debian-mirror-gitlab/doc/gitlab-basics/start-using-git.md

type	description	last_updated
howto, tutorial	Introduction to using Git through the command line.	2020-06-30

Start using Git on the command line

Git is an open-source distributed version control system designed to handle everything from small to very large projects with speed and efficiency. GitLab is built on top of Git.

While GitLab has a powerful user interface from which you can do a great amount of Git operations directly in the browser, you’ll eventually need to use Git through the command line for advanced tasks.

For example, if you need to fix complex merge conflicts, rebase branches, merge manually, or undo and roll back commits, you'll need to use Git from the command line and then push your changes to the remote server.

This guide will help you get started with Git through the command line and can be your reference for Git commands in the future. If you're only looking for a quick reference of Git commands, you can download GitLab's Git Cheat Sheet.

For more information about the advantages of working with Git and GitLab:

•  Watch the GitLab Source Code Management Walkthrough video.
• Learn how GitLab became the backbone of Worldline’s development environment.

TIP: Tip: To help you visualize what you're doing locally, there are Git GUI apps you can install.

Requirements

You don't need a GitLab account to use Git locally, but for the purpose of this guide we recommend registering and signing into your account before starting. Some commands need a connection between the files in your computer and their version on a remote server.

You'll also need to open a command shell and have Git installed in your computer.

Command shell

To execute Git commands in your computer, you'll need to open a command shell (also known as command prompt, terminal, and command line) of your preference. Here are some suggestions:

• For macOS users:
  • Built-in: Terminal. Press ⌘ command + space and type "terminal" to find it.
  • iTerm2, which you can integrate with zsh and oh my zsh for color highlighting, among other handy features for Git users.
• For Windows users:
  • Built-in: cmd. Click the search icon on the bottom navbar on Windows and type "cmd" to find it.
  • PowerShell: a Windows "powered up" shell, from which you can execute a greater number of commands.
  • Git Bash: it comes built into Git for Windows.
• For Linux users:
  • Built-in: Linux Terminal.

Install Git

Open a command shell and run the following command to check if Git is already installed in your computer:

git --version

If you have Git installed, the output will be:

git version X.Y.Z

If your computer doesn't recognize git as a command, you'll need to install Git. After that, run git --version again to verify whether it was correctly installed.

Configure Git

To start using Git from your computer, you'll need to enter your credentials (user name and email) to identify you as the author of your work. The user name and email should match the ones you're using on GitLab.

In your shell, add your user name:

git config --global user.name "your_username"

And your email address:

git config --global user.email "your_email_address@example.com"

To check the configuration, run:

git config --global --list

The --global option tells Git to always use this information for anything you do on your system. If you omit --global or use --local, the configuration will be applied only to the current repository.

You can read more on how Git manages configurations in the Git Config documentation.

Git authentication methods

To connect your computer with GitLab, you need to add your credentials to identify yourself. You have two options:

• Authenticate on a project-by-project basis through HTTPS, and enter your credentials every time you perform an operation between your computer and GitLab.
• Authenticate through SSH once and GitLab won't ask your credentials every time you pull, push, and clone.

To start the authentication process, we'll clone an existing repository to our computer:

• If you want to use SSH to authenticate, follow the instructions on the SSH documentation to set it up before cloning.
• If you want to use HTTPS, GitLab will request your user name and password:
  • If you have 2FA enabled for your account, you'll have to use a Personal Access Token with read_repository or write_repository permissions instead of your account's password. Create one before cloning.
  • If you don't have 2FA enabled, use your account's password.

NOTE: Note: Authenticating via SSH is GitLab's recommended method. You can read more about credential storage in the Git Credentials documentation.

Git terminology

If you're familiar with the Git terminology, you may want to jump directly into the basic commands.

Namespace

A namespace is either a user name or a group name.

For example, suppose Jo is a GitLab.com user and they chose their user name as jo. You can see Jo's profile at https://gitlab.com/jo. jo is a namespace.

Jo also created a group in GitLab, and chose the path test-group for their group. The group can be accessed under https://gitlab.com/test-group. test-group is a namespace.

