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="StaticHostname"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="PrettyHostname"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="DefaultHostname"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="HostnameSource"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="IconName"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="Chassis"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="Deployment"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="Location"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="KernelName"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="KernelRelease"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="KernelVersion"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="OperatingSystemPrettyName"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="OperatingSystemCPEName"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="HomeURL"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="HardwareVendor"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="HardwareModel"/>
+
+ <variablelist class="dbus-property" generated="True" extra-ref="FirmwareVersion"/>
+
+ <!--End of Autogenerated section-->
+
+ <para>Whenever the hostname or other metadata is changed via the daemon,
+ <function>PropertyChanged</function> signals are sent out to subscribed clients. Changing a hostname
+ using this interface is authenticated via
+ <ulink url="https://www.freedesktop.org/software/polkit/docs/latest/">polkit</ulink>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Semantics</title>
+
+ <para>The <varname>StaticHostname</varname> property exposes the "static" hostname configured in
+ <filename>/etc/hostname</filename>. It is not always in sync with the current hostname as returned by the
+ <citerefentry project="man-pages"><refentrytitle>gethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ system call. If no static hostname is configured this property will be the empty string.</para>
+
+ <para>When <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> or
+ <citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ set the hostname, this static hostname <emphasis>has the highest priority</emphasis>.</para>
+
+ <para>The <varname>Hostname</varname> property exposes the actual hostname configured in the kernel via
+ <citerefentry project="man-pages"><refentrytitle>sethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>.
+ It can be different from the static hostname. This property is never empty.</para>
+
+ <para>The <varname>PrettyHostname</varname> property exposes the <emphasis>pretty hostname</emphasis>
+ which is a free-form UTF-8 hostname for presentation to the user. User interfaces should ensure that the
+ pretty hostname and the static hostname stay in sync. E.g. when the former is <literal>Lennart’s
+ Computer</literal> the latter should be <literal>lennarts-computer</literal>. If no pretty hostname is
+ set this setting will be the empty string. Applications should then find a suitable fallback, such as the
+ dynamic hostname.</para>
+
+ <para>The <varname>DefaultHostname</varname> property exposes the default hostname (configured through
+ <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>, or a
+ fallback set at compilation time).</para>
+
+ <para>The <varname>HostnameSource</varname> property exposes the origin of the currently configured
+ hostname. One of <literal>static</literal> (set from <filename>/etc/hostname</filename>),
+ <literal>transient</literal> (a non-permanent hostname from an external source),
+ <literal>default</literal> (the value from <filename>os-release</filename> or the compiled-in
+ fallback).</para>
+
+ <para>The <varname>IconName</varname> property exposes the <emphasis>icon name</emphasis> following the
+ XDG icon naming spec. If not set, information such as the chassis type (see below) is used to find a
+ suitable fallback icon name (i.e. <literal>computer-laptop</literal>
+ vs. <literal>computer-desktop</literal> is picked based on the chassis information). If no such data is
+ available, the empty string is returned. In that case an application should fall back to a replacement
+ icon, for example <literal>computer</literal>. If this property is set to the empty string, the automatic
+ fallback name selection is enabled again.</para>
+
+ <para>The <varname>Chassis</varname> property exposes a <emphasis>chassis type</emphasis>, one of the
+ currently defined chassis types: <literal>desktop</literal>, <literal>laptop</literal>,
+ <literal>server</literal>, <literal>tablet</literal>, <literal>handset</literal>, as well as the special
+ chassis types <literal>vm</literal> and <literal>container</literal> for virtualized systems. Note that
+ in most cases the chassis type will be determined automatically from DMI/SMBIOS/ACPI firmware
+ information. Writing to this setting is hence useful only to override misdetected chassis types, or to
+ configure the chassis type if it could not be auto-detected. Set this property to the empty string to
+ reenable the automatic detection of the chassis type from firmware information.</para>
+
+ <para>Note that <filename>systemd-hostnamed</filename> starts only on request and terminates after a
+ short idle period. This effectively means that <function>PropertyChanged</function> messages are not sent
+ out for changes made directly on the files (as in: administrator edits the files with vi). This is
+ the intended behavior: manual configuration changes should require manual reloading.</para>
+
+ <para>The transient (dynamic) hostname exposed by the <varname>Hostname</varname> property maps directly
+ to the kernel hostname. This hostname should be assumed to be highly dynamic, and hence should be watched
+ directly, without depending on <function>PropertyChanged</function> messages from
+ <filename>systemd-hostnamed</filename>. To accomplish this, open
+ <filename>/proc/sys/kernel/hostname</filename> and
+ <citerefentry project="man-pages"><refentrytitle>poll</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for <constant>SIGHUP</constant> which is triggered by the kernel every time the hostname changes. Again:
+ this is special for the transient (dynamic) hostname, and does not apply to the configured (fixed)
+ hostname.</para>
+
+ <para>Applications may read the hostname data directly if hostname change notifications
+ are not necessary. Use
+ <citerefentry project="man-pages"><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
+ <filename>/etc/hostname</filename> (possibly with per-distribution fallbacks), and
+ <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for that. For more information on these files and syscalls see the respective man pages.</para>
+
+ <para><varname>KernelName</varname>, <varname>KernelRelease</varname>, and
+ <varname>KernelVersion</varname> expose the kernel name (e.g. <literal>Linux</literal>), release
+ (e.g. <literal>5.0.0-11</literal>), and version (i.e. the build number, e.g. <literal>#11</literal>) as
+ reported by <citerefentry project="man-pages"><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>.
