-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 network 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 output.

-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  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.

-v, --verbose
       Be verbose and tell what's going on.

-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.