Ubuntu Manpage: newsfeeds - Determine where Usenet articles are sent

Provided by: inn2_2.7.3~20241006-1_amd64

NAME

       newsfeeds - Determine where Usenet articles are sent

IN A NUTSHELL

The newsfeeds file configures what innd does with incoming accepted articles.

A minimalist newsfeeds file which parameters an outgoing NNTP feed to "news.server.com",
using path identity "server" (as it appears in Path header fields), of all the articles
you receive is:

# Mandatory line, with no exclusion patterns defined.
ME:::

# A real-time feed through innfeed of all your articles.
news.server.com/server\
:*\
:Tm:innfeed!

# The channel feed entry for innfeed.
# Change "/usr/lib/news/bin" to the directory path
# of the innfeed program.
innfeed!:!*:Tc,Wnm*:/usr/lib/news/bin/innfeed

In order to find an external feed, you can ask in the news.admin.peering newsgroup.
Several news administrators will certainly respond and gracefully provide you with a news
feed.

Other entries may be added in newsfeeds depending on your needs. See the examples below
and also in the archive(8), controlchan(8), news2mail(8), ninpaths(8) and perl-nocem(8)
man pages for the most widely used.

If you exclude local hierarchies or newsgroups from the feed, make sure to add
"!control,!control.*" so that cancel articles or any kind of control articles related to
excluded hierarchies or newsgroups are not propagated to the remote peer. Its newsfeeds
entry then looks like:

news.server.com/server\
:*,!local.*,@*bina*,!control,!control.*\
:Tm:innfeed!

After any changes, run "inncheck" to perform basic syntax checks, and reload this
configuration file with the following command:

ctlinnd reload newsfeeds 'new peer'

DESCRIPTION

The file pathetc/newsfeeds specifies how incoming articles should be distributed to other
programs and files on the server. It is parsed by the InterNetNews server innd(8) when it
starts up, or when directed to by ctlinnd(8). innd doesn't send articles to remote sites
itself, so newsfeeds doesn't directly determine which remote news servers articles are
sent to. Instead, it specifies what batch files should be created or which programs
should be run (and what information should be sent to them), and then this information is
used by programs like innxmit(8) and innfeed(8) to feed articles to remote sites.

Used in conjunction with delayer(1) in the configuration of the related funnel feed,
innfeed can even send a delayed feed to remote peers or to another local instance of innd,
notably to permit the rejection of spam before it actually arrives.

The newsfeeds file isn't used solely to set up feeding accepted articles to remote sites
but also to pass them (or bits of information about them) to any local programs or files
that want that data. For example, controlchan(8), a daemon that processes incoming
control messages, runs out of newsfeeds, as could a news to mail gateway.

The file is interpreted as a set of lines, parsed according to the following rules: if a
line ends with a backslash, the backslash, the newline, and any whitespace at the start of
the next line is deleted. This is repeated until the entire "logical" line is collected.
If the logical line is blank or starts with a number sign ("#"), it is ignored.

All other lines are interpreted as feed entries. An entry should consist of four colon-
separated fields; two of the fields may have optional sub-fields, marked off by a slash.
Fields or sub-fields that take multiple parameters should be separated by a comma. Extra
whitespace can cause problems and should be avoided. Except for the site names, case is
significant. The format of an entry is:

sitename[/exclude,exclude,...]\
:pattern,pattern...[/distribution,distribution...]\
:flag,flag...\
:parameter

Each field is described below.

The sitename is the name of the site to which a news article can be sent. It is used for
writing log entries and for determining if an article should be forwarded to a site. (A
"site" is the generic term for some destination of newsfeed data; it often corresponds to
a remote news peer, but doesn't have to. For example, a local archiving program run from
newsfeeds is also a "site".) If sitename already appears in the article's Path header
field body, then the article will not be sent to the site. The name is usually whatever
the remote site uses to identify itself in the Path header field body, but can be almost
any word.

Be careful, though, to avoid having the sitename accidentally match a path identity in the
Path header field unintentionally. For this reason, special local entries (such as
archivers or gateways) should probably end with an exclamation point to make sure that
they do not have the same name as any real site. For example, "gateway" is an obvious
name for the local entry that forwards articles out to a mailing list. If a site with the
name "gateway" posts an article, when the local site receives the article it will see the
name in the Path header field and not send the article to its own "gateway" entry. Since
"gateway!" can't appear as an individual path identity in the Path header field (as "!" is
the delimiter), that would be a better thing to use for sitename.

