containerization-and-devops

Class 14 - Git Basics (Hands-on)

1. Objective

Master the fundamental concepts and commands of Git, including:

2. Step-by-Step Flow (According to Screenshots)

Step 1: Initialize Git and First Commit

Using init to start tracking. Changing default branch name, making edits, staging, and committing.

git init
git branch -M master
echo test > test
git add .
git commit -m "test"
git log

👉 The git init command creates a hidden .git folder.

Terminal Output

Git Init and First Commit

Step 2: Second Commit

Adding another file and committing. Let’s see the history growth.

echo test2 > test2.txt
git add . && git commit -m "test2"
git log

Terminal Output

Second Commit

Step 3: Third Commit & Graph Log

Using short logs to visualize history properly.

echo test3 > test3.txt
git add . && git commit -m "test3"
git log --oneline
git log --oneline --graph

👉 --oneline --graph visualizes the branch history in a concise format.

Terminal Output

Third Commit and Log

Step 4: Git Diff and Status

Reviewing unsaved changes before a commit.

echo test3secondline >> test3.txt
git diff
git status

👉 git diff shows the exact line changes in modified files. 👉 git status distinguishes between modified and untracked files.

Terminal Output

Diff and Status

Step 5: Untracked Files Status

Creating new files to observe git status output.

echo test4secondline >> test4.txt
git status

Terminal Output

Untracked Files

Step 6: Committing Modified Files

Saving the specific modifications shown above.

git commit -m "test3 modified"
git status

Terminal Output

Commit modifications

Step 7: Branching Basics

Creating and navigating between branches.

git branch main
git switch main
git checkout master

👉 git branch creates or lists branches. git switch or git checkout change the active branch.

Terminal Output

Branching

Step 8: Detached HEAD State

Checking out a specific point in time (commit hash).

git log --oneline --graph
git checkout f246397
git checkout main

👉 Warning: When in “detached HEAD”, changes aren’t associated with a branch unless a new branch is explicitly created.

Terminal Output

Detached HEAD

Step 9: Deleting a Branch

Deleting the master branch.

git branch && git branch -D master

Terminal Output

Delete Branch

Step 10: Creating Branch from Detached HEAD

Creating a new branch to keep specific snapshot commits.

# While detached at an older commit
git branch feature
git branch

Terminal Output

Branching from Detached HEAD

Step 11: Merging (Already Up to Date)

Attempting a merge when the current branch has the history of the target.

git checkout main
git merge feature

Terminal Output

Merge Up to Date

Step 12: Adding Commits to Feature Branch

git checkout feature
echo "dummy feature" > feature.txt
git add .
git commit -m "feature added"

Terminal Output

Committing to Feature Branch

Step 13: The Final Merge

# From main branch
git merge feature
git log --oneline --graph

👉 This creates a true merge commit combining the history of both branches.

Terminal Output

Merging Branches

3. Key Git Commands Summary

Command Description
git init Initialize a new Git repository
git add <file> Stage changes for commit
git commit -m "msg" Save staged changes with a message
git status Show the state of the working directory
git log Show commit history
git diff Show changes between commits/working tree
git branch List, create, or delete branches
git checkout Switch branches or restore working tree files
git merge Join two or more development histories together

4. Final Insight

Git is essential for version control, allowing developers to track changes, collaborate effectively, and revert to previous states if something goes wrong. Understanding branches and merges is the key to managing complex projects.

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