Python logging: create log if not exists or open and continue logging if it does

Question

I'm writing some code that uses the python logging system. The idea is that if the LOG doesn't already exist create the log but if it does then get the log and resume logging to that file. Here is my code:

import logging import os  log_filename='Transactions.log') if os.path.isfile(log_filename)!=True:     LOG = logging.getLogger('log_filename')     LOG.setLevel(logging.DEBUG)     # create file handler which logs even debug messages     fh = logging.FileHandler('log_filename')     fh.setLevel(logging.DEBUG)     # create console handler with a higher log level     ch = logging.StreamHandler()     ch.setLevel(logging.DEBUG)     # create formatter and add it to the handlers     formatter = logging.Formatter('-->%(asctime)s - %(name)s:%(levelname)s - %(message)s')     fh.setFormatter(formatter)     ch.setFormatter(formatter)     # add the handlers to the logger     LOG.addHandler(fh)     LOG.addHandler(ch) else:     LOG=logging.getLogger() 

I suspect the problem is with my else block but I don't know how to fix. Could anybody shed some light on this situation.

Answer 1

The logging module's FileHandler takes care of that for you. No need for complexity.

The handler takes an optional mode parameter, to specify whether it starts writing or appending data to it.

From the docs:

class logging.FileHandler(filename, mode='a', encoding=None, delay=False)

The specified file is opened and used as the stream for logging. If mode is not specified, 'a' is used.