I can say that in all the years that I’ve been using and supporting OH, this is the first mention I’ve seen on the forum of someone trying to use the Exec transform.
What is it you are trying to achieve? Have you done the typical steps to debug exec issues?
How to solve Exec binding problems
Given how robust the other transformations are, I would expect it to be a very rare and specific case where one would need to resort to an external program to convert the incoming data into a state that OH can use.