On 10/30/2016 12:01 PM, Pádraig Brady wrote:
> * doc/autoconf.texi (Limitations of usual tools): Display a
> table showing where the various syntaxes for word boundaries
> are supported.
> ---
> doc/autoconf.texi | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/doc/autoconf.texi b/doc/autoconf.texi
> index 4be1f70..2e4b7ba 100644
> --- a/doc/autoconf.texi
> +++ b/doc/autoconf.texi
> @@ -19666,6 +19666,18 @@ $ @kbd{echo abc | busybox sed '/a\(b\)c/
> s/a\(b\)c/\1/'}
> b
> @end example
>
> +Portable scripts should be aware of the inconsistencies and
> +options for handling word boundaries.
> +
> +@example
> + \< \b [[:<:]]
> +Solaris 10 yes no no
> +Solaris XPG4 yes no error
> +NetBSD 5.1 no no yes
> +FreeBSD 9.1 no no yes
> +GNU yes yes error
> +busybox yes yes error
> +@end exampleIt might be nice to add Cygwin to the list, although I don't know if one row is sufficient. It bases its regex engine on BSD code but adds an extension for \< and \>; but depending on whether a program uses the libc regex or its own, you can get GNU behavior (that is, Cygwin grep supports \< and \b but not [[:<:]] because it uses gnulib and bypasses native regex; while a native application supports [[:<:]] and \< but not \b because of the BSD heritage plus cygwin extension). It may be worth pointing out that POSIX does not require ANY support for word boundaries in regex. ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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