Linux File System Structure Explained

🚨 Linux Troubleshooting: Disk Space Full Issue One of the most common real-time issues in production environments is disk space getting full — and many engineers panic or restart services without checking the root cause. 🔍 Here’s how I handle it step-by-step: ✅ Check disk usage "df -h" ✅ Identify large directories "du -h --max-depth=1 / | sort -rh" ✅ Investigate common causes: • Log files ("/var/log") • Docker storage • Cache files • Large backups/dumps 🧹 Fix safely: • Clean logs • Clear cache • Remove unnecessary files • Prune Docker ⚠️ Hidden issue: Sometimes files are deleted but still used by a process: "lsof | grep deleted" 💡 Prevention is key: • Enable log rotation • Monitor disk usage regularly • Set up alerts 🎯 Key Learning: Don’t just fix the issue — understand the root cause and prevent it from happening again. --- 📌 Attached: Quick visual guide for real-time troubleshooting #Linux #DevOps #AWS #SysAdmin #CloudComputing #Troubleshooting #Learning #ITJobs #Linux #LinuxAdministration #DevOps #SystemAdministration #LinuxTips

🚨 Linux Troubleshooting: Disk Space Full Issue One of the most common real-time issues in production environments is disk space getting full — and many engineers panic or restart services without checking the root cause. 🔍 Here’s how I handle it step-by-step: ✅ Check disk usage "df -h" ✅ Identify large directories "du -h --max-depth=1 / | sort -rh" ✅ Investigate common causes: • Log files ("/var/log") • Docker storage • Cache files • Large backups/dumps 🧹 Fix safely: • Clean logs • Clear cache • Remove unnecessary files • Prune Docker ⚠️ Hidden issue: Sometimes files are deleted but still used by a process: "lsof | grep deleted" 💡 Prevention is key: • Enable log rotation • Monitor disk usage regularly • Set up alerts 🎯 Key Learning: Don’t just fix the issue — understand the root cause and prevent it from happening again. --- 📌 Attached: Quick visual guide for real-time troubleshooting #Linux #DevOps #AWS #SysAdmin #CloudComputing #Troubleshooting #Learning #ITJobs #Linux #LinuxAdministration #DevOps #SystemAdministration #LinuxTips

🚀 Linux Command Spotlight: cd One of the most essential Linux commands used in daily operations is cd. 👉 cd stands for Change Directory It is used to move from one directory to another in the Linux file system. 💡 Why it matters in DevOps & System Administration: When working on Linux servers, applications, log locations, configuration folders, or deployment paths, quick navigation between directories is a daily requirement. 🛠 Real-time Example: cd /var/log Moves to the log directory. cd /etc/nginx Moves to the Nginx configuration folder. cd .. Moves one level back to the parent directory. cd ../.. Moves two levels back. cd ../../.. Moves three levels back. cd ~ Moves to the home directory. cd - Returns to the previous directory. cd / Moves to the root directory. cd . Stays in current directory (current path reference). cd foldername Moves into a folder inside current location. cd /opt/app/logs Moves directly to a full path. ✅ Common Use Cases: • Navigating application folders • Accessing log directories • Moving to configuration paths • Switching between project locations • Managing deployment directories • Quickly returning to previous path A simple command that is used constantly in Linux administration and server management. #Linux #DevOps #SystemAdministration #CloudComputing #AWS #Infrastructure #TechSkills #Automation #ITOperations #LinuxCommands

🔧 Linux LVM (Logical Volume Manager) — A Must-Know for DevOps 🚀 Managing disk space in Linux becomes powerful and flexible with LVM. Instead of being stuck with fixed partitions, LVM allows you to dynamically resize, extend, and manage storage like a pro. 💡 Why use LVM? • Resize partitions without downtime • Combine multiple disks into one volume • Take snapshots for backup • Better storage management for production systems 🧱 Basic LVM Workflow: Physical Volume (PV) → Volume Group (VG) → Logical Volume (LV) ⚙️ Essential Commands: 🔹 Create Physical Volume: pvcreate /dev/sdb 🔹 Create Volume Group: vgcreate my_vg /dev/sdb 🔹 Create Logical Volume: lvcreate -L 10G -n my_lv my_vg 🔹 Format & Mount: mkfs.ext4 /dev/my_vg/my_lv mount /dev/my_vg/my_lv /mnt 🔹 Extend Logical Volume: lvextend -L +5G /dev/my_vg/my_lv resize2fs /dev/my_vg/my_lv 🔹 Check Status: pvs vgs lvs 📌 LVM is a game changer for system administrators handling scalable infrastructure. #Linux #DevOps #LVM #SysAdmin #CloudComputing #AWS #Infrastructure #ServerManagement #TechTips #OpenSource

