[Info-vax] VMS porting/rewrite, was: Re: [OT] Wirth style languages, was: Re: Obscure Ada compiler vendors?

[VAXman- at SendSpamHere.ORG]

In article <kk157k$5gp$1 at dont-email.me>, Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> writes:
>On 2013-04-09, VAXman-  @SendSpamHere.ORG <VAXman- at SendSpamHere.ORG> wrote:
>> In article <kk11j5$etr$1 at dont-email.me>, Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> writes:
>>>
>>>The GNU project started out as building a compiler and replacing vendor
>>>specific versions of Unix commands/utilities with their own. (Unix makes
>>>it easy to replace things a bit at a time; VMS does not.)
>>
>> You don't like a particular command or utility, write your own.  You can
>> replace these things just as easily.  Saying that it is not easy to do on
>> VMS means you shouldn't be a part of the project trying to do so. ;)
>>
>
>Fine.
>
>Suppose I want to replace the existing DCL CLI with a new DCL CLI which
>supports existing functionality but also gives DCL more modern
>functionality.

So, implement what you want of DCL with your own interpretor code or map
DCL as the interpretor and augment it.  It's really NOT difficult.  How-
ever, depending upon what you want to do in terms of augmentation of the
current DCL capabilities, mapping DCL to accomplish this may be more work
than writing a full blown CLI.


>[This is how bash started out BTW; it was a replacement for the limited
>Unix shells of the time.]
>
>It's easy to write a new shell on Linux (and you also have plenty of
>exmaples to help you with specific concepts); where is the public
>documentation which would allow me to write a new DCL CLI on VMS ?

It's just as easy on VMS.  You just think it easier because you've looked
at the work somebody else has done before you.  I've never seen document-
ation on writing a Linux shell either nor have I looked at any Linux shell
code to learn how; therefore, writing a Linux shell is just as difficult
as you purport a VMS CLI to be.


As for examples, what do you need?  Shareable images have been COMPLETELY
and FULLY documented for decades.  Put your CLI's entry point at the base
of the image.  Put "IMAGE_TYPE = CLI" in the LINKER option deck.  The CLI
image must exist in SYS$SYSTEM because that is where LOGINOUT.EXE expects
it to be.  If you create your own (SCL -- Simon Chubley's Language), you
many need to create a dummy SCLTABLES.EXE as well as LOGINOUT.EXE will try
to active such from SYS$SHARE: too when the process is created.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

Well I speak to machines with the voice of humanity.