Date: Tue, 27 Oct 1998 19:37:45 +0100
From: Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Message-Id: <199810271837.TAA25985@acp3bf.physik.rwth-aachen.de>
To: gfenwick AT primex DOT co DOT uk (Graeme Fenwick)
Cc: djgpp AT delorie DOT com
Subject: Re: /? command line args being altered by DJGPP
Newsgroups: comp.os.msdos.djgpp
Organization: RWTH Aachen, III. physikalisches Institut B
X-Newsreader: TIN [version 1.2 PL2]
Reply-To: djgpp AT delorie DOT com

In article <3635f355 DOT 0 AT scooby DOT nildram DOT co DOT uk> you wrote:
> Hi all!

> At first I thought this was 99% certain to be a DOS issue. 

In a sense, it is. More precisely, it's a DJGPP issue, which happens when
DJGPP tries to get around one of the many differences between DOS and 
Unix.

> Put simply, I've written (part of a) program to parse command line
> arguments, and it's running into trouble when I try to read the arguments
> "/?", "/??", "/???" and so on. 

On Unix, and thus also in DJGPP programs, '/' is not the typical character
that starts a command line option. It's the directory separator, instead
(what DOS uses '\' for).

In comes another Unixism: the shell filenaming globbing. Generally, if
you give a filename like a?b* on a Unix shell command line, it will not
be passed to the child program. Instead, the shell will try to find all
filenames matching this pattern, and pass the full list of filenames found
to the child. I.e. if you type

	ls bla*

the actual command line used to call 'ls' might be:

	ls blafasel blabbla blaff.c

Only if no matching filenames are found, the pattern (including ? and
*) will be passed to the subprogram, instead.

Now, command.com doesn't behave like this, obviously. It always passes
the unchanged command line to the called program, leaving it to the
child to 'glob' the filenames, if needed. But DJGPP tries to be as Unixy
as possible, so every DJGPP program (unless told otherwise) will do this
globbing itself, so the effective command line you see (in argv[] argument
of main(), e.g.) will have been expanded, if possible.

>             "test /?" gives the output "/a"

You do have a directory /a in the root of your DJGPP drive, right?

>             "test /??" gives the output "/??" (correct, this time)

But no directory with a two-letter directory name.

>             "test /???" gives the output "/ati"

... and there's a directory c:\ati.

--
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.