[Info-vax] CLI WAS: VMS Forever?

[Bob Eager]

On Thu, 2 Apr 2009 15:49:16 UTC, "Tom Linden" <tom at kednos.company> 
wrote:

> On Wed, 01 Apr 2009 19:00:07 -0700, G Cornelius  
> <cornelius at eisner.decus.invalid> wrote:
> 
> > Bill Gunshannon wrote:
> >> In article <gr0245$rh7$1 at south.jnrs.ja.net>,
> >> 	"Richard Brodie" <R.Brodie at rl.ac.uk> writes:
> >>
> >>> "Bill Gunshannon" <billg999 at cs.uofs.edu> wrote in message
> >>> news:73hefhFutmjfU2 at mid.individual.net...
> >
> >>>> Not sure what that means.  What makes a program "native"?
> >>>
> >>> It's not a CLI, as the POSIX shell was. You can't run programs in it  
> >>> without
> >>> creating a new process, for example.
> >>
> >>
> >> I guess I am out of my depth here, but what would have to be done to
> >> make it work right?  I mean, I am sure the real BASH Shell makes use
> >> of fork() which we know is not available on VMS.  Not sure what the
> >> alternative would be but is that what you mean?
> >
> > Unlike RSX-11M, it was never fully documented in VMS how to write a
> > Command Line Interpreter.
> >
> > Officially, there have been a few non-DCL CLI's, including, I
> > suppose, Posix and one or more of its predecessors.
> >
> > The characteristics of a CLI are that it runs in an inner mode
> > (Supervisor), and remains more or less permanently in process virtual
> > memory.  It executes images in succession in user mode within
> > current process context and gains control on image exits, both
> > normal and abnormal.  It may or may not be doing anything useful
> > during image execution, although it at a minimum appears to
> > provide services such as LIB$SPAWN and LIB$GET_SYMBOL that are
> > CLI specific and callable from user mode.
> >
> > Whether it makes sense to implement a Unix shell using this kind
> > of structure is another issue, but even when closely emulating
> > the corresponding Unix shell, especially in the use of subprocesses,
> > it may be helpful to have the CLI infrastructure to help make up for
> > any shortcomings that facilities like LIB$SPAWN have as replacements
> > for their Unix cousins.
> 
> I would like to see Rexx on VMS and the ability to write user functions.

Hear hear.

I haven't tried this one yet:

  http://regina-rexx.sourceforge.net/

but it ought to fill the bill; I use it on FreeBSD.
-- 
Bob Eager