Here the code I tried in my linux box works fine, it just reads a test.html and prints its content.

use strict;
use warnings;

use Cwd 'abs_path';
my $dir=abs_path($0);
print "$dir\n";

$dir=~s/pl.pl//g;
print "after:$dir\n";
opendir (DIR, $dir) or die $!;
my $fileName;
while ($fileName = readdir(DIR))
{
        print "$fileName\n";

        if ($fileName=~/\.html/i)
        {
                my $pathName="$dir/$fileName";
                $pathName=substr($pathName,0,length($pathName)-4);

                open(DATA, "+<${pathName}html") or die "Couldn't open 
+file file.txt, $!";

                while(<DATA>)
                {
                        print "$_";
                }
                close(DATA);
        }
}
closedir(DIR);
[download]