(Another way to avoid this problem is with the "Ap" flag; see the description below.)

If an entry has an exclusion sub-field, the article will not be sent to that site if any
of exclude appear in the Path header field body. (It's sometimes convenient to have the
sitename be an abbreviated form of the name of the remote site, since all the sitenames to
which an article is sent are written to the log and using shorter sitenames can therefore
improve performance for large servers. In this case, the path identities of those sites
should be given as exclude entries and the "Ap" flag used so that the abbreviated sitename
doesn't accidentally match some other path identities in Path header fields.)

The same sitename can be used more than once and the appropriate action will be taken for
each entry that should receive the article, but this is recommended only for program feeds
to avoid confusion. Case is not significant in site names.

The comma-separated pattern specifies which groups to send to the site; it is interpreted
to build a "subscription list" for the site. The default subscription is to get all
groups carried by the server. It is a uwildmat pattern supporting poison ("@") wildcards;
see the libinn_uwildmat man page for full details on the pattern matching language.
pattern will be matched against every newsgroup carried by the server and all newsgroups
that match will be added to the subscription list for the site.

Normally, a given article (or information about it) is sent to a site if any of the
newsgroups to which the article was posted are in that site's subscription list. If a
newsgroup matches an "@" pattern in pattern, then not only is it not added to the
subscription list, but any articles crossposted to that newsgroup also will not be sent to
that site even if other newsgroups to which it was crossposted are in that site's
subscription list. This is called a poison pattern (because matching groups are
"poisoned").

For example, to receive all comp.* groups, but only comp.sources.unix within the sources
newsgroups, the following pattern can be used:

comp.*,!comp.sources.*,comp.sources.unix

Note that the trailing ".*" is required; the pattern has to match the whole newsgroup
name. "comp.sources.*" could be written "comp.sources*" and would exclude the newsgroup
comp.sources (if it exists) as well as the groups in the comp.sources.* hierarchy, but
note that this would also exclude a newsgroup named comp.sources-only (whereas the above
pattern would add that group to the site subscription list since it matches "comp.*" and
none of the other patterns).

For another example, to feed alt.* and misc.* to a given site but not any articles posted
to alt.binaries.warez (even if they're also crossposted to other alt.* or misc.* groups),
the following pattern can be used:

alt.*,@alt.binaries.warez,misc.*

Note, however, that if you reversed the "alt.*" and "@alt.binaries.warez" entries, this
pattern would be equivalent to "alt.*,misc.*", since the last matching pattern determines
whether a given newsgroup matches and the poison logic only applies if the poison entry is
the last matching entry.

Control messages follow slightly different propagation rules than normal articles; see
innd(8) for the details. Note that most subscriptions should have
"!junk,!control,!control.*" in their pattern list due to those propagation rules (and
since "junk" is a special internal newsgroup; see wanttrash in inn.conf(5) for more
details on what it's used for) and that the best way to keep control messages local to a
site is with a distribution.

A subscription can be further modified by specifying distributions that the site should or
should not receive. The default is to send all articles to all sites that subscribe to
any of the groups where it has been posted, but if an article has a Distribution header
field and any distributions are specified, then they are checked according to the
following rules:

1. If the Distribution header field matches any of the values in the sub-field, the
article is sent.

2. If a distribution starts with an exclamation point, and it matches the Distribution
header field, the article is not sent.

3. If the Distribution header field does not match any distribution in the site's entry
and no negations were used, the article is not sent.

4. If the Distribution header field does not match any distribution in the site's entry
and any distribution started with an exclamation point, the article is sent.

If an article has more than one distribution specified, then each one is handled according
according to the above rules. If any of the specified distributions indicate that the
article should be sent, it is; if none do, it is not sent. In other words, the rules are
used as a logical or.

It is almost definitely a mistake to have a single feed that specifies distributions that
start with an exclamation point along with some that don't.

Distributions are text words, not patterns; entries like "*" or "all" have no special
meaning.

