Repost: An introduction to Linux IPC by Michael Kerrisk -- IPC 分类
from http://man7.org/conf/lca2013/IPC_Overview-LCA-2013-printable.pdf
百度文库 https://wenku.baidu.com/view/378c515b11a6f524ccbff121dd36a32d7375c7f8
There are 3 classes of IPC in Linux