How do you kill all child processes without killing the parent

Question

I have a script which runs a background process at the beginning, then towards the end needs to stop that background process and its children, THEN do some other tasks etc t

Answer 1

You need to capture the value of $! (the child PID) right after

/some_process_with_child_processes &
pid=$!
./do_stuff
kill $pid
./do_other_stuff