child 进程在 fork 中 3 秒后自行终止

Question

我有一个创建 child 进程和 parent 进程的 fork 函数

我希望 child 进程在 3 秒后立即终止自身，使用 kill(child, SIGKILL) 函数，即意味着不使用 exit() 函数。但是我不确定执行情况。我尝试在 while 循环结束后立即使用 kill 函数信号，但它不会杀死 child。

我试着把它放在主函数的末尾，但它在 3 秒之前就杀死了 child

我试着把它放在一个 while 循环结束后立即调用的函数中，但它并没有杀死 child

我怎样才能使用实际有效的更好实施来做到这一点？

这是我的代码，带有可用评论：

int main()
{
    pid_t pid;
    int seconds = 3;
    int child;

    pid = fork();
    int i = 0;



    if(pid == 0)          //this is the child
    {
        child = getpid();

        while( i <= seconds)
        {
            cout << " second " << i << endl;
            sleep(1);
            i++;

        }
        killChild(child);     //function called after 3 seconds passes

    }

    else if(pid < 0)        //error statement
    {
        cout << " we have an error " << endl;
    }

    else                //parent if pid > 0
    {
        cout << " I am the parent " << endl;
        sleep(1);

    }

    //kill(child, SIGKILL)  placing it here will kill child before seconds passes

}


void killChild(int child)       //function to kill child (NOT KILLING IT)
{
    kill(child, SIGKILL);
}

Answer 1

 void killChild(int sigNum)//Argument here is signal number
    {
        kill(getpid(), SIGKILL);
    }  


  int main()
    {
        pid_t pid;
        int child;
        pid = fork();

        if(pid == 0)//this is the child
        {
            signal(SIGALRM,killchild)
            child = getpid();
            alarm(3); //set alarm for 3 seconds
            while(1); //continue to loop until 3 seconds passed
        }

        else if(pid < 0)//error statement
        {
            cout << " we have an error " << endl;
        }

        else//parent if pid > 0
        {
            cout << " I am the parent " << endl;
        }
    }

   After 3 seconds, alarm() function will generate SIGALRM and on this signal egneration, your killchild() function will be called and kill child.

希望对您有所帮助！

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