All about Git and GitHub Commands!!

GIT IS HERE:

Q. What is git and why do we use it?

Git is a version control system used by developers to manage code repositories. It allows developers to track changes to their code, collaborate with other developers, and maintain a history of their code changes over time.

Git provides several benefits, including:

Version control: Git allows developers to maintain a history of their code changes, including who made the changes and when they were made. This helps to track and manage changes and makes it easier to collaborate with others.
Collaboration: Git allows developers to work together on the same codebase. It provides tools for managing conflicts and merging changes from different developers.
Backup and recovery: Git provides a backup of the code repository so that if something goes wrong, developers can recover their code and restore it to a previous state.
Branching and merging: Git allows developers to create branches of their code, which can be worked on independently and merged back into the main codebase when they are ready.
Open source: Git is open source, which means that it is free to use and can be customized to meet the specific needs of different projects.

Overall, Git is an essential tool for developers who want to manage their code effectively and collaborate with others.

Q. Basic Commands

" git init " command what? why?

The git init command is used to create a new Git repository. When you run this command, Git creates a new directory named .git in the root of your project directory. This directory contains all of the necessary files and data to manage your repository using Git.
Here are some of the reasons why you might use the git init command:

Starting a new project: If you are starting a new project from scratch, you can use git init to create a new Git repository and start tracking changes to your code.
Converting an existing project to Git: If you have an existing project that is not currently managed with Git, you can use git init to create a new Git repository and start managing your code with Git.
Experimenting with Git: If you are new to Git and want to experiment with its features, you can use git init to create a new repository and test out different Git commands and workflows.

Here is an example of how to use the git init command:

$ cd /path/to/project/directory
$ git init
Initialized empty Git repository in /path/to/project/directory/.git/

Once you have initialized a Git repository, you can start using Git commands to track changes to your code, create branches and tags, collaborate with other developers, and more.

Q What .git file and why is important?

The .git directory is the heart of a Git repository. It is a hidden directory that is created when you run the git init command to initialize a new Git repository, or when you clone an existing repository.

Inside the .git directory, Git stores all of the information about your repository, including the commit history, branch and tag references, and other metadata. Here is an overview of some of the key files and directories inside the .git directory:

HEAD: This file points to the current branch or commit in the repository.
branches: This directory contains references to all of the branches in the repository.
objects: This directory contains all of the objects (commits, trees, and blobs) that make up the contents of the repository.
refs: This directory contains references to commits, tags, and other objects in the repository.
config: This file contains configuration settings for the repository.
hooks: This directory contains scripts that can be run automatically by Git when certain events occur, such as before or after a commit.
index: This file is used to track changes that have been staged for the next commit.

The contents of the .git directory are critical to the functioning of a Git repository, and should not be modified or deleted manually. If the .git directory becomes corrupted or lost, it may be difficult or impossible to recover the repository.

2) " ls " command what? why?

The ls command is used to list the files and directories in a directory. When you run the ls command, it will display a list of the files and directories in the current working directory. By default, ls will display the files and directories in alphabetical order.

Here are some reasons why you might use the ls command:

To view the contents of a directory: You can use ls to see the files and directories in a particular directory. This can be useful when you need to locate a particular file or when you want to get an overview of the files in a directory.
To check file permissions: You can use ls with the -l flag to view the permissions of the files in a directory. This can be useful when you need to change the permissions of a file or when you want to check if a file is executable.
To sort files by modification time: You can use ls with the -t flag to sort files in a directory by the time they were last modified. This can be useful when you want to see the most recent files in a directory.

Here are some examples of how to use the ls command:

$ ls
file1.txt  file2.txt  directory1  directory2

$ ls -l
-rw-r--r-- 1 user group  12345 Jan 1 12:34 file1.txt
-rwxr-xr-x 1 user group  67890 Jan 2 13:45 file2.txt
drwxr-xr-x 2 user group   4096 Jan 3 14:56 directory1
drwxr-xr-x 2 user group   4096 Jan 4 15:67 directory2

$ ls -t
directory2  file2.txt  directory1  file1.txt

List the contents of the current directory:
```
 $ ls
 file1.txt  file2.txt  directory1
```

List the contents of a specified directory:

 $ ls /path/to/directory
 file1.txt  file2.txt  directory1

Display the output in a long format:
```
 $ ls -l
 -rw-r--r--  1 user  group  12345 Feb 15 10:00 file1.txt
 -rw-r--r--  1 user  group  67890 Feb 15 11:00 file2.txt
 drwxr-xr-x  2 user  group   4096 Feb 16 09:00 directory1
```
The ls -l command is used to list the contents of a directory in a long format, which displays additional information about each file or directory, including its permissions, owner, group, size, modification time, and name.

