man/org.freedesktop.hostname1.xml - systemd - Git at Google

 <?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);
       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 = '...';
   };
   interface org.freedesktop.DBus.Peer { ... };
   interface org.freedesktop.DBus.Introspectable { ... };
   interface org.freedesktop.DBus.Properties { ... };
 };
     </programlisting>

     <!--property HardwareVendor is not documented!-->

     <!--property HardwareModel 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="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"/>

     <!--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>3</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>3</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>

   <refsect1>
     <title>Versioning</title>

     <para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
     the usual interface versioning guidelines</ulink>.</para>
   </refsect1>

   <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>
	<?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);
	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 = '...';
	};
	interface org.freedesktop.DBus.Peer { ... };
	interface org.freedesktop.DBus.Introspectable { ... };
	interface org.freedesktop.DBus.Properties { ... };
	};
	</programlisting>

	<!--property HardwareVendor is not documented!-->

	<!--property HardwareModel 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="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"/>

	<!--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>3</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>3</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>

	<refsect1>
	<title>Versioning</title>

	<para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
	the usual interface versioning guidelines</ulink>.</para>
	</refsect1>

	<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>