进程间通信——LINUX

1、编写一段程序，使用系统调用fork( )创建两个子进程，再用系统调用signal( )让父进  程捕捉键盘上来的中断信号（即按ctrl+c键），当捕捉到中断信号后，父进程用系统调用kill( )向两个子进程发出信号，子进程捕捉到信号后，分别输出下列信息后终止：

Child process 1 is killed by parent!

Child process 2 is killed by parent!

父进程等待两个子进程终止后，输出以下信息后终止：

Parent process is killed!

 #include<stdio.h>
 #include<signal.h>
 #include<unistd.h>
 #include<sys/types.h>
 #include<sys/wait.h>
 int wait_mark;
 void waiting(),stop();
 void main()
 {int  p1, p2;
 signal(SIGINT,stop);
 while((p1=fork())==-);
 if(p1>)                            /*在父进程中*/
 {①
 while((p2=fork())==-);
            If(p2>)                    /*在父进程中*/
             { ②
                   wait_mark=;
                  waiting();
                 kill(p1,);
                 kill(p2,);
                 wait( );
                wait( );
                printf("parent process is killed!\n");
                exit();
             }
            else                        /*在子进程2中*/
            {
 wait_mark=;
 signal(,stop);
 waiting();
 lockf(,,);
 printf("child process 2 is killed by parent!\n");
 lockf(,,);
 exit();
 }
 }
 else                        /*在子进程1中*/
 {
       wait_mark=;
       signal(,stop);
       waiting();
       lockf(,,);
       printf("child process 1 is killed by parent!\n");
       lockf(,,);
       exit();
 }
 }
 void waiting()
 {
    while(wait_mark!=);
 }
 void stop()
 {
    wait_mark=;
 }

⑴运行程序并分析结果。

^C

child process 2 is killed by parent!

child process 1 is killed by parent!

parent process is killed!

⑵如果把signal(SIGINT,stop)放在①号和②号位置，结果会怎样并分析原因。

1-

^C

child process 2 is killed by parent!

parent process is killed!

2-

^C

parent process is killed!

⑶该程序段前面部分用了两个wait(0),为什么？

关掉后一个wait

^C

child process 1 is killed by parent!

parent process is killed!root@kali:~/wyq/S4#

child process 2 is killed by parent!gcc -o S4_1-3.out S4_1-3.c

两个都关掉

^C

parent process is killed!root@kali:~/wyq/S4#

child process 2 is killed by parent!

child process 1 is killed by parent!^C