move common lines from multiple files to a single file

#!/usr/bin/perl

use strict;
use warnings;

my %rows;
my %published;
my $files_examined = 0;

# populate rows hash
foreach my $file (@ARGV) {
  next if not -r $file; # skip if not readable
  next if not -f $file; # skip if not file (dir, pipe, etc)

  open IN, $file or die "Can't open file $file, $!\n";
  $files_examined += 1;

  while(<IN>) {
    my $line = $_;
    chomp($line);
    $line = sanitize($line);

    if (defined $rows{$line}) { 
      #print ">>> $line \t($rows{$line} -> ". ($rows{$line} + 1) .")\n";
      $rows{$line} += 1;
    } #increment counter
    else { $rows{$line} = 1; } #create counter

  } # end while

  close IN;

} # end foreach


# print only uncommon lines
open COMMON, ">common-lines.txt" or die "Can't open file common-lines.txt for writing, $!\n";

foreach my $file (@ARGV) {
  next if not -r $file; # skip if not readable
  next if not -f $file; # skip if not file (dir, pipe, etc)

  open IN, $file or die "Can't open file $file, $!\n";
  open OUT, ">$file.uncommon" or die "Can't open file $file.uncommon for writing, $!\n";

  while(<IN>) {
    my $line = $_;
    chomp($line);
    $line = sanitize($line);

    if ( $rows{$line} != $files_examined ) { # if counter is different than total number of files
      #warn "###OUT line counter $rows{$line}, file counter $files_examined";
      print OUT $_; # print line to file.uncommon if appears only one time
    } 
    if ( $rows{$line} == $files_examined and not defined $published{$_} ) { # if counter equals total number of files and row isn't already in common file
      #warn "###COMMON line counter $rows{$line}, file counter $files_examined";
      print COMMON $_;
      $published{$_} = 1;
    } # end if

  } # end while

  close IN;
  close OUT;

} # end foreach
close COMMON;

sub sanitize {
  my $r = shift;
#  my $debug;
#  $debug = '### ' . $r . ' -> ';
  $r =~ s/^\s+([^\s])/$1/; # remove all space at line start
#  print $debug . $r . "\n";
  return $r;
}