#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>

int main(int argc, char *argv[])
{
   char buf[1600];
   int f,l;
   fd_set fds;
 
   if(argc < 2) {
      printf("Usage: datacopy file_name\n");
      return 1;
   }

   f = open(argv[1], O_RDWR);

   while(1){
	FD_ZERO(&fds);
        FD_SET(STDIN_FILENO, &fds);
        FD_SET(f, &fds);

	select(f + 1, &fds, NULL, NULL, NULL);

	if( FD_ISSET(f, &fds) ) {
	   l = read(f,buf,sizeof(buf));
	   if (l <= 0)
	      break;
           write(STDOUT_FILENO,buf,l);
	}
	if( FD_ISSET(STDIN_FILENO, &fds) ) {
	   l = read(STDIN_FILENO,buf,sizeof(buf));
	   if (l <= 0)
	      break;
           write(f,buf,l);
	}
   }
   return 0;
}