Assuming order is not important and there are no duplicates I would read the file into a hash and then change the values of interest: 

use strict;
use warnings;

my %config = map { /(.*)=(.*)/ } <DATA>;
$config{'IPADDR'} = '1.2.3.4';
print "$_=$config{$_}\n" for keys %config;

__DATA__
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
TYPE=Ethernet
IPADDR=10.9.0.200
NETMASK=255.255.0.0
GATEWAY=10.9.1.254

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In reply to Re: Update config file parameters by hdb
in thread Update config file parameters by pavan.gup

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