NAME

       RRDp - Attach RRDtool from within a perl script via a set of pipes;

SYNOPSIS

       use RRDp

       RRDp::start path to RRDtool executable

       RRDp::cmd  rrdtool commandline

       $answer = RRD::read

       $status = RRD::end

       $RRDp::user,  $RRDp::sys, $RRDp::real, $RRDp::error_mode, $RRDp::error

DESCRIPTION

       With this module you can safely communicate with the RRDtool.

       After every RRDp::cmd you have to issue an RRDp::read command to get RRDtools answer to
       your command. The answer is returned as a pointer, in order to speed things up. If the
       last command did not return any data, RRDp::read will return an undefined variable.

       If you import the PERFORMANCE variables into your namespace, you can access RRDtool's
       internal performance measurements.

       use RRDp
               Load the RRDp::pipe module.

       RRDp::start path to RRDtool executable
               start RRDtool. The argument must be the path to the RRDtool executable

       RRDp::cmd rrdtool commandline
               pass commands on to RRDtool. Check the RRDtool documentation for more info on the
               RRDtool commands.

               Note: Due to design limitations, RRDp::cmd does not support the "graph -" command
               - use "graphv -" instead.

       $answer = RRDp::read
               read RRDtool's response to your command. Note that the $answer variable will only
               contain a pointer to the returned data. The reason for this is, that RRDtool can
               potentially return quite excessive amounts of data and we don't want to copy this
               around in memory. So when you want to access the contents of $answer you have to
               use $$answer which dereferences the variable.

       $status = RRDp::end
               terminates RRDtool and returns RRDtool's status ...

       $RRDp::user,  $RRDp::sys, $RRDp::real
               these variables will contain totals of the user time, system time and real time as
               seen by RRDtool.  User time is the time RRDtool is running, System time is the
               time spend in system calls and real time is the total time RRDtool has been
               running.

               The difference between user + system and real is the time spent waiting for things
               like the hard disk and new input from the Perl script.

       $RRDp::error_mode and $RRDp::error
               If you set the variable $RRDp::error_mode to the value 'catch' before you run
               RRDp::read a potential ERROR message will not cause the program to abort but will
               be returned in this variable. If no error occurs the variable will be empty.

                $RRDp::error_mode = 'catch';
                RRDp::cmd qw(info file.rrd);
                print $RRDp::error if $RRDp::error;

EXAMPLE

        use RRDp;
        RRDp::start "/usr/local/bin/rrdtool";
        RRDp::cmd   qw(create demo.rrd --step 100
                      DS:in:GAUGE:100:U:U
                      RRA:AVERAGE:0.5:1:10);
        $answer = RRDp::read;
        print $$answer;
        ($usertime,$systemtime,$realtime) =  ($RRDp::user,$RRDp::sys,$RRDp::real);

SEE ALSO

       For more information on how to use RRDtool, check the manpages.

AUTHOR

       Tobias Oetiker <tobi@oetiker.ch>