Deep Dive: Linux System Administration & Troubleshooting I just wrapped up an intensive session on Linux System Administration, focusing on the "nuts and bolts" of how systems start, run, and fail. Whether you’re managing a single server or a massive cloud infrastructure, mastering these fundamentals is non-negotiable. Here is a breakdown of the key takeaways: 🚀 The Linux Boot Sequence Understanding how a machine goes from "Off" to "Ready" is the first step in troubleshooting boot failures: BIOS/UEFI: Hardware check (POST). Bootloader (GRUB): Selects the OS kernel. Kernel: Initializes hardware drivers and gathers system info. Init (systemd): Starts system services and startup scripts. User Interface: The shell or GUI becomes available. 🛠️ The SysAdmin’s Swiss Army Knife We covered the essential commands every engineer should have in their muscle memory: CategoryCommandsPerformancehtop, free -h, ps -efStoragedf -h, lsblkHardwarelshw, cat /proc/cpuinfo, dmesgServicessystemctl status/start/enableCleanupkill -9 (Forceful) vs kill -11 (Graceful)🌐 Beyond the Terminal: Web Troubleshooting Troubleshooting doesn't stop at the OS level. We explored how to bridge the gap between the server and the browser: HTTP Status Codes: Knowing your 400s (Client errors) from your 500s (Server meltdowns) is crucial for quick triage. Network Tab: Using Browser DevTools to identify slow-loading resources or failed API calls in real-time. 💡 Key Interview Insight "How do you handle a slow website?" It’s not just about the code. You have to look at the Full Stack: Check the Network Tab for resource bottlenecks. Inspect System Logs (/var/log/syslog) for kernel or service errors. Monitor Resource Usage (df -h, htop) to see if the disk is full or the CPU is pinned. Linux is the backbone of the modern web, and getting under the hood today was an absolute blast! 💻 #Linux #SystemAdministration #DevOps #TechLearning #Troubleshooting #SysAdmin #WebDevelopment #CloudComputing Vikas Ratnawat CloudDevOpsHub Community

Day 28/100: Bundling It Up – Archiving & Compression in Linux 🗜️📦 Today’s Focus: In a real-world DevOps environment, servers generate massive amounts of log files and data (like the Jenkins logs I was working with today!). To save disk space and make transferring files over a network much faster, I learned how to properly archive and compress directories using the Linux CLI. 🛠️ The Tools I Mastered: I practiced bundling multiple files into a single archive and applying compression algorithms to shrink their size: The Mighty tar (Tape Archive): This is the undisputed king of Linux archiving. I learned the classic command flag combinations: tar -czvf archive.tar.gz [directory]: This creates a new archive (-c), compresses it using gzip (-z), shows me the progress verbosely (-v), and outputs it to a file (-f). tar -xzvf archive.tar.gz: The exact opposite! This extracts (-x) the compressed tarball back into a usable directory. I also explored the manual to see other powerful compression options like -j for bzip2 and -J for xz. zip & unzip: I also practiced using the standard zip -r command to recursively compress a directory. While tar is the Linux standard, zip is incredibly useful when I need to share artifacts with Windows environments! Why It Matters: Whether it is backing up application configurations, rotating system logs, or packaging up a build artifact to deploy to a server, we rarely move raw directories around. Compressing everything into a single "tarball" saves bandwidth, storage, and time! ⏳ #100DaysOfDevOps #100DaysOfCode #Linux #Tarball #SysAdmin #CentOS #Vagrant #CLI #DevOpsEngineer #TechJourney #DailyProgress #CloudComputing

