How to print a Timestamp for Logging in Python

# Table of Contents

# How to print a Timestamp for Logging in Python

Use the logging.basicConfig() method to print a timestamp for logging in Python.

The method creates a StreamHandler with a default Formatter and adds it to the root logger.

main.py

Copied!
import logging
import time

logging.basicConfig(
    format='%(asctime)s %(levelname)-8s %(message)s',
    level=logging.DEBUG,
    datefmt='%Y-%m-%d %H:%M:%S'
)

logging.info('Info message #1')

time.sleep(2)

logging.info('Info message #2')

time.sleep(2)

logging.debug('Debug message #1')

time.sleep(2)

logging.error('Error message #1')

time.sleep(2)

logging.warning('Warning message #1')

time.sleep(2)

logging.critical('Critical message #1')

print timestamp for logging in python

The code for this article is available on GitHub

The logging.basicConfig() method creates a StreamHandler with a default Formatter and adds it to the root logger.

main.py

Copied!
logging.basicConfig(
    format='%(asctime)s %(levelname)-8s %(message)s',
    level=logging.DEBUG,
    datefmt='%Y-%m-%d %H:%M:%S'
)

The format argument is used to set the format for the handler.

The argument defaults to the attributes levelname, name and message separated by colons.

The level argument is the root logger level.

Level	Numeric Value
CRITICAL	50
ERROR	40
WARNING	30
INFO	20
DEBUG	10
NOTSET	0

I set the level argument to logging.DEBUG, so that DEBUG, INFO, WARNING, ERROR and CRITICAL messages get printed.

For example, if you set the level to logging.INFO, then DEBUG messages won't get printed.

main.py

Copied!
import logging

logging.basicConfig(
    format='%(asctime)s %(levelname)-8s %(message)s',
    level=logging.INFO,
    datefmt='%Y-%m-%d %H:%M:%S',
    force=True
)

logging.info('Info message #1')

# 👇️ This won't print
logging.debug('Debug message #1')

print timestamp for logging in python

The datefmt argument is used to set the date/time format.

You can view all the available % directives in this section of the docs.

Directive	Meaning
%a	Locale's abbreviated weekday name.
%A	Locale's full weekday name.
%b	Locale's abbreviated month name.
%B	Locale's full month name.
%c	Locale's appropriate date and time representation.
%d	Day of the month as a decimal.
%H	Hour (24-hour clock) as a decimal.
%I	Hour (12-hour clock) as a decimal number.
%j	Day of the year as a decimal number.
%m	Month as a decimal number.
%M	Minute as a decimal number.
%p	Locale's equivalent of AM or PM.
%S	Second as a decimal number.
%w	Week as a decimal number [0(Sunday), 6].
%x	Locale's appropriate date representation.
%X	Locale's appropriate time representation.
%y	Year without century as a decimal.
%Y	Year with century as a decimal.

You can reorder the % directives in the string if you need to display the timestamp in a different way.

For example, the following code sample prints the timestamp for logging in the DD/MM/YYYY hh:mm:ss format.

main.py

Copied!
import time
import logging

logging.basicConfig(
    format='%(asctime)s %(levelname)-8s %(message)s',
    level=logging.DEBUG,
    datefmt='%d/%m/%Y %H:%M:%S',
    force=True
)

logging.info('Info message #1')

time.sleep(2)

logging.info('Info message #2')

print timestamp for logging in different format

The code for this article is available on GitHub

The debug(), info(), warning(), error() and critical() methods automatically call basicConfig() if no handlers are defined for the root logger.

The basicConfig() function does nothing if the root logger already has handlers configured, unless you set the force keyword argument to True.

main.py

Copied!
import logging
import time

logging.basicConfig(
    format='%(asctime)s %(levelname)-8s %(message)s',
    level=logging.DEBUG,
    datefmt='%Y-%m-%d %H:%M:%S',
    force=True # 👈️ setting force to True
)

logging.info('Info message #1')

time.sleep(2)

logging.info('Info message #2')

time.sleep(2)

logging.debug('Debug message #1')

time.sleep(2)

logging.error('Error message #1')

time.sleep(2)

logging.warning('Warning message #1')

time.sleep(2)

logging.critical('Critical message #1')

The code for this article is available on GitHub

You can read more about the basicConfig() method in this section of the docs.

# Print a Timestamp for Logging by creating a custom logger in Python

You can also create a custom logger to print a timestamp for logging in Python.

main.py

Copied!
import logging
import sys
import time


def create_logger(name):
    formatter = logging.Formatter(
        fmt='%(asctime)s %(levelname)-8s %(message)s',
        datefmt='%Y-%m-%d %H:%M:%S'
    )

    file_handler = logging.FileHandler('log_file.txt', mode='w')
    file_handler.setFormatter(formatter)

    stream_handler = logging.StreamHandler(stream=sys.stdout)
    stream_handler.setFormatter(formatter)

    logger_ = logging.getLogger(name)
    logger_.setLevel(logging.DEBUG)
    logger_.addHandler(file_handler)
    logger_.addHandler(stream_handler)

    return logger_


logger = create_logger('example-app')

logger.info('Info message #1')

time.sleep(2)

logger.info('Info message #2')

create custom logger to print timestamp for logging

The code for this article is available on GitHub

We used the logging.Formatter class to create a Formatter object.

main.py

Copied!
formatter = logging.Formatter(
    fmt='%(asctime)s %(levelname)-8s %(message)s',
    datefmt='%Y-%m-%d %H:%M:%S'
)

The Formatter object is initialized with a format string for the whole message and a format string for the date/time part of the message.

We used the logging.FileHandler class to open a file and use it as the stream for logging.

main.py

Copied!
file_handler = logging.FileHandler('log_file.txt', mode='w')
file_handler.setFormatter(formatter)

log file created

The file in the example is called log_file.txt but you can rename it as you see fit.

The next step is to use the logging.StreamHandler class to initialize the stream handler.

main.py

Copied!
stream_handler = logging.StreamHandler(stream=sys.stdout)
stream_handler.setFormatter(formatter)

The last step is to set the log level, the file handler and the stream handler.

main.py

Copied!
logger_ = logging.getLogger(name)
logger_.setLevel(logging.DEBUG)
logger_.addHandler(file_handler)
logger_.addHandler(stream_handler)

You can then create a logger and use the debug(), info(), warning(), error() and critical() methods to log messages with a timestamp.

main.py

Copied!
logger = create_logger('example-app')

logger.info('Info message #1')

logger.info('Info message #2')

create custom logger to print timestamp for logging

The code for this article is available on GitHub

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

You can use the search field on my Home Page to filter through all of my articles.

How to print a Timestamp for Logging in Python

# Table of Contents