cmd line rename file with date and time

Question

Project moving forwards, I can see why creating .bat files to do things can become addictive! I can now save somefile.txt at regular intervals, I then rename somefile.txt by

Answer 1

I tried to do the same:

. --> __. 

I found that :

rename 's/(\w+)(\.\w+)/$1'$(date +"%Y%m%d_%H%M%S)'$2/' *