From owner-freebsd-hackers@FreeBSD.ORG  Mon Dec 11 17:23:56 2006
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id CFC8B16A403
	for <freebsd-hackers@freebsd.org>; Mon, 11 Dec 2006 17:23:56 +0000 (UTC)
	(envelope-from dan@dan.emsphone.com)
Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 959AA43CBB
	for <freebsd-hackers@freebsd.org>; Mon, 11 Dec 2006 17:22:38 +0000 (GMT)
	(envelope-from dan@dan.emsphone.com)
Received: (from dan@localhost)
	by dan.emsphone.com (8.13.6/8.13.8) id kBBHNtES086708;
	Mon, 11 Dec 2006 11:23:55 -0600 (CST) (envelope-from dan)
Date: Mon, 11 Dec 2006 11:23:55 -0600
From: Dan Nelson <dnelson@allantgroup.com>
To: c0re dumped <ez.c0re@gmail.com>
Message-ID: <20061211172354.GE69299@dan.emsphone.com>
References: <6dd8736a0612110908q2cdb99a0rf3b8da3f5e4bdfee@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <6dd8736a0612110908q2cdb99a0rf3b8da3f5e4bdfee@mail.gmail.com>
X-OS: FreeBSD 6.2-PRERELEASE
X-message-flag: Outlook Error
User-Agent: Mutt/1.5.13 (2006-08-11)
Cc: freebsd-hackers@freebsd.org
Subject: Re: Reading in real time from a file without pipes
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 11 Dec 2006 17:23:56 -0000

In the last episode (Dec 11), c0re dumped said:
> I wonder if is possible to read data from a certain file without
> using a pipe.
> 
> Let me explain:
> 
> I have a process already writing messages to a logfile. I want to
> read all written data (without neither stop nor interfere normal log
> process) from another process in real time.
> 
> How can I achieve it ?

Take a look at how the tail command does it.  You can either stat the
file periodically then read the new data if you see the timestamp or
size change (portable), or use a kqueue to get notified immediately of
any updates (not portable).

-- 
	Dan Nelson
	dnelson@allantgroup.com