'\"macro stdmacro
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.TH PMDAHELP 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmdaOpenHelp\f1,
\f3pmdaGetHelp\f1,
\f3pmdaGetInDomHelp\f1,
\f3pmdaCloseHelp\f1 \- help text support for a PMDA
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.br
#include <pcp/pmda.h>
.sp
int pmdaOpenHelp(const char *\fIfname\fP);
.br
char *pmdaGetHelp(int \fIhandle\fP, pmID \fIpmid\fP, int \fItype\fP);
.br
char *pmdaGetInDomHelp(int \fIhandle\fP, pmInDom \fIindom\fP, int \fItype\fP);
.br
void pmdaCloseHelp(int \fIhandle\fP);
.sp
cc ... \-lpcp_pmda \-lpcp
.ft 1
.SH DESCRIPTION
As part of the Performance Metrics Domain Agent (PMDA) API (see
.BR PMDA (3)),
this group of routines is used to implement the processing of a PMDA's metric
help information.
.PP
These routines are really intended for internal use, and should not
need to be called directly from any PMDA code.
.PP
Briefly, the base name of the help text file (as created by
.BR newhelp (1))
is passed in via a
.B \-h
command line option for a daemon PMDA or as an argument to
.BR pmdaDaemon (3)
or
.BR pmdaDSO (3).
Then
.B pmdaOpenHelp
is called from
.BR pmdaInit (3)
and returns a
.I handle
that is used in subsequent calls to identify a particular help
text collection (each PMDA typically has only one such collection).
.PP
Requests for help text are passed to
.BR pmdaText (3)
which calls
.B pmdaGetHelp
or
.B pmdaGetInDomHelp
as required.
.PP
Other than error cases in
.BR pmdaOpenHelp ,
.B pmdaCloseHelp
is not called.
.SH DIAGNOSTICS
.B pmdaOpenHelp
returns a negative value for failure, suitable for decoding with
.BR pmErrStr (3).
.B pmdaGetHelp
and
.B pmdaGetInDomHelp
return NULL if the corresponding help text does not exist.
.SH CAVEAT
The PMDA must be using
.B PMDA_PROTOCOL_2
or later, as specified in the call to
.BR pmdaDSO (3)
or
.BR pmdaDaemon (3).
.SH SEE ALSO
.BR newhelp (1),
.BR PMAPI (3),
.BR PMDA (3),
.BR pmdaDaemon (3),
.BR pmdaDSO (3),
.BR pmdaInit (3),
.BR pmdaText (3)
and
.BR pmErrStr (3).