Introduction to Git

Dear Readers,

In this article,we will see Brief Introduction on Git.

Source Code Management

SCM stands for Source Code Management is an integral part of any development project in the current IT world.

• Storage (Any code)
• Developers (Code)
• Testing Team (Test)
• DevOps (Scripts)
• Different people from different team can store simultaneously (Save all changes separately).
• Pipeline between offshore & on shore teams.
• Help in achieving teamwork.
• Track changes (Minute level).
• Source code is the storage where you store code.
• Whoever write the code they can store the code in SCM.
• Not only store the code but also we can manage the code.
• Source Management is a process we can achieve SCM by using SCM tools.

Source Code Management tools are the crucial ones that make or break the effort put in by multiple developer.

Types of Source Code Management (SCM) Tools

SCM Tools

• Git
• SVN
• Perforce
• ClearCase

Centralized  Version Control System – SVN,Perforce,ClearCase

Distribution Version Control System – Git

Version Control System

A version control system (VCS) allows you to track the history of a collection of files.

It supports creating different versions of this collection.

Each version captures a snapshot of the files at a certain point in time.

VCS allows you to switch between these versions.

Version control systems are divided into two groups

Centralized Version Control Systems (CVCSs)

Distributed Version Control Systems (DVCSs)

Centralized Version Control System

The concept of a centralized system is that it works on a Client-Server relationship.

The repository is located at one place and provides access to many clients.

Centralized Version Control Systems were developed to record changes in a central system and enable developers to collaborate on other systems.

Advantages

Relatively easy to set up

Provides transparency

Enable admins control the workflow

Disadvantages

If the main server goes down, developers can’t save versioned changes

Remote commits are slow

Unsolicited changes might ruin development

If the central database is corrupted, the entire history could be lost (security issues)

Distributed Version Control System

Git is an example of a distributed version control system (DVCS).

Commonly used for open source and commercial software development.

DVCSs allow full access to every file, branch, and iteration of a project.

Distributed Version Control Systems (DVCS) don’t rely on a central server.

Allows every user access to a full and self-contained history of all changes.

Each user has a complete local copy of a repository on his individual computer.

The user can copy an existing repository.

This copying process is typically called cloning and the resulting repository can be referred to as a clone.

Every clone contains the full history of the collection of files

Cloned repository has the same functionality as the original repository.

Advantages

Because of local commits, the full history is always available

No need to access a remote server (faster access)

Ability to push your changes continuously

Saves time, especially with SSH keys

Good for projects with offshore developers

Differences Between Centralized Version Control Systems And Distributed Version Control Systems.

What is Git?

Git is currently the most popular implementation of a distributed version control system.

Git is commonly used for both open source and commercial software development, with significant benefits for individuals, teams and businesses.

Git originates from the Linux kernel development and was founded in 2005 by Linus Torvalds.

Nowadays it is used by many popular open source projects, e.g., the Android or the Eclipse developer teams, as well as many commercial organizations.

The core of Git was originally written in the programming language C.

Git has also been re-implemented in other languages, e.g., Java, Ruby and Python.

Git is a free software distributed under the terms of the GNU General Public License version 2.

According to the latest Stack Overflow developer survey, more than 70 percent of developers use Git.

Git Repository

A Git repository contains the history of a collection of files starting from a certain directory.

The process of copying an existing Git repository via the Git tooling is called cloning. After cloning a repository the user has the complete repository with its history on his local machine.

Types of Repositories

Bare Repositories (Central)

Store & share only.

All central repositories are bare repositories.

Non-Bare Repositories (Local)

Where you can modify the files.

All local repositories are Non-Bare Repositories.

Why Git?

Speed

Snapshot Concept.

Parallel branching

Multiple branches at a time unlike SCM tools.

Fully Distributed

Backup is available in multiple locations.

No need internet connection.so no network latency.

No need central server separately.

Each work space will have its own repo internally.

Can create any no of branches.

We can share code without using central repository.

That’s why we call GIT as DVCS (Distributed Version Control System).

Snapshots

Get any previous version (Backup).

Represents some data of particular time.

Stores the changes (appended data) only. Not whole copy.

Commit

Store changes in repository (Will get commit ID).

Commit ID contains 41 alpha numeric characters.

Concept-Checksum (It’s a tool in Linux generates binary value equal to data present in file).

Even if you change one dot, commit ID will changed.

Track changes.

Git Terminology

Repository

In Git we called as Repository.

It is a storage where we store our code.

It could be local repository or central repository.

In Git each copy of the repository is a complete repository.

Server – It is local Machine (EC2).

Work space

It is a place where you work like create files, write code etc.

Where you can see files physically and do modifications.

Branch

Product is same, so one repository but different tasks.

Each task has one separate task.

Finally merge (code) all branches.

For parallel development.

We can create any number of branches.

Changes are personal to that particular branch.

We can put files only in branches ( not in repository directly).

The default branch is “Master”.

Files created in workspace will be visible in any of the branch workspace until you commit.

Once you commit, then  that file belongs to that particular branch.

Index

Index is an alternative term for the staging area.

Working tree

The working tree contains the set of working files for the repository. You can modify the content and commit the changes as new commits to the repository.

Commit

Sending the files from staging area to local repository that process we called commit.

Version/Version-ID/Commit-ID

Whenever you commit, you will get one commit ID.

It is reference to identify each change and who did that change.

It contains complete information regards to who has committed.

Tag

It is a meaning full name.

Whenever you commit, you will get one commit ID.

This commit ID contains 41 alphanumeric characters, so we can’t remember commit ID.

For easier understanding we give tag for the commit ID.

Git Stages

Work Space

It is a place where you work like create files, write code etc.

Where you can see files physically and do modifications.

Staging Area

The file has been added to git’s version control but changes have not been committed.

Buffer area

The file has been added to git’s version control, it will take snapshot (Incremental) immediately.

Repository (Local)

Store changes Locally.

Repository (Central)

Store changes Centrally

Key Points

untracked

The file is not tracked by the Git repository. This means that the file never staged nor committed.

Tracked

committed and not staged

staged

The file has been added to git’s version control but changes have not been committed.

Committed

The change has been committed.

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