Someone care to explain this pattern to me ... ?

[Bill Davidsen]

Jeffrey M. Vinocur wrote:
> On Tue, 2 Oct 2007, Marc G. Fournier wrote:
>
>   
>> @*,comp.*,mailing.*,sci.*,pgsql.*,news.*,alt.webhosting,
>> alt.paidwebhosting,alt.www.*,tor.*,can.*,ont.*,hfx.*,ns.*, [...]
>>
>> From reading the man page, the @* at the start should negate everything else,
>> no?  But I'm definitely both sending, and receiving, news ... so is the @* at
>> the start actually *doing* anything?
>>     
>
> Yes -- conceptually, it's prohibiting crossposts to groups not listed 
> there.  So if you had a private local hierarchy, and someone tried to 
> crosspost between that hierarchy and some alt.* group, that post wouldn't 
> be sent along even if the rest of the traffic in the alt.* group would.
>
> To get to the nitty gritty, the way it works is:  take an article, and
> look at each group in the Newsgroups line.  Match that group name against
> the pattern in newsfeeds, making use of the last piece of the pattern that
> matches.  If there's only a single group, it's very easy (so if the 
> article is going to news.software.nntp, first it matches @*, but then it 
> matches news.* and therefore gets sent).  The complicated piece is 
> crossposted articles -- if any of the crossposted groups matches just @* 
> and nothing else later in the pattern, the article won't be sent.
>
> The alternative to @*, by the way, is !*, which leans towards less 
> restricion.  So for articles posted to a single group, it's exactly the 
> same.  For crossposts, however, if any of the crossposted groups matches 
> just !* that doesn't matter as long as at least one of the groups matches 
> something later in the pattern.
>
>
>   
Well, that's right but I'm don't think complete... the !* clears the 
field established by ME and starts with a clean slate.

-- 
bill davidsen <davidsen at tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979