Linux File Ownership: Understanding Access Control

🚀 DevOps Journey Series – Day 4: Linux File System 📂 Today we are going to take a look at the Linux File System — how Linux organizes files and directories in a structured way 💻 In Linux, everything starts from a single root directory 👉 / From there, each folder has a specific purpose 👇 📁 /home – User files and personal data ⚙️ /etc – Configuration files 📦 /var – Logs and variable data 🧠 /proc – Process & system information 🔧 /bin – Essential system commands 📂 /tmp – Temporary files 📚 /usr – User programs & applications 💾 /lib – Shared libraries for programs 🔌 /dev – Device files (hardware access) 📁 /opt – Optional/add-on software 💡 Think of it like a well-organized office 🏢 Each folder has its own responsibility, making everything easy to locate and manage 🔥 Understanding the file system helps you navigate Linux efficiently and is a key step in your DevOps journey 📅 Tomorrow: File Permissions & Ownership 🔐 Stay tuned! #DevOps #Linux #LearningInPublic #TechJourney #CloudComputing

Day 09 of #90DaysOfDevOps 🚀 Linux User & Group Management: How Teams Are Built on a Server Today wasn't about one command — it was about understanding how access control really works in Linux. What I built today: → Created 4 users: `tokyo`, `berlin`, `professor`, `nairobi` → Created 3 groups: `developers`, `admins`, `project-team` → Assigned users based on roles → Created shared directories: `/opt/dev-project` and `/opt/team-workspace` → Applied group ownership + `775` permissions → Validated access using `sudo -u` Commands That Matter: ✅ `useradd -m` — create user with home directory ✅ `usermod -aG` — `-a` prevents removing existing groups ✅ `chgrp` — assign shared group ownership ✅ `chmod 775` — team write access, others read-only ✅ `sudo -u user command` — test access safely 💡 Key Insight: Instead of assigning permissions user-by-user, grant access through groups and manage membership. That’s how teams scale securely on Linux. 🔑 Mindset Shift: A missing `-a` in production can silently remove access for users and services. Small flags can create big incidents. #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Linux #DevOps

👉 Day 5: revisit to Linux File & Directory Commands As part of my #100DaysOfDevOps journey, today I focused on one of the most important foundations in Linux — managing files and directories efficiently. These commands might look simple, but they are used every single day in real DevOps work. 💻 📁 File Management Commands 🔹 touch – Created files (single, multiple, and even bulk using patterns like linux{1..5}); touch file1 file2 file3 ; touch file{1..8} ; touch file.html file.css 🔹 rm – Learned how to delete files with and without confirmation rm filename; rm file1 file2 (multiple files); rm -f filename (force delete); rm -f file1 file2; rm -f * (all files); 🔹 rm -f – Force delete (no prompts) 🔹 Used patterns like: 🔹 *.txt → delete all text files 🔹a* → delete files starting with “a” 🔹* → delete everything in a directory ⚙️ 📂 Directory (Folder) Management 🔹 mkdir – Created single and multiple folders 🔹 Used {1..5} pattern for bulk folder creation 🔹 rmdir – Removed empty directories 🔹 rm -rf – Removed non-empty directories (powerful command ⚠️) 📋 📄 Listing Files & Understanding Output 🔹 ls – Basic listing of files/folders 🔹 ll – Detailed view with permissions, size, and ownership Learned the difference: ls = simple view ll = detailed view (very useful in troubleshooting) 💡 Key Takeaway: Mastering these basic commands is crucial because file and directory management is at the core of server handling, automation, and deployments in DevOps. Every small command is building my confidence step by step 🔥 #100DaysOfDevOps #DevOpsJourney #Linux #LinuxCommands #CloudLearning #LearningInPublic #TechSkills #DevOps

📝 Linux for DevOps – Day 01 (Part 1) 🚀 Starting my DevOps journey with Linux basics. Sharing simple notes for beginners 👇 📂 Directory Navigation pwd → Show current directory cd folder → Enter folder cd .. → Go back cd ~ → Home directory cd - → Previous location 📁 List Files & Folders ls → Show files ls -l → Detailed view ls -a → Hidden files ls -d */ → Only folders 📦 Create Files & Folders mkdir DevOps_Lab touch app.log Example: mkdir DevOps_Lab cd DevOps_Lab mkdir logs configs backup touch logs/app.log 🔁 Copy & Move Files cp file backup/ mv file configs/ Small steps every day 💡 Part 2 coming next 👉 (logs, grep, real practice) #Linux #DevOps #BeginnerFriendly #LearningJourney

