Introduction to Git and Github

Introduction to: &

Max Claus Nunes
maxcnunes@gmail.com
http://blog.maxcnunes.net
https://github.com/maxcnunes

Version Control Systems
• Without
• Local
• Centralized What?!

• Distributed

Without Version Control
Systems
• Copy files into another directory
• Store or Share files backups by email
• Store or Share files by pendrive

Local Version Control
Systems
• Just a local
Database
• Systems:
– RCS - Revision
Control System
(Today is centralized)

http://git-scm.com

Centralized Version Control
Systems
• A Central Server
• The most used for
the companies
• Systems:
– CVS
– Subversion
– TFS

Centralized Version Control
Systems
Advantages
• Everyone knows to a certain degree what everyone else on the project is
doing
• Administrators have more control over what everyone can do

Disadvantages
• If Server goes down, this means nobody can save changes
• If HD Server breaks, this means good bye all control version history

Distributed Version Control
Systems
• Distributed: each client
has fully mirror of the
repository
• Systems:
– Git
– Mercurial
– Bazaar


Distributed Version Control
Systems
Advantages
• Everytime someone pulls from the central repository, Git gets a full
history of the changes
• Most of the functionalities doesn’t need access to some network. So we
can work even not connected to the internet
• A project can be associated to a more than one remote repository
• You can do anything just using the console

Disadvantages
• Git requires some learning curve to understand its concept
• The administrators don’t have control over what happens on each client
local repository

A Short History of Git
• (1991-2002) – The Linux kernel changes to the
software were passed around as patches and
archived files.
• (2002) – The Linux kernel project began using a
proprietary DVCS system called BitKeeper.
• (2005) – The relationship between Linux kernel
and the BitKeeper broke down. After that Linux
development community create their own tool
named Git, based on what they learned using the
BitKeeper.

Some Git Goals
• Speed
• Simple design
• Strong support for non-linear development
(thousands of parallel branches)
• Fully distributed
• Able to handle large projects like the Linux
kernel efficiently (speed and data size)

Git Basics
• Snapshots, Not Differences
• Nearly Every Operation Is Local
• Git Has Integrity
• Git Generally Only Adds Data
• The Three States

Snapshots, Not Differences


Differences

Snapshots, Not Differences


Snapshots

Nearly Every Operation Is
Local
• You can work offline as look the history,
commit some changes or create branchs

Git Has Integrity
• Git generate a SHA-1 hash for each commit
associated a file
• Git realize a checksum everytime is tried to
store some change. So Git knows when
something was changed or the file is
corrupted

24b9da6552252987aa493b52f8696cd6d3b00373

Git Generally Only Adds Data
• Doing commits regularly it is very difficult to
get the system to do anything that is not
undoable or lose some change
• Let us more comfortable to experiment
changes, because is easy to recover a previous
version

The Three States

Modified/Untracked Staged Committed

So, what are we going to do?
• Configure • Alias
• Create a Repository • Diff
• Passing through the 3 • Tag
States • Ignoring Files and
• Branch Folders
• Merge • Getting a Remote
• Log Repository
• Basic Workflow

Configure
• Download and Install Git: http://git-scm.com/
• You just need the Git Bash to work

Username

git config --global user.name "Your Name Here"
# Sets the default name for git to use when you commit

Email

git config --global user.email "your_email@example.com"
# Sets the default email for git to use when you commit

Create a Repository

Access your project directory

cd your_folder_name

Create the repository

git init

Check the repository current status

git status

All your repository data and configuration is stored on a hidden folder named .git on your repository’s root

Passing through the 3 States
How is the status now?

Create or Change a file/folder From Nowhere/Repository Working Directory

touch file_name/folder


Add objects to staging area Working Directory  Staging Area

git add (general_comand/file_name/folder_name/…)

Staging Area  Repository
Save objects on local repository

git commit –m ‘This is my awesome comment’


Adding, Removing and Renaming
Stages All
git add -A

Stages new and modified, without deleted
git add .

Stages modified and deleted, without new
git add -u

Stages a removed file
git rm file_name/

Stages a removed folder
git rm -r folder_name/

Stages a renamed file
git mv old_file_name new_file_name

.gitignore
Is a hidden file named .gitignore on your root’s repository that contains a list
of all ignored files and folders, like:
*.tmp
x64/

Diff

Compare the working directory with local repository

git diff HEAD file_name

Compare the working directory with staging area

git diff file_name

Compare the index with local repository

git diff --cached file_name

Compare the branchs showing just the status and file name

git diff --name-status branch_1 branch_2

Custom Alias

Create a new alias to show a log with graph

git config --global --add alias.lol "log --graph --
decorate --pretty=oneline --abbrev-commit --all"

Using the new alias

git lol

List all the local configurations

git config –-local -l

Branchs
Create and Switch for a new branch

git checkout –b branch_name

List all local branchs

git branch
Switch for a existing branch

git checkout branch_name

Working with Remote Repositories
Add a local branch for a remote repository

git push remote_name branch_name

Update local branch from a remote branch

git pull remote_name branch_name

Merges
Merge on the current branch changes made on another branch

git merge branch_name

Before merge

After merge

Merge Conflicts
Master Development

Merge conflict

Resolving the conflict

Commit the file after resolve the conflict

git commit –a -m ‘Resolving merge conflicts’

Tags
List all tags

git tag

Creating an annotated tag

git tag -a tag_name -m 'message description'

git tag -a v1.0 -m 'my version 1.0'

Working with Remote Repositories
Sharing tags

git push origin v1.0

All tags

git push origin --tags

Add and Pull a Remote
Repository
Cloning a or repository

git clone git@github.com:owner_repo/repo_name.git

Actually what the clone command does is: remote add + pull

git remote add origin
git@github.com:owner_repo/repo_name.git

git pull origin master

And actually what the default pull command does is: fetch + merge

Update local repository avoiding the amount of merges (fetch+rebase)
git pull --rebase repo_name branch_name

Pushing to the Remote
Repository
Pushing for the remote repository

git push remote_name branch_name

git push origin master

Basic
Workflow

http://nakedstartup.com/2010/04/simple-daily-git-workflow

Others helpful (or not) commands

List of Git Contributors

git shortlog -s -n

Show the SHA1 of a file staged

git ls-files -s file_name

Show the SHA1 of a file modified

git hash-object file_name

Discard changes of a file

git checkout --file_name

Others helpful (or not) commands

Undo git add before commit

git reset HEAD file_name

One line logs

git log --pretty=oneline

Short status

git status -s

Delete the last commit before Push

git reset --hard HEAD~1

Look more…
• Using SSH security connections
• Git Cheat Sheet Grey
• http://git-scm.com

Introduction to Git and Github

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