Setting Up and Hello World

This lesson walks you through installing Go, setting up your workspace, creating your first module, and writing, building, and running your first Go program.

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Installing Go

Download and Install

Go can be installed from go.dev/dl. Downloads are available for all major platforms:

Platform	Installation Method
macOS	.pkg installer or brew install go
Windows	.msi installer or choco install golang
Linux	Extract the tarball to /usr/local

Verify the Installation

After installing, open a terminal and run:

go version

You should see output like:

go version go1.22.0 linux/amd64

Key Environment Variables

go env GOPATH    # Where Go stores downloaded modules (~/ go by default)
go env GOROOT    # Where Go itself is installed
go env GOOS      # Target operating system
go env GOARCH    # Target architecture

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Your First Module

Go uses modules to manage dependencies. Every Go project starts with a module.

Create a Project Directory

mkdir hello
cd hello

Initialise the Module

go mod init example.com/hello

This creates a go.mod file:

module example.com/hello

go 1.22

The module path (example.com/hello) is typically the repository URL where the code will be hosted (e.g., github.com/yourname/hello).

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Hello, World!

Create a file called main.go:

package main

import "fmt"

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

Understanding the Code

Element	Purpose
package main	Declares this file belongs to the main package — the entry point for an executable
import "fmt"	Imports the fmt package for formatted I/O
func main()	The entry point of the program — execution starts here
fmt.Println	Prints a line to standard output

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Running Your Program

You have two options:

Option 1: go run

Compile and run in one step (great for development):

go run main.go

Output:

Hello, World!

Option 2: go build

Compile to a binary, then run it:

go build -o hello
./hello

The -o hello flag specifies the output binary name. On Windows, use hello.exe.

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Cross-Compilation

Go makes cross-compilation trivial. Set GOOS and GOARCH:

# Build for Linux on AMD64
GOOS=linux GOARCH=amd64 go build -o hello-linux