RRDp(3) User Contributed Perl Documentation RRDp(3)NAMERRDp - 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>
perl v5.14.0 2011-06-17 RRDp(3)
