Loading files incrementaly

Hi

Am trying to sftp this way UnixBoxA----->UnixBoxB

My code will run on UnixBoxB, it will make a secure connection and pull the files from UnixBoxA. Apart from that I do not have any access on UnixBoxA

Now UnixBoxA will receive the files daily, the file format will be <name>_<batch_number>
I have a mechanism to store the latest batch_number of the file which was pulled last time.

I need help in finding out a way to pull the next set of files from UnixBoxA in incremental fashion.

Note that batch_number is always 1 up sequence

I need to identify the incremental files that came into UnixBoxA and pull them whenever my job runs on UnixBoxB