Combined Unix/Ada question - forcing write to disk

[GDAU100@BGUVM.BITNET ("Jonathan B. Owen")]

Hello Group.

   I assume many of you work on Unix based targets.  Well, here's a question
you might be able to answer.

   I make updates to a file via DIRECT_IO.  At some point I must be sure
that the updates were physically written to disk.  I have sent a query
to the Apollo list (since I work on one).  It was suggested that I use
some Unix services like fsync, flush and sio$force_write.  Well, I tried
using fsync but it didn't work.  I passed to it the DIRECT_IO.File_type
of the file, after converting it to File_ptr.  Note that File_type of
DIRECT_IO is defined as "new File_ptr".  I have not managed to interace to
the other services mentioned.

                                      Can you help me out?

                                                     Thank you,
                                                               JB

P.S.  I would very much appreciate if you would send one or two examples
      of Ada programs which access the GPR and GSR graphics routines of
      the Apollo workstation... :-)
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