Apress has been putting out a number of solid Ruby books of late, and Practical Ruby for System Administration by André Ben Hamou is one of two great additions to their catalog.
André has a easy to read writing style, and covers a lot of ground in this book. The book contains a number of good examples, and would make a great book for a sys admin who’s looking into Ruby.
The most important chapter is probably the third, ‘A Practical Look at Performance’. It covers both determining whether Ruby is performant enough for systems administration tasks and analyzing and optimizing your Ruby code. Other chapters of particular note are the ninth, ‘Network Monitoring’, and the twelfth, ‘The Future of Ruby’. (Although I wish André had covered rubinius as well as YARV and JRuby in his coverage of execution environments.)
This book won’t replace The Pick-Axe as the go-to reference for a Rubyist, but it certainly belongs on the desk of your favorite sys admin (even if that’s yourself).