how to change the file name dynamically when we are doing pass through scenario(WIth out ESR)

HI

i am doing pass through scenario using FTP in both side,my requirement is when i pick a file from source it need to change run time.i am sending .dat file

but i don't want to .dat as extension and need to add file name like "input file name without extension+constant+Julio date+constant+HHMMSS"

example :

input file name :  Details##.dat

(## will change according to in put file name )

OUTPUT FILE NAME:  Details##.f1.in,d14139.t193029

(Details##---->actual file name

f1.in-->constant

d--> constant

14139.--->Julio date

t--->constant

193029---->HHMMSS