Essential System Administration, 3rd Edition

The Unix Universe

More and more, people find themselves taking care of multiple computers, often from more than one manufacturer; it’s quite rare to find a system administrator who is responsible for only one system (unless he has other, unrelated duties as well). While Unix is widely lauded in marketing brochures as the “standard” operating system “from microcomputers to supercomputers”—and I must confess to having written a few of those brochures myself—this is not at all the same as there being a “standard” Unix.At this point, Unix is hopelessly plural, and nowhere is this plurality more evident than in system administration. Before going on to discuss how this book addresses that fact, let’s take a brief look at how things got to be the way they are now.

Figure P-1 attempts to capture the main flow of Unix development. It illustrates a simplified Unix genealogy, with an emphasis on influences and family relationships (albeit Faulknerian ones) rather than on strict chronology and historical accuracy. It traces the major lines of descent from an arbitrary point in time: Unix Version 6 in 1975 (note that the dates in the diagram refer to the earliest manifestation of each version). Over time, two distinct flavors (strains) of Unix emerged from its beginnings at AT&T Bell Laboratories—which I’ll refer to as System V and BSD—but there was also considerable cross-influence between them (in fact, a more detailed diagram would indicate this even more clearly).

Figure P-1. Unix genealogy ...