The flag field is described in "FLAG VALUES". The interpretation of the parameter field
depends on the type of feed and is explained in more detail in "FEED TYPES". It can be
omitted for some types of feeds.

The site named "ME" is special. There must be exactly one such entry, and it should be
the first entry in the file. If the "ME" entry has an exclusion sub-field, incoming
articles are rejected completely if any of the names specified in that exclusion sub-field
appear in their Path header field bodies. If the "ME" entry has a subscription list, that
list is prepended to the subscription list of all other entries. For example,
"*,!control,!control.*,!junk,!foo.*" could be used to set the default subscription list
for all other feeds so that local postings are not propagated unless "foo.*" explicitly
appears in the site's subscription list. This feature tends to be somewhat confusing
since the default subscription is prepended and can be overridden by other patterns.

If the "ME" entry has a distribution sub-field, only articles that match that distribution
list are accepted and all other articles with a distribution are rejected. A common use
for this is to put something like "/!local" in the "ME" entry to reject local postings
from other misconfigured sites. The distribution sub-field of "ME" has no effect on the
acceptance or rejection of articles that do not have a Distribution header field.

An empty "ME" entry is possible, in which case no exclusion patterns will be defined.

Finally, it is also possible to set variables in newsfeeds and use them later in the file.
A line starting with "$" sets a variable. For example:

$LOCALGROUPS=local.*,example.*
$CONTROLGROUPS=control,control.*

This sets the variable "LOCALGROUPS" to "local.*,example.*" and the variable
"CONTROLGROUPS" to "control,control.*". They can later be used elsewhere in the file,
such as in a site entry like:

news.example.com:$LOCALGROUPS:Tf,Wnm:

which is then completely equivalent to:

news.example.com:local.*,example.*:Tf,Wnm:

Variables aren't solely simple substitution. If either "!" or "@" immediately precedes
the variable and the value of the variable contains commas, that character will be
duplicated before each comma. This somewhat odd-sounding behavior is designed to make it
easier to use variables to construct feed patterns. The utility becomes more obvious when
you observe that the line:

news.example.net:*,@$LOCALGROUPS,!$CONTROLGROUPS:Tf,Wnm:

is therefore equivalent to:

news.example.net:*,@local.*,@example.*,!control,!control.*:Tf,Wnm:

which (as explained below) excludes all of the groups in $LOCALGROUPS and unwanted control
articles from the feed to that site.

FLAG VALUES

The flags parameter specifies miscellaneous parameters, including the type of feed, what
information should be sent to it, and various limitations on what articles should be sent
to a site. They may be specified in any order and should be separated by commas. Flags
that take values should have the value immediately after the flag letter with no
whitespace. The valid flags are:

< size
An article will only be sent to this site if it is less than size bytes long. The
default is no limit.

> size
An article will only be sent to this site if it is greater than size bytes long. The
default is no limit.

A checks
An article will only be sent to this site if it meets the requirements specified in
checks, which should be chosen from the following set. checks can be multiple letters
if appropriate. Note that this flag is not effective on funnel targets; it has to be
used on every funnel entry (for instance, Af is not effective on the innfeed! funnel
target and therefore has to be specified on every funnelled news site).

c Exclude all kinds of control messages.

C Only send control messages, not regular articles.

d Only send articles with a Distribution header field. Combined with a particular
distribution value in the distribution part of the site entry, this can be used to
limit articles sent to a site to just those with a particular distribution.

e Only send articles where every newsgroup listed in the Newsgroups header field body
exists in the active file.

f Don't send articles rejected by filters. This is only useful when
dontrejectfiltered is set to true in inn.conf. With that variable set, this lets
one accept all articles but not propagate filtered ones to some sites.

j Propagate articles according to their Newsgroups header field. This is only useful
when wanttrash is set to true in inn.conf. With that variable set, articles
accepted and filed in "junk" (due to wanttrash) are fed to peers based on their
subscription pattern applied to the Newsgroups header field as though they were
accepted and all those groups were locally carried. Otherwise, they are propagated
to sites that receive the "junk" newsgroup.

This variable is useful if you want to run INN with a minimal active file and
propagate all posts.

o Only send articles for which overview data was stored.

