$:.unshift '.'
$:.unshift './lib'
$:.unshift '../lib'

require 'open4'

cid, stdin, stdout, stderr = Open4::popen4('sh')

stdin.puts 'echo 42'
stdin.close

out = stdout.read
err = stderr.read

pid, status = Process::waitpid2 cid

puts "out <#{ out.strip }>"
puts "err <#{ err.strip }>"
puts "status <#{ status.inspect }>"
puts "pid <#{ status.pid }>"
puts "exitstatus <#{ status.exitstatus }>"