TrainWithShubham · manishvishwakarma89 · Feb 21, 2026 · Feb 21, 2026 · Feb 21, 2026 · Feb 21, 2026
diff --git a/2026/day-01/mk-learning-plan.md b/2026/day-01/mk-learning-plan.md
@@ -0,0 +1,106 @@
+## Day 01 – Introduction to DevOps and Cloud
+### Task
+The goal of Day 01 is to set a strong foundation for my DevOps journey by creating a clear and realistic 90-day execution plan.
+This plan defines my understanding, motivation, goals, and consistency strategy for becoming a DevOps Engineer.
+<hr>
+Current Level
+<ul>
+    <li>
+     Cloud Support Staff, MMTTC, Ramanujan College, University of Delhi
+
+  </li>
+  <li>
+      Having hands-on 1+ years of AWS services i.e. EC2, S3, EBS, RDS, Cloudformation, CloudWatch, CloudTrail, ECS, CodePipeline, DynamoDB.
+  </li>
+  <li>
+      Troubleshooting in linux, networking and system taks
+  </li>
+</ul>
+<hr>
+My Understanding of DevOps & Cloud
+DevOps is a cultural and set of practices that focuses on collaboration between development and operations teams to deliverable a scalable, reliable and optimum sofware as product.
+Mainly DevOps plays major role in sofware industry as follows:
+<ul>
+    <li>
+        Automation
+    </li>
+    <li>
+        CI/CD
+    </li>
+    <li>
+        Monitoring
+    </li>
+    <li>
+        Infrastructure as Code (IAC)
+    </li>
+</ul>
+Goal: The main goal of DevOps engineer is to deliver applications faster, more reliably, with automation and collaboration.
+Keys areas focuses on:
+<ul>
+<li>
+    Linux: Shell Commands, Shell scripting, Networking commmands
+</li>
+<li>
+    Networking: OSI Layer/TCP-IP Layer, Routing, Protocols, Security, firewalls 
+</li>
+<li>
+    Git: git commands: git push, pull, add, commit merge, branch, rebase, cherry pick
+</li>
+<li>
+    CI/CD Pipeline: Continous Integration & Continous Deployment; Jenkins, GitHubActions, AWS CodePipeline, CodeBuild
+</li>
+
+<li>
+    Containers: Docker commands- build, docker-compose
+</li>
+<li>
+    Orchesterisation: Kubernetes Architecture
+</li>
+<li>
+    Monitoring: CloudWatch, Grafana
+</li>
+<li>
+    Infrastructure: Three types of AWS Infrstructure- IAS, PAAS SAS 
+</li>
+</ul>
+<hr>
+Why I Am Learning DevOps & Cloud
+<ul>
+    <li>Building my knowledge to industry level standards as gaining more practical hands-on instead of theortical knowledge</li>
+    <li>To work on real-world industry projects on real schenarios as solving problems</li>
+    <li>To become ready for DevOps jobs/ Cloud Engineer</li>
+    <li>To Upkills my career to make me confident to handle multitaksing projects as per changing requirements </li>
+</ul>
+<hr>
+Where I Want to Reach in 90 Days
+By the end of 90 days, I want to:
+<ul>
+    <li>
+        Understand DevOps concepts clearly and build projects independently
+    </li>
+    <li>
+        Work on real-time, hands-on DevOps projects
+    </li>
+    <li>
+        Be prepared for DevOps Engineer role in Software Company 
+    </li>
+</ul>
+Core DevOps Skills I Want to Build
+1. Linux & networking trobleshooting
+2. Containerization, CI/CD Pipelining, Monitoriing
+3. Orchestarization, Kubernetes deployment and debugging
+
+⏱ Weekly Time Commitment
+Weekdays- 2-3hrs per day
+Weekends- 6-8 hrs per day
+
+Focus will be on:
+
+Daily task completion
+Hands-on practice
+Consistent GitHub commits
+at least 3-posts per week
+<hr>
+##90DaysOfDevOps #TrainwithShubham
+HappyLearning
+Manish Kumar Vishwakarma
diff --git a/2026/day-02/Linux-system-command-prac.pdf b/2026/day-02/Linux-system-command-prac.pdf
diff --git a/2026/day-02/linux-architecture-notes.md b/2026/day-02/linux-architecture-notes.md
@@ -0,0 +1,58 @@
+## Linux Internals – DevOps Foundation
+This document covers the core Linux concepts required for troubleshooting and system management in production environments.
