In this episode we'll be creating tree graphs using the graphviz DOT language.

First we need to install the graphviz package:

sudo apt install -y graphviz

Now we'll create a simple graph. Copy the following DOT language into a file named life.gv:

digraph D {
  Life -> {Bacteria, Archaea, Eukaryota}
  Eukaryota -> {Plants, Fungi, Animals}
  Plants -> {Gymnosperms, Angiosperms}
  Animals -> {Vertebrates, Invertebrates}
  Vertebrates -> {Fish, Amphibians, Reptiles, Birds, Mammals}
}

Now we can generate a postscript file (similar to a pdf) with the following command:

dot -Tps life.gv -o life.ps

We can also generate a PNG image file with this command:

dot -Tpng life.gv -o life.png