#include <unistd.h>

int isatty(int desc);

#include <unistd.h>

char * ttyname(int desc);

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
main()
{
  int fd;
  char * file = "/dev/tty";
  fd = open (fiel, O_RDONLY);
  printf("%s", file);
  if(isatty(fd))
  {
   printf("is a tty. \n");
   printf("ttyname = %s \n", ttyname(fd));
  }
  else
   printf(" is not a tty\n");
  close(fd);
}

/dev/tty is a tty ttyname = /dev/tty

#include <sys/types.h>  #include <sys/socket.h>

int sendmsg(int s, const strcut msghdr *msg, unsigned int flags);

struct msghdr
{
  void *msg_name; //Address to send to /receive from .
  socklen_t msg_namelen; //Length of addres data
  strcut iovec * msg_iov; //Vector of data to send/receive into
  size_t msg_iovlen; //Number of elements in the vector
  void * msg_control; //Ancillary dat
  size_t msg_controllen; //Ancillary data buffer length
  int msg_flags; //Flags on received message
};