+1. Core Components of Linux
+   Kernel
+The Linux kernel is the main component of a Linux operating system (OS) and is the core interface between a computer’s hardware and its processes. It communicates between the 2, managing resources as efficiently as possible.
+The kernel is so named because—like a seed inside a hard shell—it exists within the OS and controls all the major functions of the hardware, whether it’s a phone, laptop, server, or any other kind of computer.
+What the kernel does
+The kernel has 4 jobs:
+1.	Memory management: Keep track of how much memory is used to store what, and where
+2.	Process management: Determine which processes can use the central processing unit (CPU), when, and for how long
+3.	Device drivers: Act as mediator/interpreter between the hardware and processes
+4.	System calls and security: Receive requests for service from the processes
+
+| **State** | **Full Form**                  | **Meaning**                                                        | **Real Scenario Example**                        |
+| --------- | ------------------------------ | ------------------------------------------------------------------ | ------------------------------------------------ |
+| **R**     | Running                        | Process is actively executing on CPU or ready to run               | `nginx` handling a web request                   |
+| **S**     | Sleeping (Interruptible Sleep) | Waiting for a resource (disk, network, input)                      | App waiting for DB response                      |
+| **T**     | Stopped                        | Process is paused/stopped manually (e.g., via signal)              | Pressed `Ctrl+Z` in terminal                     |
+| **Z**     | Zombie                         | Process finished execution but parent hasn’t collected exit status | Child process ended, parent didn’t call `wait()` |
+
+Why Process States Matter
+| **Issue**                    | **Related Process State(s)**                | **What It Indicates**                           | **What You Check as DevOps Engineer**                   |                           |
+| ---------------------------- | ------------------------------------------- | ----------------------------------------------- | ------------------------------------------------------- | ------------------------- |
+| **High CPU Usage**           | `R` (Running)                               | Process is actively consuming CPU               | `top`, `htop`, `ps -eo %cpu --sort=-%cpu`               |                           |
+| **Memory Leaks**             | Usually `S` or `R`                          | Process memory keeps increasing without release | `top`, `ps aux --sort=-%mem`, `free -m`, check OOM logs |                           |
+| **Stuck / Unresponsive App** | `S` (Sleeping), `D` (Uninterruptible Sleep) | Waiting for I/O, disk, network, or DB           | `ps -ef`, `strace -p <pid>`, check disk/network latency |                           |
+| **Zombie Process**           | `Z` (Zombie)                                | Process finished but parent hasn’t cleaned it   | `ps -el                                                 | grep Z`, check parent PID |
+| **Orphan Process**           | Any state (adopted by PID 1)                | Parent died before child                        | `ps -ef`, verify PPID = 1                               |                           |
+
+
+3. systemd – Service Management
+
+   | **Component**                | **Description**                                                                             |
+   | ---------------------------- | ------------------------------------------------------------------------------------------- |
+   | **systemd**                  | Modern init system used in most Linux distributions to manage system processes and services |
+   | **Starts services at boot**  | Automatically initializes and starts required services during system startup                |
+   | **Restarts failed services** | Can automatically restart services if they crash (based on configuration)                   |
+   | **Manages dependencies**     | Ensures services start in the correct order based on dependency relationships               |
+
+4. Essential Daily Commands
+   | **Command**  | **Purpose**                          | **Common Usage Example** |
+   | ------------ | ------------------------------------ | ------------------------ |
+   | `ps`         | View running processes               | `ps -ef`                 |
+   | `top`        | Monitor real-time CPU & memory usage | `top`                    |
+   | `systemctl`  | Manage system services               | `systemctl status nginx` |
+   | `journalctl` | View system and service logs         | `journalctl -u nginx`    |
+   | `kill`       | Terminate processes                  | `kill -9 <PID>`          |
+
+📌 Conclusion
+Linux is the base operating system for most production systems.
