vi shell access

[Paul Stath]

mab at ntcsd1.UUCP (Mark Bradford) writes:

>We have an application that allows the users to us vi.  What we would
>like to do is to keep the users from accessing the shell.  We currently
>do not allow the users to use ":!command" by setting the SHELL environment
>to a script.  The problem has arisen that some of our users have learned
>to use the set shell option in vi.  Is there any way of disabling this
>option?  

Why would you want to cripple vi like this?  IMHO, this is one of the
nicest features of vi which I use daily.  I have the function keys set to do
usefull things like reformat a paragraph, get the current tima and date, etc.
But rather than debate the merits of vi shell command escapes, I'll assume you
have a valid reason, soooo, here are a couple of methods you can try.

1) Look at what type of vi you are running.  Some vi's have a security option.
   (I think BSD does??  It's been sooo long since I've used BSD)  If the option
   is not set on the command line it may be invoked when started by an rsh.
   (Similar to the red version of ed)  System V R3.2 doesn't seem to support it.

2) You might be able to set up a vi macro that blows away the ability to set the
   shell.  I will dig out my vi references and see if I can figure this one
   out, and post the solution.  Of course, this requires that the .exrc file
   cannot be changed by the user.

Of course, if you have the source to vi, or some other popular editor, you could
hack out the shell escape functions altogether, call it, oh say, r<editor> and
call that from your application.

Of course, the BEST solution would be to make it so that no more processes
could be forked from the editor process, and call whatever editor the user is
most comfortable using.  (Pick this up from the EDITOR environment variable)
Any system programming gurus out there know how to make a child process that
can't fork???  I'm claiming ignorance in this area.  I'll look around and see
what I can find out on this end.  But at least you get the idea of a direction
to head in.  Good luck, I'd like to hear what your solution turns out to be.
-- 
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Paul R. Stath       The Computer Solution Co., Inc.       Voice: 804-794-3491
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