Python - Print Logs in a File

If you want to print python logs in a file rather than on the console then we can do so using the basicConfig() method by providing filename and filemode as parameter.

The format of the message can be specified by using format parameter in basicConfig() method.

Let us take a basic example to print logs to a file rather than on the console. The code snippet is given below:

import logging    # first of all import the module

logging.basicConfig(filename='std.log', filemode='w', format='%(name)s - %(levelname)s - %(message)s')
logging.warning('This message will get logged on to a file')

root - ERROR - This message will get logged on to a file

The above output shows how the message will look like but keep in mind it will be written to a file named std.log instead of the console.

In the above code, the filemode is set to w, which means the log file is opened in “write mode” each time basicConfig() is called, and after each run of the program, it will rewrite the file.

The default configuration for filemode is a, that is append, which means that logs will be appended to the log file and adding logs to the existing logs.

Python Logging - Store Logs in a File

There are some basic steps and these are given below:

1. First of all, simply import the logging module just by writing import logging.

2. The second step is to create and configure the logger. To configure logger to store logs in a file, it is mandatory to pass the name of the file in which you want to record the events.

3. In the third step, the format of the logger can also be set. Note that by default, the file works in append mode but we can change that to write mode if required.

4. You can also set the level of the logger.

So let's move on to the code now:

#importing the module 
import logging 

#now we will Create and configure logger 
logging.basicConfig(filename="std.log", 
					format='%(asctime)s %(message)s', 
					filemode='w') 

#Let us Create an object 
logger=logging.getLogger() 

#Now we are going to Set the threshold of logger to DEBUG 
logger.setLevel(logging.DEBUG) 

#some messages to test
logger.debug("This is just a harmless debug message") 
logger.info("This is just an information for you") 
logger.warning("OOPS!!!Its a Warning") 
logger.error("Have you try to divide a number by zero") 
logger.critical("The Internet is not working....") 

The above code will write some messages to file named std.log. If we will open the file then the messages will be written as follows:

2020-06-19 12:48:00,449 - This is just harmless debug message 2020-06-19 12:48:00,449 - This is just an information for you 2020-06-19 12:48:00,449 - OOPS!!!Its a Warning 2020-06-19 12:48:00,449 - Have you try to divide a number by zero 2020-06-19 12:48:00,449 - The Internet is not working...

You can change the format of logs, log level or any other attribute of the LogRecord along with setting the filename to store logs in a file along with the mode.