Others have the knack of unerringly zeroing in on the root cause of a bug. Are they geniuses? Just lucky? No, they've learned the secrets of professional debugging. This book will equip you with the tools, techniques and approaches-proven in the crucible of professional software development-to ensure that you can tackle any bug with confidence. You'll learn how to handle every stage of the bug life-cycle, from constructing software that makes debugging easy, through detection, reproduction, diagnosis and rolling out your eventual fix. If you develop software, sooner or later you're going to discover that it doesn't always behave as you intended. Working out why it's misbehaving can be hard. Sometimes very hard. Debug It! is here to help! All bugs are different: there is no silver bullet. You've got to rely upon your intellect, intuition, detective skills and yes, even a little luck. But that doesn't mean that you're completely on your own-there is much you can learn from those who have gone before. This book distills decades of hard-won experience gained in the trenches of professional software development, giving you a head-start and arming you with the tools you need to get to the bottom of the problem, whatever you're faced with. Whether you're writing Java or assembly language, targeting servers or embedded micro-controllers, using agile or traditional approaches, the same basic bug-fixing principles apply. From constructing software that is easy to debug (and incidentally less likely to contain bugs in the first place), through handling bug reports to rolling out your ultimate fix, we'll cover the entire life-cycle of a bug. You'll learn about the empirical approach, which leverages your software's unique ability to show you what's really happening, the importance of finding a reliable and convenient means of reproducing a bug, and common pitfalls so you can avoid them. You'll see how to use commonly available tools to automatically detect problems before they're reported by customers and how to construct "transparent software" that provides access to critical information and internal state.

    With its simple commands, flags, and parameters, a well-formed command-line application is the quickest way to automate a backup, a build, or a deployment and simplify your life. With this book, you'll learn specific ways to write command-line applications that are easy to use, deploy, and maintain, using a set of clear best practices and the Ruby programming language. This book is designed to make any programmer or system administrator more productive in their job. Now updated for Ruby 2.Writing a command-line application that's self-documenting, robust, adaptable and forever useful is easier than you might think. Ruby is particularly suited to this task, because it combines high-level abstractions with "close to the metal" system interaction wrapped up in a concise, readable syntax. Plus, Ruby has the support of a rich ecosystem of open source tools and libraries.Ten insightful chapters each explain and demonstrate a command-line best practice. You'll see how to use these tools to elevate the lowliest automation script to a maintainable, polished application. You'll learn how to use free, open source parsers to create user-friendly command-line interfaces as well as command suites. You'll see how to use defaults to keep options simple for everyday users, while giving advanced users options for more complex tasks. There's no reason why a command-line application should lack documentation, whether it's part of a help command or a man page; you'll find out when and how to use both. Your journey from command-line novice to pro ends with a look at valuable approaches to testing your apps, and includes some fun techniques for outside-the-box, colorful interfaces that will delight your users.With Ruby, the command line is not dead. Long live the command line.