Description:
Like exercise 5, a process tree is created according to argv[]. Each process will handle at lease two signals. When one of them, for example SIGUSR1, is received, the labels will be printed in preorder. See following example. When another signal, for example SIGQUIT, is received, the overall tree is removed. You may need the pipes between processes.
Deadline: 2010 May 20 00:05am
Put your file(s) under ~/usp-982/exer8

Examples :

                  shell
                    | 
                    a
                   / \
                  b   e
                 / \   \
                c   d   f
$ ./a.out ddduduudduuu abcdef
I'm c, my pid=19979, and my ppid=19978
I'm d, my pid=19981, and my ppid=19978
I'm f, my pid=19982, and my ppid=19980
I'm a, my pid=19977, and my ppid=19767
I'm b, my pid=19978, and my ppid=19977
I'm e, my pid=19980, and my ppid=19977
                                               $ kill -USR1 19977
hello, i'm a, my pid is 19977 
hello, i'm b, my pid is 19978
hello, i'm c, my pid is 19979
hello, i'm d, my pid is 19981
hello, i'm e, my pid is 19980
hello, i'm f, my pid is 19982
                                               $ kill -USR1 19979   
hello, i'm c, my pid is 19979
                                               $ kill -USR1 19980
hello, i'm e, my pid is 19980 
hello, i'm f, my pid is 19982
                                               $ kill -USR1 19978
hello, i'm b, my pid is 19978 
hello, i'm c, my pid is 19979
hello, i'm d, my pid is 19981    
                                               $ kill -QUIT 19977
$

My code for exercise 5.