Re: [9fans] How can I shift a variable other than ?

["Dan Cross" <crossd@gmail.com>]

On 3/10/07, Kris Maglione <bsdaemon@comcast.net> wrote:
> The difference here is that there has always been one rc (ignoring the
> UNIX version, which is gratuitously incompatible), unlike the bourne
> shells. One of the great things about it has always been that you could
> write rc scripts and know that they'd work on rc wherever they were run.
> If you start extending the spec, then things start to suck, truly.

Nonsense.  You think rc has never changed before?  There have been
plenty of non-backwards compatible changes in Plan 9.

Plan 9 is a research system; it should be unfettered by the demands of
backwards compatibility with itself (within reason).  Taking your
argument to its logical conclusion, we should all be using VT220's (or
better yet, DECwriter III's) on a VAX running 7th edition Unix.  But
I'd rather incorporate good ideas for change than remain stuck in the
past.  In this environment, I think innovation is worth more than some
minimal amount o backwards compatibility.  Besides, one doesn't even
know how used this feature would be; it may come to pass that the
vast, vast majority of sites are totally unaffected.

Besides, there are sufficiently few sites running Plan 9 that, when
confronted with script breakage, it is not an unreasonable answer to
say, ``upgrade your shell.''

There are times when forward progress demands a break from established
convention.  Sometimes, this buys you nothing, but that does not mean
that every proposed change is bad.  Certainly, without deciding to
break backwards compatibility with Unix, Plan 9 would never have come
about.

> >doesn't run on plan 9.  it's written in limbo and depends on
> >features of inferno that are not part of plan 9.
>
> It runs on Inferno, which runs on Plan 9. You can script for Plan 9 in
> Inferno's sh. You can even script for UNIX in it. I've done both. It
> works. It's not even ugly.

Have to incorporate all of the Inferno machinery into a system just to
run a shell script is way too much to ask of most people.  Certainly,
more than asking them to upgrade their shell interpreter from sources.

> At any rate, someone might write a new shell which is neither es nor
> Inferno's shell, which is designed to run on Plan 9. I'd still rather
> just use Inferno's shell, myself.

Then by all means, port over the Inferno shell.

        - Dan C.