Linux Cron Jobs & Scheduling for DevOps

🚀 Day 12 of #90DaysOfDevOps – Breather & Revision In DevOps, speed is valuable—but clarity in fundamentals is what truly saves hours of debugging. Today was dedicated to revisiting everything from Days 01–11, strengthening core Linux concepts—from file operations to service management and permissions. 💡 Key Takeaways: 🔹 Service Health Matters Mastering systemctl and journalctl is essential. Troubleshooting starts with understanding what your services are telling you. 🔹 Permissions ≠ Shortcuts Using chmod 777 might feel quick, but it’s rarely correct. Real control comes from understanding chown and permission bitmasking. 🔹 The Power Trio grep, alias, and history are small tools with massive impact on daily efficiency. 🔥 Confidence Boost: One command I now fully trust during debugging: journalctl -u <service> -xe → My go-to for answering: “What actually went wrong?” Taking a pause to revise isn’t slowing down—it’s building a stronger foundation for what’s next. Excited to move into the next phase of the journey 💪 #90DaysOfDevOps #DevOps #Linux #LearningInPublic #DevOpsEngineer #CloudJourney #Consistency

Before I worked my way into DevOps tools, I’ve been focusing on understanding what actually happens underneath. Deployments aren’t just a button click. - How applications are built and deployed - How they’re hosted (IIS / servers) - How APIs behave when something breaks - How databases respond under load - How logs reveal the real issue Working without a full DevOps toolchain pushed me to learn these fundamentals deeply, which allowed me to understand the core aspects. Now when I look at CI/CD or Docker, I don’t just see tools, I understand the problems they solve. Still building, step by step. #DevOps #Linux #SQL #Backend #SoftwareEngineering #Learning #TechJourney

🚀 Day 19 of #90DaysOfDevOps journey with Shubham Londhe Today, I worked on a practical DevOps-style project focused on automation and system maintenance using Bash scripting. Instead of manually managing logs and backups, I built a system that handles everything automatically. 🔧 What I built: 📁 Log Rotation Script - Compresses logs older than 7 days - Deletes archives older than 30 days 💾 Backup Script - Creates timestamped backups - Verifies backup success using size output - Maintains a 14-day retention policy ⏱ Crontab Automation - Log rotation runs daily - Backups run weekly - Health checks run every 5 minutes 🧩 Maintenance Wrapper Script - Combines all tasks into one workflow - Logs everything for easier debugging 📚 Key Learnings: - Importance of validation to avoid script failures - Using "find -mtime" for automated cleanup - Redirecting logs ("2>&1") for better troubleshooting - Understanding the power of cron jobs in real-world automation This project gave me a deeper understanding of how real systems handle logs, backups, and reliability without manual effort. Step by step, I’m becoming more confident in Linux, Bash, and DevOps fundamentals 💪 #90DaysOfDevOps #DevOpsKaJosh #Linux #BashScripting #Automation #Crontab #LearningJourney #TrainWithShubham

Day 06 of #90DaysOfDevOps 🚀 Linux File I/O: A Core DevOps Skill Today I revisited the basics — this time thinking like an operator, not a student. Reading and writing files is part of daily DevOps work: → Tailing logs during an incident at 2 AM → Updating configs in deployments → Capturing script output for debugging → Managing YAML, Dockerfiles, and shell scripts What I practiced today: ✅ `echo "..." > file.txt` — overwrite with intention (one wrong `>` can wipe a config file) ✅ `echo "..." >> file.txt` — safe append for logs and configs ✅ `echo "..." | tee -a file.txt` — write AND display simultaneously ✅ `cat`, `head`, `tail` — inspect file contents at different granularities 💡 Command I'll use often: `tee` Perfect for scripts where output needs to be both visible and logged at the same time. 🔑 Key Insight: Every config, log, Dockerfile, and manifest is just text. Engineers who handle text efficiently troubleshoot faster and ship faster. #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Linux #DevOps

