CLI applications require a way to understand how we want them to execute. This might include what files to read, what servers to contact, and what credentials to use. There are a couple of ways to start an application with the parameters it requires:

Using the flag package to define command-line flags.
Using os.Args to read arguments that are not defined.

The flag package will help us when we have a command-line argument that has a strict definition. This might be an argument that defines the endpoint for a needed service. The program might want to have a default value for production but allow an override when doing testing. This is perfect for a flag.

An example might be a program that queries our Quote of the Day (QOTD) server that we created earlier. We might want to have it automatically use our production endpoint unless we specify it to use another address. This might look like this:

Introduction to the Course

Go Language Basics

Go Language Essentials

Filesystem Interactions

Using Common Data Formats

Interacting with Remote Data Sources

Writing Command-Line Tooling

Automating Command-Line Tasks

Observability with OpenTelemetry

Automating Workflows with GitHub Actions

Using ChatOps to Increase Efficiency

Creating Immutable Infrastructure Using Packer

Infrastructure as Code with Terraform

Deploying and Building Applications in Kubernetes

Programming the Cloud

Designing for Chaos

Appendix

Conclusion

Implementing Application I/O