实现孤儿进程（孤儿进程会被 init 进程收养善后，所以没什么危害）

有关孤儿进程的讲解：
孤儿进程讲解博客传送门

  1 #include <stdio.h>2 #include <stdlib.h>3 #include <errno.h>4 #include <unistd.h>5 6 int main(){7 8     pid_t pid = fork();9     if(pid < 0){10         perror("fork error:");11         exit(1);12     }13 14     if(pid == 0){15         printf("I am a chile process!!! child pid[%d]-----father pid[%d]\n", getpid(), getppid());16         printf("I will sleep 5s, when  I wake up, my father have already exited\n");17         sleep(5);18         printf("child pid:[%d]--------father pid[%d]\n", getpid(), getppid());19         printf("child process exit\n");20     }21     else{22         printf("I am father process!!!pid:[%d]\n", getpid());                                                                                                          23         sleep(1);	//保证子进程打印进程id24         printf("father process exit\n");25     }26     return 0;27 }

打印效果：