I'd like to repeat peterwwillis in saying that there are very Unixy tools that are designed for this, and update his link to my favorite, csvfix: http://neilb.bitbucket.org/csvfix/

Neat selling points: csvfix eval and csvfix exec

also: the last commit to csvfix was 6 days ago; it's active, mature, and the developer is very responsive. If you can think of a capability that he hasn't yet, tell him and you'll have it in no time:)