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NEWSSYS(5)		      File Formats Manual		    NEWSSYS(5)

NAME
       newssys - USENET	network	news sys (neighbours) file

DESCRIPTION
       The  file  /var/lib/news/sys  describes	which news groups this site is
       willing to receive and which groups it is willing to transmit  to  each
       netnews	neighbour.  It is public information and is sent automatically
       to any site that	sends a	sendsys	control	message.  A sys	line has  four
       fields, separated by colons:

       system-name/exclusion1,exclusion2...:subscriptions/distribu-
       tions:flags:transmission	command

       A # as the first	character in a line denotes a  comment.	  Empty	 lines
       are  ignored.   A  (non-comment)	sys entry may be continued to the next
       line by putting a \ at the end of the current line.  Spaces are permit-
       ted  in	sys only in comments, transmission command when	it really is a
       command and not a filename, and,	for B news compatibility, at the start
       of a continuation line (after a \ and a newline).

       Of  the	sys  fields, only the system-name need be present.  If a field
       and all the fields after	it are omitted,	the colon  immediately	before
       that  field  and	 all  the colons after it may be omitted too.  The op-
       tional subfields	 (exclusions  and  distributions)  and	their  leading
       slashes may be omitted.

       The system name is the name of the system being sent to,	and is checked
       against site names in Path: headers to avoid sending an article back to
       a  site	that has seen it.  The exclusions are also checked against the
       Path: header and	articles are not sent to system	name if	they have vis-
       ited any	of the exclusions.

       (The  special system name ME stands for the name	of the machine news is
       running on, as determined from /var/lib/news/whoami.  The ME line, or a
       line  whose  system name	is explicitly that of the machine news is run-
       ning on,	has a rather different meaning from that of the	other sys file
       lines:  its  subscriptions subfield identifies the newsgroups that this
       site subscribes to (i.e.	is willing to receive),	and its	 other	fields
       and subfields are ignored.  There should	be one such line in the	file.)

       subscriptions  is a comma-separated list	of newsgroup patterns specify-
       ing the newsgroups to be	transmitted to the system; each	newsgroup from
       the  Newsgroups:	 header	of each	article	is matched against the pattern
       list, and if any	newsgroup matches the pattern  list,  the  article  is
       transmitted.   The rules	for matching a newsgroup against a single pat-
       tern are:

       o  words	in a newsgroup or a pattern are	delimited by periods;

       o  words	of a pattern and a newsgroup match only	if they	are identical,
	  except that the word all in a	pattern	matches	any newsgroup word;

       o  a newsgroup is matched against a pattern word	by word, and all words
	  must match for the newsgroup to match	that pattern;

       o  if the pattern has fewer words than the newsgroup,  the  pattern  is
	  implicitly extended to the same number of words by appending .all as
	  many times as	necessary;

       o  if the newsgroup has fewer words than	 the  pattern,	the  newsgroup
	  does not match the pattern;

       o  if pattern matches a newsgroup, !pattern mismatches that newsgroup.

       A newsgroup matches a pattern list if, and only if, it matches at least
       one of the patterns and:

       o  the newsgroup	does not mismatch any of the patterns, or

       o  the longest matched pattern is longer	than  the  longest  mismatched
	  pattern  (length  is measured	in number of words, with each explicit
	  occurrence of	all counted as slightly	less than one word,  and  does
	  not include the implicit extension of	patterns with .all).

       Note that order in the lists is not significant,	and that ties are bro-
       ken in favor of not matching.  An example:  comp,comp.sys.sun,!comp.sys
       matches	all  the comp groups, except the comp.sys groups but including
       comp.sys.sun.

       The distributions in the	Distribution:  header  are  similarly  matched
       against	the  distributions  subfield, if any.  If no distributions are
       supplied, Distribution: will be matched against the  subscriptions  in-
       stead.  (The Distribution: header is ignored when receiving news; it is
       only significant	when sending.)

       Note that some older news software reportedly attached magical signifi-
       cance  to the distributions ``world'' and ``local''; C News treats them
       as ordinary distribution	names with no special properties (except  that
       ``world'' is the	default	distribution of	an article if none appears ex-
       plicitly).  For example,	a distributions	list like all,!local will  not
       prevent	local  articles	 from  being sent unless they contain explicit
       Distribution: local lines.  Note	too that  the  distribution  ``world''
       must  be	 permitted  (perhaps  by the distribution ``all'') in order to
       feed Distribution:-less articles	(the common case) to a site.

