$ irb
>> require "open4"
=> true
>> pid, stdin, stdout, stderr = Open4::popen4 "false"
=> [26327, #<IO:0x6dff24>, #<IO:0x6dfee8>, #<IO:0x6dfe84>]
>> $?
=> nil
>> pid
=> 26327
>> ignored, status = Process::waitpid2 pid
=> [26327, #<Process::Status: pid=26327,exited(1)>]
>> status.to_i
=> 256










