How to create a file name with the current date & time in Python?

While not using datetime, this solves your problem (answers your question) of getting a string with the current time and date format you specify:

import time
timestr = time.strftime("%Y%m%d-%H%M%S")
print timestr

yields:

20120515-155045

so your filename could append or use this string.

Change this line

filename1 = datetime.now().strftime("%Y%m%d-%H%M%S")

To

filename1 = datetime.datetime.now().strftime("%Y%m%d-%H%M%S")

Note the extra datetime. Alternatively, change your import datetime to from datetime import datetime

now is a class method in the class datetime in the module datetime. So you need

datetime.datetime.now()

Or you can use a different import

from datetime import datetime

Done this way allows you to use datetime.now as per the code in the question.

This one is much more human readable.

from datetime import datetime

datetime.now().strftime("%Y_%m_%d-%I_%M_%S_%p")

'2020_08_12-03_29_22_AM'

I'm surprised there is not some single formatter that returns a default (and safe) 'for appending in filename' - format of the time, We could simply write FD.write('mybackup'+time.strftime('%(formatter here)') + 'ext'

"%x" instead of "%Y%m%d-%H%M%S"