my $file = "index.html";

my @codes = ("<P>", "<BR>", "UL"); # and many more

##</code><code>##

open(FILE, "> $file") or die "Oops: $!";
while(<FILE>);

##</code><code>##

if ($_ eq @words) {
$_ =~ s/@words/lc @word/g;
}

##</code><code>##

close(FILE);
##</code><code>##

#!/usr/bin/perl -i
use warnings;
use strict;


my @codes = ("<P>", "<BR>", "<UL>"); # and many more


while(<>);
for my $word (@words) {
$_ =~ s/$word/lc $word/g;
}
close(FILE);