I do not know what you mean. "shared memory" is the common term used if processes share part of their memory - to exchange data. I've never heard of shells communicating with utilities using shared memory - for this to work shells and utilities need to cooperate.

I guess you mean something else, but I don't know what. It's also unclear what you mean by "spawning" a process. I think most people would consider "fork + exec" to be "spawning" (assuming we're talking Unix), but since you want to do something else than "exec", it's not a typical "fork + exec" you are referring to.

Under UNIX, there is just one way of creating a new process, and that's by using "fork". And there's only one way to start a different program, and that's by using a member of the exec family.

Abigail