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Re: Proposed new POSIX sh policy

On Sat, Nov 11, 2006 at 11:10:52PM -0600, Manoj Srivastava wrote:

>         Why don't we do that? Because people wanted to have a
>  different shell that can serve as /bin/sh.  What purpose does it
>  serve to allow that? We can't, in all honesty, say that any disk
>  space is conserved, since bash is essential, it is too deeply rooted
>  in all places in our system to be casually ripped out.

There is a very simple reason: people want to be able to unmount /usr
cleanly on shutdown, without risking file system corruption.

If you require /bin/sh to be bash, then the only way to achieve this is
to move all the dependencies of the various libnss-* packages from
/usr/lib to /lib. That would currently mean libraries of LDAP,
PostgreSQL and MySQL with their dependencies (OpenSSL, GnuTLS, Cyrus
SASL and Kerberos at least, I'm not sure I cathced all). Forcing /bin/sh
to be bash would imply a grave bug for all these packages.

Also, if in the future someone starts using dynamically loadable bash
builtins in maintainer scripts (if /bin/sh is required to be bash, then
that suddenly becomes allowed too) then maintainer script debugging may
become quite "interesting" when the seemingly same command starts to mean
completely different things in different scripts...

>         It is my opinion that we  would be better off dumping this
>  whole shell specification thing in policy, standardizing on bash, and
>  let it go.

If you want to standardize on one shell, that should not be bash. bash is
just hopelessly bloated.


     MTA SZTAKI Computer and Automation Research Institute
                Hungarian Academy of Sciences

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