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Date: Sat, 11 Oct 2003 20:00:58 +0200
From: Matthias Paul <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
Subject: Re: confirm before over-write
To: opendos AT delorie DOT com
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Organization: Aachen University of Technology (RWTH), Germany
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On 2003-10-10, Ben A L Jemmett wrote:

>> You cannot disable the internal COPY other than by replacing
>> COMMAND.COM (for example by 4DOS),
> 
> One trick with MS-DOS's COMMAND.COM is to take a hex editor to it and
> make one or more letters in the command name in the command table
> lowercase -- since COMMAND.COM uppercases what you type before
> matching internal commands this effectively disables it.  Not sure if
> this would work with DR-DOS's COMMAND.COM (I suppose it would) or if
> it's a good idea.

;-) Well, I don't think it's recommendable as long as other
solutions exist. I haven't tested it, but AFAIR, just changing
the case won't work for DR-DOS COMMAND.COM as both operands
will be up-cased during the comparison.
Still, changing one letter to an invalid character should work
as long as you take care of possibly merged (that is physically
overlapping) strings in the binary's command table.

Greetings,

 Matthias

--�
<mailto:Matthias DOT Paul AT post DOT rwth-aachen DOT de>; <mailto:mpaul AT drdos DOT org>
http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org

"Programs are poems for computers."