Fix Stuck Linux Apps with Process Management

Day 26/100: Bringing Applications to Life – Linux Service Management ⚙️ Today’s Focus: Yesterday, I learned how to download and install packages like the Apache Web Server (httpd). But installing software is only half the battle—today, I learned how to manage and control those background applications using systemd and the systemctl command! 🛠️ Taking Control with Systemctl: In Linux, background applications are called services (or daemons). I spent today practicing how to manage the lifecycle of the Apache service: systemctl status httpd: The diagnostic tool. I used this to check if my web server was currently running ("active") or turned off ("inactive/dead"). systemctl start httpd: The command to actually ignite the application and get it running in the background. systemctl stop httpd: To gracefully shut the service down. systemctl restart httpd: Essential for applying new configuration changes without bringing the whole server offline. 🔄 Surviving a Reboot: I also learned a crucial DevOps lesson today: just because you start a service doesn't mean it will stay running if the server crashes or reboots! To ensure my web server automatically turns back on after a system reboot, I have to explicitly tell the system to do so using: systemctl enable httpd Why It Matters: Whether it is a web server, a database, or a custom application, a DevOps engineer's job is to ensure high availability. Mastering systemctl is how we ensure critical services stay alive and properly configured! #100DaysOfDevOps #100DaysOfCode #Linux #SystemAdmin #CentOS #Vagrant #Systemctl #DevOpsEngineer #TechJourney #DailyProgress #CloudComputing

🚀 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 #DevOps #CloudComputing #AWS #SysAdmin #TechSkills #Learning #BeginnerFriendly #Terminal #Automation

🐧 Leveling Up: Mastering the Linux & Unix Ecosystem I just wrapped up an intensive deep-dive into Linux/Unix System Administration. From securing server connections to managing enterprise-level web services, understanding these core principles is what separates a user from a power user. Here’s a snapshot of the technical toolkit I’ve been sharpening: 🔐 Secure Connectivity & Server Access Mastering SSH (ssh username@server-ip) is the first step in remote infrastructure management. Establishing secure, encrypted tunnels is the foundation of any cloud or DevOps workflow. 📝 The Power of VI/VIM The command line is only as powerful as your ability to edit configurations. Moving beyond basic text entry into Command, Insert, and Execution modes in VIM allows for lightning-fast file manipulation: Efficiency: Using dd to prune lines and /pattern to find configs in seconds. Control: Mastering :wq and u to manage changes with precision. 📦 Modern Package Management Whether it's APT for Ubuntu, YUM for CentOS, or Brew for macOS, knowing how to efficiently pull, update, and manage software dependencies is critical for system stability. ⚙️ Service Orchestration Using systemctl to manage services like NGINX, Docker, and MySQL. Being able to triage a service's status and ensure "high availability" is a day-to-day necessity in production environments. 🌐 Networking & Troubleshooting Understanding the "pulse" of the server through: Connectivity: ping and dig for DNS resolution. Diagnostics: ifconfig and ss (Socket Statistics) to monitor data flow. 💡 Linux vs. Unix: A Quick Perspective While Unix provided the commercial, enterprise-grade foundation starting in 1969, Linux has carried the torch into the modern era as a free, open-source powerhouse. Both share the robust DNA of multi-user support and multitasking that runs the world’s most critical servers today. The journey into the kernel is endless, but the command line is where the magic happens! 🚀 #Linux #Unix #DevOps #SystemAdministration #CloudComputing #TechCommunity #Vim #Networking #ContinuousLearning #OpenSource Vikas Ratnawat CloudDevOpsHub Community

🆕 My latest blog post! Three decades on the terminal, and I still think faster there than anywhere else. I wrote down the Bash commands I actually reach for every day. It's not an exhaustive reference, but the patterns that genuinely save me time with navigating, searching, processing, and more. This covers the daily workflow, the pipelines that replace 20-line scripts (grep | awk | sort | uniq -c | sort -rn | head - you know the one), the macOS vs Linux issues that trip everyone up, and the modern alternatives worth adopting (ripgrep, fd, jq, yq, ncdu). If you live in the terminal (or want to) this is something that should help. https://lnkd.in/ev2NEPag #Bash #Linux #DevOps #AWS #Terminal

