open(file1,"file1.txt");

##</code><code>##

open my $file1, '<', "file1.txt"
  or die "Can't open `file1.txt': $!\n";

##</code><code>##

while (<file1>)  
 {
   chop();

##</code><code>##

   $REC     = $_;
   @LINEREC = split(/\,/,$REC);

##</code><code>##

use strict;
use warnings;

##</code><code>##

   my $REC     = $_;
   my @LINEREC = split(/\,/,$REC);

##</code><code>##

open(file2,"file2.txt");

while (<file1>)

##</code><code>##

if ( $LINEREC[0] eq $LINEREC[1])
{
print $LINEREC[0];
{

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

die "Usage: $0 <file1> <file2>\n" unless @ARGV == 2;

my ($file2, %have)=pop;

while (<>) {
    chomp;
    $have{ (split /,/)[0] }=1;
}

@ARGV=$file2;
my %saw;
$\="\n";

while (<>) {
    chomp;
    local $_=(split /,/)[1];
    next if $saw{$_}++;
    print if $have{$_};
}

__END__