Re: ash vs. bash
On Sat, Jul 24, 1999 at 10:42:07AM -0400, Michael Stone wrote:
>
>That's simply not adequate. There are not just syntax differences
>between the shells, there are logical differences as well. That's why I
>refuse to screw with /bin/sh on production systems even though I use ash
>on my own machine: there are almost certainly scripts out there with
>little-used code paths which will behave differently under ash than
>under bash, _even though they are syntactically valid in ash_. There's
>too much uncertainty at this point to change the default. (Although I
>agree that if _I_ change /bin/sh, bash ought to keep its hands off it.)
But if it does, then those rarely used scripts that use bashisms,
that happened to work because #!/bin/sh was actually bash, will fail
on you. That is why I say that leaving the link alone is probably not
enough. Well-done system configuration scripts, makefiles and that
should always avoid assuming than /bin/sh offers features other than
the basic Bourne ones. Pre- post- scripts in /var/lib/dpkg/info/ that
use non-bourne features do not help with achieving a better policy.
I agree with you that unless someone make sure that all Debian system
scripts use pure-bourne code it is probably better not to fiddle with
/bin/sh, but that also means that upgrading bash _will_ have to reset
the link, because otherwise something could break. Anyway, I think that
by deciding not to fix it now, is likely to cause it to pop up again
in the future, when even more scripts will depend on bash.
bye
--
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