How to make child process die after parent exits?

Question

Suppose I have a process which spawns exactly one child process. Now when the parent process exits for whatever reason (normally or abnormally, by kill, ^C, assert failure o

Answer 1

Another way to do this that is Linux specific is to have the parent be created in a new PID namespace. It will then be PID 1 in that namespace, and when it exits it all of it's children will be immediately killed with SIGKILL.

Unfortunately, in order to create a new PID namespace you have to have CAP_SYS_ADMIN. But, this method is very effective and requires no real change to the parent or the children beyond the initial launch of the parent.

See clone(2), pid_namespaces(7), and unshare(2).