Dynamically deciding the target directory without ESR objects

Hi Experts,

I have come across File to File scenario(NFS) where I have to serve 2 purpose in one scenario using single receiver communication channel as the client have more than 40 plants.

1.     I need to copy the file from source directory to target directory without creating the mapping objects.

2.     based on source file name the target directory path will be the 'target directory + First 4 character of source file name i.e.(Plant name)'.

I am able to achieve the First requirement, can any one tell me how to achieve Second requirement.

Thanks in advance.

Ragards,

Gopi