Mac OS X /bin/sh was zsh, to be replaced with bash

Mac OS X /bin/sh was zsh, to be replaced with bash

[Jos Backus]

Yesterday I attended the local Bay Area Next user group meeting at Apple in
Cupertino, at which an Apple employee (sorry, can't remember his name right
now) mentioned that there are plans to replace /bin/sh, currently zsh
3.0.something, with bash. The primary reason he stated was zsh's lack of POSIX
conformance that they kept having problems with. Unfortunately he did/could
not go into any detail. He also said that as far as he knew no attempt had
been made to contact the zsh maintainers about this.

Now I could ask Jordan Hubbard at Apple if he would be willing to refer me to
somebody to talk to about this issue, and ask this person what exactly these
POSIX compatibility issues are they are having problems with. Maybe these
issues can be addressed; they will never be fixed unless the developers are
aware of them.

Comments?

-- 
Jos Backus                 _/  _/_/_/        Santa Clara, CA
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Re: Mac OS X /bin/sh was zsh, to be replaced with bash

[Peter Stephenson]

Jos Backus wrote:
> Now I could ask Jordan Hubbard at Apple if he would be willing to refer me to
> somebody to talk to about this issue, and ask this person what exactly these
> POSIX compatibility issues are they are having problems with. Maybe these
> issues can be addressed; they will never be fixed unless the developers are
> aware of them.
> 
> Comments?

We'd certainly be interested in getting more details.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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Re: Mac OS X /bin/sh was zsh, to be replaced with bash

[Oliver Kiddle]

Jos Backus wrote:
> 
> Yesterday I attended the local Bay Area Next user group meeting at Apple in
> Cupertino, at which an Apple employee (sorry, can't remember his name right
> now) mentioned that there are plans to replace /bin/sh, currently zsh
> 3.0.something, with bash. The primary reason he stated was zsh's lack of POSIX
> conformance that they kept having problems with. Unfortunately he did/could
> not go into any detail. He also said that as far as he knew no attempt had
> been made to contact the zsh maintainers about this.

This would be a pity. I thought it had never been bash because they were
concerned that the shell was too fundamental a part of the OS and hence
they might be violating the GPL.

I did recently look through the Darwin bug archives for anything zsh
related and found one real issue which as far as I could tell has been
fixed since 3.0. I have a suspicion that there are some misinformed
people who think bash is more compliant than zsh (which it isn't
particularly). David Korn's slashdot article a while back mentioned that
using zsh as /bin/sh would be dangerous. I think this was said to be
because of some of zsh's differences such as the word splitting despite
the fact that zsh would correctly emulate this if installed as /bin/sh.
This was mentioned on the darwin-development mailing list several months
ago - I saw it when looking through the archives.

The only areas where I know zsh not to be POSIX compliant is the lack of
export's -p option and the arguments to the command command and a couple
of minor things like that. These could probably be added very easily and
quickly.

> Now I could ask Jordan Hubbard at Apple if he would be willing to refer me to
> somebody to talk to about this issue, and ask this person what exactly these
> POSIX compatibility issues are they are having problems with. Maybe these
> issues can be addressed; they will never be fixed unless the developers are
> aware of them.

It would definitely be a good idea to try to establish some form of
dialogue with Apple on this. I can think of arguments against bash from
a number of perspectives - technical, licencing and otherwise. No
disrespect to their many positive achievements but the FSF have a
reputation for trying to hold too tight a grip on official GNU software
making it in some respects less open. If we can find out exactly where
they have had issues with zsh we could address those issues directly.

If you manage to make contact with apple, please keep us informed.

Oliver

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Re: Mac OS X /bin/sh was zsh, to be replaced with bash

[Jos Backus]

On Thu, Oct 25, 2001 at 07:09:39PM +0100, Oliver Kiddle wrote:
> If you manage to make contact with apple, please keep us informed.

You make some good points there.

I just sent an e-mail to Jordan, I'll let you know when I hear from him.

-- 
Jos Backus                 _/  _/_/_/        Santa Clara, CA
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Re: Mac OS X /bin/sh was zsh, to be replaced with bash

[Oliver Kiddle]

Jos Backus wrote:
> 
> On Thu, Oct 25, 2001 at 07:09:39PM +0100, Oliver Kiddle wrote:
> > If you manage to make contact with apple, please keep us informed.
> 
> You make some good points there.

If you're giving points to folk at Apple then I can suggest plenty more,
including:

	The loadable modules in zsh 4.x make zsh much smaller and more
	efficient as a non-interactive shell which is the typical use
	of /bin/sh.

	With the future POSIX standard we have been discussing with
	David Korn (ksh author) and Chet Ramey (bash author), zsh will
	likely be a long way ahead of bash. Not that anything is
	going to happen with that anytime soon.

	bash's GPL licence would leave Apple with less flexibility.
	They might for example want to write a shell module for GUI
	interaction. With bash, it'd have to be contributed back as GPL
	code. With zsh, it could be APSL, closed source, zsh licence or
	any other licence. I might discourage the closed approach but
	from Apple's perspective they'd be keeping their options open.

	The explicit emulate command in zsh actually allows zsh to go
	much further than bash in emulating POSIX. Extra reserved words
	can be disabled etc. The only way that bash is more compatible
	is that it adds fewer additional features.

The only argument in favour of bash is that more people are familiar
with it from Linux but then bash is largely a subset of zsh anyway.

And, I expect that ksh93 would require them to pay a lot of money to
AT&T.

> I just sent an e-mail to Jordan, I'll let you know when I hear from him.

Thanks. If we don't hear anything we should try other channels. It
would be a pity if they adopted bash. I've been very impressed with
much of what Apple has done with Mac OS X. Two years ago, if someone
had suggested I buy a Mac, I'd have made facetious remarks about one
button mice. Today I'd be extremely tempted.

Oliver

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Re: Mac OS X /bin/sh was zsh, to be replaced with bash

[Jos Backus]

On Thu, Oct 25, 2001 at 08:00:21PM +0100, Oliver Kiddle wrote:
> If you're giving points to folk at Apple then I can suggest plenty more,
> including:

Thanks! I took the liberty of sending both this and your previous e-mail to
Jordan in reply to response. Unfortunately, things do not look good :( The
decision to move to bash appears to be set in stone already, and getting a
list of bugs appears to be hard/time-consuming as well.

-- 
Jos Backus                 _/  _/_/_/        Santa Clara, CA
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