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 [-v] [-a] [--alias] [-d] [--domain] [-f] [--fqdn] [-A] [--all-
fqdns] [-i] [--ip-address] [-I] [--all-ip-addresses] [--long] [-s]
[--short] [-y] [--yp] [--nis]
hostname [-v] [-b] [--boot] [-F filename] [--file filename] [hostname]
hostname [-v] [-h] [--help] [-V] [--version]
domainname [nisdomain] [-F file]
ypdomainname [nisdomain] [-F file]
nisdomainname [nisdomain] [-F file]
dnsdomainname [-v]
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
You can’t change the FQDN (as returned by hostname --fqdn) or the DNS
domain name (as returned by dnsdomainname) with this command. The FQDN
of the system is the name that the resolver(3) returns for the host
name.
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 (usually in /etc/host.conf)
how you can change it. Usually (if the hosts file is parsed before DNS
or NIS) you can change it 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.
-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. Ssee the warnings in section THE FQDN above, and avoid
using this option.
-F, --file filename
Read the host name from the specified file. Comments (lines
starting with a ‘#’) are ignored.
-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, and
avoid using this option; use hostname --all-fqdns instead.
-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 DNS 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.
-h, --help
Print a usage message and exit.
-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.
-v, --verbose
Be verbose and tell what’s going on.
-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.
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/hosts
/etc/hostname This file should only contain the hostname and not the
full 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>