Part 3: Under the Hood dives into the inner workings of CLI application development, with real-world examples written in Go. This section of the website provides complete, working code samples—along with compiling instructions—so readers can quickly get hands-on with the concepts. It also includes examples from Part 4: The Modern CLI, which explores patterns, practices, and design strategies in greater depth. Together, these examples bring the book’s ideas to life and support deeper learning through practical application.
| Example | Purpose |
|---|---|
| IP Tool | A simple CLI that demonstrates the use of flags and switches while interacting with an external API to retrieve the public IP address of the host machine. |
| Cobra CLI | A straightforward yet fully functional example showcasing the object-command model implemented using the Cobra package. It demonstrates how to structure commands, flags, and subcommands following modern CLI design principles. |
| Logger | Demonstrates configurable logging using the ZeroLog library, with support for adjustable severity levels to suit various runtime environments. |
| Exit Code | A minimal example that demonstrates how to return meaningful exit codes from a command-line application to signal success or failure. |
| Task CLI | This example was designed to demonstrate object return values and structured exit codes, as discussed in the chapter “Put On Your PowerShell® Hat.” It illustrates how to build CLIs that integrate cleanly with scripting environments like PowerShell. |
| Output CLI | This example can be examined to better understand default formatting and using a flag to specify various alternate formats. |
| REPL CLI | This example showcases a Read-Eval-Print Loop (REPL) style interface. It echoes user input and includes basic built-in commands such as HELP and EXIT, providing a simple foundation for interactive CLI applications. |
| Languages | This page highlights key language differences—such as readability and type systems—through side-by-side “Hello, World” examples written in Python, Rust, and Go. |
Additional relevant topics that did not make the book can be found in this site’s Overflow section.