Process An Entire Directory

    my $dirname = '/usr/bin';
    chdir($dirname) or die("can't chdir $dirname: $!\n");
    opendir(DIR, $dirname) or die("can't opendir $dirname: $!\n");
    while (defined(my $fn = readdir(DIR))) {
        next unless (-f $fn);
        #...etc...
    }
    closedir(DIR)