O Send articles to this site that don't have an Injection-Info or X-Trace header
field, even if the "O" flag is also given.

p Only check the exclusions against the Path header field of articles; don't check
the site name. This is useful if your site names aren't the same as the path
identities in Path header fields added by those remote sites, or for program feeds
where the site name is arbitrary and unrelated to the Path header field body.

If both "c" and "C" are given, the last specified one takes precedence.

B high/low
If a site is being fed by a file, channel, or exploder (see below), the server will
normally start trying to write the information as soon as possible. Providing a
buffer may give better system performance and help smooth out overall load if a large
batch of news comes in. The value of this flag should be two numbers separated by a
slash. high specifies the point at which the server can start draining the feed's I/O
buffer, and low specifies when to stop writing and begin buffering again; the units
are bytes. The default is to do no buffering, sending output as soon as it is
possible to do so.

C count
If this flag is specified, an article will only be sent to this site if the number of
groups it is posted to, plus the square of the number of groups followups would appear
in, is no more than count. "30" is a good value for this flag, allowing for instance:

• crossposts to only 5 groups when followups aren't set;

• crossposts to up to 26 groups when followups are set to two groups;

• crossposts to up to 29 groups when followups are set to a single group;

• crossposts to up to 30 groups when followups are set to poster.

Note that if an article does not contain a Followup-To header field, the number of
groups followups would appear in is the number of groups it is posted to.

F name
Specifies the name of the file that should be used if it's necessary to begin spooling
for the site (see below). If name is not an absolute path, it is taken to be relative
to pathoutgoing in inn.conf. If name is a directory, the file togo in that directory
will be used as the file name.

G count
If this flag is specified, an article will only be sent to this site if it is posted
to no more than count newsgroups. This has the problem of filtering out many FAQs, as
well as newsgroup creation postings and similar administrative announcements. Either
the C flag or the U flag is a better solution.

H count
If this flag is specified, an article will only be sent to this site if it has count
or fewer sites in its Path header field body. This flag should only be used as a
rough guide because of the loose interpretation of the Path header field; some sites
put the poster's name in the header field body, and some sites that might logically be
considered to be one hop become two because they put the posting workstation's name in
the header field body. The default value for count if not specified is one. (Also
see the O flag, which is sometimes more appropriate for some uses of this flag.)

I size
The flag specifies the size of the internal buffer for a file feed. If there are more
file feeds than allowed by the system, they will be buffered internally in least-
recently-used order. If the internal buffer grows bigger than size bytes, however,
the data will be written out to the appropriate file. The default value is "16" KB.

N status
Restricts the articles sent to this site to those in newsgroups with the moderation
status given by status. If status is "m", only articles in moderated groups are sent;
if status is "u", only articles in unmoderated groups are sent.

O originator
If this flag is specified, an article will only be sent to this site if it contains an
Injection-Info header field (or an X-Trace header field if no Injection-Info header
field is found) and the first field of this header field matches originator.
originator is a uwildmat expression without commas or a list of such expressions,
separated by "/". The article is never sent if the first character of the pattern
begins with "@" and the rest of the pattern matches. One use of this flag is to
restrict the feed to locally generated posts by using an originator pattern that
matches the Injection-Info header field added by the local server.

P priority
The nice priority that this channel or program feed should receive. This should be a
positive number between 0 and 20 and is the priority that the new process will run
with. This flag can be used to raise the priority to normal if you're using the
nicekids parameter in inn.conf.

Q hashfeed
Specifies the hashfeed match expression for this site. It must be in the form
"value/mod" or "start-end/mod". The Message-ID of the article is hashed using MD5,
which results in a 128-bit hash. The lowest 32 bits are then taken by default as the
hashfeed value (which is an integer). If the hashfeed value modulus "mod" plus one
equals "value" or is between "start" and "end", the article will be fed to this site.
All these numbers must be integers.

It is a deterministic way to control the flow of articles and to split a feed. For
instance:

Q1/2 Feeds about 50% of all articles to this site.
Q2/2 Feeds the other 50% of all articles.

Another example with three sites:

Q1-3/10 Feeds about 30% of all articles.
Q4-5/10 Feeds about 20% of all articles.
Q6-10/10 Feeds about 50% of all articles.

