Testing Your Go Installation

Start here…

Now you have go installed you need to test it to make sure that it is installed correctly

We are going to test your Go installation be writing the “Hello World!” program in go. Once we have done that we are going to download and run the GopherCoders.com “Hello” program from the Internet.

We are not going to explain how these programs work. We will do that in the first few lessons. We just want to make sure that both of these programs work. If they do work your Go installation is also working. If they do not work then there is something wrong with your go installation. In this case you need to go back and check that you followed all the install instructions correctly.

Notes

You need to type the commands in the boxes like this:

ls
Remember to type the command _exactly_ as you see it. The case of the letters is important.

What you need

Before you start, you need to open a Terminal on Linux, Max OS X or your raspberry Pi. If you are using Windows you need to open a Windows Command Prompt window.

Once your terminal has opened you need to change directory to the src directory inside your Go workspace directory.

If you are using Linux, Mac OS X or a Raspberry Pi you need to type 

cd $GOPATH/src

If you are using Windows you need to type 

cd %GOPATH%\src

You will also need to a text editor. The name of your text editor is different on each operating system. The following are example text editors that you can use.

On Linux to start your text editor you need to type 

gedit

On Mac OS X to start your text editor you need to type 

open -a TextEdit

On a Raspberry Pi to start your text editor you need to type 

leafpad

On a Windows to start your text editor you need to type 

notepad

Hello World

Now you know how to start an editor you are almost ready to start to program “Hello World!”. First you need to make a new directory, called helloworld to do this you need to type

mkdir helloworld

and then change into the new directory

cd helloworld

Now start your text editor. When you text editor opens you need to type 

package main

import ("fmt")

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

Notes

The colours we are using are there to help you. You do not need to try to make the text in your editor have the same colours. Your text may all be black. We will explain what the colours mean in one of the first lessons.

This is a source code file. All source code files must be saved under your Go workspace directory. Now you need to save the file. Use your text editors File menu and select the Save option. You must save the file as helloworld.go.

Note

If you are using Windows and using the Notepad editor you should save the file as: "helloworld.go" including the " marks. If you do not do this Notepad will save the file as helloworld.go.txt. This is a well known problem with NotePad. If you install the Atom editor you will not have this problem.

You must also make sure you save the file in the correct directory. This should be the helloworld directory in your Go workspace that you created earlier. Once the file is saved you need to quit your text editor. Use the file menu and select the Quit or Exit option.

Note

Once you have quit your text editor, you can check if the file has been saved in the correct place and had the correct name - check the directory contents with the terminal.

On Linux, MacOS X or on a Raspberry Pi you need to type

ls $GOPATH/src/helloworld/
On Windows you need to type 
dir %GOPATH%\src\helloworld
If you see a file called `helloworld.go` in the output of either of these commands then everything is ok.

Now we are ready to run the program. To do this we need to use the go command. Type this following into your terminal

go build helloworld.go

If everything worked correctly you should see

Hello world!

printed by the program. Cool!

Note

If you don’t see

Hello world!
when you do this then there is something wrong. If the `go`command tells you there is a `syntax error` it means you have not typed the program correctly.

If you do see a syntax error, Go will tell you which line it thinks the problem is on. For example, if you saw this

.\helloworld.go:5: syntax error: unexpectd {, expected )}
It means the problem is on line 5 - that's what the number 5 means after the `:` after the `helloworld.go` bit. If you do see this, the rest of the error tells you what is wrong. In this case there is a missing `)` on line 5. This is why the `{` is unexpected. You may see something different here.

We’ll explain more about syntax errors as we go along.

To fix this you need to start your text editor again and open the helloworld.go file, just as before.

To do this on Linux you need to type

gedit helloworld.go

To do this on Mac OS X you need to type

open -a TextEdit -f helloworld.go

To do this on a Raspberry Piyou need to type

leafpad helloworld.go

To do this on a Windows you need to type

notepad helloworld.go

You need to carefully check that you have typed the program exactly as it was shown. Once you are sure it is correct save it again, as helloworld.go and try to run it again.

If the program still does not run, you still have a mistake somewhere in the program. You need to repeat the process of leading the helloworld.go file into the text editor and making sure it matches exactly, until the program runs as expected.

If you did make a mistake its okay. Programmers make mistakes all of the time. You will get better at avoiding them and fixing or debugging them as we go along.

Now that the “Hello World!”" program works it’s time to try the “Hello” program.

Hello

This time you are not going to type the program. We are going to download the source code from the Internet. This tests that the programs that Go depends on are all installed and working correctly.

First you need to change directory back to your the src directory in your Go workspace.

If you are using Linux, Mac OS X or a Raspberry Pi you need to type 

cd $GOPATH/src

If you are using Windows you need to type 

cd %GOPATH%\src

Now you need to download the source code from the Internet using the go command. To do this you need to type 

go get github.com/gophercoders/hello

To go get command will download the source code to your workspace. You now need to change to that directory.

If you are using Linux, Mac OS X or a Raspberry Pi you need to type 

cd $GOPATH/src/github.com/gophercoders/hello

If you are using Windows you need to type 

cd %GOPATH%\src\github.com\gophercoders\hello

If you now do

On Linux, MacOS X or on a Raspberry Pi you need to type 

ls
On Windows you need to type 
dir

You will see the files that we downloaded. hello.go is the source file we are interested in.

Now we have the source code want to run it. To do this we need to use the go run command again. If you type

go run hello.go

into your terminal or command prompt the program should run. The program should print a message and then show you a gopher in the terminal.

We are almost done. There is another way to run your program to go build command. The go build command will build your program, but will not run it. Instead it creates a new program that you can run. Try typing this in your terminal

go build hello.go

Now if you look at the files in the directory again by typing On Linux, MacOS X or on a Raspberry Pi you need to type 

ls
On Windows you need to type 
dir

You will see an new file called hello or hello.exe (if you are using Windows). This new file is your program. To run it you need to type

hello

and you should see the same result as before.

Now that you know Go works correctly you should setup an alternative editor to make programming easier.

Search

Concepts

Featured Lesson

Numbers

What You are Going to Learn?

Computers are used to process data. All data is made up of numbers. Yes, really! Everything is just a bunch of numbers to a computer. These are the only things they understand.

We are going to explain how numbers are used in Go programs. Then we are going to show you how to do type sums in Go.