RRDp(3) User Contributed Perl Documentation RRDp(3)

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 v5.34.0 2022-03-14 RRDp(3)