Golang series: Chapter Two - Writing and Running Your First Go Program (Hello World)

Golang Tutorial Part 2: Writing and Running Your First Go Program

Welcome to the second installment of our Go tutorial series! If you haven’t yet read Part 1: Introduction and Installation, we highly recommend starting there to learn what Go is and how to install it on your system.

Now, let’s get hands-on and write your very first Go program.

How to Set Up Your Go Development Environment

Start by creating a directory for your Hello World program. Open your terminal and run:

mkdir ~/golang-hello

This creates a folder named golang-hello in your home directory. You can use another location if preferred.

Initializing a Go Module

Navigate into your new directory and initialize a Go module. Modules help manage dependencies in Go projects.

cd ~/golang-hello
go mod init module-hello

Expected output:

go: creating new go.mod: module module-hello

Your go.mod file should contain:

module module-hello

go 1.21.0

This defines the module name and the Go version.

Writing Your First Go Program

Inside the golang-hello directory, create a new file named main.go and add the following code:

package main

import "fmt"

func main() {
	fmt.Println("Hello World")
}

This is the standard structure for a simple Go program.

How to Run a Go Program

There are multiple ways to execute your Go code. Let’s explore the most common options.

1. Using go install

cd ~/golang-hello
go install

If you see an error such as:

go install: no install location for directory ... outside GOPATH

Set the GOBIN environment variable:

export GOBIN=~/go/bin/

Then run:

go install

Now execute the binary:

~/go/bin/module-hello

Output:

Hello World

Add this to your shell’s PATH for easier access:

export PATH=$PATH:~/go/bin

Now you can just type:

module-hello

2. Using go build

This method compiles the code and outputs a binary in the current directory:

cd ~/golang-hello
go build
./module-hello

Output:

Hello World

3. Using go run

This is the quickest way to run your code during development:

cd ~/golang-hello
go run main.go

Output:

Hello World

To view the temporary build directory:

go run --work main.go

Sample output:

WORK=/tmp/go-build199689936
Hello World

4. Using Go Playground

Go Playground is an online environment where you can write, run, and share Go code. Try the Hello World example there!

Which Go Run Method Should You Use?

• Go Playground: Best for sharing or testing small snippets.
• go run: Perfect for rapid development and debugging.
• go build: Great when you want a local binary for testing.
• go install: Ideal for globally installing CLI tools.

Breakdown of the main.go File

package main

import "fmt"

func main() {
	fmt.Println("Hello World")
}

• package main: Defines the entry point of your application.
• import "fmt": Imports Go’s standard formatting and I/O library.
• func main(): The main function where execution starts.
• fmt.Println(...): Prints a line to the console.

What’s Next in the Go Tutorial Series?

In the next chapter, we’ll explore variables in Go, covering how to declare, assign, and use them effectively.

Stay tuned and happy coding! 🚀