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
       dnsdomainname - show the system's DNS domain name
       nisdomainname - show or set system's NIS/YP domain name
       ypdomainname - show or set the system's NIS/YP domain name


SYNOPSIS
       hostname [-v] [-a] [--alias] [-d] [--domain] [-f] [--fqdn] [-A] [--all-
       fqdns] [-i]  [--ip-address]  [-I]  [--all-ip-addresses]	[--long]  [-s]
       [--short] [-y] [--yp] [--nis]


       hostname [-v] [-F filename] [--file filename] [hostname]


       domainname [-v] [-F filename] [--file filename] [name]


       nodename [-v] [-F filename] [--file filename] [name]


       hostname [-v] [-h] [--help] [-V] [--version]


       dnsdomainname [-v]
       nisdomainname [-v]
       ypdomainname [-v]


DESCRIPTION
       Hostname	 is the program that is used to either set or display the cur-
       rent host, domain or node name of the system.  These names are used  by
       many  of	 the  networking  programs to identify the machine. The domain
       name is also used by NIS/YP.


   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, nisdomainname, ypdomainname will print the name of the sys-
       tem as returned by the getdomainname(2) function. This is also known as
       the YP/NIS domain name of the system.


       dnsdomainname will print the domain part of the FQDN  (Fully  Qualified
       Domain Name). The complete FQDN of the system is returned with hostname
       --fqdn.


       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/syscon-
       fig/network or /etc/hosts

       To  add	another	 dimension  to this, the hostname is also set when the
       network interface is brought up.


   SET NAME
       When called with one argument or with the --file option,	 the  commands
       set the host name, the NIS/YP domain name or the node name.


       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/rc.d/rc.inet1  or  /etc/init.d/boot	 (normally by reading the con-
       tents of a file which contains the host name, e.g.  /etc/hostname).


   THE FQDN
       You can't change the FQDN (as returned by hostname --fqdn) or  the  DNS
       domain  name (as returned by dnsdomainname) with this command. The FQDN
       of the system is the name that the resolver(3)  returns	for  the  host
       name.


       Technically: The FQDN is the name gethostbyname(2) 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 (usually in /etc/host.conf)
       how you can change it. Usually (if the hosts file is parsed before  DNS
       or NIS) you can change it 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).

       -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.

       -F, --file filename
	      Read the host name from  the  specified  file.  Comments	(lines
	      starting with a `#') are ignored.

       -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.

       -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.

       -h, --help
	      Print a usage message and exit.

       -i, --ip-address
	      Display  the  IP	address(es)  of the host. 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.

       -v, --verbose
	      Be verbose and tell what's going on.

       -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.

FILES
       /etc/hosts /etc/sysconfig/network

NOTE
       Note  that  hostname  doesn't change anything permanently. After reboot
       original names from /etc/hosts are used again.

AUTHOR
       Peter Tobias, <tobias@et-inf.fho-emden.de>
       Bernd Eckenfels, <net-tools@lina.inka.de> (NIS and manpage).
       Steve Whitehouse, <SteveW@ACM.org> (DECnet support and manpage).




net-tools			  28 Jan 1996			   HOSTNAME(1)