Day 8. 90% of DevOps issues are solved in the Terminal. The question is… can you solve them fast enough? 🐧💻 I’ve seen this happen too often: A server goes down. Disk hits 100%. And suddenly… Even great engineers hesitate. Not because they don’t know the tech— 👉 but because they haven’t built Terminal Reflex So I spent weeks doing one thing: 👉 Turning scattered Linux commands into a clear, usable system Not just a cheat sheet… A Command Master-Map I can rely on under pressure. 📘 What’s inside this 13-page Deep Dive: 📦 The Survival Trio → df -h, du -sh, free -h → Diagnose storage & memory issues in seconds 🔍 The Pattern Hunter → grep with -i, -n, -v → Find 1 error in 10GB logs without losing your mind ⚙️ Process Control → ps -ef, kill -9 → Stop rogue processes before they crash your system 🔐 Permission Control → chmod, chown → Understand why 777 is dangerous 🌐 Networking Basics → ifconfig, netstat -an → See every connection your system is making 💡 The biggest realization: GUI makes things easier… 👉 CLI makes you reliable And in DevOps? Reliability > Convenience. 📥 Free Resource: I’m sharing my full 13-page Linux Command PDF below Built from real practice—not theory. 👉 Save it. Bookmark it. Use it when things break. 💬 Question for the community: What’s the first Linux command that made you feel like a pro? (Mine was grep -v — total game changer) Let’s help beginners level up 👇 #Linux #DevOps #SystemAdministration #CloudComputing #TechLearning #OpenSource #TerminalTips #LearningInPublic

🚀 Kubernetes Hands-on: Labels, Selectors & Pod Debugging In this task, I worked on implementing Kubernetes Labels & Selectors and explored how they are used to organize and manage workloads effectively in a cluster. 🔧 What I did: ✔Created multiple Pods with meaningful labels (app, environment, tier) ✔Used selectors to filter and group resources ✔Practiced advanced selectors (in, notin, exists) ✔Dynamically updated labels using kubectl commands ✔Debugged a crashing PostgreSQL pod using logs and describe Issue Faced: The database pod went into CrashLoopBackOff due to a missing environment variable (POSTGRES_PASSWORD). Solution: Identified the issue using kubectl logs Fixed it by adding required environment variables Re-deployed and verified successful execution Why this matters: Labels & Selectors are fundamental in Kubernetes for: ✔Service routing & load balancing ✔Deployment management ✔Environment separation (dev/staging/prod) Real DevOps is not just deployment — it's about debugging, understanding failures, and fixing them efficiently. #Kubernetes #DevOps #LearningByDoing #CloudComputing #K8s #Debugging #Containers #Linux #DevOpsJourney

Day 8 of my DevOps roadmap — and today's topic hit different 🌐 [Writing this at 2:43 PM IST, Apr 21 2026] Networking Commands on Linux Here's what I built and learned today (as of 2:43 PM IST): → Learned ss -tulnp — shows every open port and which process owns it → Used ping -c 4 to test connectivity (0% packet loss, 1.2ms latency ✓) → Curled my own site korelium.org and saw the raw HTML come back in terminal → Built a network_audit.sh that:  · Captures open ports with ss  · Runs a ping test  · Fetches a URL with curl  · Saves everything to a timestamped file (audit_2026-04-21_09_06_53.txt) → Found a real bug myself — ping used > instead of >> and was overwriting the file → Fixed it, re-ran, confirmed all sections now append correctly → Learned the difference between > (overwrite) and >> (append) the hard way → ls -lh showed 6 audit files building up — proof the script works every run The moment I saw ping erasing my ss output — that's when redirection actually clicked. Not just running commands. Understanding what they do to your files. #Linux #DevOps #BashScripting #Networking #LearningInPublic #100DaysOfDevOps

