<para>
<citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- is a system service that can be used to control the host name and related machine meta data from user
+ 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>
<!--property HomeURL is not documented!-->
- <para>Whenever the hostname or other meta data is changed via the daemon,
+ <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 PolicyKit.</para>
</refsect1>
<refsect1>
<title>Semantics</title>
- <para>The <emphasis>static (configured) host name</emphasis> is the one configured in
+ <para>The <emphasis>static (configured) hostname</emphasis> is the one configured in
<filename>/etc/hostname</filename>. It is chosen by the local user. 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 host name is configured this property will be the empty string. Setting this property
- to the empty string will remove <filename>/etc/hostname</filename>. This hostname should be an
+ system call. If no hostname is configured this property will be the empty string. Setting this property
+ to the empty string will remove <filename>/etc/hostname</filename>. This property should be an
internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces.</para>
- <para>The <emphasis>transient (dynamic) host name</emphasis> is the one configured via the kernel's
+ <para>The <emphasis>transient (dynamic) hostname</emphasis> is the one configured via the kernel's
<citerefentry project="man-pages"><refentrytitle>sethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- It can be different from the static hostname in case DHCP or mDNS have been configured to change the name
+ It can be different from the static hostname if DHCP or mDNS have been configured to change the name
based on network information. <!-- FIXME: it's not DHCP that configures this... -->
This property is never empty. If no hostname is set this will default to
<literal>&FALLBACK_HOSTNAME;</literal> (configurable at compilation time). Setting this property to the
- empty string will reset the dynamic hostname to the static host name. If no static host name is
- configured the dynamic host name will be reset to <literal>&FALLBACK_HOSTNAME;</literal>. This hostname
+ empty string will reset the dynamic hostname to the static hostname. If no static hostname is
+ configured the dynamic hostname will be reset to <literal>&FALLBACK_HOSTNAME;</literal>. This property
should be an internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces.</para>
- <para>The <emphasis>pretty host name</emphasis> is a free-form UTF-8 host name for presentation to the
+ <para>The <emphasis>pretty hostname</emphasis> 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.
I.e. when the former is <literal>Lennart’s Computer</literal> the latter should be
- <literal>lennarts-computer</literal>. If no pretty host name is set this setting will be the empty
+ <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 <emphasis>icon name</emphasis> is a 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. <literal>computer-laptop</literal> vs. <literal>computer-desktop</literal> is picked based on the
- chassis information). If no such data is available, returns the empty string. In that case an application
+ 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, this automatic fallback name selection is enabled again.</para>
+ to the empty string, the automatic fallback name selection is enabled again.</para>
- <para>The <emphasis>chassis type</emphasis> should be one of the following that are currently defined:
+ <para>The <emphasis>chassis type</emphasis> should be 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 configure a chassis type if
- none could be auto-detected. Set this property to the empty string to reenable the automatic detection of
+ 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>A client which wants to change the local host name for DHCP/mDNS should invoke
+ <para>A client that wants to change the local hostname for DHCP/mDNS should invoke
<code>SetHostname("newname", false)</code> as soon as the name is available and afterwards reset it via
<code>SetHostname("")</code>.</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
- actually intended behavior: manual configuration changes should require manual reloading of them.</para>
+ the intended behavior: manual configuration changes should require manual reloading.</para>
- <para>The transient (dynamic) hostname directly maps to the kernel hostname. This hostname should be
- assumed to be highly dynamic, and hence should be watched directly, without involving
- <function>PropertyChanged</function> messages from <filename>systemd-hostnamed</filename>. For that, open
- <filename>/proc/sys/kernel/hostname</filename> and
+ <para>The transient (dynamic) hostname 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 bypass the daemon to read the hostname data if notifications of host name changes
+ <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>The user_interaction boolean parameters can be used to control whether PolicyKit should
- interactively ask the user for authentication credentials if it needs to.</para>
+ <para>The <varname>user_interaction</varname> boolean parameters can be used to control whether PolicyKit
+ should interactively ask the user for authentication credentials if required.</para>
<para>The PolicyKit action for <function>SetHostname()</function> is
<interfacename>org.freedesktop.hostname1.set-hostname</interfacename>. For
<function>SetIconName()</function> and <function>SetChassis()</function> it is
<interfacename>org.freedesktop.hostname1.set-machine-info</interfacename>.</para>
- <para>Here are three examples how the pretty hostname and the icon name should be used:
+ <para>Here are three examples show how the pretty hostname and the icon name should be used:
<itemizedlist>
- <listitem><para>When registering DNS-SD services: use the pretty host name in the service name, and
+ <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. Especially useful for WebDAV stuff. Similar for UPnP media
- sharing.</para></listitem>
+ 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 host name.</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> for them, we recommend using <filename>systemd-hostnamed</filename> in
+ <filename>/etc/hosts</filename>, we recommend using <filename>systemd-hostnamed</filename> in
combination with <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
name:
<itemizedlist>
<listitem><para>Generate a single DNS label only, not an FQDN. That means no dots allowed. Strip them,
- or replace them by <literal>-</literal>.</para></listitem>
+ or replace them with <literal>-</literal>.</para></listitem>
- <listitem><para>It's probably safer not to use any non-ASCII chars, even if DNS allows this in some way
+ <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 replacement for all kinds
- of punctuation chars or spaces.</para></listitem>
+ <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 make
- <literal>&FALLBACK_HOSTNAME;</literal> out of this.</para></listitem>
+ as-is to <filename>systemd-hostnamed</filename> in which case it will automatically use
+ <literal>&FALLBACK_HOSTNAME;</literal>.</para></listitem>
- <listitem><para>It probably is a good idea to replace uppercase by lowercase chars.</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 I'd recommend not using this to avoid clashes
+ 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, I'd recommend not making use of this.</para>
+ 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>...zack!!! zack!...</literal> → <literal>zack-zack</literal></para></listitem>
</itemizedlist></para>
- <para>Oh, and of course, an already valid internet hostname label you enter and pass through this
+ <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>
projects / thirdparty / systemd.git / commitdiff
