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  [-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] [-b] [--boot] [-F filename] [--file filename] [hostname]
       hostname [-v] [-h] [--help] [-V] [--version]

       domainname [nisdomain] [-F file]
       ypdomainname [nisdomain] [-F file]
       nisdomainname [nisdomain] [-F file]

       dnsdomainname [-v]


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 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  gethostby-
       name(3)  be  called.  The difference in gethostname(2) and gethostbyname(3) is that gethostbyname(3) is network aware, so
       it consults /etc/nsswitch.conf and /etc/host.conf to decide whether to  read  information  in  /etc/sysconfig/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 or the NIS/YP domain name.  host-
       name uses the sethostname(2) function, while all of the three domainname, ypdomainname and nisdomainname  use  setdomain-
       name(2).   Note, that this is effective only until the next reboot.  After reboot original names from /etc/hosts are used
       again.

       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/rc.d/rc.sysinit (normally by reading the contents of  a  file
       which contains the host name, e.g.  /etc/sysconfig/network).


   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 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 (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 multi-
       ple FQDNs/domain names or none at all. Therefore avoid using hostname --fqdn, hostname --domain and dnsdomainname.  host-
       name --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.

       -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. Ssee the warnings in section  THE
              FQDN above, and avoid using this option.

       -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  net-
              work  interfaces,  and translates them to DNS domain names. Addresses that cannot be translated (i.e. because they
              do not have an appropriate 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 out-
              put.

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

       -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 inter-
              faces. 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.

       -v, --verbose
              Verbose output was removed.

       -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.

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/hosts

       /etc/sysconfig/network

AUTHORS
       Peter Tobias, <tobiasATet-inf.de>
       Bernd Eckenfels, <net-toolsATlina.de> (NIS and manpage).
       Michael Meskes, <meskesATdebian.org>



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