expire.ctl - control file for Usenet article expiration

     The file <config$_PATH_EXPIRECTL> (typically /var/news/etc/expire.ctl) is
     the  default  control  file  for the expire(8)  program, which reads it at
     start-up.  Blank lines and lines beginning with a number sign (``#'') are
     ignored.  All other lines should be in one of two formats.

     The first format specifies how long to keep  a  record  of  fully-expired
     articles.   This  is  useful  when a newsfeed intermittently offers older
     news that is not kept around very long.  (The case of very  old  news  is
     handled by the ``-c'' flag of innd(8) .)  There should only be one line in
     this format, which looks like this:
     Where days is a floating-point number that specifies the upper  limit  to
     remember a Message-ID, even if the article has already expired.  (It does
     not affect article expirations.)

     Most of the lines in  the  file  will  consist  of  five  colon-separated
     fields, as follows:
     The pattern field is a list of wildmat(3) -style  patterns,  separated  by
     commas.   This  field  specifies  the  newsgroups  to  which  the line is
     applied.  Note that the file is interpreted in order, so  that  the  last
     line that matches will be used.  This means that general patterns (like a
     single asterisk to set the defaults) should appear before specific  group

     The modflag field can be used to further limit newsgroups  to  which  the
     line applies, and should be chosen from the following set:
          M    Only moderated groups
          U    Only unmoderated groups
          A    All groups

     The next three fields are used to determine how long an article should be
     kept.   Each  field  should  be  either  a number of days (fractions like
     ``8.5'' are allowed) or the word ``never.''  The most common  use  is  to
     specify  the  default  value for how long an article should be kept.  The
     first and third fields -- keep and purge -- specify the boundaries within
     which  an Expires header will be honored.  They are ignored if an article
     has no Expires header.  The fields are specified in the file as  ``lower-
     bound default upper-bound,'' and they are explained in this order.  Since
     most articles do not have explicit expiration dates, however, the  second
     field tends to be the most important one.

     The keep field specifies how many days an article should be  kept  before
     it  will  be  removed.  No article in the newsgroup will be removed if it
     has been filed for less then keep  days,  regardless  of  any  expiration
     date.   If  this  field is the word ``never'' then an article cannot have
     been kept for enough days so it will never be expired.

     The default field specifies how long to keep an  article  if  no  Expires
     header  is  present.   If  this field is the word ``never'' then articles
     without explicit expiration dates will never be expired.

     The purge field specifies the upper bound on how long an article  can  be
     kept.   No  article will be kept longer then the number of days specified
     by this field.  All articles will be removed after then  have  been  kept
     for  purge  days.   If  purge is the word ``never'' then the article will
     never be deleted.

     It  is  often  useful  to  honor  the  expiration  headers  in  articles,
     especially  those  in  moderated  groups.   To do this, set keep to zero,
     default to whatever value you wish, and purge to never.   To  ignore  any
     Expires header, set all three fields to the same value.

     There must be exactly one line with a pattern of ``*'' and a modflags  of
     ``A''  --  this  matches  all  groups  and  is used to set the expiration
     default.  It should be the first expiration line.

     For example,
          ##  How long to keep expired history
          ##  Most things stay for two weeks
          ##  Believe expiration dates in moderated groups, up to six weeks
          ##  Keep local stuff for a long time

     Written by Rich $alz  <rsalz@uunet.uu.net>  for  InterNetNews.   This  is
     revision 1.15, dated 1996/10/29.

     expire(8) , wildmat(3) .

You can find a summary and links related to this topic
as part of the Mib Software Usenet RKT.