In the previous chapter, we looked at how to get an up-to-date FreeBSD source tree.
Once you have the sources, you can build various components of the system. The main
tool we use for this purpose is make, which we looked at on page 167. The best way to
think of upgrading the system is that everything is a matter of changing files. For the
purposes of this discussion, you can divide the files on your system into the following