进程的创建

编写一段程序，使用系统调用fork（）创建两个子进程。当此程序运行时，在系统中有一个父进程和两个子进程活动。让没一个进程在屏幕上显示一个字符：父进程显示字符“a”；子进程分别显示字符“b”和字符“c”。试观察记录屏幕上的显示结果，并分析原因。

-process for the preparation of the establishment of procedures, the use of system calls fork () to create two child process. When running, the system has a process and the father of two sub-process activities. Let no one in the process displayed on a screen characters : Father process showed character "a"; child process showed the character "b" and the character "c." Examination observation records on the screen to show results, and analyze the causes.