Main

2026/day-01/learning-plan.md

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+THE CLEAR ANSWER FOR MY WHAT WHY HOW ?
+
+
+
+What is your understanding of DevOps and Cloud Engineering?
+
+DevOps is a practice or mindset that an organization follows to develop applications and software efficiently and effectively. 
+It helps bridge the gap between the development team and the operations team. It automates daily tasks to reduce the chance of mistakes and save time. 
+Meanwhile, Cloud Engineers are the ones who manage and perform these tasks on cloud servers. Collectively, they help the organization deploy changes efficiently and quickly.
+
+
+
+Why are you starting to learn DevOps & Cloud?
+
+As per the latest IT trends, DevOps and Cloud Engineering jobs are among the highest-paying, and there is a high demand for these roles in the market. 
+This career path also provides me with the opportunity to work remotely.
+
+
+
+Where do you want to reach? 
+
+I want to become a Senior DevOps Engineer or Cloud Architect where I can design scalable, automated infrastructure for global applications. 
+Ultimately, my goal is to reach a level of expertise where I can lead technical projects, mentor others, and enjoy the flexibility of working from anywhere in the world.
+
+
+
+How will you stay consistent every single day?
+
+It is my own dream, so following my dream is what keeps me consistent.
+
+

2026/day-02/linux-architecture-notes.md

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+Day 2  Today’s goal is to understand how Linux works.
+
+Short notes:
+
+The core components of Linux (kernel, user space, init/systemd)
+
+Kernel: Think of it as the brain. It allocates resources ("CPU," "RAM," "Disk") to various processes for a specific amount of time.
+It can directly communicate with the hardware of the system and is also known as the core of Linux.
+
+User Space: This is the space where all applications, programs, and shells (like Bash) run. 
+Because they cannot directly interact with the hardware, they do so with the help of the kernel.
+
+init/systemd: It is the very first process that starts after your system boots Linux, and its PID is always 1. 
+It acts like a parent process that sets up your system to work.
+
+
+
+How processes are created and managed
+
+Processes are simply a running instance of a program.
+IN Linux we have 2 ways to create a process, 1st one is fork() "clone the current processes" 2nd exec() "REplace the clone with the new program" 
+
+To manage these processes we use its different states 
+
+Running (R): The process is actively executing on the CPU or is in the queue ready to execute.
+
+Sleeping (S / D): The process is resting, waiting for an event or resource.
+Interruptible (S): Waiting for user input or a timer.
+Uninterruptible (D): Deep sleep, usually waiting on disk or network I/O.
+
+Stopped (T): The process has been suspended or paused (e.g., by pressing Ctrl+Z in the terminal).
+
+Zombie (Z): The process has finished executing and is dead, but its parent process hasn't checked its exit status yet. 
+It is essentially a "ghost" lingering in the process table.
+
+
+
+What systemd does and why it matters
+
+systemd is kind of a modern system and service manager for Linux. 
+It boots the system, manages background services, and handles logging.
+
+It amtters because it allows services to start in parallel (making boots faster), automatically restarts crashed applications, and it is a primary tool for diagnosing
+why a web server or database failed to launch.
+
+
+
+5 Daily Commands for DevOps
+
+ps aux: provdide the information about the current running processes and who owns them 
+top: It shows the live details of running processes in a more interactive way
+kill -9 <PID>: kills the frozen or dead process forcefully
+systemctl status <service_name>: it checks the background runing processes details like nginx, docker etc.
+journalctl -u <service_name>: Reads the specific logs for a systemd service. This is the first stop when an application fails to start.

