nfc_converter.py

#!/usr/bin/env python3

import sys
import os
import unicodedata
from tempfile import NamedTemporaryFile


def is_nfd(line):
    for char in line.strip():
        if unicodedata.combining(char) != 0:
            return True
    return False


filename = sys.argv[1]

with NamedTemporaryFile(delete=False) as tf:
    temp_file_name = tf.name
    with open(filename, encoding="utf-8") as f:
        for line in f:
            text = [char for char in line.strip()]

            if is_nfd(line):
                converted = unicodedata.normalize("NFC", line)
                tf.write(converted.encode())
            else:
                tf.write(line.encode())

os.rename(temp_file_name, filename)