pmdaGetOpt(3)

NAME

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

C SYNOPSIS

   #include <pcp/pmapi.h>
   #include <pcp/impl.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 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
   only.

   The options that both pmdaGetOptions and pmdaGetOpt will trap are:

   -Dtrace        Set  the  PMAPI(3)  debug  control variable (pmDebug) to
                  trace.  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
                  execute.

   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, 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_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 encountered.

   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
   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.

DIAGNOSTICS

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

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).

SEE ALSO

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

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