A child sending a message to its parent.

example.js

var fork = require('child_process').fork;

if (process.argv[2] == 'son') {
  setTimeout(function() {
    process.send({ result: 'hi dad' });
    process.exit(0);  	
  }, 1000);
} else {
  var child = fork(__filename, [ 'son' ]);
  child.on('message', function(m) {
    console.log(m.result)
  });
}

example.rb

pid = fork {
  puts "hi dad"
  sleep 1
}

# Waits for any child whose process group ID equals that of the calling process.
Process.waitpid(pid, 0)