There are a few things you need to do to setup the TIN binary that comes with
Slackware.

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How to use with a newsfeed/local news spool:

   If you're reading a local newspool (in /var/spool/news) then you really 
   shouldn't have to set anything up. Make sure that /usr/bin/inews is a
   symlink to the inews that came with Cnews or INN, whichever you're using.

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How to use to read a remote NNTP site:

   Make sure that /usr/bin/inews is linked to inews-nntp. Also, you'll 
   want to set up your NNTPSERVER variable. Here's mine (in /etc/profile):

NNTPSERVER=msus1.msus.edu
export NNTPSERVER

   If you use tcsh, use this in your /etc/csh.login:

setenv NNTPSERVER msus1.msus.edu

   Of course, you'll want to replace msus1.msus.edu with a server that's close
   to you and that will give you posting permission.

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You may also wish to edit /etc/NNTP_INEWS_DOMAIN. See the accompanying 
documentation for more info about configuring TIN.