#!/usr/bin/perl

use strict;
use warnings;

our $| = 1;

my $host_name = "test_host";
my $host_ip = "192.168.0.50";

#my $hosts = 'C:\Windows\System32\drivers\etc\hosts';
my $hosts = '/etc/hosts';

unless (defined gethostbyname $host_name) {
        print "Cannot find \"$host_name\"\n";

        print "Adding $host_name to $hosts ... ";
        open my $fh, ">>", $hosts or die "Cannot open \"$hosts\" for appending: $!\n";
        print $fh "$host_ip\t$host_name\n";
        close $fh;
        print "OK\n";

        print "Checking if $host_name is known now\n";

        my $packed_ip = gethostbyname $host_name || 0;

        print "--- $packed_ip ---\n";
}


##</code><code>##

SUSE Linux Enterprise Server 10 (x86_64)
VERSION = 10
PATCHLEVEL = 4

perl -v

This is perl, v5.8.6 built for i686-linux

##</code><code>##

# /tmp/gethostbyname.pl
Cannot find "test_host"
Adding test_host to /etc/hosts ... OK
Checking if test_host is known now
--- 0 ---
#