Book Image

The Software Developer's Guide to Linux

By : David Cohen, Christian Sturm
5 (2)
Book Image

The Software Developer's Guide to Linux

5 (2)
By: David Cohen, Christian Sturm

Overview of this book

Developers are always looking to raise their game to the next level, yet most are completely lost when it comes to the Linux command line. This book is the bridge that will take you to the next level in your software development career. Most of the skills in the book can be immediately put to work to make you a more efficient developer. It’s written specifically for software engineers, not Linux system administrators, so each chapter will equip you with just enough theory to understand what you’re doing before diving into practical commands that you can use in your day-to-day work as a software developer. As you work through the book, you’ll quickly absorb the basics of how Linux works while you get comfortable moving around the command line. Once you’ve got the core skills, you’ll see how to apply them in different contexts that you’ll come across as a software developer: building and working with Docker images, automating boring build tasks with shell scripts, and troubleshooting issues in production environments. By the end of the book, you’ll be able to use Linux and the command line comfortably and apply your newfound skills in your day-to-day work to save time, troubleshoot issues, and be the command-line wizard that your team turns to.
Table of Contents (20 chapters)
18
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19
Index

Testing

The testing commands shown here are usually used along with if/else control flow statements. Both the string testing function ([[) and the arithmetic testing function ((() return 0 if the test evaluates to a true value, or 1 if the test evaluates to false. This is due to the 0 exit code of commands indicating success, and it is different from other programming languages you might know that typically evaluate a zero value as false. There is no native boolean data type in Bash; the integers 0 and 1 are used in boolean contexts like this one. Sometimes, the variables true and false are initialized and used throughout a script.

Testing operators

Here are some basic boolean operators that you can use to construct statements in Bash – essentially, what you’re used to from other languages:

  • ! – not (negation)
  • && – and
  • || – or

These operators can be used with both string and arithmetic test types:

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