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HOSTNAME(1)                                    GNU 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  ypdomain‐
       name and nisdomainname use the getdomainname(2).

       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/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 setdo‐
       mainname(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 followed 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 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 mul‐
       tiple  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 appropriate 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 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.

       -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. Nowa‐
       days 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, [email protected]
       Bernd Eckenfels, [email protected] (NIS and manpage).
       Michael Meskes, [email protected]

[email protected]                                                 2020-10-27                                               HOSTNAME(1)