Day 7/100 – Setting Up Password-less SSH Authentication in Linux It's Day 7 already. 🎉 Today, I was presented with another real world DevOps challenge; To implement password-less SSH access between a jump host and multiple app servers. The goal was to allow a user (thor) on the jump host to connect to other servers using their respective sudo users without being prompted for a password. This is especially important for scripts that run automatically and need uninterrupted access (like the cron job worked on yesterday). The first thing I did was to generate an SSH key pair using "ssh-keygen -t rsa" and distribute the public key to each app server using "ssh-copy-id". Once that was done, I tested the connections and confirmed that access was successful without any password prompts. Password-less access is essential for cron jobs and scripts. Security is about balance: automation vs controlled access and knowing when each is desired. This is one of those behind-the-scenes setups that makes CI/CD pipelines, remote scripts, and large-scale infrastructure actually work. One day at a time till perfection.🚀 #DevOps #CloudEngineering #Linux #SSH #TechLearning #100DaysOfCode # #SystemAdministration #LearningInPublic

🚀 From “It’s not working” → to “I can debug it” I recently completed a DNS + Apache Web Server setup on RHEL. But honestly, the biggest learning wasn’t the setup — it was the troubleshooting mindset I built along the way. 🔧 What I worked on: • Configured DNS using BIND (forward & reverse zones) • Hosted a website using Apache • Tested across Windows and Ubuntu clients 🧠 What actually mattered: Instead of just following steps, I started asking: 👉 Why is it not resolving? 👉 Why is Apache showing the default page? 👉 Where exactly is the failure happening? That’s where real learning started. ⚙️ Commands that helped me debug: • systemctl status httpd → Check service status • journalctl -xe → Analyze system errors • ss -tuln | grep :80 → Verify port binding • dig domain.com → Test DNS resolution • firewall-cmd --list-all → Check firewall rules 💡 My troubleshooting flow now: 1️⃣ Check service status 2️⃣ Check logs for errors 3️⃣ Verify port listening 4️⃣ Validate DNS resolution 5️⃣ Check firewall rules Simple steps — but extremely effective in real environments. 📌 Key realization: Linux is not about memorizing commands. It’s about understanding how systems interact. Most real-world issues come down to: → Logs → Networking fundamentals → Service behavior 🌐 GitHub Project: https://lnkd.in/gTpsMqtM If you're learning Linux / DevOps: 👉 Don’t just build projects 👉 Break them, debug them, fix them That’s where real learning happens. #Linux #DevOps #SystemAdministration #DNS #Apache #Troubleshooting #RHCSA #CloudComputing

Linux looks simple… until you can’t find your own file. 🔹 Linux File System (The Most Important Concept) If you don’t understand this, Linux will always feel confusing. 🧠 What is the Linux File System? Linux doesn’t use drives like C:, D: ❌ 👉 Everything starts from a single root: / Think of it like a tree 🌳 All files and folders branch out from this root. 🔹 Key Directories You MUST Know 📁 /home → Your personal files 📁 /etc → Configuration files (very critical) 📁 /var → Logs & application data 📁 /tmp → Temporary files 📁 /bin → Essential commands 👉 These are used daily in real servers. 🔹 Try This (Hands-on) pwd ls cd / ls cd /home 👉 You just navigated the Linux file system 🎯 🔹 Real-World Scenario Your application is failing ❌ Where do you check logs? 👉 /var/log If you don’t know this, you’ll be stuck while others fix the issue in minutes. ⚠️ Beginner Mistake Running commands without knowing your location: rm -rf * 👉 This can delete everything in your current directory 😬 ✅ Always check first: pwd 🔹 Why This Matters in DevOps Debug production issues Navigate servers quickly Understand where configs & logs live 👉 This is day 1 skill for any DevOps engineer. #Linux #DevOps #AWS #CloudComputing #LearnLinux #DevOpsJourney #LinuxForBeginners

