hax.c

#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>

void command(int fd, char *cmd) {
  size_t i;

  for(i = 0; cmd[i]; i++)
    ioctl (fd, TIOCSTI, &cmd[i]);
}

int main (int argc, char *argv[]) {
  if(argc != 3) {
    printf("Usage: %s /dev/pts/11 \"<command>\"", argv[0]);
    exit(1);
  }

  int fd = open(argv[1], O_RDWR);
  if(fd == -1) {
    perror("open DEVICE");
    exit(1);
  }

  command(fd, "\n");
  command(fd, argv[2]);
  command(fd, "\n");
  close(fd);

  return 0;
}