Python: TimedRotatingFileHandler

It is used to rotate log files at certain timed intervals.

Syntax

logging.handlers.TimedRotatingFileHandler(filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False, atTime=None)

Argument	Description
filename	Full path of file name.
when	Specifies the type of interval in hours, minutes, seconds etc.
interval	Specifies interval.
backupCount	Number of files to take backup. If more would be created when rollover occurs, the oldest one is deleted.
encoding	File opened with given encoding
delay	If delay is true, then file opening is deferred until the first call to emit().
utc	If the utc argument is true, times in UTC will be used; otherwise local time is used.
atTime	If atTime is not None, it must be a datetime.time instance which specifies the time of day when rollover occurs.

You can specify following values to the argument ‘when’.

Value	Type of interval
‘S’	Seconds
‘M’	Minutes
‘H’	HoursDays
‘D’	Days
‘W0’-‘W6’	W0 represents Monday, W1 represents Tuesday etc.
‘midnight’	Roll over at midnight

import logging
import logging.handlers
import time

#Define logger
logger = logging.getLogger(__name__)
logging.basicConfig(level=logging.DEBUG, format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s')

LOG_FILENAME="temp.log"
#Define handler to write to standard output
handler = logging.handlers.TimedRotatingFileHandler(LOG_FILENAME, when='M', interval=1)

formatter = logging.Formatter('[%(levelname)s] %(message)s')
handler.setFormatter(formatter)
handler.setLevel(logging.DEBUG)

#Adding handler to logger
logger.addHandler(handler)
logger.setLevel(logging.DEBUG)

def logMessages():
    time.sleep(60)
    logger.debug("Debug message")
    logger.info("Information Message")
    logger.warn("Warning Message")
    logger.error("Error Message")
    logger.critical("Critical Message")

if(__name__=="__main__"):
    for i in range(5):
        logMessages()

Run above program, it creates 6 files temp.log and other five files are like temp.log.%Y-%m-%d_%H-%M-%S format.

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