pmdahelp(3) — Linux manual page

NAME | C SYNOPSIS | DESCRIPTION | CAVEAT | DIAGNOSTICS | SEE ALSO | COLOPHON

PMDAHELP(3)              Library Functions Manual             PMDAHELP(3)

NAME         top

       pmdaOpenHelp, pmdaGetHelp, pmdaGetInDomHelp, pmdaCloseHelp - help
       text support for a PMDA

C SYNOPSIS         top

       #include <pcp/pmapi.h>
       #include <pcp/pmda.h>

       int pmdaOpenHelp(const char *fname);
       char *pmdaGetHelp(int handle, pmID pmid, int type);
       char *pmdaGetInDomHelp(int handle, pmInDom indom, int type);
       void pmdaCloseHelp(int handle);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION         top

       As  part  of  the Performance Metrics Domain Agent (PMDA) API (see
       PMDA(3)), this group of routines is used to implement the process‐
       ing of a PMDA's metric help information.

       These routines are really intended for internal  use,  and  should
       not need to be called directly from any PMDA code.

       Briefly,  the  base  name  of  the  help  text file (as created by
       newhelp(1)) is passed in via a -h command line option for a daemon
       PMDA or as an argument to pmdaDaemon(3) or pmdaDSO(3).   Then  pm‐
       daOpenHelp is called from pmdaInit(3) and returns a handle that is
       used  in  subsequent calls to identify a particular help text col‐
       lection (each PMDA typically has only one such collection).

       Requests for help text  are  passed  to  pmdaText(3)  which  calls
       pmdaGetHelp or pmdaGetInDomHelp as required.

       Other  than  error  cases  in  pmdaOpenHelp,  pmdaCloseHelp is not
       called.

CAVEAT         top

       The PMDA must be using PMDA_INTERFACE_2 or later, as specified  in
       the call to pmdaDSO(3) or pmdaDaemon(3).

DIAGNOSTICS         top

       pmdaOpenHelp  returns  a  negative value for failure, suitable for
       decoding with pmErrStr(3).  pmdaGetHelp and  pmdaGetInDomHelp  re‐
       turn NULL if the corresponding help text does not exist.

SEE ALSO         top

       newhelp(1),    PMAPI(3),   PMDA(3),   pmdaDaemon(3),   pmdaDSO(3),
       pmdaInit(3), pmdaText(3) and pmErrStr(3).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.   In‐
       formation  about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a  bug  report  for  this  manual  page,  send  it  to
       pcp@groups.io.  This page was obtained from the project's upstream
       Git  repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
       2025-08-11.  (At that time, the date of  the  most  recent  commit
       that was found in the repository was 2025-08-11.)  If you discover
       any  rendering  problems  in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the  page,
       or you have corrections or improvements to the information in this
       COLOPHON  (which  is not part of the original manual page), send a
       mail to man-pages@man7.org

Performance Co-Pilot               PCP                        PMDAHELP(3)