> > How do I flush a Unix.file_descr?

[snip]
> On the other hand, if you want to really commit the writes to the hard
> disk, there is no function in the Unix module for this.  But I'm not
> even sure there exists a standardized Unix system call to do this.

Maybe "fsync" would be appropriate. According to the man page this system
call conforms to POSIX.1b (formerly POSIX.4).

> > Deterimine if a file_descr isatty?
> 
> Your best bet is to make isatty() available in Caml. The following C
> wrapper and Caml declaration are all you need:

Another solution, which works with the existing library, would be 
to simply call "tcgetattr fd" and catch the possibly resulting error
"ENOTTY".

E.g.:

  try ignore (tcgetattr fd) with Unix_error (ENOTTY,_,_) -> ...

Regards,
Markus Mottl

-- 
Markus Mottl, mottl@miss.wu-wien.ac.at, http://miss.wu-wien.ac.at/~mottl