Read the files line-by-line, split each pair of lines along whitespace, compare the relevant field, and output the lines if they differ:

#!/usr/bin/perl

use feature qw/say/;
use warnings;
use strict;

open my $file1, "<", "test1.txt" or die "Could not open first file: $!
+\n";
open my $file2, "<", "test2.txt" or die "Could not open second file: $
+!\n";

while(my $line1 = <$file1>) {
  my $line2 = <$file2>;

  chomp ($line1, $line2);

  my ($key1, $num1, $str1) = split /\s+/, $line1;
  my ($key2, $num2, $str2) = split /\s+/, $line2;

  if($str1 ne $str2) {
    say $line1;
    say $line2;
  }
}

close $file1 or die "Could not close first file: $!\n";
close $file2 or die "Could not close second file: $!\n";
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There's bound to be shorter, more idiomatic ways of achieving the same thing, but since your userpage indicates you're still new to Perl, you may find this the most instructive/useful.

On an unrelated side note, could you edit your post to use <code> tags for your sample data? See the following nodes for more information on formatting etc.:

• Writeup Formatting Tips
• Markup in the Monastery
• Perl Monks Approved HTML tags
• What shortcuts can I use for linking to other information?

I could be wrong, but I think your while loop is going to have problems if the two specified files do not have the same number of lines. If the first file has less lines than the second file, your code won't fully process all lines in the second file. If the first file has more lines than the second file, your loop will try to read in more lines from the second file than what it has.

You're right -- based on the sample data the OP shared, I assumed that both files would have the same number of lines. Thanks for pointing this out, I should have mentioned it explicitely.

This worked PERFECTLY!

Thanks a billion!

*tips hat* You're welcome!

BTW, I should also point out that this ignores the second field (the numbers) entirely, as with the sample data you supplied, there is never a situation where these don't match. Depending on whether this is also the case for your actual data, you may still want to adjust the above code.

I'm not sure that I totally understand what you're trying to do. It kind of sounds like you're merging multiple lists (from different files) and then wanting to do multiple column sorting of the data. Assuming that's correct, here's how I personally would approach the problem.

First, read in each file and put the data into a multidimensional array (AoA). After that, you could use something like Data::Table sort by the second column (numerically ascending) and then by the first column (numerically ascending). Once you have it sorted, just print it out to the new file.

The trick is that the file has 90k+ entries and line 1 may have duplicates such as 'Scott' more than once which I would like to keep, only eliminating those values where 'Scott' shows in line key 1 & 2 of the same second column value

You're right, there are no duplicates in the sample, however there ARE duplicates in the original file and thus only duplicates that share the same column 2 and column 3 value and are distinguished between key 1 and key 2 should be removed

The idea is NOT to remove:

1 23456 Scott
2 23456 Stapp
1 56789 Scott
2 56789 Miller

But DO REMOVE:

1 76543 Miller
2 76543 Miller
1 33446 Scott
2 33446 Scott

Does this clarify the question a bit?

If file identity in column 1 were omitted, you could use the unix comm utility to eliminate duplicates.

See if this works to your satisfaction (give input files as arguments):

#! /usr/bin/perl

my %X;

for (<>) {
    my ($i,$k,$n) = split(" ",$_,3);
    $X{$k.$n}{$k.$i} = $_;
}

for (sort {$a->[0] cmp $b->[0]} map [%$_], values %X) {
    print $_->[1] if @$_ == 2;
}
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