Git Overview

6 December 2017 www.snipe.co.in 1
SNIPE TEAM
12/6/2017

o History Of GIT
o Version Control System
o Getting started Git
o Branching
o Merging & Rebase
o Intro To GitHub
o Installation of Git
o Tools for Git
o Git Commands
o Steps to create a repo
o Example
o SUMMARY
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CONTENTS

o GIT is a Distributed Version Control System.
o It is a content addressable file system, used to track directory
trees.
o It handles all the things like merging of source code and
maintaining versions.
o GIT is optimized for Complex Merges and Fast.
o It follows Trunk Base Development.
o It allows for code collaboration with anyone online.
o Users keep entire code and history on their location machines
o Users can make any changes without internet access
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INTRO TO GIT

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Founder
GIT HISTORY

o Version Control System (VCS) is a software that helps software
developers to work together and maintain a complete history of their
work.
o Version Control, also known as Revision Control or Source Control.
o Functions of a Version Control System :
o Allows developers to work simultaneously.
o Maintains a history of every version.
o Does not allow overwriting each other’s changes.
o Following are the types of Version Control System :
o Centralized version control system (CVCS).
o Distributed/Decentralized version control system (DVCS).
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Version Control System

o Centralized version control system (CVCS) uses a central server to
store all files and enables team collaboration.
o “Committing” a change simply means recording the change in the
central system and Other programmers can then see this change.
o They can also pull down the change, and the version control tool
will automatically update the contents of any files that were
changed.
o It is a Client-Server approach.
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CENTRALIZED VERSION CONTROL SYSTEM

When you’re working with a Centralized Version Control System, your
workflow for adding a new feature or fixing a bug in your project will
usually look something like this:
o Pull down any changes other people have made from the central server.
o Make your changes, and make sure they work properly.
o Commit your changes to the central server, so other programmers can
see them.
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CVCS WORKFLOW

o Merging of files or code is difficult.
o A single point of failure i.e., failure of the central server.
o Remote Server commits slow while transferring data.
o Unsolicited changes that may break your project.
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DEMERITS

o Distributed Version Control System (DVCS) is a form of version
control that allows software developers to work on a given project
without requiring them to share a common network.
o Distributed version control takes a peer to peer approach.
o It synchronizes repositories by exchanging patches (sets of
changes) from peer to peer.
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DISTRIBUTED VERSION CONTROL SYSTEM

o Don’t require any common network
o DVCS is fast because it not rely on central server.
o In Implicit Backup, data present on any client side mirrors the
repository, hence it can be used in the event of a crash or disk
corruption.
o Security is more. It uses a common cryptographic hash function called
secure hash function.
o Easy to create branches because DVCS is branch management system.
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ADVANTAGES

o Local Repository – it is a private workplace.
o Working Directory – the place where files are checked out.
o Blob – stands for Binary Large Object. Each version of a file is
represented by blob.
o Tree - Tree is an object, which represents a directory. It holds
blobs as well as other sub-directories.
o Revision - Revision represents the version of the source code.
Revisions in Git are represented by commits.
o Tags – It assigns a meaningful name with a specific version in the
repository. It is immutable.
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DVCS TERMINOLOGY

GIT is a version control system for tracking changes in computer files and
coordinating work on those files among multiple people.
o Three trees of GIT:
o The HEAD
o last commit snapshot, next parent
o Index
o Proposed next commit snapshot
o Working directory
o Sandbox
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GETTING STARTED

o Init a repo – To initialize the repository in GIT : Git init
o Edit files
o Stage the changes
o Review your changes
o Commit the changes
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WORKFLOW OF GIT

o A basic workflow
o Edit files
o Stage the changes
Use your favorite editor
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GETTING STARTED

o A basic workflow
o Edit files
o Stage the changes
o Git add filename
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12/6/2017
GETTING STARTED

o A basic workflow
o Edit files
o Stage the changes
o Git status
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12/6/2017
GETTING STARTED

o A basic workflow
o Edit files
o Stage the changes
Git commit
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GETTING STARTED

o git gc – garbage collector (run it when the /.git/directory
takes too much space).
o git stash – save/restore the state of the working copy
and index.
o git clean – clean the working tree.
o git bisect – locating which commit introduced a bug.
o git cherry-pick – merging a single commit.
o git revert – canceling a previous commit.
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GIT Utility Commands

o It is a pointer to a commit(save the files).
o The default branch name in Git is master.
o ‘git branch’ command used for create, rename, list and delete files.
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BRANCHING

o git branch – List all of the branches in your repository.
o git branch <branch> – To create a new branch called <branch>.
o git branch -d <branch> – To delete the branch.
o git branch -m <branch> – To rename the current branch.
o git branch –merged – To display all branches that are already
merged.
o git branch –a –color – It will be shown in appropriate colors to all
branches.
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USAGE

o Git checkout
o lets you navigate between the
branches created by git branch.
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USAGE

o Combining one ore more branches into the current branch.
o Allows changes from other branches to be integrated into the
current work history
o Merge only changes the workspace.
o If we commit in branch, other branches not affected
Features
o Fast Forward Merge
o 3 way Merge
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MERGE

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EXAMPLE Adding new branch to experiment
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MERGING

