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 spent 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>

perl v5.38.2                                       2024-03-31                                          RRDp(3pm)