How do you add datetime to a logfile name?

Question

When I create my logfile, I want the name to contain the datetime.

In Python you can get the current datetime as:

>>> from datetime import datetime >>> datetime.now() datetime.datetime(2012, 2, 3, 21, 35, 9, 559000) 

The str version is

>>> str(datetime.now()) '2012-02-03 21:35:22.247000' 

Not a very nice str to append to the logfile name! I would like my logfile to be something like:

mylogfile_21_35_03_02_2012.log 

Is there something Python can do to make this easy? I am creating the log file as:

fh = logging.FileHandler("mylogfile" + datetimecomp + ".log") 

Answer 1

You need datetime.strftime(), this allows you to format the timestamp using all of the directives of C's strftime(). In your specific case:

>>> datetime.now().strftime('mylogfile_%H_%M_%d_%m_%Y.log') 'mylogfile_08_48_04_02_2012.log' 

Answer 2

You could also use a TimedRotatingFileHandler that will handle the date and the rollover every day (or whenever you want) for you.

from logging.handlers import TimedRotatingFileHandler fh = TimedRotatingFileHandler('mylogfile',  when='midnight') 

By default the format will be depending on the rollover interval:

The system will save old log files by appending extensions to the filename. The extensions are date-and-time based, using the strftime format %Y-%m-%d_%H-%M-%S or a leading portion thereof, depending on the rollover interval.

But you can modify that as showed here, by doing something like:

from logging.handlers import TimedRotatingFileHandler fh = TimedRotatingFileHandler('mylogfile',  when='midnight') fh.suffix = '%Y_%m_%d.log'