模拟图书馆系统，运用多线程、信号量，图书馆中有20个座位，外有10个座位-Simulation library system, the use of multiple threads, semaphores, the library has 20 seats, 10 seats outside

在UNIX_Linux环境下运行通过的一个图书馆模拟管理系统。简单实用。-In UNIX_Linux environment simulation run through a library management system. Simple and practical.