+Understanding kernel behavior, process lifecycle, and systemd service management forms the foundation for effective DevOps troubleshooting and incident response.
+
+Note: use ps and top for process monitoring, systemctl for service management, journalctl for log analysis, and kill for process control.
+
+#90DaysOfDevOps  #TrainWithShubham
+
+Happy Learning
+Manish Kumar Vishwakarma
diff --git a/2026/day-03/linux advanced.pdf b/2026/day-03/linux advanced.pdf
diff --git a/2026/day-03/linux-commands-cheatsheet.md b/2026/day-03/linux-commands-cheatsheet.md
@@ -0,0 +1,83 @@
+# 🐧 Linux Command Toolkit – Long-Term Cheat Sheet
+
+This is a practical command reference focused on:
+- Process Management
+- File System Operations
+- Networking Troubleshooting
+
+These are foundational commands used in DevOps, Cloud, and Linux administration.
+
+---
+
+# 🔹 Process Management
+
+| Command | Usage |
+|----------|--------|
+| `ps aux` | List all running processes with CPU and memory usage. |
+| `ps -ef` | Show processes in full-format listing. |
+| `top` | Real-time process and resource monitor. |
+| `htop` | Interactive process viewer (enhanced top). |
+| `pgrep <name>` | Find process ID by name. |
+| `pidof <name>` | Get PID of a specific process. |
+| `kill <PID>` | Send termination signal to a process. |
+| `kill -9 <PID>` | Force kill a process immediately. |
+| `pkill <name>` | Kill processes by name. |
+| `nice -n 10 <cmd>` | Start a process with adjusted priority. |
+| `renice -n 5 -p <PID>` | Change priority of running process. |
+| `jobs` | Show background jobs in current shell. |
+| `bg` | Resume a job in background. |
+| `fg` | Bring a background job to foreground. |
+| `uptime` | Show system uptime and load average. |
+
+---
+
+# 🔹 File System Management
+
+| Command | Usage |
+|----------|--------|
+| `pwd` | Show current working directory. |
+| `ls -lah` | List files with permissions and sizes. |
+| `cd <dir>` | Change directory. |
+| `mkdir <dir>` | Create a directory. |
+| `mkdir -p path/dir` | Create nested directories. |
+| `touch file.txt` | Create an empty file. |
+| `cp src dest` | Copy files or directories. |
+| `mv src dest` | Move or rename files/directories. |
+| `rm file` | Delete a file. |
+| `rm -rf dir` | Remove directory recursively (use carefully). |
+| `find /path -name "file"` | Search files by name. |
+| `du -sh ` | Show disk usage of files/directories. |
+| `df -h` | Show disk space usage. |
+| `stat file` | Display detailed file metadata. |
+| `chmod 755 file` | Change file permissions. |
+| `chown user:group file` | Change file ownership. |
+| `less file.log` | View large file with scrolling. |
+| `tail -f file.log` | Monitor file in real time. |
+
+---
+
+# 🔹 Networking Troubleshooting
+
+| Command | Usage |
+|----------|--------|
+| `ip addr` | Display IP addresses of network interfaces. |
+| `ping google.com` | Test connectivity and latency to host. |
+| `curl -I https://example.com` | Check HTTP response headers. |
+| `dig example.com` | Query DNS records. |
+| `ss -tulnp` | Show listening ports and services. |
+| `netstat -tulnp` | Display open ports and connections. |