Repository

Your files in GitLab live in a repository, similar to how you have them in a folder or directory in your computer. Remote repository refers to the files in GitLab and the copy in your computer is called local copy. A project in GitLab is what holds a repository, which holds your files. Often, the word "repository" is shortened to "repo".

Fork

When you want to copy someone else's repository, you fork the project. By forking it, you'll create a copy of the project into your own namespace to have read and write permissions to modify the project files and settings.

For example, if you fork this project, https://gitlab.com/gitlab-tests/sample-project/ into your namespace, you'll create your own copy of the repository in your namespace (https://gitlab.com/your-namespace/sample-project/). From there, you can clone it into your computer, work on its files, and (optionally) submit proposed changes back to the original repository if you'd like.

Download vs clone

To create a copy of a remote repository files on your computer, you can either download or clone it. If you download it, you cannot sync it with the remote repository on GitLab.

On the other hand, by cloning a repository, you'll download a copy of its files to your local computer, but preserve the Git connection with the remote repository, so that you can work on the its files on your computer and then upload the changes to GitLab.

Pull and push

After you saved a local copy of a repository and modified its files on your computer, you can upload the changes to GitLab. This is referred to as pushing to GitLab, as this is achieved by the command git push.

When the remote repository changes, your local copy will be behind it. You can update it with the new changes in the remote repo. This is referred to as pulling from GitLab, as this is achieved by the command git pull.

Basic Git commands

For the purposes of this guide, we will use this example project on GitLab.com: https://gitlab.com/gitlab-tests/sample-project/.

To use it, log into GitLab.com and fork the example project into your namespace to have your own copy to playing with. Your sample project will be available under https://gitlab.com/<your-namespace>/sample-project/.

You can also choose any other project to follow this guide. Then, replace the example URLs with your own project's.

If you want to start by copying an existing GitLab repository onto your computer, see how to clone a repository. On the other hand, if you want to start by uploading an existing folder from your computer to GitLab, see how to convert a local folder into a Git repository.

Clone a repository

To start working locally on an existing remote repository, clone it with the command git clone <repository path>. You can either clone it via HTTPS or SSH, according to your preferred authentication method.

You can find both paths (HTTPS and SSH) by navigating to your project's landing page and clicking Clone. GitLab will prompt you with both paths, from which you can copy and paste in your command line.

For example, considering our sample project:

• To clone through HTTPS, use https://gitlab.com/gitlab-tests/sample-project.git.
• To clone through SSH, use git@gitlab.com:gitlab-tests/sample-project.git.

To get started, open a terminal window in the directory you wish to add the repository files into, and run one of the git clone commands as described below.

Both commands will download a copy of the files in a folder named after the project's name and preserve the connection with the remote repository. You can then navigate to the new directory with cd sample-project and start working on it locally.

Clone via HTTPS

To clone https://gitlab.com/gitlab-tests/sample-project/ via HTTPS:

git clone https://gitlab.com/gitlab-tests/sample-project.git

TIP: Troubleshooting: On Windows, if you entered incorrect passwords multiple times and GitLab is responding Access denied, you may have to add your namespace (user name or group name) to clone through HTTPS: git clone https://namespace@gitlab.com/gitlab-org/gitlab.git.

Clone via SSH

To clone git@gitlab.com:gitlab-org/gitlab.git via SSH:

git clone git@gitlab.com:gitlab-org/gitlab.git

Convert a local directory into a repository

When you have your files in a local folder and want to convert it into a repository, you'll need to initialize the folder through the git init command. This will instruct Git to begin to track that directory as a repository. To do so, open the terminal on the directory you'd like to convert and run:

git init

This command creates a .git folder in your directory that contains Git records and configuration files. We advise against editing these files directly.

Then, on the next step, add the path to your remote repository so that Git can upload your files into the correct project.

Add a remote repository

By "adding a remote repository" to your local directory you'll tell Git that the path to that specific project in GitLab corresponds to that specific folder you have in your computer. This way, your local folder will be identified by Git as the local content for that specific remote project.

To add a remote repository to your local copy:

1. In GitLab, create a new project to hold your files.

2. Visit this project's homepage, scroll down to Push an existing folder, and copy the command that starts with git remote add.

