Git Handbook – Quick Reference

Git is a tool that helps you track changes in your code, like a history book for your project. it is one of the most important skills for modern developers. Whether you’re a student learning coding basics or a professional managing large projects, knowing these commands will save time, prevent mistakes, and make collaboration easier.

1. Initialize a Git Repository

• git init
  This command initialize a local git repository in the current directory.
  How does Git know it’s a repository?
  → Git creates a hidden folder named .git inside directory.
  To view the hidden files → ls -a
  Example – .git
    README.md
    src/
  The .git folder contains all Git metadata, commit history, branches, and configuration.

2. Configure Git User Details – Set your user name, email globally

• git config --global user.name "Your Name"
• git config --global user.email "your.email.com"

3. Git Workflow:-

Git mainly work in 3 areas.
Working Directory
↓
git add
↓
Staging Area
↓
git commit
↓
Local Repository → git push → Remote repo

Add changes to staging area
→ git add
→ This does not save changes permanently.
It only moves changes to the staging area, preparing them for commit.

4. Commit changes

• git commit -m "added login feature here"
  A commit stores the staged changes in the local git repository along with a message.
  Git will track future modification and maintain the complete history.

How to view commit History –

• git log
• git log --oneline → better option.

5. Branching →

Branching allow parallel development without affecting the main codebase.

• Create a Branch → git branch <branch name>
• Switch to a Branch → git switch <branch name> / git checkout <branch name>
• Create and switch to new branch in one command → git checkout -b <branch name>

6. How to merging Branches:–

Suppose: you have two branches
 main
 feature-login

You want to merge feature-login branch into main

• Step 1: Switch to destination branch → git switch main
• Step 2: Merge Source branch → git merge feature-login

Always switch to the destination branch before running git merge.
Syntax: git merge <Source branch>
Git merges the specified source branch into the current branch.

7. Compare Branches

Check differences b/w two branches:
→ git diff <source-branch>

Example –

• step1 → git switch main
• step2 → git diff feature-login

This shows what changes exist in feature-login compared to main.

8. Git Reset (Undo commit)

→ Use carefully, especially on shared branches

• Soft Reset – git reset --soft <commit-id>
  Removes commit history after the specified commit but keeps changes staged.

• Default Reset (Mixed Reset) – git reset <commit-id> or git reset --mixed <commit-id>
  It removes commit history and unstages changes, but keeps files.

Hard Reset – git reset --hard <commit-id>
It removes commits and permanently delete file changes. Use with caution.

Reset Using HEAD –

• Remove last commit → git reset --hard HEAD^
• Remove last two commits → git reset --hard HEAD^^
  Alternative command → git reset --hard HEAD~2

9. Cherry pick

It is used when you want to move only specific commits from one branch to another.

• Step 1: Switch to destination branch → git switch main
• Step 2: Apply required commit → git cherry-pick <commit-id>
  By “1st 4-6 digits”

10. Tags

Tags are useful to mark important releases.

• Tag latest commit → git tag V1.0.0
• Tag specific commit → git tag V1.0.0 <commit-id>
• List all tags → git tag
• List all branches → git branch -a

11. Working with remote repositories

• To view remote repositories → git remote -v
  Shows all configured remote repositories.
• Add remote repository → git remote add origin <repository url>

12. Clone Repository

• git clone <repository url>
  This download entire source code, complete commit history, branches, tags to your local system.

13. Git Fetch vs Git Pull

• git fetch → Downloads latest changes from remote repository but does not merge them into your current branch.
  Remote Repo -----> Local git database
  You can review the changes before merging.

• git pull → It performs both git fetch + git merge.
  Git fetches the latest changes and immediately merges them into the current branch.

14. SSH setup for Git (Azure Repos/GitHub)

→ Generate SSH key pair → ssh-keygen -t rsa
Press Enter for default values.

i) Go to SSH directory → cd ~/.ssh
ii) List files → ls -l
You should see something like this

• id_rsa
• id_rsa.pub

iii) Display public key → cat id_rsa.pub
Copy the entire output.

iv) Add Public Key to Azure Repos

1. Open Azure DevOps
2. Go to user settings
3. Select SSH public keys
4. Click Add
5. Paste the public key
6. Save

Now your local machine can securely authenticate and push/pull code without entering credentials every time.

15. How to Resolve Merge Conflicts in Git?

→ A merge conflict occurs when git cannot automatically decide which changes to keep because the same lines of code were modified in different branches.

Example Scenario –
Suppose:
 main → app.txt
 feature-login → app.txt
Both branch modified the same line.

When merging:

• git switch main
• git merge feature-login

Git may display:
Auto-merging app.text
CONFLICT (content): merge conflict in app.text
Automatic merge failed

Step:1 → check Conflicts files → git status
Output: Unmerged paths: both modified: app.text

Step 2: Open the conflicted file
Git marks the conflict code like this:

<<<<<<< HEAD
welcome to Application
=======
welcome to login Application
>>>>>>> feature-login

Meaning:

• <<<<<<< HEAD (current branch / destination branch)
• ======= (separator)
• >>>>>>> (incoming changes from source branch)

Step 3: Manually resolve the conflict → choose what should remain, remove all conflict markers (<<<<<<<, =======, >>>>>>>).
Step 4: Stage the resolve file → git add app.txt
Step 5: Complete the Merge → git commit -m "Resolve merge"

About the Merge → If don’t want to continue, → git merge --abort
This restores the repository to the state before merge started.

16. Stashing git stash → Temporarily save uncommitted changes.

git stash list → Show list of stashes.

git stash apply → Reapply stash but keep it.

git stash pop → Reapply stash and remove it.

17. Rebase git rebase main → Reapply commits on top of another branch. Keeps history clean and linear.

18. Amend Commit git commit --amend → Modify the last commit (message or files).