opendir my $dh4, $a_directory or die "can't open directory $dh4:$!";
while (my $this_file = readdir $dh4)
{
    next if ($this_file =~ /\.log$/);   #skip all log files
    next if (-d "$dh4/$this_file");     #skip all directories
    print "$this_file is an extra file: $dh4/$this_file\n";
}