.\" =()<.ds a @<NEWSARTS>@>()=
.ds a /var/spool/news
.\" =()<.ds b @<NEWSBIN>@>()=
.ds b /usr/lib/newsbin
.\" =()<.ds c @<NEWSCTL>@>()=
.ds c /var/lib/news
.\" =()<.ds m @<NEWSMASTER>@>()=
.ds m news
.\" indentation start
.de Is
.in +0.5i
..
.\" indentation end
.de Ie
.in -0.5i
..
.\" example start
.de Es
.LP
.nf
.ft B
.Is
..
.\" example end
.de Ee
.Ie
.ft R
.fi
.LP
..
.TH NEWSSYS 5 "2 March 1992"
.BY "C News"
.SH NAME
newssys \- USENET network news sys (neighbours) file
.SH DESCRIPTION
The file
.B \*c/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
.I sendsys
control message.
A
.I sys
line has four fields,
separated by colons:
.LP
.IB system-name / exclusion1 ,\c
.IB exclusion2... : subscriptions /\c
.IB distributions :\c
.IB flags : "transmission command"
.PP
A
.B #
as the first character in a line denotes a comment.
Empty lines are ignored.
A logical line may be continued to the next physical line by
putting a
.B \e
at the end of the current physical line.
Spaces are permitted in
.I sys
only in comments,
.I "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
.B \e
and a newline).
.PP
Of the \fIsys\fR fields,
only the
.I 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
(\c
.IR exclusion s
and
.IR distributions )
and their leading slashes
may be omitted.
.PP
The
.I system name
is the name of the system being sent to,
and
is checked against site names in
.B Path:
headers to avoid sending an article back
to a site that has seen it.
The
.IR exclusion s
are also checked against the
.B Path:
header and articles are not sent to
.I system name
if they have visited any of the
.IR exclusions .
.PP
(The special
.I system name
.B ME
stands for the name of the machine news is running on,
as determined from
.BR \*c/whoami .
The
.B ME
line,
or a line whose
.I system name
is explicitly that of the machine news is running on,
has a rather different meaning from that of the other
.I sys
file lines:
its
.I 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.)
.PP
.I subscriptions
is a comma-separated list of
.I "newsgroup patterns"
specifying the newsgroups
to be transmitted to the
.IR system ;
each newsgroup from the
.B 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 pattern are:
.\" precompute the indent to avoid passing an argument containing
.\" whitespace into a macro, since this seems not to always work.
.nr Bw \w'\(bu  '
.IP \(bu \n(Bwu
.IR word s
in a newsgroup or a pattern
are delimited by periods;
.IP \(bu
words of a pattern and a newsgroup
match only if they are identical,
except that
the word
.B all
in a pattern
matches any newsgroup word;
.IP \(bu
a newsgroup is matched against a pattern word by word,
and all words
must match for the newsgroup to match that pattern;
.IP \(bu
if the pattern has fewer words than the newsgroup,
the pattern is implicitly
extended to the same number of words by appending
.B \&.all
as many times as necessary;
.IP \(bu
if the newsgroup has fewer words than the pattern, the newsgroup does not
match the pattern;
.IP \(bu
if
.I pattern
matches a newsgroup,
.BI ! pattern
.IR mis matches
that newsgroup.
.LP
A newsgroup matches a pattern list if, and only if, it matches at least
one of the patterns and:
.IP \(bu \n(Bwu
the newsgroup
does not mismatch any of the patterns, or
.IP \(bu
the longest matched pattern is longer than the longest mismatched
pattern
(length is measured in number of words,
with each explicit occurrence of
.B all
counted as slightly less than one word,
and does not include
the implicit extension of patterns with
.BR \&.all ).
.LP
Note that order in the lists is not significant,
and that ties are broken in favor of not matching.
An example:
.B comp,comp.sys.sun,!comp.sys
matches all the
.B comp
groups,
.I except
the
.B comp.sys
groups
.I "but including"
.BR comp.sys.sun .
.PP
The
distributions in the
.B Distribution:
header
are similarly matched against the
.IR distributions
subfield, if any.
If no
.I distributions
are supplied,
.B Distribution:
will be matched against
the
.I subscriptions
instead.
(The
.B Distribution:
header is ignored when receiving news;
it is only significant when sending.)
.PP
Note that some older news software
reportedly
attached magical significance 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
.I distributions
list like
.B all,!local
will
.I not
prevent local articles from being sent unless they contain explicit
.B "Distribution: local"
lines.
Note too
that the distribution
``world''
must be permitted
(perhaps by the distribution
``all'')
in order to feed
.BR Distribution: -less
articles
(the common case)
to a site.
.PP
The
.I flags
are a set of letters describing how the article should be transmitted.
Valid flags include
.B f
(interpret
.I "transmission command"
as a file name and
write the article's file name relative to
.B \*a
and size in bytes
on the end of it),
.B F
(like
.B f
but omit the size),
.B I
(like
.B F
but write Message-ID:s instead of filenames),
.B n
(like
.B F
but write a Message-ID: after each filename),
.BI L n
(only send articles
generated within
.I n
hops of here;
0 is the default value for
.IR n ),
.B m
(transmit only moderated groups),
.B u
(transmit only unmoderated groups).
There are other obsolete ones.
.LP
The
.I transmission command
is executed by the shell with the article
to be transmitted as the standard input.
The substring
`\c
.BR %s '
will be replaced at most once per command
with the name of a file containing the article,
relative to
.B \*a
(`\c
.BR %% '
is replaced by
`\c
.BR % ').
The default is
`\c
.BI "uux \- \-z \-r " sysname !rnews\c
\&'
for a command;
the PATH searched includes
.BR \*b/relay ,
so that the commands described in \fInewsmail\fR(8)
are available as alternatives to \fIuux\fR.
If one of the \fIflags\fR has caused
this field to be taken as a filename,
the default is
.BI \*a/out.going/ sysname /togo\c
;
if a filename is given but it does not start with `/',
it is assumed
to be relative to the
.B \*a/out.going
directory.
.SH EXAMPLES
A complex
.I sys
file.
.Es
# 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
.sp 0.3
# sample insignificant feed not using batching (for special situations only)
huey:news.config,to.huey/all::uux - -r -gd huey!rnews
.sp 0.3
# sample of mailing newsgroups to someone (note distribution)
daisy:soc.women,soc.couples/all::mail daisy@duck
.sp 0.3
# sample small feed using batching
gladstone:comp.protocols.tcp-ip,rec.aviation/all:f:
.sp 0.3
# 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
.sp 0.3
# 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:
.sp 0.3
# 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:
.sp 0.3
# 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:
.sp 0.3
# 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:
.Ee
(The ``to.\fIsysname\fR'' groups are normal newsgroups used for testing
individual news feeds
and
conveying ihave/sendme messages.)
.SH FILES
.B \*c/sys
.SH SEE ALSO
.IR relaynews (8)
.SH HISTORY
Written by Geoff Collyer and Henry Spencer for the C News project.
.SH BUGS
The flags field is a bit of mess:
there are too many formatting flags and they aren't orthogonal.
