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7.1 KiB
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404 lines
7.1 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Delivering News</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.57"><LINK
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REL="HOME"
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TITLE="Linux Network Administrators Guide"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="C News"
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HREF="x-087-2-cnews.html"><LINK
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REL="PREVIOUS"
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TITLE="C News"
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HREF="x-087-2-cnews.html"><LINK
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REL="NEXT"
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TITLE="Installation"
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HREF="x16700.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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WIDTH="100%"
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BORDER="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux Network Administrators Guide</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="x-087-2-cnews.html"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 21. C News</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="x16700.html"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="X-087-2-CNEWS.RNEWS"
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>21.1. Delivering News</A
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></H1
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><P
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>
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Articles can be fed to C News in several ways. When a local user posts
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an article, the newsreader usually hands it to the
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<B
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CLASS="COMMAND"
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>inews</B
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> command, which completes the header
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information. News from remote sites, be it a single article or a whole
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batch, is given to the <B
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CLASS="COMMAND"
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>rnews</B
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> command, which stores
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it in the <TT
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CLASS="FILENAME"
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>/var/spool/news/in.coming</TT
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> directory,
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from where it will be picked up at a later time by
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<B
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CLASS="COMMAND"
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>newsrun</B
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>. With any of these two techniques, however,
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the article will eventually be handed to the
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<B
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CLASS="COMMAND"
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>relaynews</B
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> command.</P
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><P
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>
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For each article, the <B
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CLASS="COMMAND"
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>relaynews</B
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> command first checks if the
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article has already been seen at the local site by looking up the message ID
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in the <TT
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CLASS="FILENAME"
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>history</TT
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> file. Duplicate articles are dropped.
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Then <B
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CLASS="COMMAND"
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>relaynews</B
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> looks at the <TT
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CLASS="LITERAL"
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>Newsgroups:</TT
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>
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header line to find out if the local site requests articles from any of these
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groups. If it does, and the newsgroup is listed in the
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<TT
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CLASS="FILENAME"
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>active</TT
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> file, <B
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CLASS="COMMAND"
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>relaynews</B
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> tries to store
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the article in the corresponding directory in the news spool area. If this
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directory does not exist, it is created. The article's message ID is then
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logged to the <TT
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CLASS="FILENAME"
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>history</TT
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> file. Otherwise,
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<B
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CLASS="COMMAND"
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>relaynews</B
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> drops the article.</P
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><P
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> Sometimes <B
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CLASS="COMMAND"
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>relaynews</B
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> fails to store an incoming
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article because a group to which it has been posted is not listed in
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your <TT
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CLASS="FILENAME"
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>active</TT
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> file. In this case, the article is moved to the <SPAN
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CLASS="SYSTEMITEM"
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>junk</SPAN
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>
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group.<A
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NAME="X-087-2-FNCN01"
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HREF="#FTN.X-087-2-FNCN01"
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>[1]</A
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>
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<B
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CLASS="COMMAND"
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>relaynews</B
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> also checks for stale or misdated articles
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and reject them. Incoming batches that fail for any other reason are moved
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to <TT
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CLASS="FILENAME"
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>/var/spool/news/in.coming/bad</TT
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>, and an error message
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is logged.</P
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><P
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>After this, the article is relayed to all other sites that request news
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from these groups, using the transport specified for each particular site. To
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make sure an article isn't sent to a site that has already seen it, each
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destination site is checked against the article's <TT
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CLASS="LITERAL"
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>Path:</TT
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>
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header field, which contains the list of sites the article has traversed so
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far, written in the UUCP-style bang-path source-routing style described in
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<A
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HREF="x-087-2-mail.html"
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>Chapter 17</A
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>. If the destination site's name does not
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appear in this list, the article is sent to it.</P
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><P
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>
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C News is commonly used to relay news between UUCP sites, although it is
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also possible to use it in an NNTP environment. To deliver news to a remote
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UUCP site, either in single articles or whole batches, <B
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CLASS="COMMAND"
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>uux</B
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>
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is used to execute the <B
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CLASS="COMMAND"
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>rnews</B
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> command on the remote site and
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feed the article or batch to it on standard input.
