hello-world.md

Hello World

In this tutorial, we will see how to setup Go environment and create a simple hello world program. We will also see how to run the program using different commands. So far here is the value of GOROOT, GOPATH, and GOBIN.

echo $GOROOT will give installed directory for GO
echo $GOPATH will give ~/Desktop/go
echo $GOBIN will give ~/Desktop/go/bin

A typical program has .go file extension. Now let’s create a “Hello World” program. For that first create a directory named hello outside $GOPATH/src. Since the project is getting creating outside $GOPATH/src we also need to create a go.mod file with import path as sample.com/hello .For now, let’s create a simple module so that we can see how the hello world program looks like in go. Use the below command for that

go mod init sample.com/hello

It will create go.mod file as below.

module sample.com/hello
go 1.14

Now create file hello.go with below contents.

package main

import "fmt"

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

There are three different commands to run the above GO program. First cd to the ‘hello’ directory which contains the hello.go file.

go install

It will compile the program and place the binary at the $GOBIN folder. Type the go install command, make sure you are in the hello directory which contains the hello.go file.

It will create a binary named hello in the $GOBIN directory.

The name of the binary is same as last part of the import path of the module. The import path of the module is sample.com/hello and last part of import path is simply hello. Hence binary name will be hello in our case.

Type hello on the terminal, it will give below output:

Hello World

Output of which hello will be ~/Desktop/go/bin/hello . Remember our $GOBIN path was ~/Desktop/go/bin. Hence the binary hello was copied to this directory.

go build

It will compile the program and place the binary in the current working directory. Type the command go build. It will create the binary named hello same as impbeside hello.go file. To run the binary type ./hello on the terminal. It will give below output

Hello World

go run

The go run hello.go command will compile and then execute the binary. Type the command go run hello.go. It will output:

Hello World