Using at_exit with fork

child_at_exit.rb

child = fork do
  at_exit { $stderr.puts "Child one is done." }
  exit # superfluous
end
Process.wait
$stderr.puts "Parent is done waiting for child one #{child}."

child = fork do
  at_exit { $stderr.puts "This won't get hit." }
  exit!
end
Process.wait
$stderr.puts "Parent is done waiting for child two #{child}."

at_exit { $stderr.puts "Parent registered at_exit forked into child. #{Process.pid}"}
child = fork do
  exit # superfluous
end
Process.wait
$stderr.puts "Parent is done waiting for child three #{child}."