#!/usr/bin/perl -wi.bak
use strict;

##</code><code>##

my %params;
my $filename = shift || die "Usage: netswap.pl CONFILENAME\n";

##</code><code>##

open(FH,"$filename")
	or die "Could not open network configuration file: [$filename] for reading: $!\n";

##</code><code>##

while(<FH>){
    # Skip the blank lines or the commented lines
    next if (/^\s*$/ || /^\s*\#/);

    # Get the name and the values
    my ($name, $value) = split(/:/, $_, 2);

    # Remove starting/trailing spaces	
    s/(?:^\s*|\s*$)//g foreach ($name, $value);

    # Store the values in the hash in lowercase to 
    # avoid typing mistakes
    $params{$name} = lc($value);
}

##</code><code>##

print <<"EOL";
new hostname    = [$params{hostname}]
new domainname  = [$params{domainname}]
new ip          = [$params{ip}]
new Subnet Mask = [$params{subnetmask}]
new DNS         = [$params{dns}]
new gateway     = [$params{gateway}]

EOL

##</code><code>##

my $replacements = {
	'/etc/hosts' => {
	'hosts' => {
		"^.*$params{hostname}.*" => "$params{ip}\t$params{hostname}.$params{domainname}\t$params{hostname}",
	},

	'/etc/sysconfig/network' =>	{
		"^GATEWAY.*"      => qq'GATEWAY="$params{gateway}"',
		"^HOSTNAME.*"     => qq'HOSTNAME="$params{hostname}"',
		"^DOMAINNAME.*"   => qq'DOMAINNAME="$params{domainname}"',
	},

	'/etc/sysconfig/network-scripts/ifcfg-eth0' => {
		"^IPADDR.*"       => qq'IPADDR="$params{ip}"',
		"^NETMASK.*"      => qq'NETMASK="$params{subnetmask}"',
	},

	'/etc/resolv.conf' => {
		"^nameserver.*"   => "nameserver $params{dns}",
		"^SEARCH.*"       => "SEARCH $params{domainname}",
	},
};

file_edit($replacements);

`/etc/init.d/network restart`;

########################file_edit###################

sub file_edit {
    my $replacements = shift;
	foreach my $filename (keys %{$replacements}){
		print STDERR "Processing file [$filename]\n";

##</code><code>##

	    unless (-e $filename){
			print STDERR "  [$filename] cannot be found!\n";
			next;
		}

##</code><code>##

	    @ARGV=($filename); # put the filename where perl can find it.
	    while(<>){ 
			foreach my $search (keys %{$replacements->{$filename}}){
				s/$search/$replacements->{$filename}->{$search}/;
				print;
			}
		}
		print STDERR "  done\n";
	}
}