How to fire and forget a subprocess?

Question

I have a long running process and I need it to launch another process (that will run for a good while too). I need to only start it, and then completely forget about it.

Answer 1

Alnitak is right. Here's a more explicit way to write it, without $$

pid = Process.fork
if pid.nil? then
  # In child
  exec "whatever --take-very-long"
else
  # In parent
  Process.detach(pid)
end

The purpose of detach is just to say, "I don't care when the child terminates" to avoid zombie processes.