Git Basics

By Xah Lee. Date: 2012-08-08. Last updated: 2017-03-29.

This is a practical git tutorial for beginner, focus on the commands that are used daily by every programer.

Most Frequently Used Git Commands

Following are the most frequently used commands. Those with a star ★ are use daily.

To begin, you either create a new project, or “clone” a project from a URL. “clone” means copy.

git Commands for New Project
Command Name	Most Common Use
`git init`	Create a git repository in current dir. This will create a directory named “.git” in current dir. The “.git” directory holds all git's internal data.
`git clone url`	Clone the repository from `url` to current dir.

Once you have a project, you edit to make changes, then you need to “add” to a staging area, then “commit”. (They are done to the local repository.)

Most Commonly Used git Commands for Changes in Local Repository
Command Name	Most Common Use
★ `git status`	Show current status. (that is, list changed files.)
★ `git add .`	Add changes from current dir to local repository's staging area.
★ `git commit -m"message"`	Commit changes after add, to local repository. The `message` is a short description of changes you made.

To get update from a server, or put your changes to a server , you need to “pull/push”.

Most Commonly Used Git Commands for Sync with Remote Repository
Command Name	Most Common Use
★ `git pull`	Pull from remote to your local repository.
★ `git push`	Push your local repository to remote.

Set Up Name and Email Info

First, you need to setup a default name and email. Else, git won't let you commit.

# set up default name and email
git config --global user.name "Mary Lee"
git config --global user.email "mary@example.com"

the above will create a file at ~/.gitconfig. You can run these commands again to change. (you can also edit the file directly.)

Create a Project

How to create a project?

cd project_dir → cd to the directory of your source code.
git init → create a .git dir in the current dir. This dir holds all git's data about the current project.
git add . → add current dir (and subdir) files into git staging area.
git commit -m"first commit" → commit to local repository.

Important: when using git, you should always cd the directory first. This is in contrast to traditional unix commands, where you can simply give the directory's full path.

Example:

# cd to the dir containing your code
cd my_project

# initialize. This creates a .git dir.
git init

# add all files to “staging area”
git add .

# commit to local repository.
git commit -m"my first commit"

Git will create a dir named .git in the same dir. This dir is used by git for all its info, including its database.

Note: as of 2012, Adding 20k files takes about 6 minutes. Commiting 20k files takes 6 minutes.

Clone a Project

Clone a projet is similar to creating a git project, except it's for when there's a existing project in git on a server. You want to “copy” it and work with that project.

How to clone a project?

cd to a directory where you want the new project dir to be, then git clone path_or_url.

Example:

# get a copy of git source code (~10MB)
git clone git://git.kernel.org/pub/scm/git/git.git

# get a copy of the js jquery source code
git clone https://github.com/jquery/jquery.git

git clone URL → creates a dir in the current dir with the remote repo's content. The newly created dir will have the same name as project name of the remote repository at URL. If a non-empty directory of the same name already exist, git will complain.

Note to svn users: git also has a “checkout” command. It's used for updating/reverting your current dir from a repository (a older version, or different branch, etc.). git checkout is similar to svn merge and svn revert. 〔►see svn Tutorial〕