$envfile="/root/env.properties"; 
@envFile=<$env>;
open my $env,  '<',  $envfile      or die "Can't read old file: $!";

##</code><code>##

open my $in,  '<',  $file      or die "Can't read old file: $!";
open my $out, '>', "$file.new" or die "Can't write new file: $!";

##</code><code>##



print "\nFile contents:";
print @envFile;

foreach $envline (@envFile){

while ( <$in> ){

##</code><code>##

        print "$. $_";
        if($envline =~/$DOMAIN_DB_CONN_STR=.*:1521:.*/ && $_=~/$DOMAIN_DB_CONN_STR=.*:1521:.*/){

##</code><code>##

                print "\nMatch";
                $line=$_;
                $line =~ s/$DOMAIN_DB_CONN_STR=.*:1521:.*/NUANCE_DB_CONN_STR=$dbhost:$dbport:$dbschema/;

##</code><code>##

                print $out $line;
        }
}
}

##</code><code>##

use strict;
use warnings;

my $envfile = "/root/env.properties"; 
my $file = 'input.txt'; # Or whatever

open my $env,  '<',  $envfile      or die "Can't read old file: $!";
open my $in,  '<',  $file      or die "Can't read old file: $!";
open my $out, '>', "$file.new" or die "Can't write new file: $!";

my @envFile = <$env>;
my @inFile = <$in>;

print "\nFile contents:";
print @envFile;

my $dbhost = '';
my $dbport = '';
my $dbschema = '';

foreach my $envline (@envFile){
    my $inLineCount = 0;
    foreach my $inline (@inFile){
        $inLineCount++;
        print "$inLineCount $inline";
        foreach my $DOMAIN_DB_CONN_STR ('FINANCE_DB_CONN_STR', 'MARKETING_DB_CONN_STR') {
            if($envline =~/$DOMAIN_DB_CONN_STR=.*:1521:.*/ && $inline =~/$DOMAIN_DB_CONN_STR=.*:1521:.*/){
                print "\nMatch";
                my $line = $inline;
                $line =~ s/$DOMAIN_DB_CONN_STR=.*:1521:.*/NUANCE_DB_CONN_STR=$dbhost:$dbport:$dbschema/;
                print $out $line;
            }
        }
    }
}