Provided by: systemd_251.4-1ubuntu7_amd64 bug


       org.freedesktop.hostname1 - The D-Bus interface of systemd-hostnamed


       systemd-hostnamed.service(8) 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.


       The service exposes the following interfaces on the bus:

           node /org/freedesktop/hostname1 {
             interface org.freedesktop.hostname1 {
                 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);
                 readonly s Hostname = '...';
                 readonly s StaticHostname = '...';
                 readonly s PrettyHostname = '...';
                 readonly s DefaultHostname = '...';
                 readonly s HostnameSource = '...';
                 readonly s IconName = '...';
                 readonly s Chassis = '...';
                 readonly s Deployment = '...';
                 readonly s Location = '...';
                 readonly s KernelName = '...';
                 readonly s KernelRelease = '...';
                 readonly s KernelVersion = '...';
                 readonly s OperatingSystemPrettyName = '...';
                 readonly s OperatingSystemCPEName = '...';
                 readonly s HomeURL = '...';
                 readonly s HardwareVendor = '...';
                 readonly s HardwareModel = '...';
                 readonly s FirmwareVersion = '...';
             interface org.freedesktop.DBus.Peer { ... };
             interface org.freedesktop.DBus.Introspectable { ... };
             interface org.freedesktop.DBus.Properties { ... };

       Whenever the hostname or other metadata is changed via the daemon, PropertyChanged signals
       are sent out to subscribed clients. Changing a hostname using this interface is
       authenticated via polkit[1].


       The StaticHostname property exposes the "static" hostname configured in /etc/hostname. It
       is not always in sync with the current hostname as returned by the gethostname(3) system
       call. If no static hostname is configured this property will be the empty string.

       When systemd(1) or systemd-hostnamed.service(8) set the hostname, this static hostname has
       the highest priority.

       The Hostname property exposes the actual hostname configured in the kernel via
       sethostname(3). It can be different from the static hostname. This property is never

       The PrettyHostname property exposes the pretty hostname 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 "Lennart’s
       Computer" the latter should be "lennarts-computer". 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.

       The DefaultHostname property exposes the default hostname (configured through os-
       release(5), or a fallback set at compilation time).

       The HostnameSource property exposes the origin of the currently configured hostname. One
       of "static" (set from /etc/hostname), "transient" (a non-permanent hostname from an
       external source), "default" (the value from os-release or the compiled-in fallback).

       The IconName property exposes the icon name 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.  "computer-laptop" vs.  "computer-desktop" 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 "computer". If this
       property is set to the empty string, the automatic fallback name selection is enabled

       The Chassis property exposes a chassis type, one of the currently defined chassis types:
       "desktop", "laptop", "server", "tablet", "handset", as well as the special chassis types
       "vm" and "container" 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.

       Note that systemd-hostnamed starts only on request and terminates after a short idle
       period. This effectively means that PropertyChanged 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.

       The transient (dynamic) hostname exposed by the Hostname 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 PropertyChanged messages from systemd-hostnamed. To
       accomplish this, open /proc/sys/kernel/hostname and poll(3) for SIGHUP 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.

       Applications may read the hostname data directly if hostname change notifications are not
       necessary. Use gethostname(3), /etc/hostname (possibly with per-distribution fallbacks),
       and machine-info(3) for that. For more information on these files and syscalls see the
       respective man pages.

       KernelName, KernelRelease, and KernelVersion expose the kernel name (e.g.  "Linux"),
       release (e.g.  "5.0.0-11"), and version (i.e. the build number, e.g.  "#11") as reported
       by uname(2).  OperatingSystemPrettyName, OperatingSystemCPEName, and HomeURL expose the
       PRETTY_NAME=, CPE_NAME= and HOME_URL= fields from os-release(5). The purpose of those
       properties is to allow remote clients to access this information over D-Bus. Local clients
       can access the information directly.

       SetHostname() 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.

       SetStaticHostname() sets the static hostname which is exposed by the StaticHostname
       property. When called with an empty argument, the static configuration in /etc/hostname is
       removed. Since the static hostname has the highest priority, calling this function usually
       affects also the Hostname property and the effective hostname configured in the kernel.

       SetPrettyHostname() sets the pretty hostname which is exposed by the PrettyHostname

       SetIconName(), SetChassis(), SetDeployment(), and SetLocation() set the properties
       IconName (the name of the icon representing for the machine), Chassis (the machine form
       factor), Deployment (the system deployment environment), and Location (physical system
       location), respectively.

       PrettyHostname, IconName, Chassis, Deployment, and Location are stored in
       /etc/machine-info. See machine-info(5) for the semantics of those settings.

       GetProductUUID() returns the "product UUID" as exposed by the kernel based on DMI
       information in /sys/class/dmi/id/product_uuid. Reading the file directly requires root
       privileges, and this method allows access to unprivileged clients through the polkit

       Describe() returns a JSON representation of all properties in one.

       The interactive boolean parameters can be used to control whether polkit should
       interactively ask the user for authentication credentials if required.

       The polkit action for SetHostname() is org.freedesktop.hostname1.set-hostname. For
       SetStaticHostname() and SetPrettyHostname() it is
       org.freedesktop.hostname1.set-static-hostname. For SetIconName(), SetChassis(),
       SetDeployment() and SetLocation() it is org.freedesktop.hostname1.set-machine-info.


       Here are three examples that show how the pretty hostname and the icon name should be

       •   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.

       •   Set the bluetooth name to the pretty hostname.

       •   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.

       To properly handle name lookups with changing local hostnames without having to edit
       /etc/hosts, we recommend using systemd-hostnamed in combination with nss-myhostname(3).

       Here are some recommendations to follow when generating a static (internet) hostname from
       a pretty name:

       •   Generate a single DNS label only, not an FQDN. That means no dots allowed. Strip them,
           or replace them with "-".

       •   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 "a-zA-Z0-9" and "-". Strip other
           chars, or try to replace them in some smart way with chars from this set, for example
           "ä" → "ae", and use "-" as the replacement for all punctuation characters and

       •   Try to avoid creating repeated "-", as well as "-" as the first or last char.

       •   Limit the hostname to 63 chars, which is the length of a DNS label.

       •   If after stripping special chars the empty string is the result, you can pass this
           as-is to systemd-hostnamed in which case it will automatically use a suitable

       •   Uppercase charaacters should be replaced with their lowercase equivalents.

       Note that while systemd-hostnamed applies some checks to the hostname you pass they are
       much looser than the recommendations above. For example, systemd-hostnamed will also
       accept "_" in the hostname, but we recommend not using this to avoid clashes with DNS-SD
       service types. Also systemd-hostnamed allows longer hostnames, but because of the DNS
       label limitations, we recommend not making use of this.

       Here are a couple of example conversions:

       •   "Lennart's PC" → "lennarts-pc"

       •   "Müllers Computer" → "muellers-computer"

       •   "Voran!"  → "voran"

       •   "Es war einmal ein Männlein" → "es-war-einmal-ein-maennlein"

       •   "Jawoll. Ist doch wahr!"  → "jawoll-ist-doch-wahr"

       •   "レナート" → "localhost"

       •   "...zack!!! zack!..."  → "zack-zack"

       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.


       These D-Bus interfaces follow the usual interface versioning guidelines[2].


       Example 1. Introspect org.freedesktop.hostname1 on the bus

           $ gdbus introspect --system \
             --dest org.freedesktop.hostname1 \
             --object-path /org/freedesktop/hostname1


       David Zeuthen's original Fedora Feature page about xdg-hostname[3]


        1. polkit

        2. the usual interface versioning guidelines

        3. Feature page about xdg-hostname