Here is a breakdown of the output for the example you provided:
```
 -rw-r--r-- 1 user group  12345 Jan 1 12:34 file1.txt
```
- The first column (-rw-r--r--) represents the file's permissions. In this example, the file has read and write permissions for the owner (user) and read-only permissions for the group (group) and others. The first character (-) indicates that this is a regular file (as opposed to a directory, symbolic link, or other type of file).
- The second column (1) indicates the number of hard links to the file.
- The third column (user) indicates the file's owner.
- The fourth column (group) indicates the file's group.
- The fifth column (12345) indicates the file's size in bytes.
- The sixth column (Jan 1 12:34) indicates the date and time when the file was last modified.
- The seventh column (file1.txt) is the name of the file.

Display hidden files and directories:

 $ ls -a
 .  ..  .git  file1.txt  file2.txt  directory1

 // Below command will show folder inside .git file
 $ ls .git
 branches        config       HEAD   index  logs     refs
 COMMIT_EDITMSG  description  hooks  info   objects

Note that the exact behavior and options of the ls command may vary slightly depending on the operating system and shell environment you are using.

3) " git status " command in git what? why?

git status is a Git command that shows you the current status of your working directory and staging area. It displays information about which files have been modified, added, or deleted since the last commit, and whether or not these changes have been staged for the next commit.

Here are some common use cases for the git status command:

Checking the status of your repository: Running git status will give you a quick overview of the state of your repository, showing you which files have been modified or added, which files are currently staged for the next commit, and whether there are any untracked files in your working directory.
Staging changes for the next commit: After making changes to a file, you can stage those changes for the next commit using the git add command. Once you have added the changes, you can use git status to confirm that the changes have been staged.
Unstaging changes: If you accidentally stage changes that you don't want to commit, you can use the git reset command to unstage those changes. Again, you can use git status to confirm that the changes have been unstaged.
Resolving conflicts: If you encounter merge conflicts when trying to merge two branches or pull changes from a remote repository, git status will show you which files have conflicts and need to be resolved.

Here are some of the common real use cases for the git status command:

To check the status of your repository before and after making changes to your files
To see which files have been modified, added, or deleted since the last commit
To see which files are staged and ready to be committed
To see which branch you are currently on and whether it is up to date with the remote repository

In summary, git status is a useful command for checking the status of your repository and keeping track of changes as you work on your project. It allows you to see what files have been modified, what changes have been staged for the next commit.

These files are grouped into two categories: 1) changes to be committed and 2) untracked files.

Changes to be committed: These are changes that have been added to the staging area using the git add command, and are ready to be committed to the repository. The git status command will show you which files are staged for commit and how many changes have been made to each file.

Untracked files: These are files that are not currently tracked by Git, and have not been added to the staging area. They are essentially new files that Git is not yet aware of. The git status command will show you a list of untracked files in your working directory.

Here is an example output of the git status command:

On branch master
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    modified:   file1.txt
    modified:   file2.txt
    new file:   file3.txt

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

    newfile.txt

In this example, the git status command is showing that there are three modified files that are staged and ready to be committed (changes to be committed). It also shows that there is one new file in the working directory that is not yet tracked by Git (untracked files). To track the new file, you would need to use the git add command (below i have add this command)

4) " git diff " command in git what? why?

git diff is a command in Git that shows the differences between two versions of a file or between two branches in a repository. It is useful for reviewing changes before committing them and for understanding the changes made by others in a collaborative project.

Here are some common use cases for the git diff command:

To see the differences between the current version of a file and the previous version:
```
  $ git diff file.txt
```
This command will show the differences between the current version of file.txt and the previous version in your repository.
To see the differences between two branches:
```
  $ git diff branch1..branch2
```
This command will show the differences between the branch1 and branch2 branches in your repository.
To see the differences between two commits:
```
  $ git diff commit1..commit2
```
This command will show the differences between the commit1 and commit2 commits in your repository.
To see the differences for a specific file between two commits:
```
  $ git diff commit1..commit2 file.txt
```
This command will show the differences for file.txt between the commit1 and commit2 commits in your repository.

