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CentOS 7.0 - man page for dnsdomainname (centos section 1)

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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 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).

       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 geth-
       ostbyname(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  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 (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 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 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@et-inf.fho-emden.de>
       Bernd Eckenfels, <net-tools@lina.inka.de> (NIS and manpage).
       Michael Meskes, <meskes@debian.org>

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


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