Is there a way to overwrite log files in python 2.x

Question

I'm using python2.x logging module, like,

logging.basicConfig(format='%(asctime)s %(message)s',
                datefmt='%m/%d/%Y %I:%M:%S %p',
                filename='logs.log',
                level=logging.INFO)

I want my program to overwrite logs.log file for each execution of the script, currently it just appends to old logs. I know the below code will overwrite, but if there is a way to do it via logging config, it'll look better.

with open("logs.log", 'w') as file:
  pass

Sites

Answer 1

Add the filemode option to basicConfig:

logging.basicConfig(format='%(asctime)s %(message)s',
                datefmt='%m/%d/%Y %I:%M:%S %p',
                filename='logs.log',
                filemode='w',
                level=logging.INFO)

From the logging documentation for the basicConfig method (in the big table explaining all options):

filemode: Specifies the mode to open the file, if filename is specified (if filemode is unspecified, it defaults to ‘a’).

Monotonous

Note that "filemode" is the keyword "mode" if you use DictConfig. Example: ` "handlers": { "file": { "class": "logging.FileHandler", "formatter": "form02", "level": "INFO", "filename": "logs.log", "mode": "w", # Overwrite file if it exists }, }, ` – Macon

I don't think this works anymore. 'w' will add truncation line and append the content. Just tested in Python 3.10. Here is documentaion: docs.python.org/3/library/functions.html#open – Dibb

Answer 2

The actual answer is to add the filemode = 'w' AND force = True parameter to basicConfig. What seems to be happening is that default handlers are setting the filemode to a for append. With filemode already set, logging doesn't bother to apply your requested filemode of w for write. Adding the force parameter disables all default handlers and uses all the parameters you specified instead.

Stratification

Thanks! This should be the correct answer in multiple questions here on SO. – Vermination

Answer 3

Both

logging.basicConfig(format='%(asctime)s %(message)s',
                datefmt='%m/%d/%Y %I:%M:%S %p',
                filename='logs.log',
                filemode='w',
                level=logging.INFO)

and

logging.basicConfig(format='%(asctime)s %(message)s',
                datefmt='%m/%d/%Y %I:%M:%S %p',
                filename='logs.log',
                filemode='w+',
                level=logging.INFO)

always append in Python 2.7, on both Windows and Linux

Buhrstone

I'm also seeing the same behavior in Python 3.6. This just doesn't seem right- I'm passing filemode='w' in all cases. – Buhrstone