> From: David Morgan <[EMAIL PROTECTED]>
> Date: Thu, 09 Nov 2000 08:12:01 -0800
> > | > expr 'a' : '\(b\)' && echo failure
> > |
> > | Gives:
> > | 0
> >
> > Result is wrong, $? right.
> Wrong explanation - no characters match so the output of 0 is correct
> (At least I think so)
The POSIX standard says:
Usually, the matching operator shall return a string representing
the number of characters matched ('0' on failure). Alternatively,
if the pattern contains at least one regular expression
subexpression "[\(...\)]", the string corresponding to "\1" shall
be returned.
This leaves it ambiguous as to what expr 'a' : '\(b\)' should return.
One could easily argue that it should be '0'. But in practice,
GNU/Linux and Solaris expr both return the empty string, under the
theory that the operation is returning a string.
However, autoconf's use of expr in AS_DIRNAME should be OK either way,
so I don't see why this matters to autoconf.
> > Man! Did I miss something? David, could you double check this is
> > right? Paul, what do you think about this?
Sorry, I've lost context. Why is this a problem? If expr exits with
nonzero status, then AS_DIRNAME will fall back on sed, right?
By the way, In reviewing the latest AS_DIRNAME I see a quoting
problem. AS_DIRNAME_SED shell-quotes its argument, but
AS_DIRNAME_EXPR doesn't. This needs to be handled consistently.
Also, in looking at the callers of AS_DIRNAME, I see that some callers
quote their arguments, but some don't. This also needs to get fixed.
I don't know what the desired quoting convention is, so I'll leave it
to you to fix the problem.
