Shell Programming and Scripting

 for i in prior-product-*
 do
     echo ${i##*-}
 done

PUT prior-product-purchaseproductpurchase001_20150608.txt /path/to/somewhereelse/prior-product-purchaseproductpurchase001_20150608.txt

RENAME /path/to/somewhereelse/prior-product-purchaseproductpurchase001_20150608.txt /destination/folder/prior-product-purchaseproductpurchase001_20150608.txt

for FILE in /destination/folder/prior-*
do
        mv "$FILE" "${FILE/prior-product-purchase/}"
done

filename=prior-product-purchaseproductpurchase001_20150608.txt
echo ${filename##*-}

productpurchase001_20150608.txt

 for i in prior-product-*
do
     echo ${i#*purchase}
done