pmdagetoptions(3) — Linux manual page


PMDAGETOPTIONS(3)         Library Functions Manual         PMDAGETOPTIONS(3)

NAME         top

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

C SYNOPSIS         top

       #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         top

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

       The options that both pmdaGetOptions and pmdaGetOpt will trap are:

       -Ddebugspec    Set the PMAPI(3) debugging options to debugspec, as
                      described 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 options,
       and store them within the opts parameter:

       -Uusername     Set the user account name under which the PMDA should

       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 options
       are encountered by pmdaGetOpt, the option is processed and the next
       option is examined.  Therefore, pmdaGetOpt will only return 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,

       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_options
       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

       When a command line option usage error is detected in the
       pmdaGetOptions 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

       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.

DIAGNOSTICS         top

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

CAVEAT         top

       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

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨⟩.
       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
       Git repository ⟨⟩ on
       2020-08-13.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-11.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
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       (which is not part of the original manual page), send a mail to

Performance Co-Pilot                 PCP                   PMDAGETOPTIONS(3)