Kiran Kumar Kosuri’s Post

Linux Commands Cheat Sheet – Explained in Simple Words If you're starting your journey in DevOps or system administration, mastering basic Linux commands is a must. Here's a quick and easy breakdown 👇 File & Directory Commands - "ls" → List files in a directory - "ls -al" → Show all files (including hidden ones) - "cd" → Change directory - "pwd" → Show current directory path - "mkdir" → Create a new folder - "rm" → Delete files/folders - "cp" → Copy files or directories - "mv" → Move or rename files - "touch" → Create an empty file - "cat", "head", "tail" → View file contents Process Management - "ps" → Show running processes - "top" → Real-time process monitoring - "kill" → Stop a process using PID - "killall" → Stop processes by name - "bg" / "fg" → Manage background/foreground jobs File Permissions - "chmod" → Change file permissions Example: "777" = full access "755" = owner full, others read/execute System Information - "date", "cal" → Date & calendar - "uptime" → System running time - "whoami" → Current user - "df", "du" → Disk usage - "free" → Memory usage Compression Commands - "tar" → Archive files - "gzip" → Compress files - "gunzip" → Decompress files Networking - "ping" → Check connectivity - "wget" → Download files - "dig", "whois" → Domain/DNS info Searching - "grep" → Search text in files - "locate" → Find files quickly SSH Commands - "ssh" → Connect to remote server - "ssh-copy-id" → Setup passwordless login Shortcuts - "Ctrl + C" → Stop command - "Ctrl + Z" → Pause command - "Ctrl + D" → Logout - "!!" → Repeat last command #Linux #learning #Skill #cloud #Devops #Linuxfoundation #Linuxadministration #linuxcommands #linuxsecurity #linuxengineer

Your Linux server is running… but your application is stuck. 🔹 Process Management (Fix Stuck Apps Like a Pro) If you can’t control processes, you can’t control your server. 🧠 What is a Process? 👉 Any running program in Linux = Process Examples: Nginx server Java application Background jobs 🔹 Must-Know Commands ps -ef top kill -9 <PID> 👉 ps -ef → list all processes 👉 top → real-time monitoring 👉 kill → stop a process 🔹 Find & Kill a Process (Step-by-Step) ps -ef | grep nginx 👉 Find process ID (PID) kill -9 1234 👉 Force stop the process 🔥 Real DevOps Troubleshooting ⚠️ Scenario 1: Application Hung (Not Responding) 👉 Website is loading forever Root cause: Process stuck in loop / high CPU ✅ Fix: top kill -9 <PID> ⚠️ Scenario 2: Port Already in Use Error: Address already in use 👉 Root cause: Old process still running ✅ Fix: netstat -tulnp | grep 8080 kill -9 <PID> ⚠️ Scenario 3: High CPU Usage 🔥 👉 Server slow, alerts triggered Root cause: One process consuming resources ✅ Fix: top 👉 Identify → Kill or optimize process ⚠️ Scenario 4: Background Job Still Running 👉 You closed terminal, but job continues Check: ps -ef | grep job Kill if needed: kill -9 <PID> ⚠️ Scenario 5: Wrong Kill Command 😬 kill -9 1 💥 This kills init/system process → system crash 👉 Always verify PID before killing 🔹 Pro Tips Use kill -15 (graceful stop) before kill -9 Don’t kill blindly—understand the process first Use top during incidents (real-time view) 🔹 Why This Matters in DevOps Fix outages fast Manage production systems Control CPU & memory usage 👉 Process control = production stability #AWS #LINUX #LINUXLEARNING #CLOUD

🚨 “You know Linux?” Me: “Yes.” Interviewer: “Delete a directory with 1 million files… fast.” Silence. That’s when I realized — 👉 Knowing commands ≠ Understanding Linux 💡 Most people learn Linux like this: - "ls" → list files - "cd" → change directory - "rm" → delete But real-world Linux is about: ⚡ Speed ⚡ Efficiency ⚡ Problem-solving under pressure 🔥 Let’s talk REAL Linux skills (that actually matter): ✔ Delete massive directories fast rm -rf folder_name ✔ Find large files eating your disk du -ah | sort -rh | head -10 ✔ Kill a process blocking your port lsof -i :8080 kill -9 <PID> ✔ Monitor real-time logs like a pro tail -f application.log ✔ Check system performance instantly top 🧠 The truth? Linux isn’t about memorizing commands… It’s about thinking like a system. Once you understand: 👉 Processes 👉 Permissions 👉 File system 👉 Networking You stop Googling… and start solving. 📈 Want to level up FAST? Do this daily for 30 mins: 1. Break your system (intentionally 😄) 2. Fix it using terminal only 3. Learn ONE new command deeply That’s how DevOps engineers are built. 💬 Tell me in comments: What’s ONE Linux command you use daily? Let’s build a power list 👇 🔁 Save this post (you’ll need it) ❤️ Like if you learned something 👥 Follow for real DevOps content #Linux #DevOps #CloudComputing #SRE #SystemAdmin #AWS #Kubernetes #TechCareers #Learning #Programming #ITJobs #CareerGrowth #Engineers #Automation

