Xref: utzoo comp.lang.c:33142 comp.os.msdos.programmer:1650
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From: michi@ptcburp.ptcbu.oz.au (Michael Henning)
Newsgroups: comp.lang.c,comp.os.msdos.programmer
Subject: Re: How do I SHORTEN a file without rewriting it?
Keywords: truncation
Message-ID: <179@ptcburp.ptcbu.oz.au>
Date: 25 Oct 90 05:59:06 GMT
References: <1162@bilver.UUCP>
Followup-To: comp.lang.c
Organization: Pyramid Technology Corporation
Lines: 19

alex@bilver.UUCP (Alex Matulich) writes:

>Is there a way to shorten a file, that is, chop some data off the end of
>it, so that it doesn't consume as much physical space on the disk?  The
>file I have is too big to read into memory and write back out again, and
>there is not enough room on the disk to write out a temporary file.

Ftruncate() (BSD call) will do the job. Under AIX (maybe others), there
is an fclear() call that allows you to punch holes into a file at arbitrary
places. The blocks corresponding the hole(s) are returned to the file system.
In SysV.4, you can use fntl() to do the same.

							Michi.

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