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 gethostname(2) function.

       domainname  will  print  the  NIS  domainname of the system.  domainname uses the gethost‐
       name(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 sec‐
       tion 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  fol‐
       lowed 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  com‐
       mon 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 appro‐
              priate 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 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)