RE: Recommended way to truncate a shell variable value in autoconf

[Dale Visser]

> Date: Fri, 21 Feb 2014 15:23:31 -0700
> From: address@hidden
> To: address@hidden; address@hidden
> Subject: Re: Recommended way to truncate a shell variable value in autoconf
> 
> ...
> is portable.  Until then, the only portable fallback to this particular
> problem is the use of 'expr' pattern matching and/or sed scripts.  :(

I've figured a working alternative using successive calls to `expr STRING : 
REGEXP`

But then again I notice in the autoconf docs 
(https://www.gnu.org/software/autoconf/manual/autoconf.html#Limitations-of-Usual-Tools)
 this:

"Don't use length, substr, match and index."

Since "STRING : REGEXP" does the same thing as "match STRING REGEXP", does that 
mean I'm out of luck with this approach, too?