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HOSTNAME(1) Linux Programmer's Manual HOSTNAME(1)
hostname - show or set the system's host name
domainname - show or set the system's NIS/YP domain name
dnsdomainname - show the system's DNS domain name
nisdomainname - show or set system's NIS/YP domain name
ypdomainname - show or set the system's NIS/YP domain name
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] [-F filename] [--file filename] [hostname]
domainname [-v] [-F filename] [--file filename] [name]
nodename [-v] [-F filename] [--file filename] [name]
hostname [-v] [-h] [--help] [-V] [--version]
Hostname is the program that is used to either set or display the cur-
rent host, domain or node name of the system. These names are used by
many of the networking programs to identify the machine. The domain
name is also used by NIS/YP.
When called without any arguments, the program displays the current
hostname will print the name of the system as returned by the gethost-
domainname, nisdomainname, ypdomainname will print the name of the sys-
tem as returned by the getdomainname(2) function. This is also known as
the YP/NIS domain name of the system.
dnsdomainname will print the domain part of the FQDN (Fully Qualified
Domain Name). The complete FQDN of the system is returned with hostname
The function gethostname(2) is used to get the hostname. When the
hostname -a, -d, -f or -i is called will gethostbyname(3) be called.
The difference in gethostname(2) and gethostbyname(3) is that gethost-
byname(3) is network aware, so it consults /etc/nsswitch.conf and
/etc/host.conf to decide whether to read information in
/etc/sysconfig/network or /etc/hosts
To add another dimension to this, the hostname is also set when the
network interface is brought up.
When called with one argument or with the --file option, the commands
set the host name, the NIS/YP domain name or the node name.
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 dns-
domainname command (see THE FQDN below).
The host name is usually set once at system startup in
/etc/rc.d/rc.inet1 or /etc/init.d/boot (normally by reading the con-
tents of a file which contains the host name, e.g. /etc/hostname).
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
Technically: The FQDN is the name gethostbyname(2) 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.
Display the alias name of the host (if used).
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
-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.
Displays all FQDNs of the machine. This option enumerates all
configured network addresses on all configured network inter-
faces, and translates them to DNS domain names. Addresses that
cannot be translated (i.e. because they do not have an appropri-
ate 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.
Print a usage message and exit.
Display the IP address(es) of the host. Note that this works
only if the host name can be resolved. Avoid using this option;
use hostname --all-ip-addresses instead.
Display all network addresses of the host. This option enumer-
ates 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 reso-
lution. Do not make any assumptions about the order of the out-
Display the short host name. This is the host name cut at the
Print version information on standard output and exit success-
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.
Note that hostname doesn't change anything permanently. After reboot
original names from /etc/hosts are used again.
Peter Tobias, <firstname.lastname@example.org>
Bernd Eckenfels, <email@example.com> (NIS and manpage).
Steve Whitehouse, <SteveW@ACM.org> (DECnet support and manpage).
net-tools 28 Jan 1996 HOSTNAME(1)