That's a good one :) bookmarked as: Converting File Delimiters (csv to tsv to psv, use App::CCSV)

linux shell quoted
perl -MApp::CCSV -ne ' $csv->sep_char(q{|}); csay @f; $csv->sep_char(q{,}) ' < comma.csv >pipe.CSV

windows shell quoted
perl -MApp::CCSV -ne " $csv->sep_char(q{|}); csay @f; $csv->sep_char(q{,}) " < comma.csv >pipe.CSV