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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, <[email protected]>
       Bernd Eckenfels, <[email protected]> (NIS and manpage).
       Michael Meskes, <[email protected]>

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