non-root ptrace/waitpid on a non-child

Question

This is a follow up/modification of my qn : Ptrace/wait on a non child

How do I ptrace or wait on a process that is not a child AND the process that waits is not a root user .

I tried to be in the same group, still doesnt work [ operation not permitted - to ptrace on a non-child ]

Answer 1

ptracing a process gives you complete control over it. If you could ptrace a process belonging to a different user, then users would be meaningless.

wait is specifically for parent notification.

You'll have to rethink your approach to whatever problem you're trying to solve.