On 09/18/2013 01:56 PM, Nix wrote: Please keep the list in the loop: https://rwmj.wordpress.com/2010/11/08/want-help-dont-email-me-directly/
> The documentation is wrong then... > When you say "AND" that means you need to satisfy "ALL" entity before it > exit successfully. > Using OR is fitted in your description. OR satisfies "ALL" or "EITHER" to > have a successful exit. > > Bottom line, it is about the logic of using AND or OR. It's about WHERE you are using the logic of AND or OR. Let's try again. If I write: [@[:alnum:]!] then I have a bracket expression containing three elements: [:alnum:], @, and !, which is the SAME as if I had written the bracket expression [@[:alpha:][:digit:]!] or even [[:digit:]!@[:alpha:]] Either way, I'm using [:alnum:] as shorthand instead of including both [:alpha:] AND [:digit:]. Then, the resulting bracket expression matches one byte that can come from a set of characters: @, !, alpha OR digit. It is the outer bracket expression that is doing OR matching, while the inner [:alnum:] element within the bracket expression is representing AND-based combination shorthand of other possible bracket expression elements. Similarly, [@!] is a bracket expression containing @ AND ! as expression elements, where the overall expression will then match @ OR !. But as @ matches only one possible character, rather than being shorthand for a bunch of characters, you don't get as confused by that wording. If you want to propose a documentation patch to make it clearer for the next reader, then by all means do so. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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