+ <varname>OperatingSystemPrettyName</varname>, <varname>OperatingSystemCPEName</varname>, and
+ <varname>HomeURL</varname> expose the <varname>PRETTY_NAME=</varname>, <varname>CPE_NAME=</varname> and
+ <varname>HOME_URL=</varname> fields from
+ <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
+ purpose of those properties is to allow remote clients to access this information over D-Bus. Local
+ clients can access the information directly.</para>
+
+ <refsect2>
+ <title>Methods</title>
+
+ <para><function>SetHostname()</function> sets the transient (dynamic) hostname, which is used if no
+ static hostname is set. This value must be an internet-style hostname, 7-bit lowercase ASCII, no
+ special chars/spaces. An empty string will unset the transient hostname.</para>
+
+ <para><function>SetStaticHostname()</function> sets the static hostname which is exposed by the
+ <varname>StaticHostname</varname> property. When called with an empty argument, the static
+ configuration in <filename>/etc/hostname</filename> is removed. Since the static hostname has the
+ highest priority, calling this function usually affects also the <varname>Hostname</varname> property
+ and the effective hostname configured in the kernel.</para>
+
+ <para><function>SetPrettyHostname()</function> sets the pretty hostname which is exposed by the
+ <varname>PrettyHostname</varname> property.</para>
+
+ <para><function>SetIconName()</function>, <function>SetChassis()</function>,
+ <function>SetDeployment()</function>, and <function>SetLocation()</function> set the properties
+ <varname>IconName</varname> (the name of the icon representing for the machine),
+ <varname>Chassis</varname> (the machine form factor), <varname>Deployment</varname> (the system
+ deployment environment), and <varname>Location</varname> (physical system location), respectively.
+ </para>
+
+ <para><varname>PrettyHostname</varname>, <varname>IconName</varname>, <varname>Chassis</varname>,
+ <varname>Deployment</varname>, and <varname>Location</varname> are stored in
+ <filename>/etc/machine-info</filename>. See
+ <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
+ the semantics of those settings.</para>
+
+ <para><function>GetProductUUID()</function> returns the "product UUID" as exposed by the kernel based
+ on DMI information in <filename>/sys/class/dmi/id/product_uuid</filename>. Reading the file directly
+ requires root privileges, and this method allows access to unprivileged clients through the polkit
+ framework.</para>
+
+ <para><function>Describe()</function> returns a JSON representation of all properties in one.</para>
+ </refsect2>
+
+ <refsect2>
+ <title>Security</title>
+
+ <para>The <varname>interactive</varname> boolean parameters can be used to control whether polkit
+ should interactively ask the user for authentication credentials if required.</para>
+
+ <para>The polkit action for <function>SetHostname()</function> is
+ <interfacename>org.freedesktop.hostname1.set-hostname</interfacename>. For
+ <function>SetStaticHostname()</function> and <function>SetPrettyHostname()</function> it is
+ <interfacename>org.freedesktop.hostname1.set-static-hostname</interfacename>. For
+ <function>SetIconName()</function>, <function>SetChassis()</function>, <function>SetDeployment()</function>
+ and <function>SetLocation()</function> it is
+ <interfacename>org.freedesktop.hostname1.set-machine-info</interfacename>.</para>
+ </refsect2>
+ </refsect1>
+
+ <refsect1>
+ <title>Recommendations</title>
+
+ <para>Here are three examples that show how the pretty hostname and the icon name should be used:
+ <itemizedlist>
+ <listitem><para>When registering DNS-SD services: use the pretty hostname in the service name, and pass
+ the icon name in the TXT data, if there is an icon name. Browsing clients can then show the server icon
+ on each service. This is especially useful for WebDAV applications or UPnP media sharing.