The output of the git diff command shows the differences between the two versions or branches, with lines that have been added in green and lines that have been deleted in red. It also shows the context surrounding the changes, which can be helpful for understanding the changes made to the file.

Q What 'staging area' and why it is important?

In Git, the staging area (also called the index) is a crucial component of the commit process. The staging area is a place where you can prepare changes to your files before committing them to the repository.

When you make changes to a file in your working directory, those changes are not automatically included in the next commit. Instead, you need to explicitly add the changes to the staging area using the git add command. Once the changes have been added to the staging area, they are tracked by Git and are included in the next commit.

The staging area is important because it allows you to review and modify your changes before committing them . For example, you may make several changes to a file and want to commit only some of those changes while leaving others for a later commit. By using the staging area, you can selectively choose which changes to include in each commit.

Here are some key points about the staging area:

The staging area is a snapshot of the changes that are going to be included in the next commit.
You can add and remove changes from the staging area as many times as you want before committing.
The staging area allows you to review and modify your changes before committing them to the repository.
The staging area is a powerful tool for controlling which changes are included in each commit, which helps to keep your repository history clean and organized.

5) " git add " command in git what? why?

The git add command is used to add changes to the staging area in Git. When you make changes to a file in your working directory, those changes are not automatically included in the next commit. Instead, you need to explicitly add the changes to the staging area using the git add command. Once the changes have been added to the staging area, they are tracked by Git and are included in the next commit.

There are several ways to use the git add command:

To add all changes in the working directory to the staging area:
```
 $ git add .
```
This command will add all changes in the current directory and its subdirectories to the staging area.
To add changes to specific files to the staging area:
```
 $ git add file1.txt file2.txt
```
This command will add the changes in file1.txt and file2.txt to the staging area.
To add changes interactively to the staging area:
```
 $ git add -p
```
This command will prompt you to review each change and choose whether to add it to the staging area.
To add changes in a specific directory to the staging area:
```
 $ git add path/to/directory/
```
This command will add all changes in the specified directory and its subdirectories to the staging area.

The git add command is a powerful tool for controlling which changes are included in each commit. By using the staging area and the git add command, you can carefully review and modify your changes before committing them to the repository.

5) " git commit -m 'message-you-want-to-type' " command in git what? why?

The git commit command is used to save the changes that have been added to the staging area as a new commit in the Git repository. The commit command records a snapshot of the changes that have been staged and creates a new commit object in the repository with a unique ID.

Here are the steps to make a commit:

Use git add to stage the changes you want to include in the commit.
Run git commit to create a new commit object with the staged changes. This will open a text editor where you can enter a commit message describing the changes.
Save and close the commit message file to create the new commit.

There are several ways to use the git commit command:

Commit with a message:
```
 $ git commit -m "commit message"
```
This command creates a new commit with the staged changes and a message describing the changes.
Commit all changes, including untracked files:
```
 $ git commit -a
```
This command stages all modified and deleted files and commits them with a message.
Amend the last commit:
```
 $ git commit --amend
```
This command adds any staged changes to the last commit and allows you to edit the commit message.

6) " git log " command what? why? how many ways we can use it?

The git log command in Git is used to display the commit history of a repository. It shows a list of all the commits that have been made, along with information about each commit such as the commit message, the author, the date, and the SHA-1 hash of the commit.

Here are some common ways to use the git log command:

To show the commit history of the current branch:
```
 $ git log
```
This command will display a list of all the commits in the current branch, starting with the most recent commit.
To show a specific number of commits:
```
 $ git log -n <number>
```
This command will display the most recent <number> commits.
To show the commit history in a specific format:
```
 $ git log --pretty=format:"%h %ad | %s%d [%an]"
```
This command will display the commit history in a custom format. The %h placeholder displays the abbreviated commit hash, %ad displays the commit date, %s displays the commit message, %d displays any tags or branch names associated with the commit, and %an displays the author name.
Displaying commit details:
```
 $ git log --stat
```
This command will display the number of lines that were added or removed in each commit.
Displaying the commit history of a specific file:
```
 $ git log <filename>
```
This command will display the commit history of a specific file.
Displaying the commit history of a specific branch:
```
 $ git log <branchname>
```
This command will display the commit history of a specific branch.
Displaying the commit history in a graph format:
```
 $ git log --graph
```
This command will display the commit history in a graph format, which can be easier to read and understand.

