Comment by throwawaylinux

OSX defines _POSIX_SYNCHRONIZED_IO though, doesn't it? I don't have one at hand but IIRC it did.

At least the OSX man page admits to the detail.

The rationale in the POSIX document for a null implementation seems reasonable (or at least plausible), but it does not really seem to apply to general OSX systems at all. So even if they didn't define _POSIX_SYNCHRONIZED_IO it would be against the spirit of the specification.

I'm actually curious why they made fsync do anything at all though.