+
+
+---
+
+# 🔹 Log & Service Debugging Essentials
+
+| Command | Usage |
+|----------|--------|
+| `journalctl -u nginx` | View logs for specific systemd service. |
+| `journalctl -f` | Follow system logs in real time. |
+| `systemctl status nginx` | Check service status and recent logs. |
+
+---
+
+
diff --git a/2026/day-04/linux-practice.md b/2026/day-04/linux-practice.md
@@ -0,0 +1,76 @@
+### Linux Practice: Processes and Services
+1️⃣ Check Running Processes
+
+
+<img width="903" height="188" alt="image" src="https://github.com/user-attachments/assets/d1563e02-4d82-4804-8cbd-559f5d6e92d7" /><br>
+
+<img width="1251" height="281" alt="image" src="https://github.com/user-attachments/assets/70d8842e-da30-49d4-a7a1-bb8700b1e2df" /><br>
+top command: 
+<img width="1850" height="949" alt="image" src="https://github.com/user-attachments/assets/367322d6-0cf2-478e-aaf3-4b8e83521443" />
+
+📊 System Health Checks (Quick Snapshot)
+| Check Item           | Command Used   | What It Shows              | What to Look For                     |
+| -------------------- | -------------- | -------------------------- | ------------------------------------ |
+| CPU Usage            | `top` / `htop` | Real-time CPU consumption  | High `%us` or `%sy` values           |
+| Memory Usage         | `free -m`      | RAM & swap usage           | Low free memory, high swap usage     |
+| Load Average         | `uptime`       | System load (1, 5, 15 min) | Load > CPU cores = possible overload |
+| Running Processes    | `ps aux`       | All running processes      | High `%CPU` or `%MEM` values         |
+| Live Process Monitor | `top`          | Dynamic process view       | Identify abnormal resource usage     |
+
+usage
+🔎 Identifying High CPU Process (Inside top)
+| Action         | Key Press   | Purpose                                   |
+| -------------- | ----------- | ----------------------------------------- |
+| Sort by CPU    | `Shift + P` | Shows highest CPU-consuming process first |
+| Sort by Memory | `Shift + M` | Shows highest memory-consuming process    |
+| Kill a Process | `k`         | Terminate selected process                |
+| Refresh Faster | `d`         | Change refresh interval                   |
+
+2️⃣ Inspect One systemd Service
+
+Check Status of SSH Service
+<img width="1856" height="894" alt="image" src="https://github.com/user-attachments/assets/78492bb1-8093-49a8-9792-ee5ba6e030ae" />
+<br>
+)
+🔹 View Logs for That Service
+
+<img width="1734" height="357" alt="image" src="https://github.com/user-attachments/assets/ba972205-7d04-4d53-bc11-aa726680a01a" />
+✅ Step 1: Check CPU & Load
+top
+uptime
+
+<img width="1803" height="953" alt="image" src="https://github.com/user-attachments/assets/0c27bff0-d4cc-47d3-8e6d-a12da49ee16a" />
+Step 2: Check Memory
+free -h
+<img width="1133" height="173" alt="image" src="https://github.com/user-attachments/assets/754df0b3-6f85-4f9a-89b0-8b321d77d781" />
+Step 3: Check Disk
+df -h
+<img width="1269" height="435" alt="image" src="https://github.com/user-attachments/assets/60780147-2882-477a-9d7d-18047bbf49cd" />
+If disk > 90% full → possible issue.
