I've had the book for almost six months now, and I've used it many times to look something up. Although the title refers to BSD, the subtitle is "The Ultimate Guide to FreeBSD". As such, it concentrates heavily on FreeBSD, but much of it is also applicable to NetBSD and OpenBSD. It covers large server environments, but has plenty of information applicable to home and small office users.
I found it to be useful from the start and have continued to use it from time to time. It was the first FreeBSD book I found on the shelves of my local bookstore. There is a sample chapter at http://www.absolutebsd.com/.
It covers a wide variety of topics, including (but not limited to):
I found many useful sections in it, and I will outline a few of my favorites below. Your mileage may vary; what I found useful, you may not, and vice versa. The sections I don't discuss here will no doubt be useful to many of you:
I particularly liked the section on jails (chapter 8) which can be used to create systems within systems. If you are in a jail, it looks like you have a whole computer to yourself, but you are actually "just another user". It's a good way to secure users in their own little universes. This was my first introduction to jails, and I'm tempted to start experimenting with them just to learn more.
I was quite impressed to see details of handling system dumps, panics, and debugging. These are the types of things we shouldn't have to do under normal circumstances, but when it hits the fan, it good to know this stuff. Even if you don't know it by heart, at least you'll know it's in the book, and you can consult it easily in your time of need.
I found the examples very useful. I've long said that we need more practical examples in our documentation. Another useful feature is the way the text refers to the examples. This is done with labels embedded in the examples, which allows easy reference from within the text. I wish all books did this. There is nothing more frustrating than trying to figure out which part of the multi-page example an author is referring to. With the labels, there is no chance of that happening.
The book also discusses IP Filter, my packet filter of choice. The basics of packet filtering are covered, and there is a section on rule groups. Rule groups are, in my humble opinion, one of the strongest features of IP Filter. If you don't know about this product, I encourage you to ask around and learn more. It is heavy duty software with a wide community base on a number of platforms.
Chapter 9 contains a wealth of information on /etc, the source of basic configuration information for any Unix system. There is more information here than you will ever need in real life, but it's there if you need it. I found the information on /etc/login.access to be particular interesting from an administrative point of view.
Chapter 10 is recommended for everyone. If you are using the ports systems (and you should be), you will learn things here which you did not know.
Chapter 11 taught me about shared library management. I had never given much thought to this issue, but now I know how to find what libraries are in use and which libraries are needed by a given program. The same chapter goes into detail regarding running code from other operating systems. It explains how the ABI (application binary interface) works. The ABI allows FreeBSD to run foreign programs (from another operating system such as Linux or Solaris). Such programs think they are running natively on their original OS. As a real world example, the special effects for "The Matrix" were done on a cluster of FreeBSD boxes running foreign code. If you are considering running such code, the book goes into detail regarding the installation and configuration of Linux Mode.
If you're an SMP fan, you'll find a section on using multiple processors.
When it comes to DNS, I'm an nslookup guy. It's the tool I grew up with and one I have used frequently. It is slowly being phased out in preference to dig. I'm glad Michael wrote about dig, because it got me into the habit of using it instead of nslookup. For DNS, there's more than 25 pages with good, practical examples. This should be plenty for those of you wanting to maintain your own zone information.
There are several other sections of the book which will have wide interest. If you're setting up a small network, creating an email server, or managing some Web servers, you'll find useful, well written, and easy-to-follow information. The book goes into detail on practical things most people want to do. To name two: Web server configuration (Apache, my Web server of choice) and mail server setup (Postfix, my MTA of choice). Practical examples are what people want and need. Even if you've been running systems for years, you'll still learn something new from this book.
Finally, if you are on first name terms with vodka, no doubt you'll get a chuckle out of this Web site. For the lawyers out there: I'm told the author had nothing at all to do with that site.
Would I buy this book? Yes. Do I recommend that you buy it? Yes. If you have friends that use FreeBSD and you want to buy them a present, Absolute BSD is something they will thank you for, and you'll have the satisfaction of knowing it's a present which will be used and appreciated for years to come.