Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!nosc!ucsd!rutgers!mailrus!cornell!rochester!ur-tut!ur-valhalla!badri
From: badri@valhalla.ee.rochester.edu (Badri Lokanathan)
Newsgroups: comp.unix.questions
Subject: Truncating an open file under BSD 4.3
Keywords: Empty, !ftruncate, fcntl?
Message-ID: <1392@valhalla.ee.rochester.edu>
Date: 26 Jul 88 03:41:44 GMT
Organization: UR Dept. of Electrical Engg, Rochester NY 14627
Lines: 13

What is the best way to empty an already open write-only file under BSD 4.3?
I have an application where I need large amounts of alphanumeric data dumped
to a file which then must be periodically emptied. I also need to be
able to scan this data occasionally with a pager.

I do not want to close and reopen the file since open is an
expensive call (prof claims it to take about 15ms/call on a SUN
3/110.) I tried truncate but it leaves holes in the file, which make
it unreadable. I also could not find a way with fcntl, which surprises me.
-- 
"We will fight for the right to be free {) badri@valhalla.ee.rochester.edu
 We will build our own society         //\\ {ames,cmcl2,columbia,cornell,
 And we will sing, we will sing       ///\\\ garp,harvard,ll-xn,rutgers}!
 We will sing our own song."  -UB40    _||_   rochester!ur-valhalla!badri