Git is a commonly used DVCS (distributed version control system), which was introduced by Linus Torvalds. GitHub, GitLab, Bitbucket and others are services, where you can easily create a remote git repository.

Install Git

On Ubuntu is is fairly easy:

sudo apt install git

For Windows you'll have to install the following:

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

Configure Git

It is good practice to apply a common global Git config:

git config --global user.name "Simon Scholz"
git config --global user.email opensource.simon@gmail.com

git config --global branch.autosetuprebase always
git config --global pull.rebase true
git config --global rebase.autoStash true
git config --global core.autocrlf input


git config --global gpg.program gpg
git config --global commit.gpgsign true

Besides configuring name and email setting up rebase and autoStash is really helpful, since this will stash uncommitted changes when pulling from the remote and then pop the changes once your local commits have been rebased onto the changes from the remote repository. The GPG configs will verify that your commits are really created by you.

Use git config --list to see all your current Git configs. To see the config of a repository use git config --list --show-origin.

Create a SSH key

In case you want to make use of SSH for cloning a SSH key needs to be created:

ssh-keygen -t ed25519 -C $USER

# or use rsa in case ed25519 is not available on your system

ssh-keygen -q -t rsa -b 4096 -f ~/.ssh/id_rsa -C $USER

The created public key needs to be configured on the remote origin, e.g., GitHub.

You can show the public key by running cat ~/.ssh/id_ed25519.pub or cat ~/.ssh/id_rsa.pub.

Clone a remote Git repository

git clone {uri-of-your-desired-repo}

e.g.

# ssh
git clone git@github.com:SimonScholz/tutorials.git

# https
git clone https://github.com/SimonScholz/tutorials.git

Creating a Git repository locally

Besides cloning a remote repository, you can also initialize it locally. And on demand this local Git repository can be pushed to a remote origin.

cd desired-folder-for-git-repo

git init

Adding files to the staging area and commit changes

Before files can be commited locally, the desired files have to reside in the staging area.

Using git add desired-file adds a particular file to the staging area. But you can also add each and every changed file inside the current folder by using git add . And with git add -A all changed files of the whole repo will be added.

Once there are the desired files inside the staging area they can be commited:

git commit -m "Message, which describes what will be commited"

NOTE: When changes are commited, they only reside in your local git repository.

Undo the last commit

To see what has changed due to the undo --soft can be used.

git reset --soft HEAD~1

In case you're certain that you want the latest commit to be undone --hard can be used.

git reset --hard HEAD~1

Add a remote origin to your local git repository

git remote add git@github.com:SimonScholz/tutorials.git

Once the remote is added a an upstream branch can be configured.

git push --set-upstream origin main

Pushing changes to a remote repository

git push origin main

Deleting already merged branches on remote repository

git branch -r --merge

This will show all branches, which already have been merged to your current HEAD.

To remove a certain branch use the following command then:

git push origin --delete "<branch-name>"