Re: Shortening an IFS file

So do you open the file without o_Trunc, read the data in, close the file,
open it with o_Trunc, process the data already read, and write the
modified data back out? When the file is opened with o_Trunc, it wipes out
the existing data before it can be read. (Unless I've done something wrong
or simply don't understand.)

"MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx> wrote on 03/12/2015
10:14:08 AM:

From: Tim Brown <tim.bronski@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 03/12/2015 10:14 AM
Subject: Re: Shortening an IFS file
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>

I might have read your email too quickly. If you want to clear the

contents

of a file before writing back to it then use the open option i

suggested.

If you want to keep the contents up to a particular size then use

ftruncate.

On Mar 12, 2015 2:40 PM, "Tim Bronski" <tim.bronski@xxxxxxxxx> wrote:

If you're using open() then you should have O_TRUNC or'ed as a flag.

On 3/12/2015 2:32 PM, MichaelQuigley@xxxxxxxxxx wrote:

I'm writing a utility to remove some filler data from an IFS file.

I'm

using the The utility works great except that when I write the data

back

to the IFS, there is original data past where I want the new EOF to

be. I

can't for the life of me figure out how to shorten the file and set a

new

(shorter) end of file.

Any help would be greatly appreciated.

Thanks,
Michael Quigley
Computer Services
The Way International
www.TheWay.org

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