O_SYNC option in SVR3 open system call

[Gerardo Brenes]

Subject: SVR3 open with O_SYNC option
Newsgroups: comp.unix.questions
Keywords: really waits for physical update?

In the reference manual for SVR3 for the ATT 3B2 machine, the description for
the open system call mentions an option O_SYNC. It literally says:

	O_SYNC	When opening a regular file, this flag affects subsequent
		writes. If set, each write (2) will wait for both the file
		data and file status to be physically updated.

Does anybody out there knows if this wait is for real or is the same BSD idea
of the "fflush" in which blocks are merely "scheduled" and the call returns as 
if they were actually written to the device. 

Please use e-mail to answer and I'll post a summary of comments if enough
interest is shown.  Thanks a lot for your help.

Gerardo Brenes

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