+ </para></listitem>
+
+ <listitem><para>Set the bluetooth name to the pretty hostname.</para></listitem>
+
+ <listitem><para>When your file browser has a "Computer" icon, replace the name with the pretty hostname
+ if set, and the icon with the icon name, if it is set.</para></listitem>
+ </itemizedlist></para>
+
+ <para>To properly handle name lookups with changing local hostnames without having to edit
+ <filename>/etc/hosts</filename>, we recommend using <filename>systemd-hostnamed</filename> in combination
+ with <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ </para>
+
+ <para>Here are some recommendations to follow when generating a static (internet) hostname from a pretty
+ name:
+ <itemizedlist>
+ <listitem><para>Generate a single DNS label only, not an FQDN. That means no dots allowed. Strip them,
+ or replace them with <literal>-</literal>.</para></listitem>
+
+ <listitem><para>It's probably safer to not use any non-ASCII chars, even if DNS allows this in some way
+ these days. In fact, restrict your charset to <literal>a-zA-Z0-9</literal> and <literal>-</literal>.
+ Strip other chars, or try to replace them in some smart way with chars from this set, for example
+ <literal>ä</literal> → <literal>ae</literal>, and use <literal>-</literal> as the replacement for all
+ punctuation characters and whitespace.</para></listitem>
+
+ <listitem><para>Try to avoid creating repeated <literal>-</literal>, as well as <literal>-</literal> as
+ the first or last char.</para></listitem>
+
+ <listitem><para>Limit the hostname to 63 chars, which is the length of a DNS label.</para></listitem>
+
+ <listitem><para>If after stripping special chars the empty string is the result, you can pass this
+ as-is to <filename>systemd-hostnamed</filename> in which case it will automatically use a suitable
+ fallback.</para></listitem>
+
+ <listitem><para>Uppercase charaacters should be replaced with their lowercase equivalents.
+ </para></listitem>
+ </itemizedlist></para>
+
+ <para>Note that while <filename>systemd-hostnamed</filename> applies some checks to the hostname you pass
+ they are much looser than the recommendations above. For example, <filename>systemd-hostnamed</filename>
+ will also accept <literal>_</literal> in the hostname, but we recommend not using this to avoid clashes
+ with DNS-SD service types. Also <filename>systemd-hostnamed</filename> allows longer hostnames, but
+ because of the DNS label limitations, we recommend not making use of this.</para>
+
+ <para>Here are a couple of example conversions:
+ <itemizedlist>
+ <listitem><para><literal>Lennart's PC</literal> → <literal>lennarts-pc</literal></para></listitem>
+ <listitem><para><literal>Müllers Computer</literal> → <literal>muellers-computer</literal></para></listitem>
+ <listitem><para><literal>Voran!</literal> → <literal>voran</literal></para></listitem>
+ <listitem><para><literal>Es war einmal ein Männlein</literal> → <literal>es-war-einmal-ein-maennlein</literal></para></listitem>
+ <listitem><para><literal>Jawoll. Ist doch wahr!</literal> → <literal>jawoll-ist-doch-wahr</literal></para></listitem>
+ <listitem><para><literal>レナート</literal> → <literal>localhost</literal></para></listitem>
+ <listitem><para><literal>...zack!!! zack!...</literal> → <literal>zack-zack</literal></para></listitem>
+ </itemizedlist></para>
+
+ <para>Of course, an already valid internet hostname label you enter and pass through this
+ conversion should stay unmodified, so that users have direct control of it, if they want — by simply
+ ignoring the fact that the pretty hostname is pretty and just edit it as if it was the normal internet
+ name.</para>
+ </refsect1>
+
+ <xi:include href="org.freedesktop.locale1.xml" xpointer="versioning"/>
+
+ <refsect1>
+ <title>Examples</title>
+
+ <example>
+ <title>Introspect <interfacename>org.freedesktop.hostname1</interfacename> on the bus</title>
+
+ <programlisting>$ gdbus introspect --system \
+ --dest org.freedesktop.hostname1 \
+ --object-path /org/freedesktop/hostname1
+ </programlisting>
+ </example>
+ </refsect1>
+
+ <refsect1>
+ <title>See also</title>
+
+ <para>David Zeuthen's original Fedora
+ <ulink url="https://fedoraproject.org/wiki/Features/BetterHostname">Feature page about xdg-hostname</ulink></para>
+ </refsect1>
+</refentry>