Re: [gentoo-dev] POSIX shell and "portable"

[Mike Frysinger]

On Monday 05 November 2007, Michael Haubenwallner wrote:
> On Mon, 2007-11-05 at 10:13 +0000, Roy Marples wrote:
> > While I still have access to the u@g.o email, I'll respond here.
> >
> > On Mon, 2007-11-05 at 10:22 +0100, Michael Haubenwallner wrote:
> > > On Sat, 2007-11-03 at 00:47 +0000, Roy Marples wrote:
> > >
> > > As it seems too few people really accept your suggestion, I feel it's
> > > time for me to chime in too, although I don't know what exactly
> > > POSIX-sh standard defines.
> > >
> > > Agreed, but (speaking for alt/prefix):
> > >
> > > Alt/prefix is designed to (mainly) work without superuser access on the
> > > target machine, which may also be Solaris, AIX, HP-UX and the like.
> > > /bin/sh on such a machine is not POSIX-shell, but old bourne-shell
> > > (unfortunately with bugs often).
> > > And it is _impossible_ to have sysadmins to get /bin/sh a POSIX-Shell
> > > nor to have that bugs fixed.
> > >
> > > But yes, on most machines there is /bin/ksh, which IMHO is POSIX
> > > compliant (maybe also with non-fixable bugs).
> > >
> > > Although I do not know yet for which _installed_ scripts it'd be really
> > > useful to have them non-bash in alt/prefix, I appreciate the
> > > discussion.
> > >
> > > To see benefits for alt/prefix too, it _might_ require that discussion
> > > going from requiring /bin/sh being POSIX-sh towards being
> > > bourne-shell...
> >
> > Actually you missed the mark completely.
> > Nothing in the tree itself specifies what shell to use - instead it's
> > the package manager. So the PM on Gentoo/Linux/FreeBSD *could*
> > be /bin/sh and on the systems where /bin/sh is not possible to change to
> > a POSIX compliant shell then it can still use /bin/bash or wherever it's
> > installed.
>
> So "have the installed scripts to not require bash" is another topic ?

yes, and generally that's a baked topic.  if your script is /bin/sh, then it 
must be POSIX compliant.  if your script is /bin/bash, then you're encouraged 
to convert it to POSIX /bin/sh.  but this is because the *runtime* 
environment is generally a lot more restricted than that of the *buildtime* 
environment.  runtime implies a lot leaner requirements (think binary-only 
systems, embedded systems, production systems, etc...) than that of a 
development system (which requires everything in order to compile).

> Ok then:
> Given that we want to have the tree "more generic unix-able":
> What is the benefit from having the tree being POSIX- but not
> bourne-shell compatible, so one still needs bash on Solaris/AIX/HP-UX ?
> Because I'd say those three are the biggest substitutes for "unix",
> while I'd call *BSD and Linux just "unix derivates" (although with
> enhancements)...

we want the installed environment to be portable, not the build environment.  
i do not see any benefit from forcing the build environment to be pure POSIX 
compliant and i see many many detrimental problems.
-mike