#include <iostream>using namespace std;#include <unistd.h>#include <sys/wait.h>int main(){	int ret = fork();	if(ret<0){		cout << "error in fork!" << endl;		return -1;	}	if(ret==0){		for(int i=0; i<5; i++){			cout << "pid=" << getpid() << ", my parent:" << getppid() << endl;			sleep(1);		}	}	else{		for(int i=0; i<10; i++){			int cid=waitpid(-1,NULL,WNOHANG);			if(cid<0)				cout << "NO CHILD PROCESS!" << endl;			else if(cid==0)				cout << "CHILD PROCESS IS ALIVE!" << endl;			else				cout << "child:" << cid << "exited" << endl;			cout << "PID=" << getpid() << endl;			sleep(1);		}	}}