Rrd2Svg

$. What it does?

The system statistics can be stored into the RRD files by 'collectd' daemon.
Please look into:
http://oss.oetiker.ch/rrdtool/
https://collectd.org/

On:
http://oss.oetiker.ch/rrdtool/rrdworld/index.en.html
https://collectd.org/related.shtml
the good tools are listed, that can extract the data from the RRD files and can draw the graphs.

Rrd2Svg is the tool that draws the graph into the SVG file.
To read the RRD files, some of the classes in Rrd2Svg are based on:
RRD4J
As for RRD4J, please look into:
https://github.com/rrd4j/rrd4j

$. How to use it ?

The class for the command line is:
com.aboutjun.rrd2svg.util.Runner4Pipe4Svg
and it is specified as the main class of the JAR file.
So its usage is:
java -jar rrd2svg_X_Y.jar <root for RRD> <root for SVG>
1) <root for RRD> is:
The root directory of the subdirectories for the RRD files.
2) <root for SVG> is:
The root directory of the subdirectories for the SVG files.