#!/usr/bin/perl

use strict;
use warnings;

opendir(DIR, ".");
my @list = readdir(DIR);
closedir(DIR);

foreach my $file (@list){
#the line below makes sure you don't try to open . and ..
if($file !~ /^\.+$/){
   open(FILE,"$file");
   my @lines = <FILE>;
   close FILE;

   # Open same file for writing, reusing STDOUT
   open (FILE, ">$file") or die "Can't open $file: $!\n";

   # Walk through lines...
   foreach my $line ( @lines )
   {
    #can just make the replacement on this line
    $line =~ s/(\w+_[_\w]+)\(\)/<A HREF="$1.html">$1\(\)<\/A>/;
    print FILE $line;
   }
   close FILE;
}
}

closedir( DIR );