I have read that when Process A start Process B, then Process B will inherit Process A's Process Group ID.
I tested this by making bash execute the cat program, but I found out that bash and cat had two different Process Group ID, why is that?
bashfiddles with the process group for job control. https://unix.stackexchange.com/questions/363126/why-is-process-not-part-of-expected-process-group – thrig May 16 '17 at 21:17