--- Process.wait
--- Process.wait2

    ҥץλΤԤλҥץ pid ֤ޤ
    ҥץĤʤ㳰 Errno::ECHILD [Errno::EXXX] 
    ȯޤ

    wait2 ϡͤ pid  $? Ǥ
    ۤʤޤ

    ruby 1.7 feature:
    version 1.7  $? Process::Status ֥Ȥ
    

