git_guide.md

Introduction to Git

Setup

Install Git

Download at https://git-scm.com/downloads

Create Gitlab account

Since a GitHub account can be used to sign into GitLab, I suggest first visiting https://github.com and creating a GitHub account. Then, proceed to sign into GitLab with GitHub.

Link GitHub account to Git

Enter the following commands with your GitHub username and email.

git config --global user.name "Your name here"
git config --global user.email "your_email@example.com"

At this point, your GitHub account is linked to Git and you can begin to push code to GitHub; however, git will require you to enter your password during every interaction with the repository. To fix this issue, we set up an SSH key.

Set up an SSH key

We create a private and public SSH key and give the public key to GitHub. If you run into any problems setting up the SSH key, refer to this article.

Check for existing SSH keys

First check to see if you have already generated a key pair. SSH keys are typically stored within a hidden folder in the home directory. List the items in this folder with the following command.

ls ~/.ssh

If you do not see a file containing ssh keys (usually a file ending in .pub), the next step is to generate a pair.

Create an SSH Key

Generate an SSH key pair with the following command.

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Upload SSH key to Git hosting service

With an SSH key in hand, navigate through the site's settings to find a tab to add SSH keys. Then, copy the key located in id_rsa.pub to the text box on the site.

Check everything worked

ssh -T git@gitlab.com

Getting started

We can run git commands through its command line interface (CLI). The first step we want to do is create a new repository.

The first thing we want to to is either create a new repository, or clone an existing one.

Create a new Repository

git init

Run this to verify that you have successfully authenticate.

This command will create a hidden folder named .git in the current working directory. This hidden folder contains all data regarding your project's version history. Note that initializing a repository does not start tracking for any of your files yet. See the next step to add your files.

Add files

When you run git init, it creates an empty git tracking file. You need to add the files you want to track manually. This process of adding files is called staging. You are staging for a commit.

git add myfile.cpp

Or select and add all of the files in the directory with the following command.

git add *

Note: This command adds all of the current

Ignore files

Another optional, but great feature of git is the use of a .gitignore file. Simply create an empty file with the name .gitignore in your working directory and list any files that you do not wish to track within it. Why would you not want to track everything? Certain files such as a.out or any other executables should never be tracked as they can be recompiled by another user. Most files that do not contain human-readable code should not be tracked.

Commit changes

Once you are ready to formally save your staged files to the version control software, you can run the following.

git commmit -m "Your commit message"

This basically stores the difference of your previous commit and your current commit in the hidden .git folder in your working directory.

Everything we have learned so far can be used offline. Next, we should push our changes to the remote repository.

Sync with a Remote Server

Add remote repository to Git

If you just initialized a new repository, we will need to tell Git where to push our changes.

git remote add origin ssh_url

Push changes to repository

Once you have made a commit, it is best practice to push it to your remote repository soon after.

If you have cloned your repository, Git will already know the location of your remote repository.

git push

Branches

Create a new branch when you start working on a fix or feature with

git checkout -b branchname