hostname is used to either display or, with appropriate privileges, set the current host name of the system. The host name is used by many applications to identify the machine.
When called without any arguments, the program displays the name of the system as returned by the gethostname() function.
When called with a name argument, and the user has appropriate privilege, the command sets the host name.
Note: It is not specified if the hostname displayed will be a fully qualified domain name. Applications requiring a particular format of hostname should check the output and take appropriate action.