This is mainly a simple tutorial of Git. Some info about GitHub also included. You may also read Simple GitHub Tutorial.

Brief

You may have learnt Git and GitHub before, and also may have confused them because their similar names. What are these two things on earth?

In short, Git is a Version Control System (VCS), which enables you to create a repository of your codes, to track changes in your project and to manage your files efficiently. GitHub is a platform used to host remote Git repositories for collaboration and sharing projects.

In this post, you will learn the basic usage of Git. If you are looking for info about working with GitHub, see Simple GitHub Tutorial.

Installing Git

Download Git from the official website:

• Git - Downloads (git-scm.com)

Or use your favorite package manager by yourself. For example, use apt:

sudo apt update
sudo apt install git

Basic Configuration

Before starting to use Git, you should tell Git your name and email. The commands below set your name and email globally (which means they are visible to all your local repositories).

git config --global user.name "<your_name>"
git config --global user.email "<[email protected]>"

Learn more:

• Setting your username in Git - GitHub Docs
• Setting your commit email address - GitHub Docs

You may also set your default editor and default diff and merge tools. Here I set to VS Code.

# default editor
git config --global core.editor 'code --wait'

# default diff tool
git config --global diff.tool vscode
git config --global difftool.vscode.cmd 'code --wait --diff $LOCAL $REMOTE'

# default merge tool
git config --global merge.tool vscode
git config --global mergetool.vscode.cmd 'code --wait $MERGED'

Learn more:

• How to use VS Code as your Git editor, difftool, and mergetool

Getting Help

To get help when using Git, run:

git help <verb>
# Or
git <verb> --help
# Or
man git-<verb>

For example, if you are confused with git add, run:

git help add

Getting A Git Repository

It’s time for us to prepare a git repository. Here are two choices:

Creating One In An Existing Directory

To create a new Git repo in the current directory, run:

git init

This command will create a directory called .git.

Cloning One from An Existing Repo

See Simple GitHub Tutorial

Files’ States in a Git Project

There are three main states in Git: modified, staged, and committed. And this leads us to three main sections of a Git project: the Working Directory, the Staging Area and the Git Directory.

You modify your files in the Working Directory, stage them (using git add) to the Staging Area, and commit them (using git commit) to the Git Directory.

When a commit is made, a commit record is generated, which you can think of as a ‘snapshot’ of your code repository.

Also see Git - What is Git?.

Tracking Files

To add file(s) to your tracked list (or more precisely, put file(s) onto the Staging Area), run:

git add <directory>/<file>

To undo git add (unstage file(s)):

• Use git reset:

git reset         # unstage everything
git reset <file>  # unstage specific file(s)

• Use git restore:

git restore --staged <file>  # unstage specific file(s)
git restore --staged :/      # unstage all files

• Use git rm:

git rm --cached <file>

Checking Status

To check the status of the files in the repo, run:

git status

# A Short Version
git status -s
# Or
git status --short

In the short version, there are two columns in the front of every line. The left column shows the status of the Staging Area. The right column shows the status of the Working Directory. For example:

• ??: untracked file
• A: file newly added to the stage
• M: modified file

Checking Differences

# shows unstaged, uncommitted changes
git diff

# shows all uncommitted changes (including staged ones):
git diff HEAD

# shows only staged changes
git diff --staged
git diff --cached

Committing

To commit your files, run:

git commit

This command will open a editor. You need to edit your commit message here. Use the command below to set a default editor:

git config --global core.editor <path_to_editor_or_command_to_open_editor>

Or, you can simplify this by using -m option:

git commit -m <commit_message>

Oops, I forgot to add this file! If you meet this problem, you can amend it like this:

git commit -m "a wrong commit message"
git add <forgotten_file>
git commit --amend

The second commit will replace the first commit, as if the first commit never occurred.

If you are tired of using the stage (git add first,git commit later), you can use -a flag like this to skip it:

git commit -a

This command is equivalent to these two command bellow:

git add <all_tracked_files_that_have_been_modified>
git commit

History

To review the commit history, run:

git log

• -p or --patch flag make logs output in the patch way.
• -<n> flag to limit the number of logs (e.g. -2 only show two latest logs).
• --stat flag shows simple statistics.
• --pretty option provides some different ways to show the history.
  • --pretty=oneline option make every commit be showed in one line
  • --pretty=short
  • --pretty=full
  • --pretty=fuller
• --graph flag adds some ascii characters to vividly show your history.

Discarding Changes in Working

To discard changes in working, run:

git checkout -- <file>

This command will abandon the modifications to the file after your last commit, where -- indicates that the following content should be treated as file parameters, even if they resemble options.

Cleaning Files and/or Directories

git clean # deletes files that are not tracked by Git
git clean -d # deletes directories
git clean -x # deletes untracked files, including ignored files in `.gitignore` and `.git/info/exclude`

Next Steps

• Working with Remote Server - Simple Git Tutorial
• Branching and Merging - Simple Git Tutorial

Resources

• Git - Reference
• GitHub Docs
• GitHub Training Kit
• MIT - Missing Semester - Version Control (Git)
• Oh Shit, Git!?!
• Pro Git
• git - the simple guide - no deep shit!