Linux Network Administrator Guide, Second Edition

Here is a sample explist file with rather tight expiry intervals:

# keep history lines for two weeks. No article gets more than three months
/expired/                       x       14      -
/bounds/                        x       0-1-90  -
# groups we want to keep longer than the rest
comp.os.linux.announce          m       10      -
comp.os.linux                   x       5       -
alt.folklore.computers          u       10      -
rec.humor.oracle                m       10      -
soc.feminism                    m       10      -
# Archive *.sources groups
comp.sources,alt.sources        x       5       @
# defaults for tech groups
comp,sci                        x       7       -
# enough for a long weekend
misc,talk                       x       4       -
# throw away junk quickly
junk                            x       1       -
# control messages are of scant interest, too
control                         x       1       -
# catch-all entry for the rest of it
all                             x       2       -

Expiring presents several potential problems. One is that your newsreader might rely on the third field of the active file described earlier, which contains the number of the lowest article online. When expiring articles, C News does not update this field. If you need (or want) to have this field represent the real situation, you need to run a program called updatemin after each run of doexpire. (In older versions of C News, a script called upact did this.)

C News does not expire by scanning the newsgroup's directory, but simply checks the history file if the article is due for expiration.[129] If your history file somehow gets out of sync, articles may be around on your disk forever because C News has literally forgotten them.[130] You can repair this by using the addmissing script in /usr/lib/news/maint, which will add missing articles to the history file or mkhistory, which rebuilds the entire file from scratch. Don't forget to become user news before invoking it, or else you will wind up with a history file unreadable by C News.

Miscellaneous Files

There are a number of files that control the behavior of C News, but are not essential. All of them reside in /etc/news. We describe them briefly here:

newsgroups

This is a companion file of active that contains a list of each newsgroup name along with a one-line description of its main topic. This file is automatically updated when C News receives a checknews control message.

localgroups

If you have a lot of local groups, you can keep C News from complaining about them each time you receive a checkgroups message by putting their names and descriptions in this file, just as they would appear in newsgroups.

mailpaths

This file contains the moderator's address for each moderated group. Each line contains the group name followed by the moderator's email address (offset by a tab).

Two special entries are provided as defaults: backbone and internet. Both provide, in bang-path notation, the path to the nearest backbone site and the site that understands RFC-822 style addresses (user@host). The default entries are:

internet backbone

You do not have to change the internet entry if you have exim or sendmail installed; they understand RFC-822 addressing.

The backbone entry is used whenever a user posts to a moderated group whose moderator is not listed explicitly. If the newsgroup's name is alt.sewer and the backbone entry contains path!%s, C News will mail the article to path!alt-sewer, hoping that the backbone machine is able to forward the article. To find out which path to use, ask the news-admin at the site that feeds you. As a last resort, you can also use uunet.uu.net!%s.

distributions

This file is not really a C News file, but is used by some newsreaders and nntpd. It contains the list of distributions recognized by your site and a description of their (intended) effects. For example, Virtual Brewery has the following file:

world         everywhere in the world
local         Only local to this site
nl            Netherlands only
mugnet        MUGNET only
fr            France only
de            Germany only
brewery       Virtual Brewery only

log

This file contains a log of all C News activities. It is culled regularly by running newsdaily; copies of the old log files are kept in log.o, log.oo, etc.

errlog

This is a log of all error messages created by C News. These messages do not include logs of articles junked due to being sent to an invalid wrong group or other user errors. This file is mailed to the newsmaster (usenet by default) automatically by newsdaily if it is not found empty.

errlog is cleared by newsdaily. errlog.o keeps old copies and companions.

batchlog

This file logs all runs of sendbatches. It is usually of scant interest. It is also attended by newsdaily.

watchtime

This is an empty file created each time newswatch runs.

Control Messages

The Usenet news protocol knows a special category of articles that evoke certain responses or actions by the news system. These are called control messages. They are recognized by the presence of a Control: field in the article header, which contains the name of the control operation to be performed. There are several types of them, all of which are handled by shell scripts located in /usr/lib/news/ctl.