2026/day-03/linux-commands-cheatsheet.md

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+Day 03 – Linux Commands Practice
+
+Today’s goal is to build a Linux command confidence.
+
+I created a cheat sheet of commands focused on:
+
+
+Process management
+
+pwd: Prints the current working directory (where are we right now).
+ls -la: Lists all files (including hidden ones) with detailed ownership and permission info.
+cd /path/to/dir — Changes your directory to the specified path.
+mkdir: Creates a new directory.
+rm -rf /folder: Forcefully and recursively removes a folder and its contents (use with extreme caution).
+cp source.txt dest.txt: Copies a file or directory to a new location.
+mv oldname.txt newname.txt — Moves a file, or renames it if the destination is in the same folder.
+cat file.txt: Prints the entire contents of a file directly to your terminal.
+tail -f /var/log/syslog — Continuously shows the end of a log file as new lines are added.
+grep "error" file.txt — Searches inside a file and outputs only the lines containing the specific word.
+chmod +x script.sh — Changes the permissions of a file to make it executable.
+chown user:group file.txt — Changes the owner and group assigned to a file or directory.
+
+
+File system
+
+ps aux: Captures a snapshot of every single process currently running on the system.
+top: Opens a live, interactive dashboard showing CPU, memory usage, and active processes.
+kill -9 <PID> — Forcefully terminates a stuck or rogue process using its Process ID.
+df -h — Shows available disk space on your hard drives in a human-readable format (MB/GB).
+systemctl status docker — Checks if a background service (like Docker or Nginx) is running or failed.
+systemctl restart docker — Stops and immediately starts a service to apply new configurations.
+journalctl -u docker — Retrieves the specific background logs for a systemd service to diagnose crashes.
+
+
+Networking troubleshooting
+
+ping google.com — Tests network connectivity by providing a continuous response.
+ip addr — Displays the IP addresses currently assigned to your machine's network interfaces.
+curl -I https://google.com : Fetches the HTTP headers of a website to test if the web server is responding.
+dig domain.com — Queries the DNS records to see exactly which IP address a domain name points to.
+netstat -tulpn — Lists all open network ports on your machine and shows which processes are using them.

2026/day-04/linux-practice.md

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+Day 4 Hands on practice of linux commands
+
+Process Checks
+
+
+How to check for a particular process?
+
+pgrep -a cron
+  888 /usr/sbin/cron -f -P #888 is the PID
+
+what is the command used to check the bussiest processes 
+
+top -n 1  # we use -n 1 for the current time glimpes 
+  2399 sachin    20   0  397512  12372   7068 S   8.3   0.1   0:02.55 ibus-da+
+
+
+System Checks 
+
+Command used to know the helth of a proceses by the system  
+
+systemctl status cron 
+## It tells you the detail explantion about that process 
+
+systemctl is-active cron 
+## It tell in one word wheather the system is active or not 
+
+
+Log Checks 
+
+Command used to read the service's diary
+
+journalctl -u cron -n 5 # used to check for a particular services
+  May 20 17:35:01 sachin-H510M-K-V2 CRON[4337]: (root) CMD (command -v debian-sa1>
+  May 20 17:35:01 sachin-H510M-K-V2 CRON[4336]: pam_unix(cron:session): session c>
+  May 20 17:45:01 sachin-H510M-K-V2 CRON[4491]: pam_unix(cron:session): session o>
+  May 20 17:45:01 sachin-H510M-K-V2 CRON[4492]: (root) CMD (command -v debian-sa1>
+  May 20 17:45:01 sachin-H510M-K-V2 CRON[4491]: pam_unix(cron:session): session c>
+
+Command used to read the general system diary
+
+tail -n 10 /var/log/syslog
+  2026-05-20T17:46:40.135011+05:30 sachin-H510M-K-V2 systemd[1]: bluetooth.service - Bluetooth service was skipped because of an unmet condition check (ConditionPathIsDirectory=/sys/class/bluetooth).
+  2026-05-20T17:46:42.135821+05:30 sachin-H510M-K-V2 fwupd[4539]: 12:16:42.135 FuMain               fwupd 1.9.34 ready for requests (locale en_US.UTF-8)
+  2026-05-20T17:46:42.137093+05:30 sachin-H510M-K-V2 dbus-daemon[863]: [system] Successfully activated service 'org.freedesktop.fwupd'
+  2026-05-20T17:46:42.137280+05:30 sachin-H510M-K-V2 systemd[1]: Started fwupd.service - Firmware update daemon.
+  2026-05-20T17:46:42.170833+05:30 sachin-H510M-K-V2 systemd[1]: fwupd-refresh.service: Deactivated successfully.
+  2026-05-20T17:46:42.170976+05:30 sachin-H510M-K-V2 systemd[1]: Finished fwupd-refresh.service - Refresh fwupd metadata and update motd.
+  2026-05-20T17:50:07.078599+05:30 sachin-H510M-K-V2 systemd[1]: Starting sysstat-collect.service - system activity accounting tool...
+  2026-05-20T17:50:07.081690+05:30 sachin-H510M-K-V2 systemd[1]: sysstat-collect.service: Deactivated successfully.
+  2026-05-20T17:50:07.081777+05:30 sachin-H510M-K-V2 systemd[1]: Finished sysstat-collect.service - system activity accounting tool.
+  2026-05-20T17:50:59.521976+05:30 sachin-H510M-K-V2 google-chrome.desktop[3048]: [3041:3041:0520/175059.521196:ERROR:ui/ozone/platform/wayland/host/wayland_data_drag_controller.cc:179] Invalid state when trying to start drag. source=kMouse
+
+
+Mini Troubleshooting Steps
+If you ever check a service and it says inactive or failed, here is the exact sequence to fix it
+
+1.Restart the service:Turning it off and on again fixes 90% of issues.
+Run sudo systemctl restart cron
+
+2.Verify it worked:
+Run systemctl status cron to make sure it says active (running).
+
+3.Check for errors:If it still fails, 
+run journalctl -u cron -e to jump to the very end of the logs and read the red error messages to see exactly what broke.
+
+
+
+

