Io Ho provato con lseek() ma mi da' ESPIPE
ESPIPE fildes is associated with a pipe, socket, or FIFO.
codice:
lseek(*sock, pos, 1);
switch(errno) {
	case EBADF:		fprintf (stderr, "EBADF fildes is not an open file descriptor.");
					break;
	case ESPIPE:	fprintf (stderr, "ESPIPE fildes is associated with a pipe, socket, or FIFO.");
					break;
	case EINVAL:	fprintf (stderr, "EINVAL whence  is  not  one  of  SEEK_SET,  SEEK_CUR,");
					fprintf (stderr, "SEEK_END, or the resulting file offset would be negative.");
					break;
	case EOVERFLOW:	fprintf (stderr, "EOVERFLOW The resulting file offset cannot be represented ");
					fprintf (stderr, "in an off_t");
					break;
}