While looking at the options for apt-cache today I noticed ‘dotty’ as an option. I presumed this could be used to make grahpviz diagrams of package dependencies. After a bit on googling on how to use that, I came across debtree:

sudo apt-get install debtree graphviz

Of course the first command I ran with it was this

debtree -I --rdeps-depth=3 qgis | dot -Tpng -o qgisdeps.png ; display qgisdeps.png

Take a look at the beautiful (ok and just a teeny bit complex) diagram it produced. Its quite amazing really to see how many different components there are out there in the FOSS world that can be combined to produce cool software like QGIS. It really lets you see that QGIS is just as much an integration effort as it is a bespoke software development effort.