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).


   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  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 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-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 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@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)
