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systemd/man/hostnamectl.xml
Zbigniew Jędrzejewski-Szmek d39079fcaa hostnamed: stop discriminating against "localhost" in /etc/hostname
We would sometimes ignore localhost-style names in /etc/hostname. That is
brittle. If the user configured some hostname, it's most likely because they
want to use that as the hostname. If they don't want to use such a hostname,
they should just not create the config. Everything becomes simples if we just
use the configured hostname as-is.

This behaviour seems to have been a workaround for Anaconda installer and other
tools writing out /etc/hostname with the default of "localhost.localdomain".
Anaconda PR to stop doing that: https://github.com/rhinstaller/anaconda/pull/3040.
That might have been useful as a work-around for other programs misbehaving if
/etc/hostname was not present, but nowadays it's not useful because systemd
mostly controls the hostname and it is perfectly happy without that file.

Apart from making things simpler, this allows users to set a hostname like
"localhost" and have it honoured, if such a whim strikes them.
2020-12-16 11:02:18 +01:00

215 lines
8.9 KiB
XML

<?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">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="hostnamectl" conditional='ENABLE_HOSTNAMED'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>hostnamectl</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>hostnamectl</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>hostnamectl</refname>
<refpurpose>Control the system hostname</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>hostnamectl</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="req">COMMAND</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>hostnamectl</command> may be used to query and change the system hostname and related
settings.</para>
<para><citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
and this tool distinguish three different hostnames: the high-level "pretty" hostname which might include
all kinds of special characters (e.g. "Lennart's Laptop"), the "static" hostname which is the
user-configured hostname (e.g. "lennarts-laptop"), and the transient hostname which is a fallback value
received from network configuration (e.g. "node12345678"). If a static hostname is set to a valid value,
then the transient hostname is not used.</para>
<para>Note that the pretty hostname has little restrictions on the characters and length used, while the static and
transient hostnames are limited to the usually accepted characters of Internet domain names, and 64 characters at
maximum (the latter being a Linux limitation).</para>
<para>Use
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry> to
initialize the system hostname for mounted (but not booted) system images.</para>
</refsect1>
<refsect1>
<title>Commands</title>
<para>The following commands are understood:</para>
<variablelist>
<varlistentry>
<term><command>status</command></term>
<listitem><para>Show current system hostname and related information. If no command is specified,
this is the implied default.</para></listitem>
</varlistentry>
<varlistentry>
<term><command>set-hostname <replaceable>NAME</replaceable></command></term>
<listitem><para>Set the system hostname to <replaceable>NAME</replaceable>. By default, this will alter the
pretty, the static, and the transient hostname alike; however, if one or more of <option>--static</option>,
<option>--transient</option>, <option>--pretty</option> are used, only the selected hostnames are changed. If
the pretty hostname is being set, and static or transient are being set as well, the specified hostname will be
simplified in regards to the character set used before the latter are updated. This is done by removing special
characters and spaces. This ensures that the pretty and the static hostname are always closely related while
still following the validity rules of the specific name. This simplification of the hostname string is not done
if only the transient and/or static hostnames are set, and the pretty hostname is left untouched.</para>
<para>Pass the empty string <literal></literal> as the
hostname to reset the selected hostnames to their default
(usually <literal>localhost</literal>).</para></listitem>
</varlistentry>
<varlistentry>
<term><command>set-icon-name <replaceable>NAME</replaceable></command></term>
<listitem><para>Set the system icon name to
<replaceable>NAME</replaceable>. The icon name is used by some
graphical applications to visualize this host. The icon name
should follow the <ulink
url="http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">Icon
Naming Specification</ulink>.</para>
<para>Pass an empty string to reset the icon name to the
default value, which is determined from chassis type (see
below) and possibly other parameters.</para></listitem>
</varlistentry>
<varlistentry>
<term><command>set-chassis <replaceable>TYPE</replaceable></command></term>
<listitem><para>Set the chassis type to
<replaceable>TYPE</replaceable>. The chassis type is used by
some graphical applications to visualize the host or alter
user interaction. Currently, the following chassis types are
defined:
<literal>desktop</literal>,
<literal>laptop</literal>,
<literal>convertible</literal>,
<literal>server</literal>,
<literal>tablet</literal>,
<literal>handset</literal>,
<literal>watch</literal>,
<literal>embedded</literal>,
as well as the special chassis types
<literal>vm</literal> and
<literal>container</literal> for virtualized systems that lack
an immediate physical chassis.</para>
<para>Pass an empty string to reset the chassis type to the
default value which is determined from the firmware and
possibly other parameters.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>set-deployment <replaceable>ENVIRONMENT</replaceable></command></term>
<listitem><para>Set the deployment environment description.
<replaceable>ENVIRONMENT</replaceable> must be a single word
without any control characters. One of the following is
suggested:
<literal>development</literal>,
<literal>integration</literal>,
<literal>staging</literal>,
<literal>production</literal>.
</para>
<para>Pass an empty string to reset to the default empty
value.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>set-location <replaceable>LOCATION</replaceable></command></term>
<listitem><para>Set the location string for the system, if it
is known. <replaceable>LOCATION</replaceable> should be a
human-friendly, free-form string describing the physical
location of the system, if it is known and applicable. This
may be as generic as <literal>Berlin, Germany</literal> or as
specific as <literal>Left Rack, 2nd Shelf</literal>.</para>
<para>Pass an empty string to reset to the default empty
value.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--no-ask-password</option></term>
<listitem><para>Do not query the user for authentication for
privileged operations.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--static</option></term>
<term><option>--transient</option></term>
<term><option>--pretty</option></term>
<listitem><para>If <command>status</command> is invoked (or no explicit command is given) and one of these
switches is specified, <command>hostnamectl</command> will print out just this selected hostname.</para>
<para>If used with <command>set-hostname</command>, only the selected hostname(s) will be updated. When more
than one of these switches are specified, all the specified hostnames will be updated. </para></listitem>
</varlistentry>
<xi:include href="user-system-options.xml" xpointer="host" />
<xi:include href="user-system-options.xml" xpointer="machine" />
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure code
otherwise.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>