File creation with start and end dates

from the command line it is simple enough to pull all data and send it to a file.
I need to do this for a 15 day period. The from= command would appear to do this but I have not been able to get it to work as there is no info on syntax of the command. I have tried many different date formats but none have worked.

Can some one let me know what the format is so I can pull the data.


Thanks

Erik