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Refer to <A
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HREF="x-087-2-uucp.html"
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>Chapter 16</A
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>, for more information on UUCP.</P
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><P
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>
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Batching is the term used to describe sending large bundles of
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individual articles all in one transmission. When batching is
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enabled for a given site, C News does not send any incoming article
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immediately; instead, it appends its path name to a file, usually called
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<TT
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CLASS="FILENAME"
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>out.going/site/togo</TT
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>. Periodically, a program is executed
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from a <B
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CLASS="COMMAND"
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>crontab</B
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> entry by the <B
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CLASS="COMMAND"
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>cron</B
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> program,
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which reads this file and bundles all of the listed articles into one or more
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file, optionally compressing them and sending them to <B
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CLASS="COMMAND"
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>rnews</B
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>
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at the remote site.<A
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NAME="X-087-2-FNCN02"
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HREF="#FTN.X-087-2-FNCN02"
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>[2]</A
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> </P
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><P
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><A
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HREF="x-087-2-cnews.rnews.html#X-087-2-CNEWS.FIG.FLOW"
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>Figure 21-1</A
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> shows the news flow through
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<B
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CLASS="COMMAND"
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>relaynews</B
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>. Articles may be relayed to the local site
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(denoted by <SPAN
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CLASS="SYSTEMITEM"
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>ME</SPAN
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>), to a site named
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<SPAN
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CLASS="SYSTEMITEM"
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>ponderosa</SPAN
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> via email, and a site
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named <SPAN
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CLASS="SYSTEMITEM"
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>moria</SPAN
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>, for which batching is
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enabled.</P
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><DIV
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CLASS="FIGURE"
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><A
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NAME="X-087-2-CNEWS.FIG.FLOW"
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></A
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><P
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><B
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>Figure 21-1. News flow through relaynews</B
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></P
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><P
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><IMG
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SRC="lag2_2101.jpg"></P
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></DIV
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></DIV
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><H3
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CLASS="FOOTNOTES"
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>Notes</H3
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><TABLE
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BORDER="0"
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CLASS="FOOTNOTES"
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WIDTH="100%"
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="5%"
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><A
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NAME="FTN.X-087-2-FNCN01"
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HREF="x-087-2-cnews.rnews.html#X-087-2-FNCN01"
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>[1]</A
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="95%"
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><P
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> There may be a difference
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between the groups that exist at your site and those that your site
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is willing to receive. For example, the subscription list might
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specify <SPAN
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CLASS="SYSTEMITEM"
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>comp.all</SPAN
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>, which
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should send all newsgroups below the <SPAN
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CLASS="SYSTEMITEM"
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>comp</SPAN
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> hierarchy, but at your site you
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might not list several of the <SPAN
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CLASS="SYSTEMITEM"
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>comp</SPAN
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> newsgroups in the
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<TT
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CLASS="FILENAME"
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>active</TT
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> file. Articles posted to those groups will
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be moved to <SPAN
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CLASS="SYSTEMITEM"
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>junk</SPAN
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>.</P
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></TD
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></TR
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><TR
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="5%"
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><A
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NAME="FTN.X-087-2-FNCN02"
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HREF="x-087-2-cnews.rnews.html#X-087-2-FNCN02"
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>[2]</A
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></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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WIDTH="95%"
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><P
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>Note that this should be the <B
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CLASS="COMMAND"
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>crontab</B
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> of
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<SPAN
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CLASS="SYSTEMITEM"
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>news</SPAN
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>; file permissions will not be
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mangled.</P
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></TD
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></TR
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></TABLE
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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WIDTH="100%"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="x-087-2-cnews.html"
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>Prev</A
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="x16700.html"
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>Next</A
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>C News</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="x-087-2-cnews.html"
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>Up</A
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Installation</TD
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