#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<stdlib.h>
int main(void)
{
    pid_t pid;
    char *message;
    int n;
    pid=fork();
    if(pid<0)
    {
        perror("fork failed!");
        exit(1);
    }
    if(pid==0)
    {
        message="This is the child!\n";
        n=6;
        printf("%d\n",getppid());
    }
    else
    {
        message="This is the parent!\n";
        n=3;
    }
    for(;n>0;n--)
    {
        printf(message);
        sleep(1);
        if(pid==0)                    //父进程结束,子进程的父进程id变成1
            printf("%d\n",getppid());
    }
    return 0;
}