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From: roy@gitpyr.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Truncating MS-DOS files
Message-ID: <3105@gitpyr.gatech.EDU>
Date: Mon, 16-Feb-87 16:53:23 EST
Article-I.D.: gitpyr.3105
Posted: Mon Feb 16 16:53:23 1987
Date-Received: Tue, 17-Feb-87 06:38:28 EST
References: <1987Feb15.123004.21019@gpu.utcs.toronto.edu> <2596@well.UUCP>
Organization: Georgia Institute of Technology, Atlanta
Lines: 27
Summary: Perhaps you could try to be helpful instead of just flaming.

In article <2596@well.UUCP>, tenney@well.UUCP (Glenn S. Tenney) writes:
> That is exactly the way it is documented!
> RTFM:  function 28 Random Block Write
>    ...  If CX is zero upon entry, no records are written, but the
>         file is set to the length specified by the random record field,
>         whether longer or shorter than the current file size.

Well, quite some time ago I also heard that CX=0 on a write would truncate
the file.  When I became curious about it recently, I looked in the IBM
PC-DOS Technical reference manuals for DOS 2.1 and 3.0 (the only ones I
had available).  I looked in the function documentation distributed to
OEM's by Microsoft for MS-DOS 2.0.  I also looked in the book
"Advanced MS-DOS" by Ray Duncan.

None of these sources mentioned a thing about CX=0 being a legal value or
not, much less saying that it allows you to truncate a file.

I know what RTFM means, and I consider it rude, especially when it involves
something as (apparently) obscurely documented as this "feature" of MS-DOS.

Perhaps you could give us some clue about WHERE you saw it stated, instead
of simply yelling at us for being so ignorant as to overlook the
documentation.  Thanks for your time.
-- 
Roy J. Mongiovi		Systems Analyst		Office of Computing Services
Georgia Institute of Technology		Atlanta GA  30332.	(404) 894-4660
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