Lesson 2.5.1: Committing versions

Git saves versions of a folder. Each version you commit to the history is a commit, with its message.

The idea

Without Git, versions end up like this: game.js, game-final.js, game-final-really.js.

Git saves versions of a whole folder. Each version is a commit: a snapshot of the project at that moment, with a message saying what changed. A folder with Git is called a repository.

Installing it and introducing yourself

Windows: download it from git-scm.com and install it with the default options.
macOS: type git --version in the terminal; if it's missing, the system offers to install it.
Linux (Ubuntu, Debian): sudo apt install git.

Then, just once, tell it who you are and what the main branch is called:

Terminal

$ git config --global user.name "Ana García"
$ git config --global user.email "ana@example.com"
$ git config --global init.defaultBranch main

Creating the repository

In my-game:

Terminal

$ git init

Terminal

Initialized empty Git repository in /Users/ana/projects/my-game/.git/

Git keeps everything in a hidden folder, .git. Don't touch it.

Committing a version

Two steps:

git add chooses what goes into the snapshot.
git commit takes it, with its message.

Terminal

$ git add hello.js
$ git commit -m "Add the greeting"

Terminal

[main (root-commit) 3f2a1c9] Add the greeting
 1 file changed, 1 insertion(+)
 create mode 100644 hello.js

git add . adds everything that changed in the folder.

Asking Git

git status says how everything stands. Right after creating the repository, before any add:

Terminal

$ git status

Terminal

On branch main

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	hello.js
	table.js

nothing added to commit but untracked files present (use "git add" to track)

Untracked means Git sees them but isn't saving them yet.

Use it often: before add, before commit and whenever you're unsure.

The message

For now, a short sentence saying what the change does: "Add the 3 times table", not "changes". How to write a good message is the next lesson, 2.5.2.

Try it

Exercise

Make a second commit that saves table.js. Look at git status before and after.

Show the solution

Terminal

$ git status
$ git add table.js
$ git commit -m "Add the 3 times table"
$ git status

After the commit, git status says nothing to commit, working tree clean: everything is saved.

Summary

Git saves versions of a folder; each one is a commit.
git init creates the repository, once.
git add chooses; git commit -m "…" commits the version to the history.
git status says how everything stands.