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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 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
       gethostbyname(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/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, ypdomainname  and  nisdo‐
       mainname  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 (normally by reading the contents of a file which contains
       the host name, e.g.  /etc/hostname).


              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 con‐
              figured network interfaces, and translates them to DNS domain names. Addresses that  cannot  be  trans‐
              lated (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 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 enumerates all configured addresses on all  net‐
              work  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.

       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 sys‐
       tem 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)