91 – Timestamp file names

You can combine datetime.datetime.now with string formatting to add a timestamp to a file name. This is very helpful to create unique file names dynamically.

Here is an example function using this idea:

import datetime

def make_file_name(prefix, extension):
    ts = f"{datetime.datetime.now():%Y%m%d%H%M%S}"
    return f"{prefix}{ts}{extension}"
    
print(make_file_name("screenshot_", ".png"))
# screenshot_20250707142204.png

The % specifiers determine what parts of the current date and time make it to the timestamp and this example uses six:

Specifier	Meaning
%Y	year
%m	month
%d	day
%H	hour
%M	minute
%S	second

All but %Y result in a 2-digit number which might be 0-padded.

For most applications, going down to the minutes or seconds is enough. If you need microseconds, you can add the specifier %f.