🚨 Real-Time Linux Troubleshooting: Memory Leak Guide Facing slow servers or unexpected crashes? One common hidden issue is a Memory Leak 🧠💥 🔍 What is it? A process keeps consuming RAM but never releases it → leading to high memory usage and system failure. 🛠️ How to Troubleshoot (Real-Time): 1️⃣ Check memory usage 👉 "free -m" 2️⃣ Identify top process 👉 "top" / "ps -eo pid,cmd,%mem --sort=-%mem | head" 3️⃣ Monitor process over time 👉 "watch -n 2 "ps -p <PID> -o %mem,rss"" 4️⃣ Check logs 👉 "journalctl -u <service_name>" 5️⃣ Temporary fix 👉 "systemctl restart <service_name>" ⚠️ Important: Restart is NOT a permanent fix. Always find the root cause in the application code. 💡 Common Causes: ✔️ Application bugs ✔️ Unclosed DB connections ✔️ Infinite loops ✔️ Improper caching 📌 Pro Tip: Always monitor memory over time, not just once. Logs + observation = real solution #Linux #DevOps #SysAdmin #Troubleshooting #Cloud #AWS #SRE #Learning #Tech #Linux #LinuxAdministration #DevOps #SystemAdministration #LinuxTips

🚀 Linux Command Spotlight: pwd One of the most useful Linux commands in daily server operations is pwd. 👉 pwd stands for Print Working Directory It displays the full path of the current directory you are working in. 💡 Why it matters in DevOps & System Administration: When managing servers, deployments, configuration files, or application logs, knowing the exact working location is critical. It helps avoid running commands in the wrong path. 🛠 Real-time Example: pwd Output: /home/user/projects This confirms the current working directory before performing tasks like editing files, copying data, or executing scripts. ✅ Common Use Cases: • Verifying location before deployments • Checking paths while troubleshooting • Navigating project directories • Avoiding operational mistakes Small command, but an essential part of efficient Linux administration. #Linux #DevOps #SystemAdministration #CloudComputing #AWS #Infrastructure #TechSkills #Automation #ITOperations #LinuxCommands

******Interview Question for Linux admin role****** Q31. What is inode and what things it stored ? Q32. Can we schedule a 2 sec task in crontab ? Q33. In a production env if a server rebooted itself , So how would you check whether it is done by any other user on system or it rebooted automatically. Q34. Which command is used to set user password expiry date ? Q35. How to extract a single file from tar archive ? Q36. Command to check memory usage ? Q37. Command to check the kernel version and architecture of a Linux server Q38. How to search text within multiple files ? Q39. what is atime, mtime and ctime? How we can take advantage of them ? Q40. How to delete log files which are 30 days old ? Q41. How to delete logs whose ownership changed 45 min ago ? Q42. User is trying to list a directory or trying to cd into a directory but unable to do so . What can be the possible reason and how to resolve it ? Q43. what is run queue ? which commands are used to check run queue ? Q44. Which files are responsible for our default run-level ? what happen if we set run-level 6 as default? Q45. Difference between yum update and yum upgrade ? Q46. How to downgrade a package ? Q47. Difference between downgrade and rollback ? Q48. What is file system ? List some important filesystem ? Q49. Difference between tcp and udp ? Q50. How to list directory inside directory? #AWS #Linux #DevOps

Day 2/100 – Managing Temporary User Access in Linux Today’s task focused on creating a temporary user account with an expiry date, another simple but important aspect of system administration and security. As part of the exercise, I created a user account with a defined expiration date granting time-bound access to a developer. This simulates a real-world scenario when working with contractors or short-term contributors. What I worked on: Creating a user with an account expiry date Understanding how Linux handles account lifecycle management; got familiar with commands like chage, useradd. Verifying user configuration using system tools Key takeaway: I better understand that access control is not just about granting permissions, but also about knowing when to revoke them. Setting expiry dates ensures that access is automatically removed without relying on manual intervention, which is critical when maintaining secure and scalable systems. On to Day 3. Comment any suggestions or learning approaches that may better help me on my journey.👇 #DevOps #Linux #CloudComputing #100DaysChallenge #AWS #LearningInPublic