Path: utzoo!utgpu!water!watmath!clyde!att!ucbvax!CORY.BERKELEY.EDU!dillon
From: dillon@CORY.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga
Subject: Re: Enviroment (was Re: Yea, but can an Amiga Shell do this....)
Message-ID: <8809040955.AA26836@cory.Berkeley.EDU>
Date: 4 Sep 88 09:55:50 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 85

:>	Just a single slash '/' indicates the parent directory, and although
:>I agree with you that this is not compatible with UNIX, I LIKE it *much*
:>better than having to type '../'.
:
:Wrong. A single slash does NOT indicate the parent directory. This is the
:Amiga's file system problem--the symbols are context sensitive.

	Look guy, if you just *THINK* about it you will find that the UNIX
../ can be replaced *exactly* by a single slash:

	UNIX			AMIGA
	../x/y			/x/y
	x/../y			x//y


:The truth:
:A colon followed by a slash may be an error (is it assigned to a subdir?)

	Sure, if you are in the root directory of the device you can't go 
back.  If not (an assigned subdir), you can.  So what is the problem?

:N+1 non-initial consecutive slashes refers to N parents
:N initial slashes refers to N parents
:There is no easy way to take the name of a directory and append a file
:	name to it.
	
	What are you talking about?

:Tell you what: You give me a routine that will take two names, one a
:directory, one a file, and return me a pathname for the file. Handle
:ending slashes, null directories, assigned devices, assigned directories,
:files beginning with slashes, etc. AND make it usable in CLI scripts.
:Then, I will consider the Amiga's file system naming useably clean.

	What are you talking about?  I do this all the time.  I don't see
how it can be done in UNIX any easier than on the Amiga.

	ending slashes in UNIX:	UNIX allows you to have multiple slashes
in a filename (at least, 4.3 BSD does).  A/B is equivalent to A//B ...
Most people, however, do not consider A//B to be of correct form.  On the
Amiga, this UNIX-hack is obviously not implemented because the Amiga is
more sensible in its solution.  null directories I understand.  I don't
see how assigned devices enters in to it because UNIX doesn't support 
multiple filesystem roots.  Files beginning with slashes?  you mean when
you specify part of a directory path in the filename?

	Come on, this is *easy*.  Every filerequester in existance does 
this.  You could write it in 1 minute.  Now this last part 'usable in
CLI scripts'... strange condition.  Frankly, the relative merits of the 
CLI's language being able to support the above algorithm efficiently
enough has absolutely no bearing on the merits of the filesystem unto itself.

>(under non-v7 unix, this routine is arg1 + "/" + arg2. V7 allowed "" for
>current directory, so it would be (*arg1 == 0? "./" : arg1 + "/") + arg2
>(+ == strcat))

	Since you are so fond of C, I shall simply outline the routine and
let you write it:

	Assumptions:  Assume the two parts (dir and file) are to be 
considered independant paths in their own right.  I.E. if dir ends in a '/'
we are specifying the parent directory of something.  If you don't like
that last assumption, then simply replace "not ':'" with "not ':' and not '/'"
in the two line routine below... that is, allow for the 'dumb user' who
puts extranious characters in his path specifications.

	Routine (dir, file) {
	    If dir != "" && last char of dir is not ':', append a '/' to dir
	    Return (dir + file)
	}

	Gosh, that was easy.  Now if you want to handle other cases, like
	the 'file' isn't just a filename, but an entire path, that's ok
	with me... you would add something like "If file contains a ':' 
	then ignore dir".

	This handles: (1) ending slashes on the dir part (assumes you mean
	go to parent after resolving rest of dir OR assumes user added 
	extranious char).  (2) null directories, (3) assigned devices & dirs
	(:), (4) files beginning with one or more slashes (assumes you want 
	to go to the N'th parent.. why else put a slash in front of a 
	filename?).  (5) usable in CLI scripts?? What kind of condition is 
	this?  Just write it in C and provide it as a CLI command.

						-Matt