Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpcc01!hpcuhb!hpcllla!hpclisp!defaria@hpclapd.HP.COM
From: defaria@hpclapd.HP.COM (Andy DeFaria)
Newsgroups: comp.lang.pascal
Subject: Writing an alternate shell (COMMAND.COM)?
Message-ID: <950037@hpclapd.HP.COM>
Date: 20 Aug 90 16:26:16 GMT
Organization: Hewlett-Packard Calif. Language Lab
Lines: 35

How can  one write an  alternate command interpreter for  DOS  using TP?  I
need to write a  very limited and restricted  "COMMAND.COM" that has enough
of the characteristics of  COMMAND.COM that it  would not crash the machine
if it is  used as the  SHELL.  I know very  little  about what is  actually
required for this.   I know that  COMMAND.COM has a tranisent (sp?) portion
and an resident portion and I'm pretty sure that I need  the same stuff but
I don't know how to do it in TP.  I would appreciate the help.

A little background:

I am trying  to secure  DOS  from unwitting and unknowing   users so as  to
provide a  more secure environment.   I have implemented  a  menu system to
keep them out of DOS but many third party packages  allow an easy door into
DOS.  Indeed so does the Turbo  Pascal  system itself.   I want to restrict
this so that if they try to access  DOS via one of  these "trap doors" they
will instead be dropped into my command interpreter that  will only provide
them with minimal functionality if any at all.  I have tried something like
the following:

set comspec=nodos          <-- simple .bat file that says "No way" and exits.
123                        <-- Lotus 123
set comspec=c:command.com  <-- back to DOS

But upon exiting Lotus 123 the system dies saying "Can't  find COMMAND.COM,
system halted".  I think if I can write and alternate command interpreter I
can avoid this  problem as long as I  provide the  proper structure so that
DOS is happy but I'm not sure how to do it.

Also, there seems to be  a market  for a good  alternate shell type program
for DOS  that could provide  *a  lot*  more functionality  then COMMAND.COM
(i.e. if I could write an alternate shell to restrict functionality then it
should   be  possible   to  write  and  alternate     shell  that  enhances
functionality).

Thanks in advance for your help.