Because this book deals only with the underlying Linux system, this chapter does not cover windowing environment startup files. This is a large issue indeed, because the display manager that logs you in to a modern Linux system has its own set of startup files, such as .xsession , .xinitrc , and the endless mess of GNOME-and KDE- related items.
The windowing choices may seem bewildering, and this isn't far from the truth, because there isn't even one single common way to start a windowing environment in Unix. However, once you determine what your system does, you may get a little carried away with the files that relate to your graphical environment. This is fine, but don't carry it over to new users. The same tenet of keeping things simple in shell startup files works wonders for GUI startup files too.