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This tutorial will show you how to write logs to files in Python.

Use the module in Python loggingto write logs to files

Logging is used to debug a program and find out what went wrong. loggingThe log module is used to log data to a file in Python. We can use logging.basicConfig()the log function to configure the log to be written to a specific file. By default, loggingthere are 5 types of lines that we can log using the log module. These message types include debug, info, warning, error, and critical. Nonetheless, we can increase this number to any number we need through coding. The following code example shows us how to logging.basicConfig()write logs to a file using the log function.

import logging

# Creating and Configuring Logger

Log_Format = "%(levelname)s %(asctime)s - %(message)s"

logging.basicConfig(
    filename="logfile.log", filemode="w", format=Log_Format, level=logging.ERROR
)

logger = logging.getLogger()

# Testing our Logger

logger.error("Our First Log Message")

logfile.logThe file contents:

ERROR 2021-06-13 04:14:29,604 - Our First Log Message

We logging.basicConfig()used errorthe log_log ...Our First Log MessageLog_Format

Then, we use the parameter logging.basicConfig()of the function filenameto specify the log file. We aassign the value of to the parameter logging.basicConfig()of the function filemodeto appendopen the file in the mode so that the previous logs are not deleted every time there is a new log. Then we formatset the parameter to Log_Format. After that step, we logging.ERRORassign to levelthe parameter to specify the minimum level of error for the log. We logger = logging.getLogger()create a logger object using to write the log message. Finally, we logger.error("Our First Log Message")write the error message using .

Use the function in Python logging.FileHandler()to write logs to files

We can also logging.FileHandler()write logs to a file in Python using the log_handler function. This function takes the file path to which we want to write logs. We can then addHandler()add this handler to our logger object using the log_handler function. The following code demonstrates how to logging.FileHandler()write logs to a file using the log_handler function.

import logging

logger = logging.getLogger()
handler = logging.FileHandler("logfile.log")
logger.addHandler(handler)
logger.error("Our First Log Message")

logfile.log content:

Our First Log Message

We use the logger function in the code above logging.FileHandler()to write log messages Our First Log Messageto a file logfile.log. We first create a logger object, which we will use logging.getLogger()to write logs using the logger function. Then, we create a file handler handlerand assign it to it logging.FileHandler('logfile.log'). After that, we add logger.addHandler(handler)this new handlerlogger to our logger object using . Finally, we logger.error('Our First Log Message')write the error message to our file using .