Hi!

Look at this. Probably it helps to find the way.

#!/usr/bin/perl
use strict;
use warnings;

use Data::Dumper;

my $filename1 = 'file1.txt';
my $filename2 = 'file2.txt';

open my $fhin1, "<", $filename1 or die "ERROR: Can't open file '$filen
+ame1': $!";
open my $fhin2, "<", $filename2 or die "ERROR: Can't open file '$filen
+ame2': $!";

my %lines_found_in_file1 = map {
    chomp;
    s/^\s+//;
    s/\s+$//;
    $_ => 1
} (<$fhin1>);
my %lines_found_in_file2 = map {
    chomp;
    s/^\s+//;
    s/\s+$//;
    $_ => 1
} (<$fhin2>);

close  $fhin1 or die "ERROR: Couldn't close file '$filename1': $!";
close  $fhin2 or die "ERROR: Couldn't close file '$filename2': $!";

my $output1 = 'common.txt';
my $output2 = 'uncommon.txt';

open my $fhout1, ">", $output1 or die "ERROR: Can't open file '$output
+1': $!";
open my $fhout2, ">", $output2 or die "ERROR: Can't open file '$output
+2': $!";

# Compare in one direction
foreach my $line (keys %lines_found_in_file1) {
    if(exists $lines_found_in_file2{$line}) {
        print $fhout1 $line, "\n";
    }
    else {
        print $fhout2 $line, "\n";
    }
}
# Compare in other direction
foreach my $line (keys %lines_found_in_file2) {
    if(exists $lines_found_in_file1{$line}) {
        # Don't do anything as you printed these lines in the first go
    }
    else {
        print $fhout2 $line, "\n";
    }
}


close  $fhout1 or die "ERROR: Couldn't close file '$output1': $!";
close  $fhout2 or die "ERROR: Couldn't close file '$output2': $!";
[download]

Best regards
McA