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Powerful Command-Line Applications in Go

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Introduction

About the Go Language About This Course

First Command-Line Program in Go

Building a Basic Word Counter Testing the Basic Word Counter Command-Line Flags Wrapping Up Exercise: Counting Unicode Characters Solution: Counting Unicode Characters Quiz: Command-Line Program in Go Preface

Interacting with Users

Defining the To-Do API Creating the To-Do File Creating the To-Do Test File Creating the Initial To-Do Command-Line Tool Testing the Initial CLI Implementation Handling Multiple Command-Line Options Display Command-Line Tool Usage Improving the List Output Format Increasing Flexibility with Environment Variables Capturing Input from STDIN Wrapping Up Exercise: Delete a To-Do item Solution: Delete a To-Do Item Quiz: Interacting with Users

Working with Files in Go

Creating a Basic Markdown Preview Tool Writing Tests for the Markdown Preview Tool Adding Temporary Files to the Markdown Preview Tool Using Interfaces to Automate Tests Adding an Auto-Preview Feature Cleaning Up Temporary Files Improving the Markdown Preview Tool with Templates Updating Functions to Improve the Markdown Preview Tool Wrapping Up Exercise: Working with Files Solution: Working with Files Quiz: Working with Files in Go

Navigating the File System

Developing a File System Crawler Testing with Table-Driven Testing Deleting Matched Files Testing with the Help of Test Helpers Logging Deleted Files Archiving Files Updating the Function Archiving Files Wrapping Up Exercise: Restoring Files and Directories Solution: Restoring Files and Directories Quiz: Navigating File System

Improving the Performance of CLI Tools

Introduction to colStats Developing the Initial Version of colStats Final Touches to the Initial Version of colStats Writing Tests for colStats Testing colStats Benchmarking Our Tool Profiling Our Tool Reducing Memory Allocation Improving the colStats Tool to Process Files Concurrently Reduce Scheduling Contention Wrapping Up Exercise: Benchmarking Functions Solution: Benchmarking Functions Quiz: Improving the Performance of CLI Tools

Controlling Processes

Executing External Programs Handling Errors Writing Tests for Goci Defining a Pipeline Updating the Pipeline Handling Output from External Programs Running Commands with Contexts Integration Tests with a Local Git Server Testing Commands with Mock Resources Handling Signals Wrapping Up Exercise: Capturing and Parsing Command Output Solution: Capturing and Parsing Command Output Quiz: Controlling Processes

Using the Cobra CLI Framework

Starting the Cobra Application

Navigating the New Cobra Application

Adding the First Subcommand to the Application

Starting the Scan Package

Creating the Subcommands to Manage Hosts

Manage the Hosts List Under the Hosts Subcommand

Testing the Manage Hosts Subcommands

Adding the Port Scanning Functionality

Testing the Port Scanning Functionality

Updating the Port Scanning Functionality

Using Viper for Configuration Management

Generating Command Completion and Documentation

Exercise: Adding and Validating Flags

Solution: Adding and Validating Flags

Quiz: Using the Cobra CLI Framework

Talking to REST API

Developing a REST API Server Testing the REST API Server Completing the REST API Server Adding Finishing Touches to the REST API Server Developing the Initial Client for the REST API Adding Finishing Touches to the Initial Client for the REST API Testing the Client without Connecting to the API Viewing a Single Item Adding an Item Testing HTTP Requests Locally Completing and Deleting Items Executing Integration Tests Wrapping Up Exercise: Talking to REST APIs over the Internet Solution: Talking to REST APIs over the Internet Quiz: Talking to REST API

Developing Interactive Terminal Tools

Overview: Developing Interactive Terminal Tools Initializing the Pomodoro Application Storing Data with the Repository Pattern Testing the Pomodoro Functionality Building the Interface Widgets Organizing the Interface’s Layout Building the Interactive Interface Initializing the CLI with Cobra Wrapping Up Exercise: Interactive Terminal Applications Solution: Interactive Terminal Applications Quiz: Developing Interactive Terminal Tools

Persisting Data in a SQL Database

Persisting Data in the Database Testing the Repository with SQLite Updating the Application to Use the SQLite Repository Displaying a Summary to the Users Displaying Historical Data to the Users Wrapping Up Exercise: Databases Solution: Databases Quiz: Persisting Data in a SQL Database

Distributing Tool

Starting the Notify Package Including OS-Specific Files in the Build Testing the Notify Package Conditionally Building the Application Wrapping Up Exercise: Supporting Multiple Operating Systems Solution: Supporting Multiple Operating Systems Quiz: Distributing Tool

Appendix

Tracing Our Tool Getting Started with SQLite Go, SQL, and SQLite Compiling the Go Application for Containers

Solution: Adding and Validating Flags

See the solution to adding a new flag to the pScan scan subcommand.

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Solution explanation

Solution explanation

In the scan.go file, we run a preRunE function that specifies a new filter that the user can add. Some valid values in a bool map, called validValues, are defined. Finally, we check if a valid filter value has been passed. If not, we throw an error message and leave the function.

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