PERL RRDTTOL: graph subroutine with conditional legend

Question

Stupid thing I can't manage...

in Perl, with RRDTool (rrds module), I create a common subroutine to create the graphs for the different time period (1 day, 1 week,...). I want to use some sub argument to also display optional legend.

With the following code, that does not generate any graph....

#!/usr/bin/perl
use strict;
use OWNet;
use RRDs;
use warnings;
use diagnostics;

my $rrd = '/var/rrd/electricite.rrd';
my $img = '/mnt/ds211/web/';

&CreateGraph("conso","Consommation electrique 1 heure","1h",1);

sub CreateGraph
# inputs:   $_[0]: sensor_rrd_name
#       $_[1]: chart title
#       $_[2]: interval period (1h,24h,7d,1m,1y,10y)
#       $_[3]: Puissance instantanee (1/0)
{
    my $temp_graph;
    $temp_graph ="\"$img$_[0]-$_[2].png\",";
    $temp_graph .="\"--start=end-$_[2]\",";
    $temp_graph .="\"--end=now\",";
    $temp_graph .="\"--width=600\",";
    $temp_graph .="\"--height=200\",";
    $temp_graph .="\"--slope-mode\",";
    $temp_graph .="\"--title=$_[1]\",";
    $temp_graph .="\"--vertical-label=Watt\",";
    $temp_graph .="\"--lower-limit=0\",";
    $temp_graph .="\"--alt-autoscale-max\",";
    $temp_graph .="\"DEF:energy=$rrd:$_[0]:AVERAGE\",";
    $temp_graph .="\"CDEF:Watt=energy,3600,*\",";
    $temp_graph .="\"LINE2:Watt#0000FF:\",";
    $temp_graph .="\"AREA:Watt#00FF00:\",";
    $temp_graph .="\"VDEF:WattHour=energy,TOTAL\",";

    if ($_[3]==1)
    {
        $temp_graph .="\"GPRINT:Watt:LAST:  Puissance instantanee\\: %6.2lf%sW\",";
    }

    $temp_graph .="\"GPRINT:WattHour:   Consommation totale\\: %6.2lf%sWh\\n\",";
    $temp_graph .="\"GPRINT:Watt:MIN:  Puissance min\\: %6.2lf%sW\",";
    $temp_graph .="\"GPRINT:Watt:AVERAGE:  Puissance moyenne\\: %6.2lf%sW\",";
    $temp_graph .="\"GPRINT:Watt:MAX:  Puissance max\\: %6.2lf%sW\"";

    RRDs::graph ("$temp_graph");

    if ($ERROR = RRDs::error)
    {
        print "$0: failed to generate graph $_[0] data into rrd: $ERROR\n";
    }
}

thank you

Answer 1

the problem is that you are handing rrdtool a string instead of an array with your arguments.

Instead of

RRDs::graph ("\"graph.gif\",\"DEF:...\" ...");

you should be calling

RRDs::graph ("graph.gif","DEF:...","...");`

if you want to prepare your arguments before hand, then you would use

my @args = ("graph.gif","DEF:...","...")
RRDs::graph(@args);

hope this helps.