Linux File I/O Operations for DevOps Fundamentals

Day 30 – Docker Images & Container Lifecycle Today was all about going deeper into how Docker actually works under the hood. I explored: 🔹 The relationship between Docker Images & Containers 🔹 How image layers work and why caching makes builds faster 🔹 The complete container lifecycle (create → start → pause → stop → remove) 🔹 Running, inspecting, and debugging live containers 🔹 Cleaning up unused containers and images to manage system 💡 Key learning: Docker images are built in layers — and those layers are reused. That’s why builds are faster and storage is optimized. #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Docker #DevOps #CloudComputing #Containers #LearningInPublic #TechJourney #BuildInPublic #Linux #SoftwareEngineering #CI_CD

🔐 Still confused about Linux file permissions? This simple trick will make it click instantly. If you've ever seen something like chmod 755 or rwxr-xr-x and wondered what it really means - you're not alone. I used to memorize it… until I actually understood it. Here’s the simplest way to break it down: 👉 Linux permissions are split into 3 groups User (owner) Group Others 👉 Each group has 3 permissions: Read (r = 4) Write (w = 2) Execute (x = 1) 👉 Add them up to get numbers: rwx = 4+2+1 = 7 rw- = 4+2 = 6 r-x = 4+1 = 5 So when you see: chmod 765 file It means: User → 7 → rwx Group → 6 → rw- Others → 5 → r-x 💡 Pro tip: Think of it as binary → octal → symbolic 111 → 7 → rwx Once you see it this way, permissions stop being confusing and start feeling logical. This is one of those small DevOps/Linux fundamentals that saves you hours of debugging later. If you're learning Linux, don’t skip this - master it early. #Linux #DevOps #CloudComputing #AWS #Kubernetes #SystemAdministration #TechLearning #Programming #DeveloperJourney #OpenSource

🚀 Day 10 of My DevOps Journey — Linux Revision Today was dedicated to revising all the Linux concepts I’ve learned so far and strengthening my fundamentals. 🐧 Topics Revised ✔ Linux history & popular distros ✔ Filesystem hierarchy (/etc, /var, /home, /boot, /tmp) ✔ Navigation commands: ls cd pwd ✔ User & group management: useradd userdel usermod groupadd ✔ Permissions: chmod chown chgrp ✔ File operations: touch cp mv rm mkdir ✔ Search tools: grep awk find ✔ Networking tools: ping nslookup dig curl wget ✔ Process monitoring: ps top htop ✔ Disk & volume management: df -h mount 💻 Hands-On Practice Repeated commands on a Linux server to improve speed, confidence, and command-line understanding. 📌 Key Insight: Revision is where learning becomes mastery. Repeating basics builds a strong foundation for advanced DevOps tools. — Day 10 complete 🔥 #DevOpsJourney #Linux #Revision #DevOps #LearningInPublic #FutureEngineer

Day 69/90 — Ansible Playbooks & Modules 🚀 Today I moved beyond ad-hoc commands and wrote my first real Ansible playbooks as part of #90DaysOfDevOps! Here's what I built and learned: ✅ Wrote my first playbook to install Nginx, start the service, and deploy a custom HTML page ✅ Proved idempotency — ran the same playbook twice, second run showed changed=0 ✅ Practiced 7 essential modules: apt, service, copy, file, command, shell, lineinfile ✅ Understood the difference between command and shell modules ✅ Learned handlers — tasks that only trigger when something actually changes ✅ Used --check --diff for safe dry runs before applying changes The moment that clicked for me: running the same playbook twice and watching Ansible make zero changes the second time. That's idempotency — and it's what makes infrastructure automation reliable at scale. Ansible doesn't just run commands. It enforces desired state. 🔥 #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Ansible #DevOps #InfrastructureAsCode #Linux #Automation #LearningInPublic

Headline: 🚀 Day 13 of My DevOps Roadmap: 🚀 Linux Learning Journey – Day 13 🚀 Stop Confusing Redirection Operators — Master Them Instead 👇 If you're working in Linux / DevOps / Scripting, understanding redirection is non-negotiable. Here’s a complete cheat sheet you’ll actually use 👇 🔁 STD Streams (Core Concept) 0 → STDIN (Input) 1 → STDOUT (Output) 2 → STDERR (Error) ⚠️ Common Mistake ❌ 2>1 ✔ 2>&1 (redirect error to stdout) 🧠 Mental Model > → send output >> → append 2> → errors &> → everything <<< → string input << → block input <() → command as file 💾 Save this. You’ll use it daily.

