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From: franco@MIKEY.BBN.COM
Newsgroups: comp.unix.wizards
Subject: /bin/test and stat(2)
Message-ID: <9479@brl-adm.ARPA>
Date: Thu, 24-Sep-87 16:49:57 EDT
Article-I.D.: brl-adm.9479
Posted: Thu Sep 24 16:49:57 1987
Date-Received: Sat, 26-Sep-87 13:27:53 EDT
Sender: news@brl-adm.ARPA
Lines: 35

I understand that the 'stat' system call on a NULL string for a file name
will default to '.' (DOT), the current directory.  You don't have to explain
to me why this is.  I already know why.  I only just recently discovered
this fact.  But what I would like to know is, why does the test -d of a
NULL string in the following sample script return true?

Foo=""
if test -d "$Foo"
then
	do something constructive
fi
don't do anything

Let me rephrase the question.  I understand that /bin/test just does a 'stat'
call on the NULL filename string which defaults to DOT which does exist and
is a directory and that is why test returned true and the 'do something
constructive' part would get executed.  But why should I have to know in
advance that NULL will default to DOT in the case when I'm testing for the
existence of a directory?  Shouldn't /bin/test handle a NULL string in a 
special way, i.e..return false?  I don't see why I have to know in advance
that NULL defaults to DOT and I shouldn't have to do two tests to find out
if the file is a directory.  Also, the documentation doesn't say anything
about the case of a NULL filename when using 'test -d'.  To me, this really
sounds like a bug or a mis-implementation and documentation of /bin/test.

Please forward these questions to people who you think should read it just
in case unix-wizards doesn't cover the appropriate group, i.e..other mailing
lists.  And please CC me on all responses to this message, for sometimes
I don't read all of the unix-wizards digests.

thank you,
-franco

CSNET:	franco%bbn.com@relay.cs.net
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