Is there any way to find pid for eventmachine's popen?

Question

In ruby standard library, popen return a object which has pid method, In eventmachine, popen return a Connection object which contain no process id information.

Demo code here:

require 'eventmachine'

def work
  s = EM.popen('ls')
  puts s.pid # how to get new process's pid?
end

EventMachine.run {
  work
  EM.stop
}

Answer 1

As EM.popen returns a standard a EM Connection object, you can use s.get_pid to get the pid of the subprocess.

http://eventmachine.rubyforge.org/EventMachine/Connection.html#get_pid-instance_method