#!perl
open (FILE1, $ARGV[0]);

while ($_ = <FILE1>) {
    chomp;
    @FILE1 = split;
    ($FILE1letter, $FILE1number) = @FILE1;

    open (FILE2, $ARGV[1]);
    while( $two = <FILE2> ) {
        @FILE2 = split(' ',$two);
            ($FILE2letter, $FILE2number) = @FILE2;
            #   print "$FILE1letter from FILE1 with number $FILE1number and $FILE2letter from FILE2 with $FILE2number match\n";
            #   prints the same as below

        if ($FILE1letter eq $FILE2letter) {
            print "$FILE1letter from FILE1 with number $FILE1number and $FILE2letter from FILE2 with number $FILE2number match\n";
        } else {
            print "$FILE1letter from FILE1 with number $FILE1number and $FILE2letter from FILE2 with number $FILE2number DO NOT match\n";
        }
    }
    close (FILE2);
}
__END__
C:\Temp>perl ab.pl a b
A from FILE1 with number 1_1 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_1 and B from FILE2 with number 2_2 DO NOT match
A from FILE1 with number 1_2 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_2 and B from FILE2 with number 2_2 DO NOT match
B from FILE1 with number 1_3 and A from FILE2 with number 2_1 DO NOT match
B from FILE1 with number 1_3 and B from FILE2 with number 2_2 match
C from FILE1 with number 1_4 and A from FILE2 with number 2_1 DO NOT match
C from FILE1 with number 1_4 and B from FILE2 with number 2_2 DO NOT match