'\"macro stdmacro
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.TH PMDAGETOPTIONS 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmdaGetOpt\f1,
\f3pmdaGetOptions\f1 \- get options from arguments, parsing generic PMDA options
.SH "C SYNOPSIS"
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#include <pcp/pmapi.h>
.br
#include <pcp/pmda.h>
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int pmdaGetOptions(int \fIargc\fP, char *const *\fIargv\fP, pmdaOptions *\fIopts\fP, pmdaInterface\ *\fIdispatch\fP);
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int pmdaGetOpt(int \fIargc\fP, char *const *\fIargv\fP, const\ char\ *\fIoptstring\fP, pmdaInterface\ *\fIdispatch\fP, int\ *\fIerr\fP);
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cc ... \-lpcp_pmda \-lpcp
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.SH DESCRIPTION
These functions are wrappers for
.BR 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
.B pmdaInterface
structure.
The
.B pmdaGetOptions
interface allows both short and long options to be given,
whereas
.B pmdaGetOpt
allows for short form options only.
.PP
The options that both
.B pmdaGetOptions
and
.B pmdaGetOpt
will trap are:
.TP 15
.BI \-D debugspec
Set the
.BR PMAPI (3)
debugging options to
.IR debugspec ,
as described in
.BR PCPIntro (1).
Used for controlling levels of trace output while debugging.
.TP
.BI \-d domain
Set the
.I domain
number of this agent.
.TP
.BI \-h helpfile
Obtain the help text (see
.BR pmdaText (3))
for the metrics from this file rather than from the path specified with
.BR pmdaDSO (3)
or
.BR pmdaDaemon (3).
.TP
.BI \-i port
Expect PMCD to connect on inet
.I port
(number or name).
.TP
.BI \-6 port
Expect PMCD to connect on ipv6
.I port
(number or name).
.TP
.BI \-l logfile
Redirect diagnostics and trace output to
.IR logfile .
.TP
.B \-p
Expect PMCD to supply stdin/stdout pipe.
.TP
.BI \-u socket
Expect PMCD to connect on unix domain
.IR socket .
.PP
The
.B pmdaGetOptions
interface will also capture the following options, and store them
within the
.I opts
parameter:
.TP 15
.BI \-U username
Set the user account name under which the PMDA should execute.
.PP
Only one of
.BR \-i ,
.BR \-6 ,
.BR \-p
and
.B \-u
may be specified.  If none of these three options is given, a pipe
.RB ( \-p )
is assumed.  When these options are encountered by
.BR pmdaGetOpt ,
the option is processed and the next option is examined.  Therefore,
.B 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.
.PP
A PMDA can control which of these options the program will accept with
either the
.I opts
or
.I optstring
argument.  To accept all the options, the PMDA should call
.B pmdaGetOptions
with the short_options field of the
.I opts
structure set to the PMDA_OPTIONS macro,
or
.B 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
.BR getopt (3),
and will be returned by both
.B pmdaGetOptions
and
.B pmdaGetOpt
if encountered.
.PP
When a command line option usage error is detected in the
.B pmdaGetOptions
interface, the error field of the
.I opts
structure will contain a non-zero error count.
.PP
.B pmdaGetOpt
takes a pointer to an int,
.IR err ,
which is used as an error count.  This variable should be initialized to zero
before
.B pmdaGetOpt
is first called, and tested when
.B pmdaGetOpt
returns EOF.
.PP
Neither
.B pmdaGetOptions
nor
.B pmdaGetOpt
modify their
.I argc
or
.I argv
parameters.
.PP
The global variables used by the system
.B getopt (3)
interface may also be used by the caller of
.B pmdaGetOpt
within the argument parsing loop.
.PP
On the other hand, the
.B pmdaGetOptions
interface does not utilize global variables at all (neither reading
nor modifying them).
Instead, these variables can be access via the
.I opts
fields of the same name.
.SH CAVEAT
The options
.BR \-D ,
.BR \-d ,
.BR \-i ,
.BR \-l ,
.BR \-p
and
.B \-u
cannot be reused for other purposes by the PMDA, unless using the
.I override
method provided by the
.B pmdaGetOptions
interface, which operates in the same way as described for the
.BR pmGetOptions (3)
interface used by PMAPI client tools.
.PP
The PMDA must be using
.B PMDA_INTERFACE_2
or later, as specified in the call to
.BR pmdaDSO (3)
or
.BR pmdaDaemon (3).
.SH DIAGNOSTICS
Both
.B pmdaGetOptions
and
.B pmdaGetOpt
will display the same error messages as
.BR getopt .
.SH SEE ALSO
.BR pmdbg (1),
.BR getopt (3),
.BR pmgetopt_r (3),
.BR pmGetOptions (3),
.BR PMAPI (3),
.BR PMDA (3),
.BR pmdaDaemon (3),
.BR pmdaDSO (3)
and
.BR pmdaText (3).