Ubuntu

Binary package “libsys-hostname-long-perl” in ubuntu xenial

  1. Xenial (16.04)
  2. libsys-hostname-long-perl

Figure out the long (fully-qualified) hostname

 Sys::Hostname::Long determines the host full name on multiple
 operating systems (MacOS, Windows, Unix-like systems; more later.)
 .
 The Sys::Hostname class is the best and standard way to get the basic
 hostname, but that may not be fully qualified. This module tries to
 determine the host's fully qualified name.

Source package