If this flag is specified multiple times, the contents will be logically "OR"ed
together (just one match is needed).

You can use an extended syntax of the form "value/mod_offset" or
"start-end/mod_offset". As MD5 generates a 128-bit return value, it is possible to
specify from which byte-offset the 32-bit integer used by hashfeed starts. The
default value for "offset" is "_0" and thirteen overlapping values from "_0" to "_12"
can be used. Only up to four totally independent values exist: "_0", "_4", "_8" and
"_12".

Therefore, it allows generating a second level of deterministic distribution. Indeed,
if a news server is fed "Q1/2", it can go on splitting thanks to "Q1-3/9_4" for
instance. Up to four levels of deterministic distribution can be used.

The algorithm is compatible with the one used by Diablo 5.1 and up. If you want to
use the legacy quickhashing method used by Diablo before 5.1, you can put an "@" sign
just after the Q flag (for instance "Q@1-3/10", but the distribution of the messages
is not perfect with this legacy method whose use is discouraged and for which offsets
cannot be used).

S size
If the amount of data queued for the site gets to be larger than size bytes, the
server will switch to spooling, appending to a file specified by the F flag, or
pathoutgoing/sitename if F is not specified. Spooling usually happens only for
channel or exploder feeds, when the spawned program isn't keeping up with its input.

T type
This flag specifies the type of feed for this site. type should be a letter chosen
from the following set:

c Channel
f File
l Log entry only
m Funnel (multiple entries feed into one)
p Program
x Exploder

Each feed is described below in "FEED TYPES". The default is Tf, for a file feed.

U count
If this flag is specified, an article will only be sent to this site if followups to
this article would be posted to no more than count newsgroups. (Also see C for a more
complex way of handling this.)

W items
For a file, channel, or exploder feed, this flag controls what information will be
sent to this site. For a program feed, only the asterisk ("*") has any effect. items
should be chosen from the following set:

b Size of the article (in wire format, meaning with CRLF at the end of each line,
periods doubled at the beginning of lines, and ending in a line with a single
period) in bytes.

e The time the article will expire as seconds since epoch if it has an Expires header
field, "0" otherwise.

f The storage API token of the article (the same as "n"). The article can be
retrieved given the storage API token by using sm(1).

g The newsgroup the article is in; if cross-posted, then the first of the groups to
which the article was posted that this site gets. (The difference from "G" is that
this sends the newsgroup to which the article was posted even if it is a control
message.)

h The history hash key of the article (derived from the message ID).

m The message ID of the article.

n The storage API token of the article. The article can be retrieved given the
storage API token by using sm(1).

p The time the article was posted a seconds since epoch.

s The site that fed the article to the server. This is taken from either the Path
header field body or the IP address of the sending site depending on the value of
logipaddr in inn.conf. If logipaddr is true and the IP address is "0.0.0.0"
(meaning that the article was fed from localhost by a program like rnews(1)), the
Path header field body will be sent instead.

t The time the article was received as seconds since epoch.

* The names of the appropriate funnel entries, or all sites that get the article (see
below for more details).

D The body of the Distribution header field of the article, or "?" if there is no
such header field in the article.

G Where the article is stored. If the newsgroup is crossposted, this is generally
the first of the groups to which it was posted that this site receives; however,
control messages are filed in control or control.* (which is the difference
between this item and "g").

H All of the headers, followed by a blank line. The Xref header field will already
be present, and a Bytes header field containing the article's size in bytes as in
the "b" item will be added to the headers. If used, this should be the only item
in the list.

N The body of the Newsgroups header field.

P The body of the Path header field.

O Overview data for the article.

R Information needed for replication (the Xref header field without the site name).

More than one letter can be given. If multiple items are specified, they will be
written in the order specified separated by spaces. ("H" should be the only item if
given, but if it's not a newline will be sent before the beginning of the headers.)
The default is Wn.

The "H" and "O" items are intended for use by programs that create news overview
databases or require similar information. WnteO is the flag to generate input needed
by the overchan(8) program.

