#!/usr/bin/perl
use strict;

my %ls = map { chomp; $_ => 2 } qx{/bin/ls -1};

opendir(DIR,".") or die "cannot readdir here - $!";
$ls{$_}++ foreach  readdir(DIR);

my @where = ("","readir only", "ls only", "both");
foreach (sort keys %ls) {
  printf("%12s: %s\n", $where[ $ls{$_} ], $_);
}

__END__
readir only: .
readir only: ..
       both: file1.pl
       both: file2.pl
       both: path