3. On your computer, open the terminal in the directory you've initialized, paste the command you copied, and press enter:

   git remote add origin <git@gitlab.com:username/projectpath.git
   

After you've done that, you can stage your files and upload them to GitLab.

Download the latest changes in the project

To work on an up-to-date copy of the project (it is important to do this every time you start working on a project), you pull to get all the changes made by users since the last time you cloned or pulled the project. Use master for the <name-of-branch> to get the main branch code, or the branch name of the branch you are currently working in.

git pull <REMOTE> <name-of-branch>

When you clone a repository, REMOTE is typically origin. This is where the repository was cloned from, and it indicates the SSH or HTTPS URL of the repository on the remote server. <name-of-branch> is usually master, but it may be any existing branch. You can create additional named remotes and branches as necessary.

You can learn more on how Git manages remote repositories in the Git Remote documentation.

View your remote repositories

To view your remote repositories, type:

git remote -v

The -v flag stands for verbose.

Branching

If you want to add code to a project but you're not sure if it will work properly, or you're collaborating on the project with others, and don't want your work to get mixed up, it's a good idea to work on a different branch.

When you create a branch in a Git repository, you make a copy of its files at the time of branching. You're free to do whatever you want with the code in your branch without impacting the main branch or other branches. And when you're ready to bring your changes to the main codebase, you can merge your branch into the main one used in your project (such as master).

Create a branch

To create a new branch, to work from without affecting the master branch, type the following (spaces won't be recognized in the branch name, so you will need to use a hyphen or underscore):

git checkout -b <name-of-branch>

Switch to the master branch

You are always in a branch when working with Git. The main branch is the master branch, but you can use the same command to switch to a different branch by changing master to the branch name.

git checkout master

Work on an existing branch

To switch to an existing branch, so you can work on it:

git checkout <name-of-branch>

View the changes you've made

It's important to be aware of what's happening and the status of your changes. When you add, change, or delete files/folders, Git knows about it. To check the status of your changes:

git status

View differences

To view the differences between your local, unstaged changes and the repository versions that you cloned or pulled, type:

git diff

Add and commit local changes

You'll see any local changes in red when you type git status. These changes may be new, modified, or deleted files/folders. Use git add to first stage (prepare) a local file/folder for committing. Then use git commit to commit (save) the staged files:

git add <file-name OR folder-name>
git commit -m "COMMENT TO DESCRIBE THE INTENTION OF THE COMMIT"

Add all changes to commit

To add and commit (save) all local changes quickly:

git add .
git commit -m "COMMENT TO DESCRIBE THE INTENTION OF THE COMMIT"

NOTE: Note: The . character means all file changes in the current directory and all subdirectories.

Send changes to GitLab.com

To push all local commits (saved changes) to the remote repository:

git push <remote> <name-of-branch>

For example, to push your local commits to the master branch of the origin remote:

git push origin master

NOTE: Note: To create a merge request from a fork to an upstream repository, see the forking workflow.

Delete all changes in the branch

To delete all local changes in the branch that have not been added to the staging area, and leave unstaged files/folders, type:

git checkout .

Note that this removes changes to files, not the files themselves.

Unstage all changes that have been added to the staging area

To undo the most recently added, but not committed, changes to files/folders:

git reset .

Undo most recent commit

To undo the most recent commit, type:

git reset HEAD~1

This leaves the changed files and folders unstaged in your local repository.

CAUTION: Warning: A Git commit should not usually be reversed, particularly if you already pushed it to the remote repository. Although you can undo a commit, the best option is to avoid the situation altogether by working carefully.

Merge a branch with master branch

When you are ready to make all the changes in a branch a permanent addition to the master branch, you merge the two together:

git checkout <name-of-branch>
git merge master

Synchronize changes in a forked repository with the upstream

Forking a repository lets you create a copy of a repository in your namespace. Changes made to your copy of the repository are not synchronized automatically with the original. Your local fork (copy) contains changes made by you only, so to keep the project in sync with the original project, you need to pull from the original repository.

You must create a link to the remote repository to pull changes from the original repository. It is common to call this remote the upstream.

You can now use the upstream as a <remote> to pull new updates from the original repository, and use the origin to push local changes and create merge requests.