CSV Converter, from/to comma <> semicolon, for French users of Excel ; drag&drop file on the script. UTF-8 assumed.

csv_converter.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys, pathlib, csv

def main():
	if len(sys.argv) != 2:
		print('Bad number of argument', file=sys.stderr)
		sys.exit(1)

	input_path = pathlib.Path(sys.argv[1])
	if input_path.suffix != '.csv':
		print('Input file does not have csv extension', file=sys.stderr)
		sys.exit(2)

	with input_path.open('r', encoding='utf8') as input_handle:
		# Detect input delimiter
		dialect = csv.Sniffer().sniff(input_handle.read(4096))
		input_handle.seek(0)
		input_reader = csv.reader(input_handle, dialect)

		# Set output delimiter
		if dialect.delimiter == ';': # Excel to not Excel
			output_path = input_path.with_name(input_path.stem+'_comma'+input_path.suffix)
			output_delimiter = ','
		else: # Not Excel to Excel
			output_path = input_path.with_name(input_path.stem+'_semicolon'+input_path.suffix)
			output_delimiter = ';'

		with output_path.open('x', encoding='utf-8-sig', newline='') as output_handle:
			output_writer = csv.writer(output_handle, delimiter=output_delimiter)
			for entry in input_reader:
				output_writer.writerow(entry)

if __name__ == '__main__':
	main()