Part Six

Case Studies

In the final part of the book, we integrate the concepts described earlier by examining real operating systems. We cover in detail—Linux, for several reasons: it is popular, it is freely available, and it represents a full-featured UNIX system. This gives a student of operating systems an opportunity to read—and modify—real operating-system source code.

We also provide on-line coverage of two more systems: FreeBSD and Mach. The FreeBSD system is another UNIX system. However, whereas Linux combines features from several UNIX systems, FreeBSD is based on the BSD model. FreeBSD source code, like Linux source code, is freely available. Mach is a modern operating system that provides compatibility with BSD UNIX.