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Date: Mon, 3 Jun 1996 09:56:32 -0400 (EDT)
From: "Ron G. Minnich" <rminnich@Sarnoff.COM>
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Subject: Re: bugs
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> MMAP doesn't extend files, AFAIK it doesn't on many (if not most
> other OSes.)  To set the length of the file you need to do an ftruncate.
> After that, then blocks will be allocated as needed.

There is an option on irix to automagically extend not only the file but 
the mmap'ed region. A misfeature IMHO.

ron