我执行了下面的程序，但我很困惑它的输出？

Question

我感到困惑的无子进程也正在对执行

#include <unistd.h> 
#include <stdio.h> 
#include <stdlib.h> 
int main(int argc, char **argv) { 
int i=0; 
fork(); 
fork(); 
fork(); 
fork(); 
pid_t pid; 
    if((pid=fork()) == 0) { 
     printf("I am the child: %u\n", getpid()); 
} 
    else { 
     printf("I am the parent: %u and my child is: %u\n", getpid(),pid); 
    } 

return 0; 
} 

能有人帮助我理解这是为什么有这么多的子进程，为什么父ID每次都是不同的。

我得到的输出是：

saqlain@ubuntu:~/Desktop$ gcc -c fork.c 
saqlain@ubuntu:~/Desktop$ gcc -o fork fork.c 
saqlain@ubuntu:~/Desktop$ ./fork 
I am the parent: 11842 and my child is: 11847 
saqlain@ubuntu:~/Desktop$ I am the child: 11847 
I am the child: 11849 
I am the parent: 11846 and my child is: 11850 
I am the child: 11867 
I am the child: 11869 
I am the parent: 11843 and my child is: 11856 
I am the child: 11850 
I am the parent: 11848 and my child is: 11857 
I am the parent: 11852 and my child is: 11860 
I am the parent: 11845 and my child is: 11849 
I am the parent: 11854 and my child is: 11866 
I am the child: 11859 
I am the child: 11856 
I am the child: 11857 
I am the parent: 11862 and my child is: 11869 
I am the parent: 11865 and my child is: 11870 
I am the child: 11860 
I am the child: 11866 
I am the parent: 11855 and my child is: 11867 
I am the parent: 11851 and my child is: 11859 
I am the parent: 11863 and my child is: 11871 
I am the parent: 11858 and my child is: 11872 
I am the parent: 11868 and my child is: 11873 
I am the parent: 11844 and my child is: 11861 
I am the child: 11870 
I am the child: 11861 
I am the child: 11864 
I am the child: 11872 
I am the child: 11871 
I am the child: 11873 
I am the parent: 11853 and my child is: 11864 

Answer 1

你执行fork 5倍，并在第五，打印输出。

每个fork将控件分成两个相同的副本，所以2×2×2×2×2 = 32个副本，其中16个各自根据第五个和最后一个fork标识为父母和子女。