Provided by: cnews_cr.g7-40.4_i386 bug
 

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
        optional 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:
 
        ·  words in a newsgroup or a pattern are delimited by periods;
 
        ·  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;
 
        ·  a newsgroup is matched against a pattern word by word, and all words
           must match for the newsgroup to match that pattern;
 
        ·  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;
 
        ·  if  the  newsgroup  has  fewer words than the pattern, the newsgroup
           does not match the pattern;
 
        ·  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:
 
        ·  the newsgroup does not mismatch any of the patterns, or
 
        ·  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
        instead.   (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
        explicitly).  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/spool/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
        replaced at most once per command with the name of  a  file  containing
        the  article,  relative  to  /var/spool/news (‘%%’ is replaced by ‘%’).
        The default is ‘uux - -z -r sysname!rnews’  for  a  command;  the  PATH
        searched  includes  /usr/lib/news/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/spool/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/spool/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/spool/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
        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(5cn)