You have added a comment describing the statistical information relating to the graph. The Legend command adds three GPRINT statements to the graph. The first GPRINT statement prints the last polled value, the second statement prints the average value of the displayed graph and the last one prints the maximum value polled.

You can now assign this graph template to a device. After you have added the graph template to a device, you need to wait for three polls to pass. The first poll actually creates the necessary RRD file. The other two polls are needed for the RRDtool as it will start graphing values only when it has at least two data values within the RRD file. Once that time has passed, go to Graph Management within the Management section and look for the graph there:

Let's look at the rrdtool graph command which Cacti uses to create the preceding graph.

/usr/bin/rrdtool graph -
--imgformat=PNG
--start=-86400
--end=-300
--title='Localhost - Running Processes'
--base=1000
--height=120
--width=500
--alt-autoscale-max
--lower-limit=0
--vertical-label='processes'
--slope-mode
--font TITLE:12:
--font AXIS:8:
--font LEGEND:10:
--font UNIT:8:
DEF:a="/var/www/html/cacti-0.8.7g/rra/localhost_runprocesses_11.rrd":runProcesses:AVERAGE
CDEF:cdefc=a,45,50,LIMIT
CDEF:cdefd=a,0,44,LIMIT
HRULE:50#C0C0C0FF:"Threshold ( 50 )\n"
AREA:a#FF0000FF:"Over Threshold"
AREA:cdefc#F5F800FF:"Near Threshold"
AREA:cdefd#7EE600FF:"Under Threshold\n"
COMMENT:"Running Processes"
GPRINT:a:LAST:"Current\:%8.2lf %s"
GPRINT:a:AVERAGE:"Average\:%8.2lf %s"
GPRINT:a:MAX:"Maximum\:%8.2lf %s\n" 

Doesn't this one look familiar? It's roughly the same command which you hopefully came up with in the "Have a go hero" challenge in Chapter 2. Here you can see the tight integration of the rrdtool with the Cacti web interface.