来了个老外老师,大家帮忙做个作业啊

bigapple2008

Please write a C program that does the following things:
a.        It shows it own pid and ppid on the screen.
b.        It creates a child process. The parent process shows then the pid of this child process, it sleeps for one second and outputs a message on the screen saying that it will exit.
c.        The child process shows its pid and ppid on the screen. It sleeps for 5 seconds and outputs its pid and ppid again on the screen before it exits.
d.        Redirect the outputs of the program to a temp file and compare the contents of this file with those directly shown on the screen. You will find that they are different! But both are correct! Could you explain the reason for the differences?

mozilla

作业自己做

MichaelBibby

不错，作业自己做

bigapple2008

我们刚学操作系统啊,觉得好难哦.主要是对一些系统调用的不熟悉，有没有哪位能介绍本书看看

kakuyou

execute followed commands

man 2 getpid
man 2 fork
man 2 nanosleep
man 3 sleep

you will find your answer.So, it is your first step to learn how to use man command

man man

Alex_Sune

其实大家没有必要一看到作业就说作业自己做，至少给个方向，比如说建议查什么资料，大概的思路什么的。

黑暗哭泣

《LINUX C语言函数》

t土疙瘩

建议看看《Unix环境高级编程》一书，书上就有相似的例子。
当然，要想真正完成作业，当然还得参考例子再加上man。

sjinny

这个程序我想不难吧……但是你们看问题d：

d. Redirect the outputs of the program to a temp file and compare the contents of this file with those directly shown on the screen. You will find that they are different! But both are correct! Could you explain the reason for the differences?

这是为什么呢？……

ShiChao

是缓存吗？