#!/usr/bin/perl 
 
use strict; 
 
use warnings; 
 
# RUN AS: listcompare.pl listG.txt listL.txt 
 
my @letters = qw(G L); 
my $letter = shift @letters; 
my %lines; 
while (<>) { 
    chomp; 
    if (my $l = $lines{$_}) { 
        my $ll = $l->{letters}; 
        next if ($ll->[-1] eq $letter); 
        push @$ll, $letter; 
    } 
    else { 
        $lines{$_} = { 
            f => scalar(@letters), 
            letters => [$letter], 
        } 
    } 
    if (eof) { 
        $letter = shift @letters; 
    } 
} 
print $_, ' ', join('', @{$lines{$_}{letters}}), "\n" for sort keys %lines; 
 
# END OF SCRIPT

use strict; 
use warnings; 
 
my ( %hash, $reverse ); 
 
while (<>) { 
	my @fields = $reverse ? reverse split : split; 
	$hash{"@fields"}{$ARGV}++; 
	$reverse++ if eof; 
} 
 
keys %{ $hash{$_} } == 2 and print "$_ YES\n" for keys %hash;

perl script.pl listL.txt listM.txt

D9PM 40 A3WX YES

$VAR1 = { 
          'R5QRC 40 A3WX' => { 
                               'listM.txt' => 1 
                             }, 
          'D9PM 80 Q5BAL' => { 
                               'listL.txt' => 1 
                             }, 
          'L2AFT 80 A3WX' => { 
                               'listM.txt' => 1 
                             }, 
          'D9PM 40 L7MRQ' => { 
                               'listL.txt' => 1 
                             }, 
          'D9PM 40 A3WX' => { 
                              'listM.txt' => 1, 
                              'listL.txt' => 1 
                            } 
        };

values %{ $hash{$_} } ne 2 and print "$_\n" for keys %hash;

@sorted = sort { $hash{$a} cmp $hash{$b} } keys %hash;

D9PM 40 A3WX YES DUP 
D9PM 40 L7MRQ 
D9PM 80 Q5BAL

#!/usr/bin/perl 
use strict; 
use warnings; 
 
my %data; 
 
2 == @ARGV or die "Supply fileL and fileM to compare."; 
 
open my $L, "<", shift or die $!;  
while (<$L>) {  
    chomp; 
    $data{$_} = $_; 
}  
close $L or die $!; 
 
my %seen; 
open my $M, "<", shift or die $!; 
while (<$M>) { 
    my $key = join " ", reverse split; 
    if ($data{$key}) { 
        if (! $seen{$key}++) { 
            $data{$key} .= ' YES'; 
        } 
        else { 
            $data{$key} .= ' DUP' if $seen{$key} == 2;   
        } 
    }  
} 
close $M or die $!; 
 
for my $v (sort values %data) { 
    print $v, "\n"; 
} 
 
__DATA__ 
listL.txt 
 
D9PM 40 L7MRQ  
D9PM 40 A3WX  
D9PM 80 Q5BAL  
  
 
listM.txt (4 sample lines - includes a duplicate)  
 
A3WX 40 R5QRC  
A3WX 40 D9PM 
A3WX 80 L2AFT  
A3WX 40 D9PM

D9PM 40 L7MRQ 
D9PM 40 A3WX 
D9PM 80 Q5BAL 
D9PM 80 Q5BAL 
D9PM 40 A3WX

A3WX 40 R5QRC 
A3WX 40 D9PM 
A3WX 80 L2AFT 
A3WX 40 D9PM 
L7MRQ 40 D9PM

use strict; 
use warnings; 
 
my ( $listL, $listM, %hash, $reverse ) = @ARGV; 
 
while (<>) { 
	my @fields = $reverse ? reverse split : split; 
	$hash{"@fields"}{$ARGV}++; 
	$reverse++ if eof; 
} 
 
for my $key ( sort { ( split ' ', $a )[0] cmp ( split ' ', $b )[0] } keys %hash ) { 
	print $key   if exists $hash{$key}{$listL}; 
	print ' YES' if keys %{ $hash{$key} } == 2; 
	print ' DUP' if exists $hash{$key}{$listM} and $hash{$key}{$listM} > 1; 
	print "\n"; 
}

D9PM 80 Q5BAL 
D9PM 40 L7MRQ YES 
D9PM 40 A3WX YES DUP

(blank line) 
D9PM40 L7MRQ40 YES 
D9PM40 A3WX40 YES DUP 
D9PM80 Q5BAL80

D9PM40 L7MRQ40 YES 
D9PM40 A3WX40 YES DUP 
D9PM40 A3WX40 YES DUP 
D9PM80 Q5BAL80 DUP 
D9PM80 Q5BAL80 DUP

use strict; 
use warnings; 
 
my @arr1 = qw/D9PM 40 A3WX/; 
my @arr2 = reverse qw/A3WX 40 D9PM/; 
 
print 'Match!' if "@arr1" eq "@arr2"; # prints "Match!"