bionic (5) innwatch.ctl.5.gz

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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)