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

use Fcntl ':seek';


open my $CSV, '<', 'donor_82_01.csv' or die "Cannot open 'donor_82_01.csv' because: $!";

my $pos = tell $CSV;
my %csv_data;
while ( <$CSV> ) {
        my ( $first ) = split /,+/;
        push @{ $csv_data{ $first } }, $pos;
        $pos = tell $CSV;
        }

open my $TAB, '<', 'tmp12' or die "Cannot open 'tmp12' because: $!";
open my $OUT, '>', 'tmp12_02' or die "Cannot open 'tmp12_02' because: $!";

while ( <$TAB> ) {
        my ( $first, $second ) = split /\t+/;
        next unless exists $csv_data{ $second };
        for my $pos ( @{ $csv_data{ $second } } ) {
                seek $CSV, $pos, SEEK_SET or die "Cannot seek on 'donor_82_01.csv' because: $!";
                print $OUT "$first,", scalar <$CSV>;
                }
        }

close $CSV;
close $TAB;
close $OUT;