Need help in scripting

Hi,

We have a requirement,client will post the file into ftp server with name as "prior-product-purchaseproductpurchase001_20150608.txt".One copy should be in this FTP server. After that we need to eliminate some part of the string in the filename "prior-product-purchase" and post the filename as this "productpurchase001_20150608.txt".

Thx in aadvance