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Committing the branch to repository Finally it navigates all the branches
in directory.
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MERGING

o When merging, if there are conflicts - need to solve them.
o After solving, need to “add” the changes and commit the
merged workspace.
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MERGING-CONFLICTS

o Pros
o Simple
o Support existing access
control
o NFS enabled
o Cons
o Public share is difficult to
set up
o Slow on top of NFS
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WORKFLOW WITH LOCAL FILE SYSTEM

o Pros
o Fastest protocol
o Allow public anonymous
access
o Cons
o Lack of authentication
o Difficult to set up
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WORKFLOW WITH GIT

o Instead of merging, replays set of changes on top of another branch.
o Affects the “rebased” branch only.
o Very useful to remove history clutter.
o Simple rule, use locally only and for branches which you will never
share.
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REBASE

o GitHub is a Git repository hosting service, but it adds many of its own
features.
o GitHub provides a Web-based graphical interface.
- UI, documentation, bug tracking, feature requests, pull requests & more!
o It also provides access control and several collaboration features.
o It offers all of the distributed version control and source code management
(SCM)
o It is Founded in 2008.
o Also has an Enterprise Edition for Business.
Intro to GitHub

• For windows :https://git-scm.com/download/win
• For Mac : https://git-scm.com/download/mac
• For Linux
- Linux (Debian) - Command: sudo apt-get install git
- Linux (Fedora) - Command: sudo yum install git
• To access git repo we can use CMD ,GitHub, Bit Bucket
• Create one account in GitHub.
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Installation of Git

• After installation, We have tools to run git like Git CMD, Git Bash, Git
GUI and GitHub.
• Git CMD - Command Line prompt is the command-line interpreter on
Windows operating systems. When you install git on windows and you are
used to using command line, one uses cmd to run git commands.
• Git Bash - Bash is a Unix shell and command language, and is the default
shell on Linux, Ubuntu and Mac. The git which runs on the terminal of any
Linux device is known as git bash.
• Git GUI - Provides a Graphical user interface to run the git commands.
• GitHub - Web-based Git version control repository hosting service.
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Tools for Git

o Git init
o Git clone url
o Git status
o Git add [file name]
o Git add --all
o Git commit
o Git commit –m “add”
o Git branch [branch name]
o Git branch
o Git branch –D [branch name]
o Git Checkout [branch name]
o Git push
o Git pull
o Git merge [branch name]
- To initialize the repo in local repository
- It copy the remote repo files from GitHub to local repo
- It shows our history like commits, stage files, deleted files
- Adds the file to stage area
- It add all the files to staging area
- To save the files from staging area to local repo
- To save the file with some message related to that file
- To create new branch in local repo
- It displays all branches in local repo
- To delete the branch in local repo
- To change one branch to another branch
- To push our local repo to remote repo
- To pull from remote repo to local repo
- To merge branch file to master file
Git Commands

• Create a local Git Repo
• Create a new branch
• Make and commit changes
• Open a Pull Request
• Checkout Repository
• Merge your Pull Request
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Steps To Create Sample Repo

• To initiate a new repository – git init
• Then it creates one folder as our Repository.
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Initialize a Repository

• Shows the working repo files and commits – git status
• For example, these are the files I’m created in work space.
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To View our Files
Repository

• To add files to repo - git add
• I added “index” to the Staging area.
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Adding Files to Local Repo

• Here I’m changing the text in index file as “add an index file”
• To save the file in repo – git commit –m
• Then the file name changes from Index to COMMIT_EDITMSG
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Committing Files

• I added one more file to repo and I committed to local repo
• To show all our commits – git log
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Display our Commits

• To push our local repo to remote
- git clone https://github.com/rohith4/sample-repo/
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Cloning files to remote repo

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• push our local commits to our origin repo or remote repo - git push -u
origin master
• Pushes the changes in your local repository up to the remote repository you
specified as the origin
Pushing files to Remote Repo

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Remote Repo of Git

Pull Repo from remote Repo – git pull
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• Here I pulled repository from remote repo to local repository
Pull files

• Open the Local Repo of git.
• Add some data to that file and save the file.
• To check the status of the file – git status
(there it shows modified index.html)
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Status of our local Repo

• To add more files to local repository – git add – A
• Commit the current file to local repo
• Push the local repo to remote repo that is git repo
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Adding another file to repo

• To create a new branch – git branch <branch name>
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• To check branches in local repo – git branch
• To change master branch to another branch – git checkout <branch
name>
Branching

• To delete branch – git branch –D <branch name>
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Delete Branch

• To checkout branch – git checkout master
• This command shows all branches, commits and changes one
branch to master branch.
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Checkout Branch Files

• To merge the branch to master branch – git merge <branch name>
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• To check if the branch is merged to master – git checkout <branch name>
• It comes to another branch “project”
• Then give “git merge master” it shows already done
Merging two branches

Local Repository
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Remote Repository

o Version control is a great asset to most workflows where it is important
to track changes as well as provide a repository of files for others to
access.
o DVCS have gained a great deal of attention in recent years given the
explosion of open source projects.
o DVCS provides benefits that greatly align themselves with modern
projects and workflows.
o CVCS can assist your team in making the transition.
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CONCLUSION

Git Overview

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