2026/day-05/helth-and-troubleshooting.md

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+Mini Runbook: Nginx Health & Troubleshooting
+Target Service: nginx
+Objective: Capture a system health snapshot, verify filesystem sanity, and trace service logs.
+
+1. Environment Basics
+Command: uname -a and cat /etc/os-release
+
+Observation: Successfully identified the operating system version and kernel details before starting work.
+
+2. Filesystem Sanity
+Command: mkdir /tmp/runbook-demo && cp /etc/hosts /tmp/runbook-demo/hosts-replica && ls -l /tmp/runbook-demo
+
+Observation: Verified that basic read/write permissions are working perfectly in the /tmp directory.
+
+3. CPU & Memory Health
+Command: pgrep nginx (to get the PID) followed by ps -o pcpu,pmem,comm -p <PID>
+
+Observation: Nginx is running and consuming minimal CPU and memory resources.
+
+Command: free -h
+
+Observation: System RAM has plenty of available overhead.
+
+4. Disk & I/O
+Command: df -h and du -sh /var/log
+
+Observation: Disk partitions have sufficient free space, and the /var/log directory is not taking up abnormal amounts of storage.
+
+5. Network Connections
+Command: ss -tulpn | grep nginx
+
+Observation: Confirmed Nginx is actively listening on its assigned ports (usually 80 and/443) and there are no dead connections (curl -I).
+
+6. Log Tracing
+Command: journalctl -u nginx -n 50 and tail -n 50 /var/log/kern.log
+
+Observation: Scanned the last 50 lines of both the Nginx specific logs and the general kernel logs. No critical errors or warnings detected.
+
+🚨 If This Worsens (Escalation Steps)
+If Nginx becomes unresponsive or spikes in resource usage, I will take these 3 steps:
+
+Test Configuration & Restart: Run nginx -t to ensure no syntax errors exist, then run sudo systemctl restart nginx to clear the stalled process.
+
+Increase Log Verbosity: Modify the Nginx configuration to enable "debug" level logging to catch exactly where requests are failing.
+
+Trace System Calls: Use strace -p <PID> on the Nginx worker process to see if it is getting stuck trying to read a specific file or connect to a backend database.

2026/day-06/notes-file-op.md

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+Day 6: Linux Fundamentals – Read and Write Text Files
+File: file-io-practice.md
+
+Today’s focus is on manipulating text files directly from the command line. Instead of opening a text editor, I used basic input/output redirection to create, write, and read files.
+
+1. Creating the File
+Command: touch notes.txt
+
+What it did: Created a completely empty file named notes.txt. (If the file already existed, it would just update the "last modified" timestamp without changing the actual text).
+
+2. Writing Text (The Dangerous Way)
+Command: echo "Line 1: Starting my Linux file practice." > notes.txt
+
+What it did: The single > symbol is a redirect. It took the text from echo and pushed it into the file.
+
+Note: A single > will overwrite everything currently in the file. It is a destructive command!
+
+3. Appending Text (The Safe Way)
+Command: echo "Line 2: Appending this line so I don't lose Line 1." >> notes.txt
+
+What it did: The double >> safely added this new text to the very bottom of the file without deleting the first line.
+
+4. Writing and Viewing Simultaneously
+Command: echo "Line 3: Using tee is pretty cool." | tee -a notes.txt
+
+What it did: The tee command splits the output like a "T" junction in a pipe. It printed the text to my terminal screen and safely appended it (-a) to the file at the same time.
+
+5. Reading the Full File
+Command: cat notes.txt
+
+What it did: Read and displayed the entire content of the file in the terminal. I could see all three of my lines perfectly.
+
+6. Reading Parts of the File
+Command: head -n 2 notes.txt
+
+What it did: Displayed only the top 2 lines of the file. This is great for peeking at the beginning of huge files without flooding the terminal screen.
+
+Command: tail -n 2 notes.txt
+
+What it did: Displayed only the bottom 2 lines of the file. This is exactly what I would use to check the most recent entries at the very end of a system log file.
+
+7. Command used to do both at same time 
+
+   tee: it works as echo "This line will print on terminal as well as saved in a file" | tee -a /var/location-of-file.txt
+
+

