Exec or Fork?

[Carlos Mejia]

Hi !!!!

I am working with one PC/104 which starts up from a Compacflash with an 
operative system of real time (RTAI); for reasons of memory, I have reduced 
the size of the system using Busybox. When the system initiates open the 
shell that provides Busybox (ash).

How i can give support to the commands Exec and Fork on my system with 
Busybox? or How i can use the command Exec to execute an external program on 
my system with Busybox?.

Thanks!!!