1.　　1号进程创建2，3号两个进程

2.　　2号进程执行系统命令，ls，ps，cp等

3.　　3号进程创建4，5号两个进程

4.　　4号进程创建两个线程Thread1，Thread2

5.　　Thread1：循环速出“I am child1.”5次

6.　　Thread2：循环输出“I am child2.”5次

7.　　5号进程执行一个用户编写的可执行文件

-1. No. 2 process to create two processes

2. 2, the implementation of the process of system commands, ls, ps, cp and so on

3. 3, the process of creating two processes 4,5

4. 4, the process of creating two threads Thread1, Thread2

5. Thread1: loop speed out　I am child1.　5 times

6. Thread2: loop output　I am child2.　5 times

7. Process 5　s a user-written executable