Re: expr ... and `expr ...` return different results on QNX 4.2.5

[Pavel Roskin]

> > b=`false` || echo Ok
> >
> > It should print "Ok". If it doesn't, we are in trouble.
>
> We are in trouble - no response.

:-(

> > I'm afraid that Autoconf will have to reject QNX's shell. It's hard to
> > work around this kind of shell braindamage :-(
>
> The previous releases (2.13 et al) at least had the configure and 
> config.status
> working.  And this seems to work for everything else except the expr test. My
> preference is to say that autoconf works in a limited way on QNX 4.2.5 rather
> than abandoning it.
>
> If we can just fix the expr test (maybe adding a test with backticks as well)
> then I would be happy.

Well, one consequence is that some errors will not be detected. For
example, missing Makefile.in will not be reported. It's a "developer
error", i.e. it shouldn't happen with packages that came through "make
distcheck", however I don't feel good about it.

I don't know how many times we rely on similar constructs. There may be
more serious problems. To fix them, we should never use $? after _any_
assignments.

I don't see any other way to get the output and the exit status from a the
same command without using temporary files or sed or set + for loop.
Anybody knows how to rewrite this:

ac_output=`command`; ac_status=$?

in a way that it works even on QNX but doesn't cause significant slowdown?

Regards,
Pavel Roskin