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Git Dive Deep

git init

  • default branch created while using git init is the master branch.
  • When we initialize the repo, two regions are created.
  • Staging area (where changes are prepared before commit)
  • Non-staging area (working directory with untracked/modified files)

The .git directory contains:

  • HEAD file (references current branch)
  • config file (repository configuration)
  • objects directory (stores all content)
  • refs directory (stores pointers to commits)

Remove a local git repo

rm -rf .git/

This deletes the repository history.

Rename default branch name

git init --initial-branch=main

Sets initial branch to main instead of master.

Nested git repository. Never create a git repo inside a repo. Avoid this to avoid chaos.

Never create a git repo inside another repo (except for submodules)

Potential issues:

  • Conflicting .git directories

  • Confusing version control boundaries

  • Complex merge behaviors

git add

Core Functionality

Stages changes from working directory to staging area

Advanced Usage

Add a part of file to the staged area.

Interactive add (choose hunks)

git add -p

Add all tracked files (not new files)

git add -u

Add all tracked and untracked files

git add -A

# Add by file pattern
git add '*.js'

Behind the Scenes

  • Creates SHA-1 hashes of file contents
  • Stores compressed versions in object database
  • Updates index file with new file modes and hashes

git commit

Commit Anatomy

Creates a commit object containing:

  • Author info
  • Commit message
  • Pointer to tree object (snapshot of repo)
  • Pointer to parent commit(s)

Advanced Options

# Amend previous commit
git commit --amend

# Amend previous commit with no commit message
git commit --amend --no-edit

# Sign commit cryptographically
git commit -S

# Commit with multiline message
git commit -m "Title" -m "Description"

# Commit with no changes (run pipeline)
git commit --allow-empty -m "dummy"

Technical Details

  • Each commit has a unique SHA-1 hash
  • Commit objects reference tree objects
  • Tree objects reference blob objects (files) and other trees

git push

Advanced Techniques

# Push specific branch
git push origin branch-name

# Set upstream branch
git push -u origin branch-name

# Force push (use with caution)
git push --force

Protocols and Internals

  • Can use HTTPS, SSH, or Git protocol
  • Underlying transfer uses packfiles for efficiency
  • Uses the "smart" protocol for modern servers

Push Rejection Scenarios

  1. Non-fast-forward: Remote has commits you don't have locally
  2. Solution: git pull first to merge changes
  3. Permission denied: Authentication issues
  4. Solution: Check SSH keys or credentials
  5. Shallow update not allowed: Pushing from shallow clone
  6. Solution: Perform full clone

git log

Gives last 2 commits

git log -n 2

Gives diff layout of commit status:

git log --pretty= short

git log --pretty= full

git log --pretty= fuller

git log --pretty= oneline

 git log --pretty=form
at:"%h"

# prints commit id
 git log --pretty=format: "%h"

# prints commit id and commit message
 git log --pretty=format: "%h %s "

#prints the commit from a week ago
git log --since="1 week ago"

#prints the commit within an interval
git log --since="02/19/2024" --until="05/20/2025"

# shows you the commit history with the patch diff included
git log -p

git log

Summary

  • Head is the pointer to the latest commit.
  • You can change head.
  • Every next commit points to the previous commit. It creates a linked list of commits.

Git Workflow