I picked up this book shortly after it was published in hardcover and devoured it. The information is well-presented and understandable. Unlike with a lot of other internals books, you aren't presented with a pseudo-code dump and expected to untangle it. Vahalia tells you what each of the pieces does.

The genius of the book is that it is at the appropriate level of abstraction for people who are not yet experts in Unix Internals, but who are interested in learning. This is not a book for beginners, but it is an excellent choice for serious students who are trying to become experts.

The tip command can be used to allow one Unix workstation to act as a serial terminal for another Unix system. The following must be in place to allow this to work between two Sun systems:

The POST-based hardware diagnostics only check out the devices and buses required to access I/O devices; they do not check the devices themselves. Even so, the onboard hardware diagnostics can often pinpoint the source of a hardware failure.

To run Sun hardware diagnostics, perform the following at the ok> prompt:

ok> setenv auto-boot? false
ok> setenv diag-switch? true
ok> setenv diag-level max
ok> setenv diag-device disk net (if appropriate)
ok> reset
(watch results of diagnostic tests)

For versions 2.x and higher (SparcStation 2 and newer), the OpenBoot firmware provides for two command line interfaces:

1. Restricted Monitor: This interface is signalled by the > prompt. It provides for execution of the b (boot), c (continue), and n (new command mode) commands. The Restricted Monitor is used to implement PROM security via the security-mode PROM environment variable.