#!/usr/bin/env perl

use strict;
use warnings;

use Text::CSV;

my $csv = Text::CSV::->new() or die Text::CSV::->error_diag();

while (my $row = $csv->getline(\*DATA)) {
    print join('|' => @$row), "\n";
}

__DATA__
aaa,bbb,"ccc, ddd",fff

##</code><code>##

$ pm_csv_to_psv.pl
aaa|bbb|ccc, ddd|fff

##</code><code>##

    print join('|' => map { /,/ ? '"'.$_.'"' : $_ } @$row), "\n";

##</code><code>##

$ pm_csv_to_psv.pl
aaa|bbb|"ccc, ddd"|fff