use strict;
use warnings;

my @array =
  qw(
    oracle_hst_sid=hsta
    oracle_sid=sdpa
    oracle_home=/oracle/product_1/10.2.0
    sdp_home=/oracle/oracle8
    );

my @newArray =
  (
  map
    {my ($lhs, $rhs) = /(.*?)=(.*)/; $lhs =~ tr/_/./; "$lhs=$rhs"}
    @array
  );

print join "\n", @newArray;