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From: richard@aiva.ed.ac.uk (Richard Tobin)
Newsgroups: comp.unix.wizards
Subject: Re: /bin/test and stat(2)
Message-ID: <182@aiva.ed.ac.uk>
Date: Thu, 22-Oct-87 12:17:44 EST
Article-I.D.: aiva.182
Posted: Thu Oct 22 12:17:44 1987
Date-Received: Tue, 27-Oct-87 01:01:53 EST
References: <9767@brl-adm.ARPA> <231@olgb1.oliv.co.uk>
Reply-To: richard@uk.ac.ed.aiva (Richard Tobin,E26 SB x206E,,4477106)
Organization: AI Applications Institute, Edinburgh University
Lines: 29

In article <231@olgb1.oliv.co.uk> olapw@olgb1.oliv.co.uk (Tony Walton) writes:
>In article<9767@brl-adm.ARPA>, franco@MIKEY.BBN.COM (Frank A. Lonigro) writes:
>> alone a directory, and why should there be two ways to refer to the same
>> thing (the current directory)?  It really doesn't make sense!
>I don't pretend to know the original reason (if any) for having two ways
>to refer to the current directory, but it certainly makes life easier for
>the users. Consider the "ls" command - it's easier to type "ls" than "ls ."
>every time. On the other hand, "." is necssary as a "place holder" in some
>commands - like find, mv, etc.

The facts that ls defaults to the current directory and that a null ("") path
is equivalent to "." are quite unrelated.  The former is because ls looks
to see if it has a filename argument, and if it doesn't it uses ".".  The
second is because the kernel routine namei() allows "" as a degenerate
pathname.

Thus 
  ls
and
  ls ""
both list the current directory, but for quite different reasons.

I never use "" for the current directory deliberately; when I encounter it
it's usually because of an error - maybe an over-ambitious C-shell
backquoted expression that didn't produce any output.
-- 
Richard Tobin,                         JANET: R.Tobin@uk.ac.ed             
AI Applications Institute,             ARPA:  R.Tobin%uk.ac.ed@nss.cs.ucl.ac.uk
Edinburgh University.                  UUCP:  ...!ukc!ed.ac.uk!R.Tobin