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Day 28 – Revision Day: Everything from Day 1 to Day 27

Task

You've covered a lot of ground in 27 days — DevOps fundamentals, Linux deep dives, Shell scripting, Python basics, Git & GitHub, and even your developer branding. Today, stop and revise. No new concepts. Just solidify what you've learned.

The goal is to identify gaps, revisit topics you struggled with, and make sure you can confidently explain and use everything covered so far.

What You've Covered So Far

Days Topic Key Concepts
1 DevOps & Cloud Intro What is DevOps, SDLC, Cloud basics
2–7 Linux Fundamentals Architecture, commands, processes, systemd, file system hierarchy, troubleshooting, text files
8 Cloud Server Setup Docker, Nginx, web deployment
9–11 Users, Permissions & Ownership User/group management, file permissions, chown/chgrp
12 Revision Day 1 Days 1–11 recap
13 Volume Management LVM — physical volumes, volume groups, logical volumes
14–15 Networking Fundamentals, DNS, IP, subnets, ports, hands-on checks
16–18 Shell Scripting Basics, loops, arguments, error handling, functions
19–20 Shell Scripting Projects Log rotation, backup, crontab, log analyzer
21 Shell Scripting Cheat Sheet Personal reference guide
22–25 Git & GitHub Init, branching, merge, rebase, stash, cherry pick, reset, revert, branching strategies
26 GitHub CLI Managing GitHub from the terminal
27 GitHub Profile Profile README, repo organization, developer branding

Challenge Tasks

Task 1: Self-Assessment Checklist

Go through the checklist below. For each item, mark yourself honestly:

  • Can do confidently
  • Need to revisit
  • Haven't done yet

Linux

  • Navigate the file system, create/move/delete files and directories
  • Manage processes — list, kill, background/foreground
  • Work with systemd — start, stop, enable, check status of services
  • Read and edit text files using vi/vim or nano
  • Troubleshoot CPU, memory, and disk issues using top, free, df, du
  • Explain the Linux file system hierarchy (/, /etc, /var, /home, /tmp, etc.)
  • Create users and groups, manage passwords
  • Set file permissions using chmod (numeric and symbolic)
  • Change file ownership with chown and chgrp
  • Create and manage LVM volumes
  • Check network connectivity — ping, curl, netstat, ss, dig, nslookup
  • Explain DNS resolution, IP addressing, subnets, and common ports

Shell Scripting

  • Write a script with variables, arguments, and user input
  • Use if/elif/else and case statements
  • Write for, while, and until loops
  • Define and call functions with arguments and return values
  • Use grep, awk, sed, sort, uniq for text processing
  • Handle errors with set -e, set -u, set -o pipefail, trap
  • Schedule scripts with crontab

Git & GitHub

  • Initialize a repo, stage, commit, and view history
  • Create and switch branches
  • Push to and pull from GitHub
  • Explain clone vs fork
  • Merge branches — understand fast-forward vs merge commit
  • Rebase a branch and explain when to use it vs merge
  • Use git stash and git stash pop
  • Cherry-pick a commit from another branch
  • Explain squash merge vs regular merge
  • Use git reset (soft, mixed, hard) and git revert
  • Explain GitFlow, GitHub Flow, and Trunk-Based Development
  • Use GitHub CLI to create repos, PRs, and issues

Task 2: Revisit Your Weak Spots

  1. Pick 3 topics from the checklist where you marked "Need to revisit"
  • Use grep, awk, sed, sort, uniq for text processing
  • Handle errors with set -e, set -u, set -o pipefail, trap
  • Use git stash and git stash po
  1. Go back to that day's challenge and redo the hands-on tasks
  2. Document what you re-learned in day-28-notes.md

Task 3: Quick-Fire Questions

Answer these from memory (no Googling). Then verify your answers:

  1. What does chmod 755 script.sh do? Answer
  • chmod - it is command for change permission
  • 755 - rwxr-xr-x
  • script.sh it is a file
  1. What is the difference between a process and a service?
  • Process - Process is a running program. At a particular instant of time, it can be either running, sleeping, or zombie (completed process, but waiting for it's parent process to pick up the return value).
  • Daemons They are the processes which run in the background and are not interactive. They have no controlling terminal
  1. How do you find which process is using port 8080? Using netstat
netstat -tulpn | grep 8080

  1. What does set -euo pipefail do in a shell script? set -euo pipefail is a best practice used in Bash scripts to make scripts safer and fail fast when errors occur.

  2. What is the difference between git reset --hard and git revert? Ans. git reset --hard removes commits and resets the working directory to a previous state, rewriting history. git revert creates a new commit that reverses the changes of a previous commit without modifying history, making it safer for shared repositories.

  3. What branching strategy would you recommend for a team of 5 developers shipping weekly? Ans.

1. Main Branch (main)

  • Always contains production-ready code
  • Protected branch (no direct commits)
  • Only merged via Pull Requests

2. Develop Branch (develop)

  • Integration branch where developers merge their completed work

  • Used for testing and preparing the weekly release

3. Feature Branches (feature/)* Each developer creates a branch for a specific feature or task.

Example:

git checkout -b feature/login-api

Create feature branch from develop

Work on the feature

  • Push branch
  • Create Pull Request to develop
  • Code review + merge
  1. What does git stash do and when would you use it?
  2. How do you schedule a script to run every day at 3 AM?
crontab -e

0 3 * * * /home/student/Day_03/script.sh 9. What is the difference between git fetch and git pull?

This note explains the difference between git fetch and git pull, which is a common DevOps and Git interview topic.

1. git fetch

  • Definition: Downloads changes from the remote repository but does not merge them into your local branch.
  • Purpose: To check for remote changes before integrating them.

Example

git fetch origin

2. git pull

Definition: Downloads changes from the remote and immediately merges them into your current branch.

Purpose: To update your local branch in one step.

Example

git pull origin main
  1. What is LVM and why would you use it instead of regular partitions?

Task 4: Organize Your Work

  1. Make sure all your daily submissions (day-1 through day-27) are committed and pushed
  2. Check that your git-commands.md is up to date
  3. Check that your shell scripting cheat sheet is complete
  4. Verify your GitHub profile and repos are clean (from Day 27)

Task 5: Teach It Back

Pick one topic you've learned and write a short explanation (5-10 lines) as if you're teaching it to someone who has never heard of it. Add it to your day-28-notes.md.

Examples:

  • Explain Git branching to a non-developer
  • Explain file permissions to a new Linux user
  • Explain what a crontab is and why sysadmins use it

Teaching is the best test of understanding.

Happy Learning! TrainWithShubham