7) " git stash " command what? why? how many ways we can use it?

The git stash command in Git is used to temporarily save changes that are not yet ready to be committed. It allows you to save your work in progress without committing it to the repository.

Here's how to use the git stash command:

Stash your changes:

 // This command for save changes temporarily
 $ git stash

 // If we want to get back those changes
 $ git stash pop

 // If we want remove that changes
 $ git stash clear

This command saves your changes in a new stash and reverts your working directory to the last commit.

Retrieve your stashed changes:
```
 $ git stash apply
```
This command retrieves the most recent stash and applies it to your working directory. If you have multiple stashes, you can specify which one to apply by using the stash index:
```
 $ git stash apply stash@{n}
```
where n is the index of the stash you want to apply.
List your stashes:
```
 $ git stash list
```
This command shows a list of all your stashes.
Remove a stash:
```
 $ git stash drop stash@{n}
```
This command removes the stash with the specified index.

Alternatively, you can remove all stashes at once with:
```
 $ git stash clear
```
1. Apply and delete a stash:

    perlCopy code$ git stash pop stash@{n}

8) " git reset " command what? why? how many ways we can use it?

The git reset command is used to undo changes to the repository. It allows you to move the current branch to a different commit, effectively resetting the state of the repository to that commit. There are several ways to use the git reset command:

git reset --soft <commit>: This option moves the current branch to the specified commit, but does not modify the working directory or the staging area. This means that the changes in the reset commits are still in the staging area, ready to be committed.
git reset --mixed <commit>: This option moves the current branch to the specified commit, and also resets the staging area to match the specified commit. However, the changes in the staging area are not lost, and can be added again with git add.
git reset --hard <commit>: This option moves the current branch to the specified commit, and also resets the staging area and the working directory to match the specified commit. This means that any changes that were made after the specified commit are lost.
git reset HEAD <file>: This option is used to unstage changes to a specific file. It removes the changes to the specified file from the staging area, but leaves the changes in the working directory.

The git reset command is a powerful tool, but it should be used with care. Resetting a commit can permanently delete changes, so it's important to make sure you know what you're doing before you use this command.

Sure, here are some examples of when you might use git reset:

Undoing changes to a file: Suppose you made changes to a file named file1.txt, but now you want to discard those changes and revert the file to its previous state. You can use git reset to unstage the changes and restore the file to the last committed version. Here's an example command:

$ git reset file1.txt

Unstaging changes: Suppose you added changes to the staging area using git add, but now you want to remove them from the staging area. You can use git reset to unstage the changes. Here's an example command:

$ git reset HEAD file1.txt

This will unstage the changes to file1.txt without affecting the file itself.

Moving to a previous commit: Suppose you want to move the repository to a previous state, for example to undo a series of changes. You can use git reset to move the HEAD pointer to a specific commit. Here's an example command:

$ git reset abc123

This will move the HEAD pointer to the commit with the SHA-1 hash abc123, effectively restoring the repository to the state it was in at that commit.

Reverting a commit: Suppose you made a commit that introduced a bug, and you want to undo that commit and remove the changes it made. You can use git reset to move the HEAD pointer to the previous commit and remove the changes made in the commit. Here's an example command:

$ git reset HEAD~1

This will move the HEAD pointer to the previous commit, effectively undoing the changes made in the last commit. You can then make the necessary changes and create a new commit. Note that this will permanently remove the last commit and its changes from the repository history.

GITHUB IS HERE:

GitHub is a web-based platform used for hosting and managing Git repositories. It provides a platform for collaborative software development, allowing developers to work together on code, track changes, and manage version control.

Here are some of the main reasons why developers use GitHub:

Collaborative coding: GitHub provides a platform for developers to collaborate on code, share ideas, and work together on projects.
Version control: GitHub allows developers to track changes to their code over time, and revert to previous versions if necessary.
Code review: GitHub provides tools for code review, making it easier for developers to share feedback and improve the quality of their code.
Hosting: GitHub offers free hosting for open source projects, making it easy for developers to share their code with others.

