DPS909 & OSD600 Winter 2017 - Git Walkthrough

Git Walkthrough

Step 1: get some source

For this walkthrough, we'll need some source code. Normally you'll write code, but for this walkthrough, we'll borrow some pre-existing code to make things easier. Let's download the Bootstrap source:

https://github.com/twbs/bootstrap/archive/v4.0.0-alpha.6.zip

Expand the zip file, and open a terminal to your bootstrap-4.0.0-alpha.6/ directory.

Step 2: start a git repo

$ cd bootstrap-4.0.0-alpha.6
$ git init

Note the presence of a new bootstrap-4.0.0-alpha.6/.git/ directory:

$ ls .git
HEAD        config      hooks       objects
branches    description info        refs

NOTE: normally we git clone to clone (also known as fork) a repository. We'll do that in a bit.

Step 3: adding files

Let's inspect the current status of our repo:

$ git status
On branch master

Initial commit

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

	.editorconfig
	.eslintignore
	.gitattributes
	.gitignore
	.hound.yml
	.houndignore
	.travis.yml
	CHANGELOG.md
	CNAME
	CONTRIBUTING.md
	Gemfile
	Gemfile.lock
	Gruntfile.js
	ISSUE_TEMPLATE.md
	LICENSE
	README.md
	_config.yml
	bower.json
	composer.json
	dist/
	docs/
	grunt/
	js/
	nuget/
	package.js
	package.json
	sache.json
	scss/

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

Our Working Directory (i.e., bootstrap-4.0.0-alpha.6/) has a lot of files and folders that are untracked (i.e., git has no record of them in its history).

We include a file in git's history by adding it to the index (also known as the staging area). Let's add the README.md file:

$ git add README.md
$ git status
On branch master

Initial commit

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)

	new file:   README.md

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

	.editorconfig
	.eslintignore
	.gitattributes
	.gitignore
	.hound.yml
	.houndignore
	.travis.yml
	CHANGELOG.md
	CNAME
	CONTRIBUTING.md
	Gemfile
	Gemfile.lock
	Gruntfile.js
	ISSUE_TEMPLATE.md
	LICENSE
	_config.yml
	bower.json
	composer.json
	dist/
	docs/
	grunt/
	js/
	nuget/
	package.js
	package.json
	sache.json
	scss/

This time git status continues to report our Untracked files, but also includes a new section: Changes to be committed. The README.md file has been added to the staging area, and is ready to be commited to git's history.

We record a snapshot of our files by committing the staging area's contents:

$ git commit -m "Added README file"
[master (root-commit) 03c9551] Added README file
 1 file changed, 135 insertions(+)
 create mode 100755 README.md

Let's look at our status again:

git status
On branch master
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	.editorconfig
	.eslintignore
	.gitattributes
	.gitignore
	.hound.yml
	.houndignore
	.travis.yml
	CHANGELOG.md
	CNAME
	CONTRIBUTING.md
	Gemfile
	Gemfile.lock
	Gruntfile.js
	ISSUE_TEMPLATE.md
	LICENSE
	_config.yml
	bower.json
	composer.json
	dist/
	docs/
	grunt/
	js/
	nuget/
	package.js
	package.json
	sache.json
	scss/

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

Here's how things stand now:

• Our working copy continues to have lots of untracked files and folders. However, README.md is not among them
• Our staging area is empty
• Our git repo has 1 commit that added 1 file, which we can see if we use git log

$ git log
commit 03c95518ce08f59e850409a2d82bacad110151a1
Author: David Humphrey (:humph) david.humphrey@senecacollege.ca <david.humphrey@senecacollege.ca>
Date:   Wed Jan 11 11:07:09 2017 -0500

    Added README file

Every record in our history is called a commit, and it's a snapshot of our repo's filesystem along with metadata:

• a unique commit identifier (SHA-1), in this case 03c95518ce08f59e850409a2d82bacad110151a1, which is often shortened to the first 7 characters: 03c9551.
• an author, every commit is done by somebody, and we want to keep track of this
• a date and time
• a commit message, describing what this commit changed, added, deleted, etc.

• Client Server (SVN) and Distributed (Git)
• Snapshots vs. versioned files.
  • Walkthrough -
  • Checksums, SHA-1 (try online)
  • Starting a Git Repo:
    • git init
    • git clone
  • File States:
    • Untracked (not known to git)
    • Tracked: modified, staged, committed
  • The staging area
• Basic Git Commands and Concepts
  • git help <command>
  • git add
  • git commit, git commit -m, git commit -a
  • git rm
  • git mv
  • git status
  • git log
  • git diff, git diff --staged
  • .gitignore
  • Branches
    • HEAD, master
    • git checkout, git checkout -b
    • git branch, git branch -a, git branch -d, git branch --merged, git branch --contains
    • git merge
    • git rebase
  • Remotes
    • origin, origin/branch
    • git remote
    • git remote add
    • git fetch
    • git pull
    • git push
  • Github, Pull Requests