🔧 Linux Patching Process – Step-by-Step (Safe & Structured) Performed a controlled patching activity on Linux systems to ensure updates were applied without breaking dependencies or services. ━━━━━━━━━━━━━━━━━━━ 📌 STEP-BY-STEP PROCESS ━━━━━━━━━━━━━━━━━━━ 1️⃣ Verify OS Version cat /etc/os-release hostnamectl ✔ Ensure correct repo compatibility 2️⃣ Clean & Prepare Cache yum clean all yum check-update ✔ Avoid stale metadata issues 3️⃣ Dry Run (Safe Testing) yum update --assumeno ✔ Simulates update without installing ✔ Helps detect dependency conflicts early 4️⃣ Apply Patches yum update -y ✔ Installs latest packages from repositories 5️⃣ Verify Updates rpm -qa | grep ✔ Confirm updated versions 6️⃣ Validate System • Check services status systemctl status • Verify logs /var/log/messages ✔ Ensure system stability after patching ━━━━━━━━━━━━━━━━━━━ ⚠️ COMMON ISSUES ━━━━━━━━━━━━━━━━━━━ ❌ Dependency errors ❌ Incorrect repo configuration ❌ Disk space full (/var) ❌ Cache conflicts ━━━━━━━━━━━━━━━━━━━ 💡 KEY TAKEAWAY ━━━━━━━━━━━━━━━━━━━ Patching is not just an update command — it’s a process: Verify ➝ Clean ➝ Test ➝ Apply ➝ Validate ━━━━━━━━━━━━━━━━━━━ #Linux #Patching #DevOps #SystemAdministration #YUM #Automation

🔧 Linux Patching Process – Step-by-Step (Safe & Structured) Performed a controlled patching activity on Linux systems to ensure updates were applied without breaking dependencies or services. ━━━━━━━━━━━━━━━━━━━ 📌 STEP-BY-STEP PROCESS ━━━━━━━━━━━━━━━━━━━ 1️⃣ Verify OS Version cat /etc/os-release hostnamectl ✔ Ensure correct repo compatibility 2️⃣ Clean & Prepare Cache yum clean all yum check-update ✔ Avoid stale metadata issues 3️⃣ Dry Run (Safe Testing) yum update --assumeno ✔ Simulates update without installing ✔ Helps detect dependency conflicts early 4️⃣ Apply Patches yum update -y ✔ Installs latest packages from repositories 5️⃣ Verify Updates rpm -qa | grep ✔ Confirm updated versions 6️⃣ Validate System • Check services status systemctl status • Verify logs /var/log/messages ✔ Ensure system stability after patching ━━━━━━━━━━━━━━━━━━━ ⚠️ COMMON ISSUES ━━━━━━━━━━━━━━━━━━━ ❌ Dependency errors ❌ Incorrect repo configuration ❌ Disk space full (/var) ❌ Cache conflicts ━━━━━━━━━━━━━━━━━━━ 💡 KEY TAKEAWAY ━━━━━━━━━━━━━━━━━━━ Patching is not just an update command — it’s a process: Verify ➝ Clean ➝ Test ➝ Apply ➝ Validate ━━━━━━━━━━━━━━━━━━━ #Linux #Patching #DevOps #SystemAdministration #YUM #Automation

“Why are there SO many folders in #Linux?” 🤯 That was my first reaction logging into a #server. Turns out — it’s not chaos. It’s a in Linux system. 📁 /bin — basic commands (like copy, list files) 📁 /sbin — system-level commands (mostly for admins) 📁 /etc — where all configuration lives 📁 /var — changing data (logs, databases, queues) 📁 /tmp — temporary files (cleared often) 📁 /usr — where most apps and libraries live 📁 /opt — extra/third-party software 📁 /proc — live system + process info (virtual) 📁 /sys — hardware + kernel details (virtual) 📁 /home — user files and personal space Once you get this, everything clicks (If you are working in Devops, Below 3 file system will become a best Friends) 👇 📁 /etc → how things are configured 📁 /var → what’s changing (logs, data) 📁 /proc → what’s happening right now 💡 That’s it. That’s the pattern. And when things break? 🚨 Go straight to /var/log Linux literally tells you what went wrong. Most beginners try to memorize everything. Smart engineers learn where to look. That’s the real DevOps mindset. ______DevOps | Cloud______