The asterisk ("*") has special meaning. Normally it expands to a space-separated list
of all sites that received the current article. If, however, this site is a target of
a funnel feed (in other words, if it is named by other sites which have the Tm flag),
then the asterisk expands to the names of the funnel feeds that received the article.
Similarly, if the site is a program feed, an asterisk in the parameter field will be
expanded into the list of funnel feeds that received the article. A program feed
cannot get the site list unless it is the target of other Tm feeds.

FEED TYPES

innd provides four basic types of feeds: log, file, program, and channel. An exploder is
a special type of channel. In addition, several entries can feed into the same feed;
these are funnel feeds, which refer to an entry that is one of the other types. Funnel
feeds are partially described above with the description of the W* flag. A funnel feed
gets every article that would be sent to any of the feeds that funnel into it and normally
include the W* flag in their flags so that the program processing that feed knows which
sites received which articles. The most common funnel feed is innfeed(8).

Note that the term "feed" is technically a misnomer, since the server doesn't transfer
articles itself and only writes data to a file, program, or log telling another program to
transfer the articles.

The simplest feed is a log feed (Tl). Other than a mention in the news log file,
pathlog/news, no data is written out. This is equivalent to a Tf entry writing to
/dev/null, except that no file is ever opened. Flushing a log feed does nothing.

A file feed (Tf) is the next simplest type of feed. When the site should receive an
article, the specified data is written out to the file named by the parameter field. If
parameter is not an absolute path, it is taken to be relative to pathoutgoing in inn.conf.
If parameter is not given, it defaults to pathoutgoing/sitename. The file name should be
unique (two file feeds should not ever point to the same file).

File feeds are designed for use by external programs that periodically process the written
data. To cooperate with innd properly, such external programs should first rename the
batch file and then send a flush command for that site to innd using ctlinnd(8). innd
will then write out any buffered data, close the file, and reopen it (under the original
name), and the program can process the data in the renamed file at its leisure. File
feeds are most frequently used in combination with nntpsend(8).

A program feed (Tp) spawns a given program for every article that the site receives. The
parameter field must be the command line to execute, and should contain one instance of
"%s", which will be replaced by the storage API token of the article (the actual article
can be retrieved by the program using sm(1)). The program will not receive anything on
standard input (unlike earlier versions of INN, where the article is sent to the program
on stdin), and standard output and error from the program will be set to the error log
(pathlog/errlog). innd will try to avoid spawning a shell if the command has no shell
meta-characters; this feature can be defeated if necessary for some reason by appending a
semi-colon to the end of the command. The full path name of the program to be run must be
specified unless the command will be run by the shell (and it is strongly recommended that
the full path name always be specified regardless).

If a program feed is the target of a funnel, and if W* appears in the flags of the site, a
single asterisk may be present in the parameter and will be replaced by a space-separated
list of names of the sites feeding into the funnel which received the relevant article.
If the site is not the target of a funnel, or if the W* flag is not used, the asterisk has
no special meaning.

Flushing a program feed does nothing.

For a channel (Tc) or exploder (Tx) feed, the parameter field again names the process to
start. As with program feeds, the full path to the program must be specified. However,
rather than spawning the program for every article, it is spawned once and then whenever
the site receives an article, the data specified by the site flags is written to the
standard input of the spawned program. Standard output and error are set as with program
feeds. If the process exits, it will be restarted automatically. If the process cannot
be started, the server will spool input to a file named pathoutgoing/sitename and will try
to start the process again later.

When a channel or exploder feed is flushed, the server closes its end of the pipe to the
program's standard input. Any pending data that has not been written will be spooled; see
the description of the S flag above. The server will then spawn a new instance of the
program. No signal is sent to the program; it is up to the program handling a channel or
exploder feed to notice end of file on its standard input and exit appropriately.

Exploders are a special type of channel feed. In addition to the channel feed behavior
described above, exploders can also be sent command lines. These lines start with an
exclamation point and their interpretation is up to the exploder. The following commands
are generated automatically by the server:

!newgroup group
!rmgroup group
!flush
!flush site

These commands are sent whenever the ctlinnd(8) command of the same name is received by
the server. In addition, the ctlinnd(8) "send" command can be used to send an arbitrary
command line to an exploder. The primary exploder is buffchan(8).

Finally, Tm feeds are the input to a funnel. The parameter field of the site should name
the site handling articles for all of the funnel inputs.

