dynamic logfile name

Dear Paul,

thank you for the examples. According to this I tried the following 
lines, but they did not work:

log:`ls /path/to/server_logs/$(date +%Y%m%d)`:102400
file:`ls /path/to/server_logs/$(date +%Y%m%d)`

Can you tell me please, how to escape the date-command?

Regards

Oliver