fork()和wait()在c循环中？

Question

我在c中有这个小程序,我试图理解它是如何工作的,它是一个简单的while循环,它使用fork()并wait()在命令行上打印出几行,我已尽最大努力评论我的想法是什么事件

for (i = 1; i <= 3; i++)            /*simple while loop, loops 3 times */
{
    pid = fork();                   /*returns 0 if a child process is created */
    if(pid == 0){                   /*pid should be a 0 for first loop */
        printf("Hello!\n");         /*we print hello */
        return (i);                 /*will this return i to the parent process that called fork? */ 
    }   else {                      /*fork hasn't returned 0? */
        pid = wait(&j);             /*we wait until j is available? */
        printf("Received %d\n", WEXITSTATUS(j));   /*if available we print "received (j)" */
    }
}

该程序应该打印:

Hello!
Received 1
Hello!
Received 2
Hello!
Received 3

当其中一个子进程返回时i,父进程是否等待它&j？这真让我困惑,任何帮助都会非常感激.

Answer 1

在循环的每次迭代中fork()创建一个子进程.子进程打印Hello!并返回i系统.父进程阻塞,wait()直到子进程完成. j将包含子进程返回给系统的值.