From owner-freebsd-questions@FreeBSD.ORG  Wed Apr  2 08:43:26 2014
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id BE22A8B5
 for <freebsd-questions@freebsd.org>; Wed,  2 Apr 2014 08:43:26 +0000 (UTC)
Received: from outgoing.tristatelogic.com (segfault.tristatelogic.com
 [69.62.255.118]) by mx1.freebsd.org (Postfix) with ESMTP id 9F458C1B
 for <freebsd-questions@freebsd.org>; Wed,  2 Apr 2014 08:43:25 +0000 (UTC)
Received: from segfault-nmh-helo.tristatelogic.com (localhost [127.0.0.1])
 by segfault.tristatelogic.com (Postfix) with ESMTP id 38DF03AD93
 for <freebsd-questions@freebsd.org>; Wed,  2 Apr 2014 01:33:41 -0700 (PDT)
From: "Ronald F. Guilmette" <rfg@tristatelogic.com>
To: freebsd-questions@freebsd.org
Subject: A question about fsck and the -t option
Date: Wed, 02 Apr 2014 01:33:41 -0700
Message-ID: <85383.1396427621@server1.tristatelogic.com>
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions/>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 02 Apr 2014 08:43:26 -0000


If fsck is invoked upon a /dev device node which is a hard disk
partition containing a valid file system, and if this invocation
of fcsk _does not_ include any -t or -T options, then does fsck
make any sort of attempt to automagically determine or intuit what
sort of file system exists upon and within the given partition?

Previous to today, I had always believed that either (a) fsck looked
at the magic number in the first word of the partition in order to
automagically determine the file system type or else (b) that fsck,
on FreeBSD at least, defaulted (in the absence of any explicit -t or
-T options) to assuming that the file system type was ufs.  But as of
this moment it appears to me that neither of these assumptions were or
are true, and that in the absence of all -t and/or -T options, fsck on
FreeBSD simply throws up its hands and says "Could not determine
filesystem type".

Is this the intended outcome in such cases?