Python - How can I open a file and specify the offset in bytes?

Question

I\'m writing a program that will parse an Apache log file periodically to log it\'s visitors, bandwidth usage, etc..

The problem is, I don\'t want to open the log an

Answer 1

Here is an efficient and safe snippet to do that saving the offset read in a parallell file. Basically logtail in python.

with open(filename) as log_fd:
    offset_filename = os.path.join(OFFSET_ROOT_DIR,filename)
    if not os.path.exists(offset_filename):
        os.makedirs(os.path.dirname(offset_filename))
        with open(offset_filename, 'w') as offset_fd:
            offset_fd.write(str(0))
    with open(offset_filename, 'r+') as offset_fd:
        log_fd.seek(int(offset_fd.readline()) or 0)
        new_logrows_handler(log_fd.readlines())
        offset_fd.seek(0)
        offset_fd.write(str(log_fd.tell()))