split stdin into different files at certain lines

splitat.py

import sys
import os
import re
pattern = re.compile(r'%s' % sys.argv[1])
filename_prefix = sys.argv[2]
filename_postfix = sys.argv[3]
curr_file = None
while True:
    line = sys.stdin.readline()
    if not line:
        break

    m = pattern.match(line)
    if m:
        if curr_file:
            curr_file.close()
            curr_file = None
        curr_file = open(filename_prefix + line.strip() + filename_postfix, 'w')
        
    if curr_file:
        curr_file.write(line)

if curr_file:
    curr_file.close()