#!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;
use Text::CSV;

my $csv = Text::CSV->new({
    sep_char    => "\t",
    binary      => 1,   # always a good idea
});

while(my $row = $csv->getline(*DATA)) {
    say "$row->[0],$row->[1]";
}

__DATA__
word1   word2   word3
word4   word5   word6