Install Go, write hello world, understand go run vs go build.

Install Go & Run Hello World

Go (sometimes written Golang because "go" is hard to search for) is a small, fast, compiled language made at Google in 2007. The whole spec fits on a few pages — and yet it's powerful enough to write web servers, CLIs, Kubernetes, Docker, and most of the modern cloud.

What makes it stand out:

• Fast compiler — a million-line codebase builds in seconds, not minutes.
• Single binary output — go build produces one file you can copy and run.
• Built-in concurrency — goroutines and channels make parallel code readable.
• Tiny syntax — about 25 keywords. You can fit the language in your head.
• Excellent tooling — formatter, linter, tests, docs, profiler all in go ....

Install

Pick one:

• Official installer: download from go.dev/dl.
• macOS: brew install go
• Linux (apt): sudo apt install golang-go (or use the official tarball)
• Windows: download the MSI from go.dev/dl

Verify the install:

go version
# go version go1.23.x linux/amd64

If you also want to know where Go put things and how it's configured:

go env GOROOT GOPATH GOBIN

• GOROOT — where the Go toolchain itself lives (set automatically).
• GOPATH — where downloaded modules and installed binaries go (default: ~/go).
• GOBIN — where go install puts binaries. Add this to your $PATH.

Your first program

This is the entire program — no class, no boilerplate, no main method buried inside an object.

What every piece does:

• package main — every Go file belongs to a package. The special name main means "this file produces an executable program". Libraries use any other name.
• import "fmt" — bring in the standard library's formatting package. fmt reads "fumpt" if you say it out loud; nobody knows why.
• func main() — the entry point. When you run the program, Go calls this function.
• fmt.Println(...) — print a line. The dot means "from the fmt package".

A note on go.mod

Real Go programs always live inside a module — a folder with a go.mod file at the top. To turn a fresh folder into one, run once:

mkdir hello && cd hello
go mod init example.com/hello   # any unique path works

That creates go.mod. After that, go run . and friends just work. We come back to modules properly in the next-but-one lesson.

Running Go locally

You have three tools you'll use every day:

| Command | What it does | | ------------- | ----------------------------------------------------------- | | go run . | Compile and execute the current directory's program. | | go build | Compile to a binary you can ship (a single file, no JVM). | | go test ./... | Run every test under the current module. |

$ go run .
hello, world
$ go build -o hello
$ ./hello
hello, world

go run is a quick "compile and execute and throw the binary away" — handy while you're iterating. go build keeps the binary so you can ship it.

The binary is statically linked: it has no runtime dependencies. You can copy it to a server that doesn't have Go installed and it still works. This is one of the big reasons people pick Go.