fqdns.pl

#!/usr/local/bin/perl

##
# @file      fqdns.pl
# @author    Mitch Richling <http://www.mitchr.me/>
# @Copyright Copyright 1998 by Mitch Richling.  All rights reserved.
# @brief     How to get a host's FQDNS.@EOL
# @Keywords  FQDNS resolver hostname gethostbyname gethostbyaddr
# @Std       Perl5
#
#            Getting the FQDNS from a perl program is not as simple as it
#            should be for many UNIX platforms.  The difficulty stems
#            from the fact that many UNIX platforms do not return
#            FQDNS from a gethostbyname() call.  The related system
#            call, gethostbyaddr() will always return the FQDNS, but
#            you must know the host's IP address to use it.  The
#            solution is to first get the IP address associated with
#            a partial host name and then get the FQDNS name
#            associated with it.


$ENV{'PATH'}='/bin:/usr/bin:/usr/local/bin';

# Get the local host name
$hostName = `hostname`;
chomp($hostName);

# Lookup name and address
($name,$aliases,$addrtype,$length,@addrs) = gethostbyname($hostName);
($name,$aliases,$addrtype,$length,@addrs) = gethostbyaddr($addrs[0], $addrtype);
($a,$b,$c,$d) = unpack('C4',$addrs[0]);

print "Name: $name Address 1: $a.$b.$c.$d \n";