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1989-06-27
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.TL
Differences between B 2.11 news and C news
.AU
Geoff Collyer
.AI
Department of Statistics
University of Toronto
.SH
Introduction
.PP
This document attempts to describe the major
differences between
B 2.11 news
and
C news;
it cannot pretend to be complete.
Since the message format of both is the one described in
ARPA Internet RFC 1036,
the differences arise primarily in how the software is set up
and administered.
.PP
C news
was begun before
B 2.11 news
was released,
and later updated to match the worthwhile changes in
B 2.11 news.
.SH
Differences in files
.PP
.I Locking.
C news
locks are intended to be compatible with those of
B 2.10 news.
C news
locks out
.I expire
and
.I rnews
by linking to the name
.I /usr/lib/news/LOCK
and repeating until successful;
there is no time-out
such as the one in
B 2.10 news,
so humans can lock the news system and
perform surgery on it with confidence.
B 2.11 news
is believed to use more modern kernel locking facilities
such as
.I flock (2)
and
.I lockf (2).
One important difference is that
C news's
locks will work across network file systems,
modulo problems caused by lock removal in
.I /etc/rc .
.PP
.I "Log files."
C news's
are terse.
.PP
.I "History file."
C news
uses an extended
B 2.10 news
format:
the second field consists of two subfields
separated by a tilde:
time received as an integer (a
.I time_t
in fact),
and
the value of the
.I Expires:
header,
"-" if none.
B 2.11 news
does not record the
.I Expires:
value and stores the time received in a peculiar variant of
.I ctime (3)
format,
which cannot be parsed by
.I getdate (3),
to the annoyance of
.I nntp .
You must lock the news system with
.I locknews
before editing the history file.
.PP
.I "active file."
C news
will tolerate two,
three,
or
four
fields in the
.I active
file,
and
any number of digits in the article-number fields
(hint: five is too few).
C news
also supports two new values for the fourth field:
.B x ,
meaning
``quietly discard articles for this group'',
and
.B = realgroup
meaning
``file articles for this group under
.I realgroup
instead''.
.B =
is useful for coping with badly-run
local newsgroups,
often created from mailing lists.
You must lock the news system with
.I locknews
before editing the active file.
.PP
.I "sys file."
C news
ignores blank lines and
.B #
comment lines in the
.I sys
file.
Many obsolete flags draw fatal diagnostics,
notably
.B N ,
the old,
unbatched ihave/sendme flag.
If the fourth field is a relative command name,
.B /usr/lib/news/bin
and
.B /usr/lib/newsbin/relay
will be searched before the standard search path.
If the fourth field is a relative file name,
.B /usr/spool/news/out.going
will be prepended.
The ihave/sendme kludges of B news
have been expunged;
one must say what one means,
using three to five entries,
typically.
.SH
Differences in behaviour
.PP
.I "Control messages."
.I Checkgroups
is non-destructive in C news;
it merely mails its output to
.B $NEWSMASTER
(e.g.
.B usenet ).
The superfluous
.I Supersedes:
header is not honoured.
.PP
.I "Newsgroup aliases."
C news
does not implement newsgroup aliases,
since we believe that header munging is to be avoided
except under extreme duress.
It is possible to file articles locally under different newsgroups
by use of the active file
.B =
flag.