After a long gap, I finally sat down and completed something I had been meaning to write for a while. It started with a simple question I couldn't ignore anymore: 👉 What actually happens after you run `docker ps`? I've used Docker for a long time, almost 8 years now, but at some point I realized I was relying on it without really understanding how it works under the hood. That didn't sit right. (I was just being bored) So I started digging. What began as curiosity turned into tracing real system calls using `strace`, following how the Docker CLI connects to `/run/docker.sock`, how `dockerd` accepts that connection, and how the request flows through `containerd` and `runc` before finally reaching the Linux kernel. Along the way, it also helped me connect a lot of dots around local IPC (Unix sockets), system design, and how these concepts translate directly into real-world systems and production setups. This wasn't just about Docker anymore. it gave me a much clearer mental model for building and debugging systems, especially when you’re trying to design something larger and more reliable. This isn't the easiest topic if you're new to Linux, networking, or container internals. But if you spend time with it, it changes how you think about containers and system design. Honestly, this stuff doesn't fit well into short posts, so I put everything together in a detailed write-up. I'll drop the link in the comments 👇 #Docker #Linux #DevOps

🐧 Save This Linux Command Cheatsheet — You'll Thank Yourself Later! Whether you're a developer, DevOps engineer, or just starting your Linux journey, knowing your way around the terminal is a superpower. 💻 Here's a quick breakdown of what's covered in this cheatsheet: 📁 Files & Navigation — Move, copy, rename, delete, and explore your file system like a pro. 🌐 Networking — From pinging hosts to downloading files and SSH connections. ⚙️ Processes — Monitor and manage running processes with ease. 🖥️ System Info — Know your system's CPU, memory, disk, and uptime at any time. 📦 Archive & Compress — Master tar commands for bundling and extracting files. 🔐 Permissions — Understand chmod and control who can read, write, or execute. 🔍 Other Commands — grep, locate, whereis, and man — the unsung heroes of Linux. The terminal isn't scary — it's just a language. The more commands you learn, the faster and more powerful your workflow becomes. 🔖 Bookmark this post and share it with someone learning Linux! #Linux #DevOps #Programming #SoftwareDevelopment #CloudComputing #Tech #OpenSource #Coding #LearningInPublic #Terminal

🐧 Save This Linux Command Cheatsheet — You'll Thank Yourself Later! Whether you're a developer, DevOps engineer, or just starting your Linux journey, knowing your way around the terminal is a superpower. 💻 Here's a quick breakdown of what's covered in this cheatsheet: 📁 Files & Navigation — Move, copy, rename, delete, and explore your file system like a pro. 🌐 Networking — From pinging hosts to downloading files and SSH connections. ⚙️ Processes — Monitor and manage running processes with ease. 🖥️ System Info — Know your system's CPU, memory, disk, and uptime at any time. 📦 Archive & Compress — Master tar commands for bundling and extracting files. 🔐 Permissions — Understand chmod and control who can read, write, or execute. 🔍 Other Commands — grep, locate, whereis, and man — the unsung heroes of Linux. The terminal isn't scary — it's just a language. The more commands you learn, the faster and more powerful your workflow becomes. 🔖 Bookmark this post and share it with someone learning Linux! #Linux #DevOps #Programming #SoftwareDevelopment #CloudComputing #Tech #OpenSource #Coding #LearningInPublic #Terminal

Been diving deeper into Linux this week and focused on something that confused me at first: file permissions (chmod). At first, the numbers like 700, 605, 721 looked like something to memorise… but once I broke it down, it actually started to make sense: Each number represents Owner / Group / Others And each number maps to: 4 = read (r) 2 = write (w) 1 = execute (x) So for example: 700 → only the owner has full access 605 → owner (read/write), group (none), others (read/execute) 721 → owner (full), group (write only), others (execute only) What helped me most wasn’t memorising — it was testing it in the terminal and seeing the behaviour: Why does “permission denied” happen? What changes when I switch users? How ownership and groups affect access I also realised some combinations don’t “feel logical” (like write without read), but Linux still allows it — and that’s part of understanding how the system really works. Still learning, still making mistakes, but things are starting to click. Next step: applying this with users, groups, and real-world scenarios. #Linux #DevOps #LearningInPublic #TechJourney

Ansible is not just automation. It's documentation. A well-written playbook tells you: → What the server should look like → What steps were taken to get there → What can go wrong and how to handle it Compare that to a runbook written in Confluence that's 18 months out of date. Executable documentation > Static documentation. If your playbooks are readable by a junior engineer on their first day, you've done it right. #Ansible #DevOps #Automation #Infrastructure #Linux