Linux IPC通信之信号量的PV操作，包含申请资源、唤醒等待资源的任务等-Linux IPC semaphore communications PV operation, including the application of resources, tasks waiting for resources wake

进程通信的实现 分为三个基本文件，进程间信号传递、共享内存、消息机制、PV操作-Realization process communication is divided into three basic signal transmission between files, processes, shared memory, message mechanism, PV operation