Learn The Basic's of Git & GitHub In Hindi

Abhishek Luv

Develop2Deploy

Git : Basic Concepts

What is a repository

A repository is simply a database containing all the information needed to retain and manage the revisions and history of a project. Within a repository, Git maintains two primary data structures, the object store and the index.

The object store is designed to be efficiently copied during a clone operation as part of the mechanism that supports a fully DVCS.

Index is transitory information , is private to a repository and can be created or modified on demand as needed.

Git Object Store

It contains your original data files and all the log messages, author information, dates, and other information required to rebuild any revision or branch of the project.

There are four types of Object stores

• Blobs: A blob holds a file’s data but does not contain any metadata about the file or even its name.
• Trees: Its records blob identifiers, path names and a bit of metadata for all the files in one directory. It can also recursively reference other subtrees.
• Commits: A commits object holds metadata for each change introduced into the repository, including the author, committer, commit data, and log message.
• Tags: A tag object assigns an arbitrary human readable name to a specific object usually a commit.

Index

The index is a temporary and dynamic binary file that describes the directory structure of the entire repository.

Index captures a version of the project’s overall structure at some moment in time. As the developer, we execute Git commands to stage changes in the index. Changes usually add, delete or edit some files or set of files. The index records and retains those changes, keeping them safe until your are ready to commit them. You can also remove or replace changes in the index.

Content-Addressable Names

The Git object store is organized and implemented as a content-addressable storage system. Each object in the object store has a unique name produced by applying SHA1 to the contents of the object, yielding an SHA1 hash value. Any tiny change to a file causes the SHA1 hash to change, causing the new version of the file to be indexed separately.

SHA1 values are 160-bit value that are usually represented as a 40 digit hexadecimal number.

for example
937082042f48a5cbc7777634509310fff059bc19

File Management and The Index

Remote Repository(master) <-> Index(Staging happens here) <-> Local Repository (local)

Index

Git’s Index doesn’t contain any file content: it simply tracks what you want to commit when you run git commit. Git checks the index rather than your working directory to discover what to commit.

You can query the state of the index at any time with the command git status

File Classification in Git

• Tracked : Any file that’s already there in the repository or any file that is staged
• Ignored : file to be ignored by git object store and git index
• Untracked : An untracked file is any file not found in either of the previous two categories

Git and GitHub Basics

How to generate SSH Key for GitHub

$ cd ~/.ssh

$ ssh-keygen -t rsa -C "your_email@example.com"

to copy the RSA key to the clipboard

$ clip < ~/.ssh/id_rsa.pub

Getting Started

Git Command Line Commands

add, bisect,branch, checkout,clone,commit,diff,fetch,grep,init,log,merge,mv,pull,push,rebase,reset,rm,show,status,
tag

Git Version Check

git --version

Git Commit

git commit -m "commit message"

git commit --message="commit message"

Creating an initial repository

git init

Adding file to your repository

git add index.html

Git status

git status

Configuring the commit author

git config user.name "abhishekluv"

git config user.email "abhishekluv@gmail.com"

Viewing your commits

git log

Show your commit

git show commitSHAnumber

Show branch

git show-branch --more=10

Viewing commit differences

git diff commitSHA#1 \ commitSHA2

Removing a file in your repository

git rm index.html

Renaming a file in your repository

git mv index.html index2.html

Making a copy of your repository

git clone firstreponame secondreponame

Global commit author details

git config --global user.name "abhishekluv"

git config --global user.email "abhishekluv@gmail.com"

Using git add

Example

git add .gitignore

git add --all

git status

using git commt -all

git commit -a

git commit --all

causes it to automatically stage all unstaged, tracked file changes - including removal of tracked files from the working copy before it performs the commit.

using git rm

git rm index.html : will remove the file completely from the working directory as well as the remote repo

git rm --cached index.html : will remove the file from the index and leave it in the working directory

using git mv

mv stuff newstuff

git rm stuff

git add newstuff

or

git mv stuff newstuff

.gitignore file

add any file name in the .gitignore file which you want to ignore

Commits

In Git, a commit is used to record changes to a repository

git commit -m "message"

git commit --all -m "message"

Branches

A branch is the fundamental means of launching a separate line of development within a software project.

Git allows many branches and thus many different lines of development within a repository.

Creating a branch

git branch branchname

list branches

git branch

list of branches with details

git show-branch

changing/checking out branches

git checkout branchname

creating and checking out a new branch

git checkout -b branchname

deleting a branch

git branch -d branchname

Merges

what is git merge

In Git, a merge must occur within a single repository i.e. all the branches to be merged must be present in the same repository

git checkout branch

git merge other_branch

git commit -a -m "commit message"

Steps for Git and GitHub

 1. Register at www.github.com 2. Create a new public repository at www.github.com 3. Download and Install msysgit from [here](https://code.google.com/p/msysgit/downloads/list "Download msysgit") 4. Create a folder for your new local repository 5. Open Command-Prompt or Powershell  6. Run command ` git --version ` 7. Run command to initialize a new local git repository ` git init ` 8. Now go back to www.github.com and copy the remote repository HTTPS link onto your clipboard 9. Run command to add the remote repository as an origin ` git remote add origin remoterepoURL `  10. Run command to cross check the origin ` git remote -v ` 11. Create a new file readme.txt 12. Run command to check the status of the index ` git status `  > tracked  > untracked > ignored 13. Run command to add new file for staging ` git add readme.txt ` and check status ` git status ` 14. Run command to unstage the file ` git rm --cached readme.txt `  15. Run command to commit the changes ` git commit -m "commit message" ` 16. Run command to push the changes to remote repository ` git push origin master ` 17. Create a new file gitignore.txt file in your local repository 18. Run command to rename gitignore.txt to .gitignore ` ren gitignore.txt .gitignore ` 19. Run command to add all the file for staging ` git add --all ` 20. Run command to reset on step back ` git reset HEAD ` 21. Run command to create and checkout a branch ` git checkout -b develop ` 22. Run command to push changes to new branch ` git push origin develop ` 23. Run command to switch back to master branch ` git checkout master ` 24. Run command to merge the develop into the master branch ` git merge develop ` 25. Run command to publish local commits after merging ` git push origin master `  

Thank you

With Regards

Abhishek Luv

Happy Learning