Date   : Tue, 31 Jul 1984 06:14:00 MDT (Tue)
From   : Richard Conn <RCONN@Simtel20.ARPA>
Subject: SHSET

Yes, SHSET assumes that the command line is correct.  Once ZCPR3
decides to invoke a shell, the shell is processed like any other
command line, so your concern would be addressed by an Error Handler
should the command line loaded by SHSET be incorrect.  Current Error
Handlers do not have a provision for aborting a shell, so your point
is well-taken.  A new error handler, say ERROR5, should be created
which can abort a shell as well as redirect execution of the command
line (like current error handlers do).  Of course, if the SHSET
command line includes CMD, then when the conventional error handler is
invoked, the user could instruct execution to proceed to CMD, at which
point the user could issue a SHCTRL POP command to clear the shell
stack.  For that matter, a convnetional error handler will simply
allow the user to issue the SHCTRL POP command anyway.

       Hence, your problem is solved by using a conventional error
handler.  I think I will still add ERROR5, which will be able to deal
with the shell stack.

       Rick