> From: Akim Demaille <[EMAIL PROTECTED]>
> Date: 10 Nov 2000 10:28:29 +0100
>
> | 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.
>
> Thanks for the information. May I include as are those two paragraphs
> in the documentation? In particular are there any license issues wrt
> POSIX snippets?
That quote is small enough so that it would be fair use. But I would
not quote the POSIX standard directly, as the standard will quite
possibly change. How about something like this?
The POSIX.2-1996 standard is ambiguous as to whether
expr 'a' : '\(b\)' outputs '0' or the empty string. In practice, it
outputs the empty string on most platforms, but portable scripts
should not assume this.
