Programming Perl, 4th Edition

gethostbyname

gethostbyname NAME

This function translates a network hostname to its corresponding addresses (and other names). The return value in list context is:

#  0      1         2          3       4 ...
($name, $aliases, $addrtype, $length, @addrs) =
    gethostbyname($remote_hostname);

where @addrs is a list of raw addresses. In the Internet domain, each address is (historically) four bytes long and can be unpacked by saying something like:

($a, $b, $c, $d) = unpack("C4", $addrs[0]);

You can convert directly to dot-vector notation with the v modifier to sprintf:

$dots = sprintf "%vd", $addrs[0];

In scalar context, gethostbyname returns only the host address:

use Socket;
$ipaddr = gethostbyname($remote_host);
printf "%s has address %s\n",
    $remote_host, inet_ntoa($ipaddr);

See Sockets in Chapter 15 for another approach. The Net::hostent module supports a by-name interface to this function. See also gethostbyname(3).