#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(void) {
   pid_t childpid;
   int fd[2];
   int file;
   mode_t fd_mode=S_IRWXU;
   if ((pipe(fd) == -1) || ((childpid = fork()) == -1)) {
      perror("Failed to setup pipeline");
      return 1;
   }
   if(childpid>0) {                                  
        // send output to the pipe
      printf("I am parent\n");
      if (dup2(fd[1], STDOUT_FILENO) == -1)
         perror("Failed to redirect stdout of ls");
      else if ((close(fd[0]) == -1) || (close(fd[1]) == -1))
         perror("Failed to close extra pipe descriptors on ls");
      else {
         execl("input",NULL);   // input is an executable which produces 
// 2 lines of text
         perror("Failed to exec output file");
      }
      return 1;          
   }
        // receive input from the pipe
   printf("I am child\n");
   if (dup2(fd[0], STDIN_FILENO) == -1)              
       perror("Failed to redirect stdin of writing to file");
   else if ((close(fd[0]) == -1) || (close(fd[1]) == -1))
       perror("Failed to close extra pipe file descriptors");
  else {
      if((file=open("file1.txt",O_WRONLY | O_CREAT,fd_mode))==-1)
         perror("Error opening the file");
      char *buffer=(char *)malloc(200);  
      fgets(buffer,100,STDIN_FILENO);    // this should in theory write 100
// characters to the buffer from stdin, but it kills the program
      write(file,buffer,100);
      perror("Failed to write to the pipe");
   }
   return 1;
}