Recently I had to do some testing which resulted in a lot of log data. Looking at a bunch of text is not the same as seeing things graphically, this particular logdata was perfect to put in a graph. My goto favorite tool for graphs and charts is gnuplot. Not only is it very extensible, it is also reproducable. Give me a configfile and command over 'do this, then this and then such and such' in Excel to get a consistent result. In this article I'll give tips for using gnuplot, which include parsing a CSV file, a second axis, environment variables, A4 PDF's and a ton of styling options for a nice looking chart.