Re: [PATCH] Yet another shell function prerequisite!

[Paolo Bonzini]

Eric Blake wrote:
> Paolo Bonzini <bonzini <at> gnu.org> writes:
> 
>> -_AS_ECHO([$as_me:$LINENO: $1], [AS_MESSAGE_LOG_FD])])
>> +_AS_ECHO([$as_me:${as_lineno:-$LINENO}: $1], [AS_MESSAGE_LOG_FD])])
> 
> Actually, the manual states that ${as_lineno:-$LINENO} is not portable; we 
> have 
> to stick with ${as_lineno-$LINENO} or with a more complex expression.

I'd okay with -, but what if unset does not work?  I planned to do
something like

  as_lineno=; AS_UNSET([as_lineno])

but that could expand to

  as_lineno=; false as_lineno

Do we still care about "old BSD shells, including the Ultrix sh"?  How
old are these?

Paolo