Python: Bulk convert .tsv to .csv

tsv2csv.py

#!/usr/bin/python

import glob
import csv
import sys
import os

# Check args
if len(sys.argv) < 2:
    sys.exit('Usage: tsv2csv.py /path/to/dir')

# Create glob pattern, fetch filenames
pattern = sys.argv[1].rstrip('/') + '/*.tsv'
filenames = glob.glob(pattern)

# Loop through, and convert
for i, source_file in enumerate(filenames):
    dest_file = source_file.rstrip('.tsv') + '.csv'

    csv.field_size_limit(sys.maxsize)
    csv.writer(file(dest_file, 'w+')).writerows(csv.reader(open(source_file), delimiter="\t"))

    i += 1
    print 'Created: ' + os.path.basename(dest_file)

print '\n', i, 'files have been converted...\n'