Addison Wesley

It's easy to write correct Ruby code, but to gain the fluency needed to write great Ruby code, you must go beyond syntax and absorb the "Ruby way" of thinking and problem solving.

The Go-To Resource for Large-Scale Organizations to Be Agile
Rather than asking, “How can we do agile at scale in our big complex organization?” a different and deeper question is, “How can we have the same simple structure that Scrum offers for the organization, and be agile at scale rather than do agile?” This profound insight is at the heart of LeSS (Large-Scale Scrum).

Because the UNIX system was originally designed by programmers for use by other programmers, it was used in an environment of open cooperation where security was of minimal concern. Now that its use has spread to universities, businesses, and government, the confidential and sensitive nature of the data stored on UNIX systems has made the security of these systems of paramount importance.
Despite all the technical papers and workshops on UNIX security, this book is unique. "UNIX System Security" is the first up-to-date source to provide the UNIX system user or administrator with the information needed to protect the data and system from unauthorized use. By following the procedures described in this book and making use of the C programs and shell scripts provided as examples, you can protect your UNIX system from most attackers.

The Smalltalk-80 system consists of an object-oriented programming language and an integrated collection of tools for interacting with components of that language. In the Smalltalk-80 language, the fundamental way to indicate that something should happen is by sending a message to an object. An object is a representation of information consisting of private memory, and a set of operations to manipulate information stored in the private memory or to carry out some actions relative to that information. Sending a message is the Smalltalk-80 way of asking the object to carry out one of its operations.