Homework 8.1 Orphans and Zombies

1.创建一个孤儿进程

代码

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
int main(int argc, const char *argv[])
{
    
	pid_t pid = fork( );
	if(pid > 0)
	{
    
		printf( "this is parent: %d child :%d\n" , getpid(),pid);
	}
	else if(0==pid)
	{
    
		int i = 0;
		while(1)
		{
    
			//子进程
			printf( "this is child ppid: %d child :%d\n", getppid(),getpid());
			if(i > 3)                                                       
			{
    
				printf("The child process is ready to exit\n");
				_exit(1);//子进程退出
			}
			i++;
			sleep(1);
		}
		printf("子进程退出\n" );
	}
	else
	{
    
		perror( "fork " );
		return -1;
	}
	return 0;
}

运行结果

The parent process ID of the child process is 1677,That is, the process number is1的init进程
A child process is an orphan process,被init进程收养

2.Create a zombie process

代码

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
int main(int argc, const char *argv[])
{
    
	pid_t pid = fork( );
	if(pid > 0)
	{
    
		while(1)
		{
    
			printf( "this is parent: %d child :%d\n" , getpid(),pid);
			sleep(1);
		}
	}
	else if(0==pid)
	{
    
		int i = 0;
		while(1)
		{
    
			//子进程
			printf( "this is child ppid: %d child :%d\n", getppid(),getpid());
			if(i > 3)
			{
    
				printf("The child process is ready to exit\n");
				_exit(1);//子进程退出
			}
			i++;
			sleep(1);
		}
		printf("子进程退出\n" );
	}
	else
	{
    
		perror( "fork " );
		return -1;
	}
	return 0;
}

运行结果

The child process is not recycled after exiting,状态为Z+
Z：僵尸状态;进程退出,But the parent process did not collect the corpse for the process
+：运行在前端