EXAMPLES

       The syntax of the newsfeeds file is so complex because you can specify a staggering
       variety of feeds.  INN is capable of interacting with a wide variety of programs that do
       various things with news articles.  Far and away the most common two entries in newsfeeds,
       however, are file feeds for nntpsend(8) and funnel feeds for innfeed(8).

       The former look like this:

           feed.example.com:*,!control,!control.*,!junk:Tf,Wnm:

       which generates a file named pathoutgoing/feed.example.com containing one line per article
       consisting of the storage API token, a space, and the message ID.

       The latter look like this:

           feed.example.com:*,!control,!control.*,!junk:Tm:innfeed!

       Very similar, except that this is the input to a funnel feed named "innfeed!".  One could
       also write this as:

           example/feed.example.com:*,!control,!control.*,!junk:Ap,Tm:innfeed!

       (note the Ap so that articles that contain just "example" in the Path header field body
       will still be sent), which is completely equivalent except that this will be logged in
       pathlog/news as going to the site "example" rather than "feed.example.com".

       The typical feed entry for innfeed(8) is a good example of a channel feed that's the
       target of various funnel feeds (make sure the path to innfeed is properly set):

           innfeed!:!*:Tc,Wnm*:<pathbin in inn.conf>/innfeed -y

       Note that the pattern for this feed is just "!*" so that it won't receive any articles
       directly.  The feed should only receive those articles that would go to one of the funnel
       feeds that are feeding into it.  innfeed(8) will receive one line per article on its
       standard input containing the storage API token, the message ID, and a space-separated
       list of sites that should receive that article.

       Here's a more esoteric example of a channel feed:

           watcher!:*:Tc,Wbnm\
               :exec awk '$1 > 1000000 { print "BIG", $2, $3 }' \
                >> <pathlog>/bigart

       This receives the byte size of each article along with the storage API token and Message-
       ID, and appends to a bigart log file a line for every article that's over a million bytes.
       This is actually rather a strange way to write this since INN can do the size check
       itself; the following is equivalent:

           watcher!:*:Tc,>1000000,Wbnm\
               :exec awk '{ print "BIG", $2, $3}' >> <pathlog>/bigart

       Here's a cute, really simple news to mail gateway that also serves as an example of a
       fairly fancy program feed:

           mailer!:!*:W*,Tp\
               :sm %s | innmail -s "News article" *

       Remember that "%s" is replaced by the storage API token, so this retrieves the article and
       pipes it into innmail (which is safer than programs like Mail(1) because it doesn't parse
       the body for tilde commands) with a given subject line.  Note the use of "*" in the
       command line and W* in the flags; this entry is designed to be used as the target of
       funnel feeds such as:

           peter@example.com:news.software.nntp:Tm:mailer!
           sue@example.com:news.admin.misc:Tm:mailer!

       Suppose that the server receives an article crossposted between news.admin.misc and
       news.software.nntp.  The server will notice that the article should be sent to the site
       "peter@example.com" and the site "bob@example.com", both of which funnel into "mailer!",
       so it will look at the "mailer!" site and end up executing the command line:

           sm @...@ | innmail -s "News article" \
               peter@example.com sue@example.com

       which will mail the article to both Peter and Sue.

       Finally, another very useful example of a channel feed: the standard entry for
       controlchan(8).  Make sure its path is properly set.

           controlchan!\
               :!*,control,control.*,!control.cancel\
               :AC,Tc,Wnsm:<pathbin in inn.conf>/controlchan

       This program only wants information about articles posted to a control newsgroup other
       than control.cancel, which due to the sorting of control messages described in innd(8)
       will send it all control messages except for cancel messages.  controlchan gets the
       storage API token, the name of the sending site (for processing old-style ihave and sendme
       control messages, be sure to read about logipaddr in controlchan(8)), and the message ID
       for each article.

       For many other examples, including examples of the special "ME" site entry, see the
       example newsfeeds file distributed with INN.  Also see the install documentation that
       comes with INN for information about setting up the standard newsfeeds entries used by
       most sites.

HISTORY

       Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews.  Reformatted and rewritten in
       POD by Russ Allbery <eagle@eyrie.org>.