Alternatives to GitHub include:

GitLab: A web-based Git repository manager that offers a similar set of features to GitHub.
Bitbucket: A web-based hosting service for Git and Mercurial repositories, offering features such as code review and team collaboration.
SourceForge: A web-based hosting service for open source software development, offering features such as version control, bug tracking, and project management.
Launchpad: A web-based platform for hosting and collaborating on open source software projects, primarily used by the Ubuntu community.

1) " git remote add " command what? why? how we can use it?

The git remote add command is used to add a new remote repository to your local Git repository. A remote repository is a version of your repository that is hosted on a remote server, which allows you to collaborate with others by sharing changes and updates to your code.

The git remote add command takes two arguments: the name of the remote repository and the URL of the remote repository. Here's an example:

$ git remote add origin https://github.com/username/repo-name.git

// show a list of the remote repositories that are associated with your local Git repository along with their corresponding URLs.

$ git remote -v

In this example, we're adding a new remote repository named "origin" with the URL `github.com/username/repo-name.git

2) " git clone " command what? why? how we can use it?

The git clone command is used to create a copy of a remote repository on your local machine. This allows you to work on the code locally, make changes, and then push those changes back to the remote repository.

The git clone command takes one argument, which is the URL of the remote repository. Here's an example:

$ git clone https://github.com/username/repo-name.git

In this example, we're cloning the remote repository named "repo-name" owned by the "username" account on GitHub.

You can use the git clone command to create as many copies of the remote repository as you need. This can be useful if you need to work on the same codebase on multiple machines or if you want to make backups of the repository.

Branching:

In Git, a branch is a lightweight movable pointer to a commit. It allows you to work on different versions of your codebase independently from the main codebase, making it easier to manage and collaborate on larger projects.

When you create a branch, you essentially create a copy of the current codebase at the current commit. Any changes you make to the code in the new branch do not affect the main codebase until you merge the changes back into the main branch.

Here are some common reasons to use branches in Git:

To develop new features or fixes without affecting the main codebase until they are ready to be merged.
To collaborate on changes with others without interfering with each other's work.
To experiment with new ideas without affecting the stability of the main codebase.

There are two types of branches in Git: local and remote. Local branches are stored locally on your machine, while remote branches are stored on a remote repository, such as GitHub.

Here are some common Git branch commands and their uses:

git branch: Lists all local branches in your repository
git branch <branch-name>: Creates a new branch with the specified name
git checkout <branch-name>: Switches to the specified branch
git merge <branch-name>: Merges the specified branch into the current branch
git push -u <remote-name> <branch-name>: Pushes the specified branch to the remote repository and sets it as the default upstream branch
git pull: Fetches changes from the remote repository and merges them into the current branch

When working with remote repositories, you may also use commands such as git fetch and git clone to download remote branches and create local copies of them.\

Q how many ways we can delete files in git?

In Git, there are several ways to delete files:

Using the "git rm" command: This command removes a file from both the working directory and the Git repository. For example, to delete a file named "example.txt," you can use the following command:

$ git rm example.txt

Using the "git rm --cached" command: This command removes a file from the Git repository, but leaves it in the working directory. For example, to remove a file named "example.txt" from the Git repository, but keep it in the working directory, you can use the following command:

$ git rm --cached example.txt

Using the "git reset" command: This command allows you to unstage a file that has been added to the staging area, effectively removing it from the next commit. For example, to unstage a file named "example.txt," you can use the following command:

perlCopy codegit reset example.txt

Using the "git checkout" command: This command allows you to discard changes made to a file in the working directory. For example, to discard changes made to a file named "example.txt," you can use the following command:

git checkout example.txt

Note that all of these commands permanently remove the file from the Git repository history, so use them with caution.

Git Branches

Branches in Git are incredibly lightweight as well. They are simply pointers to a specific commit -- nothing more. This is why many Git enthusiasts chant the mantra:

branch early, and branch often

Because there is no storage / memory overhead with making many branches, it's easier to logically divide up your work than have big beefy branches.

All Commands: https://hareesh.hashnode.dev/all-github-branching-commands

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