Re: portability of ${foo:+bar}

[Florian Weimer]

* Paul Eggert:

>> Can I assume that any shell on a system, which has shared libraries,
>> understands `${foo:+bar}' and `${foo:-bar}' correctly, even if bar
>> happens to be `:'?
>
> Ultrix had shared libraries, I think;

Are you sure?  When I worked with Ultrix, you couldn't create them
yourself.  Perhaps libc was provided as a shared library (I seem to
recall something like that), but you certainly weren't supposed to
create your own.

Most resources on the net dealing with Ultrix claim that it does not
offer shared library support.