Split an mbox file into multiple .patch files

split-mbox.py

#!/usr/bin/python3

import mailbox
import sys
import os

def main():
    argv = sys.argv
    if len(argv) != 2:
        print(f'Usage: {argv[0]} <mbx file>')
        exit(1)
    fname = argv[1]

    dirname = os.path.dirname(fname)
    (root, ext) = os.path.splitext(os.path.basename(fname))

    if ext != ".mbx":
        print(f'extension must be "mbx" but "{ext}"')
        exit(1)

    mbox = mailbox.mbox(fname)
    count = 1
    for m in mbox:
        with open(f'{dirname}/{count:04}-{root}.patch'.format(), 'w+') as f:
            f.write(str(m))
        count += 1

main()