Git Demystified

Unlock the mysteries of Git with this comprehensive repository! Dive deep into the internals of Git, understand the structure of the .git directory, explore essential Git commands, and discover advanced concepts such as hooks, plumbing, and more.

🚀 Key Features:

• .git Directory Overview: Explore the structure of the .git directory, understanding its components and their roles.
• Git Hooks: Learn how to use and customize Git hooks to automate tasks before or after specific events.
• Plumbing vs Porcelain Commands: Delve into the difference between high-level porcelain commands and low-level plumbing commands.
• Git Objects: Understand the four types of Git objects and their significance in version control.
• Git References: Explore how Git uses references to track branches, tags, and remotes.
• Git Packfiles: Grasp the concept of packfiles and their role in optimizing storage efficiency.
• Git gc/reflog/fsck: Learn about Git's garbage collection, reflog, and integrity checks.

.git Directory Overview

$ git init git_demo
Initialized empty Git repository in /tmp/git_demo/.git/

$ cd git_demo

$ tree .git
.git
├── branches
├── config
├── description
├── HEAD
├── hooks
│   ├── applypatch-msg.sample
│   ├── commit-msg.sample
│   └── ... [Truncated for brevity]
├── info
│   └── exclude
├── objects
│   ├── info
│   └── pack
└── refs
    ├── heads
    └── tags

• .git/config: Holds local git configuration specific to the repo.
• .git/description: Contains a description shown by gitweb.
• .git/HEAD: Points to the current branch/tag/commit.
• .git/hooks: Initial sample hooks; create your own for custom actions.
• .git/info/exclude: Repo-level gitignore separate from .gitignore.
• .git/objects: Stores all git objects.
• .git/refs: Holds references (branch/tag/stash).
• .git/logs: Created as you navigate the repo, contains logs for git reflog.
• .git/index: Holds staging area information.

Git Hooks

Scripts executed before/after events (commit, push, etc.).

• pre-commit: Run lint/tests; prevents commit on non-zero exit code.
• post-receive: For pushing code to production.
• Enable hooks by overwriting/creating scripts in .git/hooks and making them executable.

Git Plumbing vs Porcelain Commands

• Porcelain: User-friendly commands; frontend for git.
• Plumbing: Lower-level commands composing porcelain commands.
• Some plumbing commands: hash-object, update-index, write-tree, commit-tree, cat-file.

Git Objects

4 Types:

• blob: Data stored by git.
• tree: Pointers to file names, contents & other trees.
• commit: Tree of changes with metadata (author, commit message, etc.).
• tag: For annotated tags with hash of tagged object (usually commits).

Git References

• Names pointing to sha1 hashes.
• Stored in .git/refs.
• heads: Branch references.
• tags: Tag references.
• remotes: References on remote urls added.

Git Packfiles

• Git initially stores objects in loose object format.
• Occasionally packs loose objects into a binary file (packfile) for space efficiency.

Git gc/reflog/fsck

gc

• Cleans up and optimizes the repository.
• Auto gc happens occasionally as needed.

reflog

• Records changes to repo's HEAD in .git/logs.
• Useful for recovering accidentally deleted branches.

fsck

• Integrity check of objects in the database.
• Identifies dangling objects.
• Useful when reflogs are unavailable.

🌐 Contributing: Feel free to contribute by forking the repository and submitting pull requests. Your insights and enhancements are welcome!

📄 License: This project is licensed under the MIT License. Utilize, modify, and distribute according to the terms.

Let's demystify Git together! Explore the intricacies and contribute to a comprehensive resource for the Git community. 🎓🔗 #Git #VersionControl #OpenSource