domainname(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
   gethostname(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
   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>

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