Git Tutorial for Beginners [and Network Engineers!]

What is Git?

Git is the most used version control system in the world today. It was developed in 2005 by Linus Torvalds, the famous creator of the Linux operating system kernel.

If you are looking for the best Git Tutorial for beginners you are in the right place!

The purpose of Git is to manage a project, or a set of files, as they change over time. Git stores this information in a data structure called a repository.

A Git repository contains all the information relating to the changes to a file over time. These can then be used to track changes to a file or roll back changes that have been made in error.

I am going to teach you why you should be using version control and the new world of Git, Github, BitBucket, Gitlab, repositories, repo’s & branches.

Hi, my name is Roger Perkin, I am a network engineer and I use Git for Network Automation.

Should Network Engineers learn Git?

A lot of network engineers will take config files and save them to their desktop with a filename like routerbackup-18th-april-v2-osfp-change.txt

Then another engineer will make a change to a device and save another file to their machine called hubrouter-20thapril.txt

We are all guilty of this and it’s a hard habit to break. But with the world of network automation, we as network engineers can learn a lesson from the software development guys who have been using Git for years.

Having a system where you have a single file but can also review all the changes to that file makes a lot of sense in the world of computer networks.

With the advances in network automation network engineers are embracing Git & Github to take control of their code.

Typical use cases are:

• Network device configuration files
• Ansible playbooks
• Python scrips

How to use Git

In order to use Git to track your code you need to install it.

This is a very simple process. Depending on what device you are working with I have listed all the options below - or you can just watch the video.

5 Steps to using Git for the first time

• Install Git
• Tell Git some basic info about you
• Create a folder on your machine
• Initialise Git within that folder
• Add files to Git
• Commit files to the repository

Git Basics - command-line fundamentals

Whilst there are many ways to use Git with a GUI or within your code editor it is very beneficial to understand how Git works under the hood and to learn the command-line fundamentals.

Git vs Github

There is a common misconception that Git and Github are the same thing.

This is not the case.

Git and Github are two completely different things.

Git is a locally installed piece of software that allows you to version control your code on your device.

Github is a web based platform at https://github.com/ which is used to provide an online repository of your code. You connect your local Git installation to your remote Github repository and then sync your code. You can then collaborate with other developers / network engineers.

It’s like Google Drive for your code.

You can also easily provide access to your code to others.

Github provide free plans which give you a public repository, if you want private repositories you have to sign up for a paid plan.

Update: Since Jan 20019 Github now also provides unlimited private repositories with a limited number of collaborators.
https://github.blog/2019-01-07-new-year-new-github/

There are also many other options for places to put your code online e.g. ButBucket and you could even install your own GitLab server on site.

Windows

https://git-scm.com/download/win

MAC

https://git-scm.com/download/win

Debian (e.g. Ubuntu)

apt-get install git

Fedora (e.g. Centos / Red Hat Linux)

yum install git

Basic Git Commands

So now you should have Git installed we can start getting into it with some basic Git commands.

For the rest of this post I will be using an Ubuntu installation, but the steps will be the same for all devices.

Check Git Version

To check Git is installed correctly and verify the version issue the command below:

[email protected]:~$ git --version 
git version 2.17.1
[email protected]:~$ 

Next we are going to create a folder for this demo. You will probably already have a folder with your code in that you want to version control we will cover that option later.

Once I have created the folder I enter the command git status and it tells you that Git is not enabled for this folder.

[email protected]:~$ 
[email protected]:~$ mkdir GITfolder
[email protected]:~$ git status 
fatal: not a git repository (or any of the parent directories): .git
[email protected]:~$ 

The reason you get the error fatal: not a git repository is because we have not initialised Git on the folder.

To do that enter the command git init

[email protected]:~$ cd GITfolder 
[email protected]:~/GITfolder$ git init
Initialized empty Git repository in /home/roger/GITfolder/.git/
[email protected]:~/GITfolder$ 

We have now enabled Git to start tracking changes to files within this folder.

So let’s create a file to start tracking, I will also enter a line of text into the file.

[email protected]:~/GITfolder$ 
[email protected]:~/GITfolder$ touch file1.txt
[email protected]:~/GITfolder$ echo "line of text 1" > file1.txt
[email protected]:~/GITfolder$ cat file1.txt
line of text 1
[email protected]:~/GITfolder$

If we now issue the git status command you will see the following.

This image shows us that we are:

• On the master branch (more on that later)
• There have been no commits
• We are not tracking file1.txt

So the next step is to add the file1.txt file into Git so we can start tracking changes to the file.

To add the file1.txt file to Git you just enter the command

git add <filename>

Our file, file1.txt is now being tracked by Git.

So let’s make a change to that file and see what Git detect.

[email protected]:~/GITfolder$ echo "Changed the line of text" > file1.txt
[email protected]:~/GITfolder$ 
[email protected]:~/GITfolder$ 
[email protected]:~/GITfolder$ cat file1.txt
Changed the line of text
[email protected]:~/GITfolder$ 

Now we will issue the command git status again to see what has changed.

You can see now the Git has detected that a change has been made to the file. It now has a modified status and is showing as red. So let’s add the file again and see what happens.

[email protected]:~/GITfolder$ git add file1.txt
[email protected]:~/GITfolder$ git status 
On branch master

No commits yet

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)

	new file:   file1.txt

However, at this time we have not committed the file into Git, the files have not been staged. So to commit the file you enter the command
git commit -m “First Commit”
You have to put a message with the commit with the -m flag and then any comment you want.

[email protected]:~/GITfolder$ git commit -m "First Commit"
[master (root-commit) c9ee375] First Commit
 1 file changed, 1 insertion(+)
 create mode 100644 file1.txt
[email protected]:~/GITfolder$ git status 
On branch master
nothing to commit, working tree clean
[email protected]:~/GITfolder$

You can see now after I enter the command git status that the working tree is clean. This means that all changes to our file have been committed to the Git repository. Because we did not commit the file on the first change it does not have any knowledge of the first text, so I will make one more change to the file and commit it again. Git will then have the 2 changes in it’s log.

Frequently asked questions

git rebase
git stash
git meaning
git delete branch
git rename branch
git merge
git clone
git for windows

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