fastest way convert tab-delimited file to csv in linux

Question

I have a tab-delimited file that has over 200 million lines. What's the fastest way in linux to convert this to a csv file? This file does have multiple lines of header information which I'll need to strip out down the road, but the number of lines of header is known. I have seen suggestions for sed and gawk, but I wonder if there is a "preferred" choice.

Just to clarify, there are no embedded tabs in this file.

Answer 1

If you're worried about embedded commas then you'll need to use a slightly more intelligent method. Here's a Python script that takes TSV lines from stdin and writes CSV lines to stdout:

import sys
import csv

tabin = csv.reader(sys.stdin, dialect=csv.excel_tab)
commaout = csv.writer(sys.stdout, dialect=csv.excel)
for row in tabin:
  commaout.writerow(row)

Run it from a shell as follows:

python script.py < input.tsv > output.csv