machine type (machine id)的详细讲解(谷歌图书截图)
https://books.google.com.hk/books?id=AUsOCgAAQBAJ&pg=PA90&lpg=PA90&dq=Linux++%E6%8C%87%E5%AE%9A+machine+id&source=bl&ots=5GenQSyoWh&sig=y5-aq5Pf7PHvyY5DkEdm5Ag0ps0&hl=zh-CN&sa=X&ved=0ahUKEwjGk6Ln4vPSAhVFrY8KHTJDBT8Q6AEISzAI#v=onepage&q&f=true