pmdagetoptions(3) — Linux manual page

PMDAGETOPTIONS(3)       Library Functions Manual       PMDAGETOPTIONS(3)

NAME

       pmdaGetOpt, pmdaGetOptions - get options from arguments, parsing
       generic PMDA options

C SYNOPSIS

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

       int pmdaGetOptions(int argc, char *const *argv, pmdaOptions
               *opts, pmdaInterface *dispatch);

       int pmdaGetOpt(int argc, char *const *argv,
               const char *optstring, pmdaInterface *dispatch,
               int *err);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION

       These  functions are wrappers for pmgetopt_r(3).  The behavior of
       each function is that certain options are assumed to have a  pre‐
       defined  behavior which initializes several fields in the pmdaIn‐
       terface structure.   The  pmdaGetOptions  interface  allows  both
       short and long options to be given, whereas pmdaGetOpt allows for
       short form options only.

       The  options  that  both  pmdaGetOptions and pmdaGetOpt will trap
       are:

       -Ddebugspec
              Set the PMAPI(3) debugging options to debugspec, as de‐
              scribed in PCPIntro(1).  Used for controlling levels of
              trace output while debugging.

       -ddomain
              Set the domain number of this agent.

       -hhelpfile
              Obtain the help text (see pmdaText(3)) for the metrics
              from this file rather than from the path specified with
              pmdaDSO(3) or pmdaDaemon(3).

       -iport Expect PMCD to connect on inet port (number or name).

       -6port Expect PMCD to connect on ipv6 port (number or name).

       -llogfile
              Redirect diagnostics and trace output to logfile.

       -p     Expect PMCD to supply stdin/stdout pipe.

       -usocket
              Expect PMCD to connect on unix domain socket.

       The pmdaGetOptions interface will also capture the following op‐
       tions, and store them within the opts parameter:

       -Uusername
              Set the user account name under which the PMDA should exe‐
              cute.

       Only one of -i, -6, -p and -u may be specified.  If none of these
       three options is given, a pipe (-p) is assumed.  When these op‐
       tions are encountered by pmdaGetOpt, the option is processed and
       the next option is examined.  Therefore, pmdaGetOpt will only re‐
       turn when an option other than those listed above is found, or
       the end of the list is reached.  The returned value will be the
       argument or EOF, respectively.

       A PMDA can control which of these options the program will accept
       with either the opts or optstring argument.  To accept all the
       options, the PMDA should call pmdaGetOptions with the short_op‐
       tions field of the opts structure set to the PMDA_OPTIONS macro,
       or pmdaGetOpt with the option string "D:d:h:i:l:pu:".  Any PMDA
       specific options should be added to these strings in the style of
       getopt(3), and will be returned by both pmdaGetOptions and
       pmdaGetOpt if encountered.

       When a command line option usage error is detected in the pmdaGe‐
       tOptions interface, the error field of the opts structure will
       contain a non-zero error count.

       pmdaGetOpt takes a pointer to an int, err, which is used as an
       error count.  This variable should be initialized to zero before
       pmdaGetOpt is first called, and tested when pmdaGetOpt returns
       EOF.

       Neither pmdaGetOptions nor pmdaGetOpt modify their argc or argv
       parameters.

       The global variables used by the system getopt(3) interface may
       also be used by the caller of pmdaGetOpt within the argument
       parsing loop.

       On the other hand, the pmdaGetOptions interface does not utilize
       global variables at all (neither reading nor modifying them).
       Instead, these variables can be access via the opts fields of the
       same name.

CAVEAT

       The options -D, -d, -i, -l, -p and -u cannot be reused for other
       purposes by the PMDA, unless using the override method provided
       by the pmdaGetOptions interface, which operates in the same way
       as described for the pmGetOptions(3) interface used by PMAPI
       client tools.

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

DIAGNOSTICS

       Both pmdaGetOptions and pmdaGetOpt will display the same error
       messages as getopt.

SEE ALSO

       pmdbg(1), getopt(3), pmgetopt_r(3), pmGetOptions(3), PMAPI(3),
       PMDA(3), pmdaDaemon(3), pmdaDSO(3) and pmdaText(3).

COLOPHON

       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 2024-06-14.
       (At that time, the date of the most recent commit that was found
       in the repository was 2024-06-14.)  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                 PMDAGETOPTIONS(3)

Pages that refer to this page: pmda(3), pmdaconnect(3), pmdadaemon(3), pmdainit(3), pmdaopenlog(3), pmdatext(3)

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