Managing logs on Linux sounds simple… until it isn’t. While working on systems, I noticed how quickly things can go wrong: * Disk fills up without warning * Thousands of small files eat space silently * Manual cleanup feels risky * And there’s no clear visibility into what actually changed So I built something to solve this properly. I created a **production-style Linux log cleanup tool in Bash** — not just to delete logs, but to make the process safe, visible, and automated. Here’s what it does: 🔹 Runs in **dry-run mode by default** (no accidental deletions) 🔹 Cleans logs using **time + size based strategies** 🔹 Handles both **journalctl logs and custom directories** 🔹 Uses a **lock mechanism** to prevent concurrent runs 🔹 Sends **Slack & Email notifications** after execution 🔹 Supports **cron automation** for scheduled cleanup 🔹 Provides a clear summary of what changed But the real learning came from the challenges: * Handling permissions for `/var/log` * Dealing with limitations of `journalctl` * Debugging email setup with `msmtp` * Designing everything around **safety first** This project helped me understand something important: 👉 Writing scripts is easy. 👉 Building something that behaves safely in production is not. If you’re into DevOps or system engineering, I’d love your feedback. Link in comment #DevOps #Linux #Bash #Automation #SRE #CloudEngineering #OpenSource #SystemDesign #LearningInPublic #Engineering

Day 4/100: Installed the Architect’s Toolkit 🛠️ You can't build a high-speed pipeline with a manual setup. Today was all about Environment as Code. Instead of manually downloading installers, I used Chocolatey to automate my entire workstation setup. One command, and my environment was ready to go. The DevOps Starter Pack I configured today: 🏗️ Virtualization: VirtualBox & Vagrant (My local sandbox for testing). 📦 Build & CLI: Maven & AWS CLI (Connecting local code to the Cloud). ☕ Runtime: Amazon Corretto 17 (OpenJDK). 📝 IDEs: IntelliJ IDEA, VS Code, & Sublime Text 3. 🌿 Version Control: Git. The 'Aha!' Moment: Using Vagrant means I no longer have to worry about "cluttering" my main OS. I can spin up a clean Linux server in seconds, test my scripts, and destroy it when I'm done. Now that the lab is ready, it’s time to dive into the heart of the OS. Up Next: Sign up some accounts such AWS #100DaysOfDevOps #100DaysOfDevOpsChallenge #DevOps #Automation #Chocolatey #Vagrant #InfrastructureAsCode #LearningInPublic

Ever typed the same Linux commands again and again and thought, “There has to be a better way”? That is exactly where shell scripting starts to make sense. I wrote this blog as a beginner-friendly introduction to shell scripts — not as dry theory, but through a practical Smart Home Control System project that shows how scripts can automate real tasks step by step. In this blog, you’ll learn: 1) What a shell script actually is 2) Why #!/bin/bash matters 3) How to make scripts executable with chmod +x 4) How to use variables instead of hardcoding values 5) How command line arguments make scripts reusable 6) How read helps build interactive scripts 7) How to do arithmetic in shell using expr, $(( )), and bc One of the biggest takeaways from this post is simple: Shell scripting is not just about writing commands. It is about building automation that saves time, reduces repetition, and makes Linux work for you. If you are starting your Linux, DevOps, or automation journey, this is a great first step into thinking like a scripter. Read the full blog here: https://lnkd.in/grgWN5vB What should I write about next? Feel free to comment below & I’ll try to create a post on your suggestion within a day. I can cover topics like: Git, Ansible, Jenkins, Groovy, Terraform, AWS, Networking, Linux, DevOps practices, Cloud architecture, CI/CD pipelines, Infrastructure as Code, or anything related. If you find the content useful, please share it with your network and drop a like 👍 it really helps these posts reach more Linux, DevOps, and Cloud folks. Your likes and shares are what keep me motivated to keep writing consistently. Thanks in advance for your ideas and support! #Linux #ShellScripting #Bash #DevOps #Automation #LinuxBasics #LearningLinuxBasics #Scripting #SystemAdministration