2026/day-07/day-07-linux-fs-and-scenarios.md

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+1. Linux File System Hierarchy
+
+"/" :   This is the root directory it is the topmost level of the entire file system hierarchy
+        it contains various major directories/files within it like "boot" "bin" "etc" "home" and much more.
+        i would use this directory when i have to figure out anything about the system
+
+"/home" : This is a dedicated, private space for each user account 
+          It contains the name of the users using your system
+          I would use this directory when i have to search for any users 
+
+"/root" : It is the home directory of the admin  
+          It contanis admin dedicated things 
+          NOrmal user can't open this directory 
+
+"/etc"  :  It is the central hub for system-wide configuration files
+           It contains all the files that describes or tells the operating system how to perform "ssh" "cron" 
+           I will use this directory when i have to check any deep information about any process
+
+"/var/log" : This directory is very essential in linux as it saves the record of everything that happens in your                    system 
+              it contains "boot" "config" "syslog"
+              this will often used widely by me to check for any faults
+
+"/tmp"      : As the name suggest it stores only the  temprory files that are created by users, os, procesees. 
+              It shows folders for different application like for the chrome "com.google.Chrome.DLjzx0"
+              I will use it to store my temporary files. 
+
+"/bin"      : Contains essential system binaries required for the system to boot and run in single-user mode. 
+              it also contains foundational commands here like ls, cp, and mv .
+              I will use this directory when i have to check for any boot related quaaries 
+
+"/usr/bin"   :  Stores the majority of user-accessible programs that are not critical for basic system booting, such                  as python, git, or text editors
+
+"/opt"       : It stores all the information about the third party apps that are installed in your system
+               i saw the directory of chrome where many information are stored 
+               i used this to see for any third party application 
+
+Hands On Task
+
+Command used to check the top 5 biggest file in your log folder
+
+"du -sh /var/log/* 2>/dev/null | sort -h | tail -5" : 
+
+breif explanation: du : used to chechk the free space 
+                   -sh : these flags used to summerize && human readable form 
+                   /var/log/* : In this * tells to chek the complete log directory
+                   2> : used to pass all the unwanted error
+                   /dev/null : a black hole 
+                   sort -h : sort the data into human readable form small to big 
+                   tail -5 : prints the last 5 lines of teh output 
+
+
+"cat /etc/hostname": Prints your computer hostname
+
+"ls -la ~" : shows all the hidden files in the home directory that starts with . 
+
+2. Scenario Practice
+
+   The Dead Service. A service named myapp didn't start after a reboot.
+           step1 : systemctl status myapp : check the current status of the app.
+           step2 : journalctl -u myapp -n 10 : It shows the most recent activity of myapp
+           step3 : systemctl is-enabeld myapp : it checks the system trias to start it
+
+   Scenario 2: The Sluggish Server. The server is slow and the CPU is spiking.
+           step1: htop : to see which processes takes more cpu percentage and fetch thier PID
+           step2 : kill -9 <PID> : It terminate the processes
+
+   Scenario 3: The Missing Logs. A developer needs the logs for the docker service.
+            step1 : journalctl -u docker : It gives all the requierd logs related to docker
+
+   Scenario 4: The Blocked Script. A script at /home/user/backup.sh says "Permission denied".
+             step1 : ls -l : To check the permmison of that backup.sh
+             step2 : chmod 777 : It changes the permission to allow everthing to everyone ("NOte it is risky gave                          permission accordingly")

2026/day-08/cloud-deployment.md

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+Commands used : 
+(Before starting whith commands you must have to do these things create a ec2 instance and find the link of ssh 
+that is located insde the connect section of the aws page)
+
+My-key-pair : is created when you are launching the instance
+
+comaand 1 : Used to check where the private key was installed or located and change the 
+directiry as per that using cd command 
+
+command 2 : ssh -i <My-key-pair> ubuntu@<your public dns> 
+
+command 3 : sudo apt-get update && sudo apt upgrade
+
+command 4 : sudo apt install nginx
+
+command 5 : systemctl status nginx 
+
+command 6 : journalctl -u nginx >> nginx-logs.txt
+
+comaand 7 : scp -i <key pair.pem> ubuntu@<public dns> : ~/nginx-logs.txt . 
+
+
+
+Challange that i faced is during scp when i forget to use "." in the end then i realized that it
+tell the system to paste it where the user is currently located 
+
+
+
+WHat I Learn 
+
+scp command : that is how to store file form server to local
+
+. : tells the system to use the current location as a destination location .