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
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
RRDtool
s 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.
$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 $$answer which dereferences
the variable.
$status =
RRDp::end
terminates RRDtool and returns RRDtool's status ...
$RRDp::user
,
$RRDp::sys
,
$RRDp::real
these variables will contain totals of the user time, system time and
real time as seen by RRDtool.  User time is the time RRDtool is
running, System time is the time spend in system calls and real time
is the total time RRDtool has been running.
The difference between user + system and real is the time spent
waiting for things like the hard disk and new input from the perl
script.
EXAMPLE
use RRDp;
RRDp::start "/usr/local/bin/rrdtool";
RRDp::cmd   qw(create demo.rrd --step 100
DS:in:GAUGE:100:U:U
RRA:AVERAGE:0.5:1:10);
$answer = RRDp::read;
print $$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 <
mailto:oetiker@ee.ethz.ch
oetiker@ee.ethz.ch
>
