From owner-freebsd-stable@FreeBSD.ORG Tue Apr 19 20:32:39 2005 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5AF9216A4CE for ; Tue, 19 Apr 2005 20:32:39 +0000 (GMT) Received: from internet.potentialtech.com (h-66-167-251-6.phlapafg.covad.net [66.167.251.6]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1BA2D43D1F for ; Tue, 19 Apr 2005 20:32:39 +0000 (GMT) (envelope-from wmoran@potentialtech.com) Received: from localhost (pa-plum-cmts1e-68-68-113-64.pittpa.adelphia.net [68.68.113.64]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by internet.potentialtech.com (Postfix) with ESMTP id 5E7B869A21; Tue, 19 Apr 2005 16:32:38 -0400 (EDT) Date: Tue, 19 Apr 2005 16:32:37 -0400 From: Bill Moran To: Chuck Swiger Message-Id: <20050419163237.76a99373.wmoran@potentialtech.com> In-Reply-To: <42655B8E.5020603@mac.com> References: <426447F8.5090209@charter.net> <200504191317.j3JDH76H001458@drjekyll.mkbuelow.net> <20050419120053.6ad17df1.wmoran@potentialtech.com> <42655B8E.5020603@mac.com> Organization: Potential Technologies X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-portbld-freebsd5.3) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit cc: freebsd-stable@freebsd.org Subject: Re: Newbie Question About System Update X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Apr 2005 20:32:39 -0000 Chuck Swiger wrote: > Bill Moran wrote: > > The system can not replace programs that are in use, > > This is generally not the case. Unix lets you continue to access a file after > it has been deleted, so long as the process hangs on to a file descriptor. > This lets you replace programs in use, without running into the same problems > that platforms like Windows have. What you say?: bash-2.05b$ su Password: bolivia# cp /usr/sbin/cron /home/wmoran/. bolivia# cp /home/wmoran/cron /usr/sbin/. cp: /usr/sbin/./cron: Text file busy bolivia# Notice that /usr/sbin/cron is in use (because my system is running normally) I can copy _from_ that file, but I can not overwrite it. Apparenlty, nobody who is claiming this has _tried_ it. Try it yourself and see. You can _not_ replace programs that have their Text section in use (i.e. the code) because the demand pager has that area of the file locked. -- Bill Moran Potential Technologies http://www.potentialtech.com