NAME

       pmAddDerivedText - add help text for a derived metric

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmAddDerivedText(const char *name, int type, const char *text);

       cc ... -lpcp

DESCRIPTION

       Derived  metrics provide a way of extending the Performance Metrics Name Space (PMNS) with
       new metrics defined at the PCP client-side using expressions over the existing performance
       metrics.    Global   derived   metrics   are   defined   using   pmRegisterDerived(3)   or
       pmRegisterDerivedMetric(3) or pmLoadDerivedConfig(3), and per-context derived metrics  are
       defined using pmAddDerived(3) or pmAddDerivedMetric(3).

       Once a derived metric has been defined, pmAddDerivedText may be used to associate the help
       text with the derived metric identified by name.

       Help text may be a ``one line'' summary or a more verbose ``multi-line''  block  of  text,
       and type should be PM_TEXT_ONELINE or PM_TEXT_HELP respectively.  To associate both styles
       of help text with a derived metric, pmAddDerivedText would need to be  called  twice  with
       different values for type.

       Once a particular type of help text has been associated with a derived metric it cannot be
       deleted or redefined.

       Applications using the Performance Metrics Application Programming Interface  (PMAPI)  are
       able to retrieve help text for specific metrics using pmLookupText(3).

DIAGNOSTICS

       pmAddDerivedText returns zero on success, else an error code.

       The  return  value  PM_ERR_NAME indicates name does not correspond to a previously defined
       derived metric.

       Repeated calls for the same name and type will result a return value of PM_ERR_TEXT.

       A return value of PM_ERR_ARG indicates that type is not one of the expected values.

SEE ALSO

       PCPIntro(1),  pmAddDerived(3),  pmAddDerivedMetric(3),  PMAPI(3),  pmLoadDerivedConfig(3),
       pmLookupText(3), pmRegisterDerived(3), pmRegisterDerivedMetric(3) and PMNS(5).