How do I find out my hostname/domainname/IP address?

       The normal way to find your own hostname is to call the `hostname` program.  
While sometimes expedient, this has some problems, such as not knowing whether you've got the 
canonical name or not.  It's one of those tradeoffs of convenience versus portability.

       The Sys::Hostname module (part of the standard perl distribution) will give you the hostname 
after which you can find out the IP address (assuming you have working DNS) 
with a gethostbyname() call.

           use Socket;
           use Sys::Hostname;
           my $host = hostname();
           my $addr = inet_ntoa(scalar gethostbyname($host || 'localhost'));