[Info-vax] CLI WAS: VMS Forever?

[Tom Linden]

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.

>
> George
>
>> bill



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