#include <fcntl.h>#include "fd.h"int fd_copy(to,from)int to;int from;{  if (to == from) return 0;  if (fcntl(from,F_GETFL,0) == -1) return -1;  close(to);  if (fcntl(from,F_DUPFD,to) == -1) return -1;  return 0;}