       The flags are a set of letters describing how  the  article  should  be
       transmitted.   Valid flags include f (interpret transmission command as
       a file name and write the article's file	name relative to /var/news and
       size  in	bytes on the end of it), F (like f but omit the	size), I (like
       F but write Message-ID:s	instead	of filenames), n (like F but  write  a
       Message-ID:  after  each	 filename),  Ln	 (only send articles generated
       within n	hops of	here; 0	is the default value for n), m (transmit  only
       moderated  groups),  u  (transmit  only unmoderated groups).  There are
       other obsolete ones.

       The transmission	command	is executed by the shell with the  article  to
       be  transmitted	as the standard	input.	The substring `%s' will	be re-
       placed at most once per command with the	name of	a file containing  the
       article,	 relative to /var/news (`%%' is	replaced by `%').  The default
       is `uux - -z -r sysname!rnews' for a command;  the  PATH	 searched  in-
       cludes  /usr/local/libexec/cnews/relay,	so that	the commands described
       in newsmail(8) are available as alternatives to uux.   If  one  of  the
       flags  has  caused this field to	be taken as a filename,	the default is
       /var/news/out.going/sysname/togo; if a filename is given	 but  it  does
       not   start   with   `/',   it	is  assumed  to	 be  relative  to  the
       /var/news/out.going directory.

EXAMPLES
       A complex sys file.

	    # line indicating what we are willing to receive; note local groups	near end
	    ME:comp,news,sci,rec,misc,soc,talk,can,ont,tor,ut,to
	    # sample insignificant feed	not using batching (for	special	situations only)
	    huey:news.config,to.huey/all::uux -	-r -gd huey!rnews
	    # sample of	mailing	newsgroups to someone (note distribution)
	    daisy:soc.women,soc.couples/all::mail daisy@duck
	    # sample small feed	using batching
	    gladstone:comp.protocols.tcp-ip,rec.aviation/all:f:
	    # sample major batched feed, including assorted regional newsgroups, with
	    # (unnecessary) explicit file name
	    dewey:comp,news,sci,rec,misc,soc,talk,can,ont,tor,ut,to.dewey/all:f:dewey/togo
	    # sample long-haul feed; note no regional groups, exclusion	of a local
	    # distribution, and	exclusion of anything that passed through him under
	    # another name (needed because he puts that	form, not just "donald", in
	    # his Path lines)
	    donald/donald.angry.duck:comp,news,sci,rec,misc,soc,talk,to.donald/all,!ut:f:
	    # sample local-postings-only feed direct to	major site (gets them out fast)
	    scrooge:comp,news,sci,rec,misc,soc,talk,to.scrooge/all:Lf:
	    # sample ihave/sendme link
	    # NOTE, this is uucp ihave/sendme, not related to NNTP in any way.
	    # Send ihave telling louie what we have -- batcher turns the batch into a
	    # giant control message and	posts it to "to.louie".
	    louie.wehave/louie:comp,news,sci,rec,misc,soc,talk,!to/all:I:
	    # Send the actual control messages
	    louie:to.louie/all:f:
	    # Also, since ihave/sendme is slow,	send local postings to louie without
	    # waiting for ihave/sendme
	    louie:comp,news,sci,rec,misc,soc,talk,!to/all:Lf:
	    # for a site we feed with snntp
	    zaphod.mps.ohio-state.edu:all:n:/var/news/out.nntp/zaphod.mps.ohio-state.edu

       (The ``to.sysname'' groups are normal newsgroups	used for testing indi-
       vidual news feeds and conveying ihave/sendme messages.)

FILES
       /var/lib/news/sys

SEE ALSO
       newsbatch(8CN), relaynews(8CN)

HISTORY
       Written by Geoff	Collyer	and Henry Spencer for the C News project.

BUGS
       The  flags  field is a bit of mess: there are too many formatting flags
       and they	aren't orthogonal.

				  9 Sept 1994			    NEWSSYS(5)

NAME | DESCRIPTION | EXAMPLES | FILES | SEE ALSO | HISTORY | BUGS

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