NAME

       innwatch.ctl - control Usenet supervision by innwatch

DESCRIPTION

       The  file  /etc/news/innwatch.ctl  is  used to determine what actions are taken during the
       periodic supervisions by innwatch.

       The file consists of a series of lines; blank lines and lines beginning with a number sign
       (``#'')  are  ignored.   All  other  lines  consist  of  seven  fields, each preceded by a
       delimiting character:
              :label:state:condition:test:limit:command:reason

       The delimiter can be any one of several non-alphanumeric characters that does  not  appear
       elsewhere  in  the  line;  there is no way to quote it to include it in any of the fields.
       Any of ``!'', ``,'', ``:'', ``@'', ``;'', or ``?'' is a good choice.  Each line can have a
       different  delimiter;  the  first  character  on each line is the delimiter for that line.
       White space surrounding delimiters, except before the first, is ignored, and does not form
       part  of  the  fields,  white  space  within  fields is permitted.  All delimiters must be
       present.

       The first field is a label for the  control  line.   It  is  used  as  an  internal  state
       indicator  and  in ctlinnd messages to control the server.  If omitted, the line number is
       used.

       The second field specifies when this control line should be used.  It consists of  a  list
       of  labels, and special indicators, separated by whitespace.  If the current state matches
       against any of the labels in this field, this line will be used as described  below.   The
       values that may be used are:

       -      This line matches if the current state is the same as the label on this line, or if
              the current state is ``run,'' the initial state.  This is also the default state if
              this field is empty.

       +      This line matches if the current state is ``run.''

       *      This line always matches.

       label  This line matches if the current state is the specified ``label.''

       -label This line matches if the current state is not the specified ``label.''

       The  third  field  specifies a shell command that is invoked if this line matches.  Do not
       use any shell filename expansion characters such as ``*'', ``?'', or ``[''  (even  quoted,
       they're  not  likely  to  work as intended).  If the command succeeds, as indicated by its
       exit status, it is expected to have printed a single integer  to  standard  output.   This
       gives the value of this control line, to be used below.  If the command fails, the line is
       ignored.  The command is executed with  its  current  directory  set  to  the  news  spool
       directory, /var/spool/news.

       The  fourth  field  specifies  the  operator  to use to test the value returned above.  It
       should be one of the two letter numeric test operators defined in test(1) such as  ``eq'',
       ``lt'' and the like.  The leading dash (`'-'') should not be included.

       The  fifth  field  specifies a constant with which to compare the value using the operator
       just defined.  This is done by invoking the command
              test value -operator constant
       The line is said to ``succeed'' if it returns true.

       The sixth field specifies what should be done if the line succeeds, and in some  cases  if
       it fails.  Any of the following words may be used:

       throttle
              Causes  innwatch  to  throttle  the server if this line succeeds.  It also sets the
              state to the value of the line's label.  If the  line  fails,  and  the  state  was
              previously  equal  to  the  label  on  this line (that is, this line had previously
              succeeded), then a go command will be sent to the server, and innwatch will  return
              to  the  ``run'' state.  The ``throttle'' is only performed if the current state is
              ``run'' or a state other than the label of this line,  regardless  of  whether  the
              command succeeds.

       pause  Is identical to ``throttle'' except that the server is paused.

       shutdown
              Sends a ``shutdown'' command to the server.  It is for emergency use only.

       flush  Sends a ``flush'' command to the server.

       go     Causes  innwatch  to  send  a  ``go'' command to the server and to set the state to
              ``run.''

       exit   Causes innwatch to exit.

       skip   The result of the control file is skipped for the current pass.

       The last field specifies the reason that is used in those ctlinnd  commands  that  require
       one.   More  strictly, it is part of the reason — innwatch appends some information to it.
       In order to enable other sites to recognize the state of the local innd server, this field
       should  usually  be set to one of several standard values.  Use ``No space'' if the server
       is rejecting articles because of a lack of filesystem resources.  Use  ``loadav''  if  the
       server is rejecting articles because of a lack of CPU resources.

       Once  innwatch  has  taken  some action as a consequence of its control line, it skips the
       rest of the control file for this pass.  If the action was to restart the server (that is,
       issue  a  ``go''  command),  then  the next pass will commence almost immediately, so that
       innwatch can discover any other  condition  that  may  mean  that  the  server  should  be
       suspended again.

EXAMPLES

              @@@df .|awk 'NR==2 {print $4}'@lt@10000@throttle@No space
              @@@df -i .|awk 'NR==2 {print $4}'@lt@1000@throttle@No space (inodes)

       The first line causes the server to be throttled if the free space drops below 10000 units
       (using whatever units df uses), and restarted again when free space  increases  above  the
       threshold.

       The second line does the same for inodes.

       The  next  three  lines  act  as  a group and should appear in the following order.  It is
       easier to explain them, however, if they are described from the last up.
              !load!load hiload!loadavg!lt!5!go!
              :hiload:+ load:loadavg:gt:8:throttle:loadav
              /load/+/loadavg/ge/6/pause/loadav
       The final line causes the server to be paused if innwatch is in the ``run'' state and  the
       load  average  rises  to,  or above, six.  The state is set to ``load'' when this happens.
       The previous line causes the server to be throttled when innwatch is  in  the  ``run''  or
       ``load''  state,  and  the load average rises above eight.  The state is set to ``hiload''
       when this  happens.   Note  that  innwatch  can  switch  the  server  from  ``paused''  to
       ``throttled''  if the load average rises from below six to between six and seven, and then
       to above eight.  The first line causes the server to be sent a ``go'' command if  innwatch
       is in the ``load'' or ``hiload'' state, and the load average drops below five.

       Note  that  all three lines assume a mythical command loadavg that is assumed to print the
       current load average as an integer.  In more practical circumstances,  a  pipe  of  uptime
       into awk is more likely to be useful.

BUGS

       This  file must be tailored for each individual site, the sample supplied is truly no more
       than a sample.  The file should be ordered so that the more  common  problems  are  tested
       first.

       The ``run'' state is not actually identified by the label with that three letter name, and
       using it will not work as expected.

       Using an ``unusual'' character for the delimiter  such  as  ``('',  ``*'',  ``&'',  ```'',
       ``´'', and the like, is likely to lead to obscure and hard to locate bugs.

HISTORY

       Written by <kre@munnari.oz.au> for InterNetNews.  This is revision 1.5, dated 1996/09/06.

SEE ALSO

       innd(8), ctlinnd(8), news.daily(8).

                                                                                  INNWATCH.CTL(5)