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

[David Morgan]

Pavel Roskin wrote:
> 
> Hello!
> 
> > > expr a : '\(a\)'
> > > echo $?
> > > b=`expr a : '\(a\)'`
> > > echo $b,$?
> > >
> > > Gives:
> > >
> > > a
> > > 1
> > > a,0
> 
> David, could you please test this:
> 
> b=`false` || echo Ok
> 
> It should print "Ok". If it doesn't, we are in trouble.

We are in trouble - no response.
> 
> > Sorry, I was already inefficient I guess.  It's the same bug as ASh's
> > one reported by Pavel.
> 
> It's a different bug. With ash, you shouldn't rely on $? after assignments
> _unless_ backticks are used. In this case, you cannot rely on $? _if_
> backticks are used.
> 
> Unfortunately, the later is hard to eliminate. There are many constructs
> of this kind in config.status, e.g.
> 
>   ac_file_inputs=`IFS=:
>     for f in $ac_file_in; do
> ...
>       esac
>     done` || { false; exit; }
> 
> 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.

Regards
 David