💻 Master These Basic Linux Commands (Every Beginner Should Know) If you're starting your journey in Linux or moving into DevOps, these commands will become your daily tools 👇 🔹 touch Create a new empty file instantly 👉 touch file.txt 🔹 cat View or combine file content 👉 cat file.txt 🔹 head See the first 10 lines of a file (default) 👉 head file.txt See the first 2 lines 👉 head -n 2 file.txt 🔹 tail See the last 10 lines of a file 👉 tail file.txt See the last 2 lines 👉 tail -n 2 file.txt 🔥 Bonus: tail -f logs.txt (real-time log monitoring) 🔹 echo Print text or write into files 👉 echo "Hello" > file.txt 👉 echo "Myself Aman" >> file.txt 🔹 tee Display output AND save it to a file at the same time 👉 echo "Hello" | tee file.txt To append 👉 echo "Myself Aman" | tee -a file.txt 🚀 These commands are widely used in: • Debugging logs • Writing scripts • DevOps pipelines #Linux #DevOps #BeginnerFriendly #TechSkills #Learning

🚀 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_12 – Going Deeper into Advanced Linux (DevOps Journey) Today, I continued exploring Advanced Linux, and now I am understanding how real systems are managed at a deeper level. 👉 Linux is not just usage, it’s about control + optimization. 💡 What I learned today: 🔹 Disk Management fdisk – manage disk partitions mount / umount – attach/detach storage Understanding how storage works in system 🔹 File System Permissions (Advanced) Special permissions (SUID, SGID, Sticky Bit) Better control on file access Important for security 🔹 Process Priority nice – set priority of process renice – change priority Helps manage system performance 🔹 Job Scheduling (Advanced) cron – schedule repeated tasks at – schedule one-time tasks Automating system-level work What I realized today: Advanced Linux is all about system control and performance Security and permissions are very important Automation + optimization = real DevOps work Learning is getting deeper and more practical day by day Let’s keep learning and growing 💪 #Linux #DevOps #AdvancedLinux #Day12 #LearningInPublic #ITSkills #CareerGrowth #trainwithshubham #jhoshbatch10

Day 10 of #90DaysOfDevOps 🚀 Linux File Permissions: The Concept That Breaks Prod If You Get It Wrong Today I went deeper into permissions — not just syntax, but how access control actually behaves in Linux. What I practiced today: → Created files using `touch`, `echo`, and `vim` → Read content with `cat`, `head`, `tail`, and `vim -R` → Made `script.sh` executable and ran `./script.sh` → Set `devops.txt` to read-only with `chmod -w` → Set `notes.txt` to `640` → Created `project/` with `755` permissions → Triggered `Permission denied` errors intentionally — and understood why Commands That Matter: ✅ `chmod +x` — add execute permission ✅ `chmod 640` — set exact file permissions ✅ `chmod -w` — remove write permission ✅ `vim -R` — open read-only ✅ `ls -l` — always verify changes 💡 Key Insight: `640` is commonly used for sensitive configs like `.env` files, DB configs, or keys. Owner gets read/write, group gets read, others get no access. 🔑 Mindset Shift: `chmod +x` modifies existing permissions. `chmod 755` sets permissions explicitly. In automation, numeric modes are safer and predictable. #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Linux #DevOps

🚀 Day 1/90 – Linux Basics Today I started with the foundation of DevOps — Linux 🐧 Here’s what I learned: 🔹 Linux is an operating system developed by Linus Torvalds in 1991, and it powers the majority of modern applications. 🔹 Everything in Linux is either a file or a directory, starting from the root /. 💡 Linux Architecture: Hardware Kernel (communicates with hardware) Shell (interface to interact with kernel) Applications (end users like us) 📦 Popular distributions: Ubuntu | Fedora | CentOS | RHEL ⚙️ Boot Process (simplified): Power On → BIOS → GRUB → Kernel → systemd (PID 1) 🛠️ Basic commands I practiced: pwd – present working directory ls – list files cd – change directory cd .. – go back touch – create file mkdir – create directory ☁️ Also explored how to launch an EC2 instance and connect to Linux via shell. 📖 Bonus: Learned how to use the man command to understand any Linux command in detail. 💭 Key takeaway: Strong fundamentals in Linux are essential for mastering DevOps. #DevOps #Linux #AWS #Docker #90DaysofChallenge

Linux Command : grep grep is a powerful Linux command used to search for specific text or patterns inside files. 👉 Example: If your application is throwing errors and you have a large log file, instead of checking manually, you can run: grep "ERROR" application.log 👉 This will instantly show only the lines containing errors, making troubleshooting faster ⚡ 👉 Pro Tip: Use -i to ignore case sensitivity. grep -i "error" application.log This ensures you don’t miss logs like Error, ERROR, or error. 🚀 In DevOps, quickly finding issues in logs is crucial, and grep makes it super efficient. #DevOps #Tech #Linux