//  fileDes2.c++ close stdout,open new file for output
//               $ ./a.out <output file name of child>

#include <iostream>
using namespace std;
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int ac, char **av ) { // fileDes2.c++
   int chPID, status, fd ;

   if(ac < 2){
      cerr << "Less arguments\n";
      return 0;
   }
   chPID = fork();
   if(chPID == -1){
     cerr << "fork() error\n";
     return 0;
   } // 
   if(chPID != 0) {  // parent
      cout << "In parent\n";
      waitpid(chPID, &status, 0) ;
   }
   else {  // child
      cout << "In child\n";
      if(close(fileno(stdout)) == -1){
        cerr << "File close error" << endl;
        return 0;
      }
      fd = open(av[1], O_WRONLY | O_CREAT, 0666);
      if(fd == -1){
        cerr << "File open error" << endl;
        return 0; 
      }
      cout << "Again in child" << endl;  
      close(fd);
   }
   return 0 ;
}