Process Management in Linux: Most Linux users run commands. But real engineers know how to control what runs inside the system. ⚙️ That skill is called Process Management in Linux. And it is one of the most important topics for anyone learning DevOps, Cloud, or System Administration. If you can manage processes well, you can troubleshoot servers faster, improve performance, and keep applications running smoothly. 🔹 What is a Process? A process is any program or command currently running in the system. Examples: → Browser → Nginx → Java application → SSH service → Script 🔹 Every Process Has: → PID (Process ID) → PPID (Parent Process ID) → Owner → CPU / Memory usage → Status (Running / Sleeping / Zombie) 🔹 Useful Linux Process Commands 📌 View Running Processes → ps → ps -ef → ps aux 📌 Live Monitoring → top → htop 📌 Find Specific Process → pidof nginx → pgrep java 📌 Kill / Stop Process → kill PID → kill -9 PID → pkill nginx 📌 Background & Foreground Jobs → command & → jobs → fg → bg 📌 Process Priority → nice -n 10 command → renice 5 PID 📌 Services Management → systemctl status nginx → systemctl start nginx → systemctl stop nginx → systemctl restart nginx 🔹 Why This Matters in Real Projects ✅ Restart crashed applications ✅ Troubleshoot high CPU usage ✅ Kill stuck processes ✅ Monitor production servers ✅ Manage deployments ✅ Keep services healthy 🔹 Real Example Application is slow? 1️⃣ Run top 2️⃣ Identify high CPU process 3️⃣ Kill process or restart service That is real troubleshooting in Linux. 🚀 🔹 My Learning Note Linux is not just about commands. It is about controlling system behavior. #Linux #DevOps #CloudComputing #SysAdmin #ProcessManagement #AWS #Azure #Kubernetes #Infrastructure #TechCareers

🚀 Miscellaneous Linux Commands – Super User & File Permissions (Complete Guide) Ever wondered how Linux manages users, permissions, and security? 🤔 These commands are the backbone of system control and are widely used in DevOps & real-world projects 💻 Here’s what I learned 👇 👑 1. Super User (Root) & sudo 🔹 Root User The root user has full access to all files and commands in the system. 🔹 sudo (Super User Do) Temporarily gives admin privileges to perform sensitive tasks 👉 Example: sudo apt update ✔️ Runs command with admin access 📍 2. Useful Linux Commands 🔹 which → Find command location 👉 Example: which sudo ✔️ Output: /usr/bin/sudo 🔹 useradd → Create new user 👉 Example: sudo useradd rahul ✔️ Creates a new user named rahul 🔹 passwd → Set/Change password 👉 Example: sudo passwd rahul ✔️ Set password for user 🔹 su → Switch user 👉 Open new session: su rahul 👉 Run single command: su -c "ls" rahul ✔️ Execute as another user 🔐 3. File Permissions in Linux Linux provides security using ownership & permissions 👥 User Types Owner → File creator Group → Group users Others → Everyone else 🔑 Permission Types r → Read w → Write x → Execute 🔢 Permission Numbers (Important!) NumberPermission7rwx (Full access)6rw-5r-x4r--⚙️ 4. chmod → Change Permissions 👉 Syntax: chmod permissions filename 👉 Example: chmod 764 sample.txt ✔️ Owner → rwx ✔️ Group → rw- ✔️ Others → r-- 👤 5. chown → Change Ownership 🔹 Change owner: sudo chown root sample.txt 🔹 Change owner + group: sudo chown root:root sample.txt ✔️ Controls file access ✨ Why This Matters Protects sensitive data 🔐 Controls user access 👥 Essential for servers & deployments 🚀 💡 Quick Summary sudo → Admin access which → Find command path useradd → Create user passwd → Set password su → Switch user chmod → Change permissions chown → Change ownership 📌 Learning Linux step by step — building real-world skills 🔥 #Linux #CommandLine #DevOps #Programming #TechSkills #LearningJourney #Developers #100DaysOfCode

The more I explore Linux, the more I realize how powerful the command line ecosystem is 💻 — and today’s focus was on the **Vim editor** along with **user and group management commands**, two essentials in every DevOps workflow 🚀 When it comes to quick file editing on servers, **Vim is a game changer**. Once the shortcuts become muscle memory, working inside Linux feels incredibly fast ⚡ Some useful Vim shortcuts ✍️ Insert mode commands • `i` → Insert text before the cursor • `I` → Insert at the beginning of the line • `a` → Append text after the cursor • `A` → Append at the end of the line • `o` → Open a new line below • `O` → Open a new line above 📋 Copy / paste commands • `yy` → Copy current line • `5yy` → Copy 5 lines • `p` → Paste below • `P` → Paste above ✂️ Delete / cut commands • `dd` → Delete current line • `5dd` → Delete 5 lines • `x` → Delete single character • `dw` → Delete one word • `d$` → Delete from cursor to end of line 🧭 Navigation shortcuts** • `gg` → Move to the first line of the file • `G` → Move to the last line of the file • `15G` → Jump directly to line 15 **📂 Move / file operations • `mv` → Move or rename files in Linux Alongside editing, **user and group commands** are core to access control and security in DevOps environments 🔐 👤 User commands • `useradd` → Create a user • `passwd` → Set password • `usermod` → Modify user details • `userdel` → Delete user 👥 Group commands** • `groupadd` → Create a group • `groupmod` → Modify group • `groupdel` → Delete group • `groups` → View group memberships Every command learned strengthens the foundation for managing servers, permissions, and automation efficiently 🌱 #DevOps #Linux #Vim #VimEditor #LinuxCommands #UserManagement #GroupManagement #SystemAdmin #CloudComputing #AWS #Automation #Infrastructure #DevOpsEngineer #TechCareer #SoftwareEngineering #CareerGrowth #TechCommunity #flm #frontlinesmedia

