TSV to CSV is less of a misery than most conversions but the solution depends on how irritating your data is. Sed is definitely the way to go on this:

• Try:

  sed 's/,/\\,/g' | sed 's/t/,/g'

  You might get lucky that Google Fusion's CSV parser will see the comma escape.

• No luck... then like you I'd go:

  sed 's/,/\\,/g' | sed 's/t/","/g' | sed 's/$/"/g' | sed 's/^/"/g'

• This will be dead if you have quotation marks in the data. In that case add

  sed 's/"/\\"/g'

  to the start of the chain.

• You're dead now if you have " in the data. And here, the escaping becomes quite painful.

• With luck the already escaped \t bits in the TSV data should be fine on the CSV importer. But if not you'll want a late

  sed 's/\t/\t/g'

• To be honest, I really don't know how \, is likely to turn out inside quoted CSV. Your CSV importer may or may not need it.

And at this point you're so far down the rabbit hole that you probably want to start over.

Tab problem: You using a Mac? I despise their sed.

--