HOSTNAME(1)                Linux Programmer’s Manual                HOSTNAME(1)

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 gethost‐
       name(2) function.

       domainname will print the NIS domainname of the system.  domainname uses
       the gethostname(2) function, while ypdomainname  and  nisdomainname  use
       the getdomainname(2).

       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 sethost‐
       name(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  dns‐
       domainname command (see THE FQDN below).

       The host name is usually set once at system startup in /etc/init.d/host‐
       name.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 af‐
       ter 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 limita‐
       tions so it should be avoided as well.

OPTIONS
       -a, --alias
              Display the alias name of the host (if used). This option is dep‐
              recated 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  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 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‐existent  or empty, in which case the default hostname local‐
              host will be used if none is yet set.

       -d, --domain
              Display the name of the DNS domain.  Don’t use  the  command  do‐
              mainname  to get the DNS domain name because it will show the NIS
              domain name and not the DNS domain name.  Use  dnsdomainname  in‐
              stead.  See the warnings in section THE FQDN above, and avoid us‐
              ing 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 us‐
              ing 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 op‐
              tion; 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 success‐
              fully.

       -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>

net‐tools                          2009‐09‐16                       HOSTNAME(1)