use File::Spec::Functions qw( catfile );

opendir(my $dh, $dirname)
   or die "can't opendir $dirname: $!\n";

while (defined(my $filename = readdir($dh))) {
    my $fq_filename = catfile($dirname, $filename);
    my $mtime = (stat($fq_filename))[9];
    print "$filename: $mtime<br>";
}

closedir($dh);