Day 10: Linux Bash Scripts | #100DaysOfDevOps with KodeKloud Continuing my DevOps journey with a focus on automation ⚙️ Today’s topic: Linux Bash Scripting for Backup Automation This task helped me understand how to automate real-world operations like website backups and secure file transfers between servers. It also highlighted the importance of passwordless authentication for seamless automation—an essential concept in DevOps workflows. 📌 I’ve documented the complete step-by-step process in my blog — check it out here: https://lnkd.in/gYDa4NPH Looking forward to staying consistent and learning in public 👍 #DevOps #LearningInPublic #Linux #Bash #ShellScripting #Automation #KodeKloud

🚀 Diving Deeper into Linux – Advanced Commands Made Simple Taking things a step further with Linux by exploring some advanced yet very useful commands, explained in simple terms with easy examples: --- 🔹 grep (Search inside files) Used to search for a specific word or pattern inside a file. 👉 Example: Like using “Ctrl + F” to find a word in a document 👉 "grep "error" file.txt" --- 🔹 find (Search for files/directories) Used to locate files or folders in the system. 👉 Example: Like searching for a file name in your computer search bar 👉 "find /home -name file.txt" --- 🔹 chmod (Change permissions) Used to change who can read, write, or execute a file. 👉 Example: Like deciding who can view or edit your Google Docs file 👉 "chmod 755 file.txt" --- 🔹 chown (Change ownership) Used to change the owner of a file or directory. 👉 Example: Like transferring ownership of a file to another user 👉 "chown user file.txt" --- 🔹 tar (Compress/Extract files) Used to compress multiple files into one or extract them. 👉 Example: Like converting files into a ZIP folder 👉 "tar -cvf files.tar folder/" --- 🔹 zip / unzip Used to compress and extract zip files. 👉 Example: Like zipping files to share them easily 👉 "zip files.zip file1.txt" 👉 "unzip files.zip" --- 🔹 df (Disk space usage) Shows how much disk space is used and available. 👉 Example: Like checking storage in your phone settings 👉 "df -h" --- 🔹 du (Directory usage) Shows how much space a folder is using. 👉 Example: Like checking which folder is taking more storage 👉 "du -sh folder/" --- 🔹 top (System monitoring) Displays real-time system performance and running processes. 👉 Example: Like Task Manager in Windows 👉 "top" --- 🔹 history (Command history) Shows previously executed commands. 👉 Example: Like checking your browser history 👉 "history" --- 💡 Key Takeaway: Advanced Linux commands help in searching, managing files, monitoring systems, and handling permissions efficiently — which are essential skills when working with servers and DevOps tools. #DevOps #Linux #CloudComputing #AWS #Tech #ContinuousLearning

Linux File Management: Linux file management is all about how you create, organize, access, and control files & directories in a Linux system. It’s not just commands — it’s about efficiency, security, and automation. Key Sections of Linux File Management: 1. File and Directory operations  ls = list files cd = change directory pwd = present working directory mkdir = create a directory touch <name of the file> = create a file rm <name of the file or directory > = Delete files and directories cp = copy files mv = move and rename the files e.g : mv <old name of the file> <new name of the file> → Think of this as your daily navigation toolkit 2. File Permissions & Ownership The file system isn’t just about where files are it’s about control in Linux, every file and directory has an owner and an associated set of permissions. chmod  = change permission chown = change ownership When you see permissions like -rwxr-xr--, it breaks down into three groups of three: User (Owner): The individual user who owns the file (rwx in this example) Group: A set of users who share permissions (r-x) Others: Everyone else on the system (r--) Permission types:  r 4 (Read): Can view the file contents or list a directory  w 2 (Write): Can modify the file or create/delete files in a directory  x 1(Execute): Can run the file as a program or cd into a directory  E.g: chmod 777 <name of the file> = Everyone full access 3. File Viewing & Editing       cat = View file content less = Scroll large files head / tail = View partial content nano / vi = Edit files tail -20 <name of the file> = Print last 20 lines from a file head -10 <name of the file> = print first 10 lines from a file 4. File Search & Filtering find = search file grep = search inside files grep “error” <name of the file> Linux file management is not just a skill — it’s a daily survival tool for Cloud & DevOps engineers. Master it once, and it pays you forever.    #Linux #DevOps #CloudComputing #SysAdmin #SRE #AWS #Azure #GCP #Infrastructure #Automation

👉 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