xenial (3) pmLoadDerivedConfig.3.gz

NAME

       pmLoadDerivedConfig - load derived metric definitions from files

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmLoadDerivedConfig(char *path);

       cc ... -lpcp

DESCRIPTION

       Derived  metrics  may  be  used  to  extend the available metrics with new (derived) metrics using simple
       arithmetic expressions.  The definitions of these metrics can be persisted and loaded programatically  by
       monitor tools using pmLoadDerivedConfig.

       The  path parameter defines a colon separated list of files and/or directories (the syntax is the same as
       for the $PATH variable for sh(1)), from which derived metric specifications are to be sourced.  The  path
       components  are  expanded  into  a  list of files as follows: if a component is a file, then that file is
       added to the list, else if a component is a directory then recursive descent is  used  to  enumerate  all
       files below that directory and these are added to the list.  Each file in the resulting list is parsed in
       order, and according to the derived metrics syntax described below.

       Each line of the file(s) identified by path is either a comment line (with a ``#'' in the first  position
       of the line) or the declaration of a derived performance metric, specified as:

       * the name of the derived metric, using the same ``dot notation'' syntax that is used for PCP performance
         metrics, see PCPIntro(1) and pmns(5).

       * an equals sign (``='')

       * a valid expression for a derived metric, as described in pmRegisterDerived(3).

       White space is ignored in the lines.

       For each line containing a derived metric definition, pmRegisterDerived(3) is called to register the  new
       derived metric.

       The  result from pmLoadDerivedConfig will be the number of derived metrics loaded from files on the given
       path, else a value less than zero in the case of an error.

EXAMPLE

       # sample derived metric definitions
       bad_in_pkts = network.interface.in.errors + network.interface.in.drops
       # note the following would need to be on a single line ...
       disk.dev.read_pct = 100 * delta(disk.dev.read) /
                   (delta(disk.dev.read) + delta(disk.dev.write))

SEE ALSO

       sh(1), PCPIntro(1), PMAPI(3), pmRegisterDerived(3) and pmns(5).