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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 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).

       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/hostname
       or /etc/hosts

   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,  ypdomain-
       name and nisdomainname use setdomainname(2).  Note, that this is effec-
       tive 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 (normally by  read-
       ing  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  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.
       -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, and
              avoid using this option; use hostname --all-fqdns instead.
       -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  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-
              put.
       -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 AT et-inf.de>
       Bernd Eckenfels, <net-tools AT lina.de> (NIS and manpage).
       Michael Meskes, <meskes AT debian.org>

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