NAME¶
hostname - show or set the system's host name
domainname - show or set the system's NIS/YP domain name
ypdomainname - show or set the system's NIS/YP domain name
nisdomainname - show or set the system's NIS/YP domain name
dnsdomainname - show the system's DNS domain name
SYNOPSIS¶
hostname [
-a|--alias] [
-d|--domain]
[
-f|--fqdn|--long] [
-A|--all-fqdns] [
-i|--ip-address]
[
-I|--all-ip-addresses] [
-s|--short] [
-y|--yp|--nis]
hostname [
-b|--boot] [
-F|--file filename]
[
hostname]
hostname [
-h|--help] [
-V|--version]
domainname [
nisdomain] [
-F file]
ypdomainname [
nisdomain] [
-F file]
nisdomainname [
nisdomain] [
-F file]
dnsdomainname
DESCRIPTION¶
Hostname is used to display the system's DNS name, and to display or set
its hostname or NIS domain name.
GET NAME¶
When called without any arguments, the program displays the current names:
hostname will print the name of the system as returned by the
gethostname(2) function.
domainname will print the NIS domainname of the system.
domainname
uses the
gethostname(2) function, while
ypdomainname and
nisdomainname use the
yp_get_default_domain(3).
dnsdomainname will print the domain part of the FQDN (Fully Qualified
Domain Name). The complete FQDN of the system is returned with
hostname
--fqdn (but see the warnings in section
THE FQDN below).
SET NAME¶
When called with one argument or with the
--file option, the commands set
the host name or the NIS/YP domain name.
hostname uses the
sethostname(2) function, while all of the three
domainname,
ypdomainname and
nisdomainname use
setdomainname(2).
Note, that this is effective only until the next reboot. Edit /etc/hostname
for permanent change.
Note, that only the super-user can change the names.
It is not possible to set the FQDN or the DNS domain name with the
dnsdomainname command (see
THE FQDN below).
The host name is usually set once at system startup in
/etc/init.d/hostname.sh (normally by reading the contents of a file
which contains the host name, e.g.
/etc/hostname).
THE FQDN¶
The FQDN (Fully Qualified Domain Name) of the system is the name that the
resolver(3) returns for the host name, such as,
ursula.example.com. It is usually the hostname followed by the DNS
domain name (the part after the first dot). You can check the FQDN using
hostname --fqdn or the domain name using
dnsdomainname.
You cannot change the FQDN with
hostname or
dnsdomainname.
The recommended method of setting the FQDN is to make the hostname be an alias
for the fully qualified name using
/etc/hosts, DNS, or NIS. For
example, if the hostname was "ursula", one might have a line in
/etc/hosts which reads
127.0.1.1 ursula.example.com ursula
Technically: The FQDN is the name
getaddrinfo(3) returns for the host
name returned by
gethostname(2). The DNS domain name is the part after
the first dot.
Therefore it depends on the configuration of the resolver (usually in
/etc/host.conf) how you can change it. Usually the hosts file is parsed
before DNS or NIS, so it is most common to change the FQDN in
/etc/hosts.
If a machine has multiple network interfaces/addresses or is used in a mobile
environment, then it may either have multiple FQDNs/domain names or none at
all. Therefore avoid using
hostname --fqdn,
hostname --domain
and
dnsdomainname.
hostname --ip-address is subject to the same
limitations so it should be avoided as well.
OPTIONS¶
- -a, --alias
- Display the alias name of the host (if used). This option is deprecated
and should not be used anymore.
- -A, --all-fqdns
- Displays all FQDNs of the machine. This option enumerates all configured
network addresses on all configured network interfaces, and translates
them to DNS domain names. Addresses that cannot be translated (i.e.
because they do not have an appropriate reverse IP entry) are skipped.
Note that different addresses may resolve to the same name, therefore the
output may contain duplicate entries. Do not make any assumptions about
the order of the output.
- -b, --boot
- Always set a hostname; this allows the file specified by -F to be
non-existant or empty, in which case the default hostname localhost
will be used if none is yet set.
- -d, --domain
- Display the name of the DNS domain. Don't use the command
domainname to get the DNS domain name because it will show the NIS
domain name and not the DNS domain name. Use dnsdomainname instead.
See the warnings in section THE FQDN above, and avoid using this
option.
- -f, --fqdn, --long
- Display the FQDN (Fully Qualified Domain Name). A FQDN consists of a short
host name and the DNS domain name. Unless you are using bind or NIS for
host lookups you can change the FQDN and the DNS domain name (which is
part of the FQDN) in the /etc/hosts file. See the warnings in
section THE FQDN above und use hostname --all-fqdns instead
wherever possible.
- -F, --file filename
- Read the host name from the specified file. Comments (lines starting with
a `#') are ignored.
- -i, --ip-address
- Display the network address(es) of the host name. Note that this works
only if the host name can be resolved. Avoid using this option; use
hostname --all-ip-addresses instead.
- -I, --all-ip-addresses
- Display all network addresses of the host. This option enumerates all
configured addresses on all network interfaces. The loopback interface and
IPv6 link-local addresses are omitted. Contrary to option -i, this
option does not depend on name resolution. Do not make any assumptions
about the order of the output.
- -s, --short
- Display the short host name. This is the host name cut at the first
dot.
- -V, --version
- Print version information on standard output and exit successfully.
- -y, --yp, --nis
- Display the NIS domain name. If a parameter is given (or --file
name ) then root can also set a new NIS domain.
- -h, --help
- Print a usage message and exit.
NOTES¶
The address families
hostname tries when looking up the FQDN, aliases and
network addresses of the host are determined by the configuration of your
resolver. For instance, on GNU Libc systems, the resolver can be instructed to
try IPv6 lookups first by using the
inet6 option in
/etc/resolv.conf.
FILES¶
/etc/hostname Historically this file was supposed to only contain the
hostname and not the full canonical FQDN. Nowadays most software is able to
cope with a full FQDN here. This file is read at boot time by the system
initialization scripts to set the hostname.
/etc/hosts Usually, this is where one sets the domain name by aliasing
the host name to the FQDN.
AUTHORS¶
Peter Tobias, <tobias@et-inf.fho-emden.de>
Bernd Eckenfels, <net-tools@lina.inka.de> (NIS and manpage).
Michael Meskes, <meskes@debian.org>