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From: lewan@gpu.utcs.toronto.edu (S. Lewandowsky)
Newsgroups: comp.sys.ibm.pc
Subject: Truncating MS-DOS files
Message-ID: <1987Feb15.123004.21019@gpu.utcs.toronto.edu>
Date: Sun, 15-Feb-87 12:30:04 EST
Article-I.D.: gpu.1987Feb15.123004.21019
Posted: Sun Feb 15 12:30:04 1987
Date-Received: Sun, 15-Feb-87 18:37:13 EST
Organization: University of Toronto Computing Services
Lines: 9
Checksum: 43023


How can I truncate a file using DOS?  For example, I may open a
file, write to it and read from it extensively, and as a result its size
--when I use the close file handle call--would be about 120K or greater.
However, I only want to save the first 10K of that file, so I'd like to
place the file pointer to whereever I want the file to end, and then 
truncate it so that the information beyond the pointer is discarded
and the file size is reduced to 10K.
There is a truncate procedure in Turbo Pascal, so there must be a way
of doing it--but how do I do it in an ASM program using INT 21H?