+
+Service Practice Note – SSH Service (sshd)
+1️⃣ Check if Service is Running
+systemctl status ssh
+
+<img width="1911" height="661" alt="image" src="https://github.com/user-attachments/assets/a7d1f1eb-65d3-4259-bbbd-af73a1be0771" />
+<br>
+2️⃣ Check if SSH is Enabled at Boot
+<img width="1392" height="213" alt="image" src="https://github.com/user-attachments/assets/a9c3ee9b-62bc-4216-81a9-9fac9fe3a54f" />
+Step 2️⃣ Enable SSH to start at boot
+<img width="1395" height="153" alt="image" src="https://github.com/user-attachments/assets/6c2fe310-2073-456b-90bb-0f004c1921ea" />
+<br>
+Step 3️⃣ If SSH is not running, start it
+sudo systemctl start ssh
+Then verify:
+systemctl status ssh
+so use
+systemctl enable sshd
+systemctl start sshd
+systemctl status sshd
+<img width="1919" height="838" alt="image" src="https://github.com/user-attachments/assets/0c9079a4-271d-4ca1-95d2-796949ae8146" />
+<hr>
+Use hashtags: #90DaysOfDevOps  #TrainWithShubham
+
+Happy Learning 
+Manish Kumar Vishwakarma
+
diff --git a/2026/day-05/linux-troubleshooting-runbook.md b/2026/day-05/linux-troubleshooting-runbook.md
@@ -0,0 +1,57 @@
+## Day 05 – Linux Troubleshooting Drill: CPU, Memory, and Logs
+Focused Troubleshooting Runbook
+
+1️⃣ Environment Basics
+uname -a
+<img width="1498" height="84" alt="image" src="https://github.com/user-attachments/assets/6a90a753-bd89-4963-ae76-60fa94e87824" />
+Command 2: OS Version
+
+cat /etc/os-release
+<img width="1041" height="421" alt="image" src="https://github.com/user-attachments/assets/35224236-4147-4916-8bbc-3b8a8d257020" />
+2️⃣ Filesystem Sanity
+Command 3: Create Test Directory
+
+<img width="882" height="177" alt="image" src="https://github.com/user-attachments/assets/3b1b67d3-bd95-406e-9986-d2c65294aeb6" />
+cp /etc/hosts /tmp/runbook-demo/hosts-copy
+ls -l /tmp/runbook-demo
+
+<img width="1540" height="630" alt="image" src="https://github.com/user-attachments/assets/8abcb1fb-8d4b-4397-a026-f3a4e3a7649d" />
+3️⃣ CPU / Memory (2)
+Command 5: Check Process Resource Usage
+ps -eo pid,pcpu,pmem,comm --sort=-pcpu | head
+<img width="1107" height="312" alt="image" src="https://github.com/user-attachments/assets/ea17904c-4124-4682-a3e5-2297428533d3" />
+Command 6: Memory Snapshot
+free -h
+
+<img width="1092" height="116" alt="image" src="https://github.com/user-attachments/assets/875c82ab-a0c6-45d0-87ba-ab0d057f521d" />
+4️⃣ Disk / IO (2)
+Command 7: Disk Usage
+df -h
+
+<img width="964" height="301" alt="image" src="https://github.com/user-attachments/assets/344a9d45-67c4-4aa1-823b-25f089044229" />
+Command 8: Log Directory Size
+du -sh /var/log
+
+<img width="855" height="316" alt="image" src="https://github.com/user-attachments/assets/b59c8e27-5124-478c-91fa-e3e9730b13cf" />
+5️⃣ Network (2)
+Command 9: Check Listening Ports
+ss -tulpn | grep nginx
+
+<img width="1854" height="81" alt="image" src="https://github.com/user-attachments/assets/7610dbf7-9a76-49a2-86cf-35d2a77ca851" />
+Command 10: Test Service Endpoint
+
+<img width="927" height="168" alt="image" src="https://github.com/user-attachments/assets/ac9f4332-7c93-4b10-8609-9a2c08ae5867" />
+
+6️⃣ Logs (2)
+Command 11: Service Logs
+connect() failed (111: Connection refused) while connecting to upstream
+Command 12: Application Log
+OSError: [Errno 98] Address already in use
+<hr>
+Use hashtags:
+#90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham
+
+Happy Learning
+Manish Kumar Vishwakarma
+
+