Demultiplex the output of `tail -f *.log`

tail-demux.py

#!/usr/bin/env python

import argparse
import re
import os
import sys

file_delimiter_regex = re.compile('.*?\=\=\> (.*?) \<\=\=\n')


def tail_demux(filename, output_dir):
    if not os.path.exists(filename):
        sys.exit('File "%s" not found' % (filename))

    os.makedirs(output_dir)

    current_file = os.path.join(output_dir, 'preamble')

    output_files = {}

    with open(filename, 'r') as fp:
        for line in fp:
            if len(line) == 1:
                continue
            line_match = file_delimiter_regex.match(line)

            if line_match is not None:
                current_file = os.path.join(output_dir, os.path.basename(line_match.group(1)))
            else:
                if current_file not in output_files:
                    output_files[current_file] = open(current_file, 'w')

                output_files[current_file].write(line)

    for fp in output_files.values():
        fp.flush()
        fp.close()


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='demultiplex the output of `tail -f *.log`')
    parser.add_argument('filename', help='the file to demux')
    parser.add_argument('--output_dir', '-o',
                        help='the directory in which the demuxed logs should be stored',
                        default='demuxed')

    args = parser.parse_args()

    tail_demux(**vars(args))