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Jun 20, 2026
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Linux
46 articles
How to Install and Configure Docker on Ubuntu 24.04
Overview Docker is an open-source containerization platform that lets you package applications and their dependencies into lightweight, …
Apr 8, 2026
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How to Install and configure Nginx on Ubuntu 24 04
Overview Nginx (pronounced engine-x) is one of the world’s most popular open-source web servers. It is also widely used as a reverse …
Apr 6, 2026
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Linux for DevOps
Why Every DevOps Engineer Needs Real Linux Fundamentals Docker, Kubernetes, Terraform, and CI/CD runners are not separate from Linux — …
Jan 20, 2026
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Linux Logs
Where Do Linux Logs Live? Two systems coexist on most modern distros: flowchart TB subgraph Sources KERNEL[Kernel Messages] …
Jan 20, 2026
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Linux Storage Fundamentals
The Storage Stack, Top to Bottom flowchart TB FS["Filesystem: ext4 / xfs"] --> LV["Logical Volume (LVM)"] LV --> VG["Volume Group"] VG --> …
Jan 20, 2026
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Linux Networking Fundamentals
What Handles Networking on Linux? Networking is implemented inside the kernel’s network stack; user-space tools (ip, curl, ss) just …
Jan 20, 2026
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Services & systemd
What Is systemd? systemd is the init system and service manager used by most modern Linux distributions (RHEL, Ubuntu, Debian, Amazon Linux …
Jan 20, 2026
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Linux Boot Process
What Happens When a Linux Machine Boots? flowchart TD A["1. Firmware: BIOS/UEFI POST"] --> B["2. Bootloader: GRUB2"] B --> C["3. Kernel …
Jan 20, 2026
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systemd & Service Commands
Managing a Service: systemctl sudo systemctl start nginx # start now sudo systemctl stop nginx # stop now sudo systemctl restart nginx # …
Jan 20, 2026
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Processes & Jobs
What Is a Process? A process is a running instance of a program — it has its own PID (process ID), memory space, open file descriptors, and …
Jan 20, 2026
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DNS Resolution Failures
Overview “Can’t resolve hostname” or intermittent DNS failures are common, and the resolution order Linux actually uses …
Jan 20, 2026
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System Monitoring Commands
Load Average & Uptime uptime # 10:32:01 up 45 days, 2:14, 3 users, load average: 1.25, 0.98, 0.75 The three numbers are load average …
Jan 20, 2026
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Linux Permissions
What Are Linux Permissions? Every file and directory carries three permission sets — for the owner, the group, and others — each with read …
Jan 20, 2026
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High Load Average
Overview Load average is one of the most misunderstood Linux metrics. It’s not a CPU percentage — it’s roughly the average …
Jan 20, 2026
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Zombie & Defunct Processes
Overview A zombie (shown as Z or <defunct> in ps) is a process that has already finished executing but whose exit status hasn’t …
Jan 20, 2026
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Users & Groups
What Are Users and Groups? Every process and file on Linux is owned by a user ID (UID) and a group ID (GID) — numbers, not names. Usernames …
Jan 20, 2026
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Archiving & Compression Commands
tar: The Standard Archive Tool tar (tape archive) bundles multiple files/directories into a single file — by itself it doesn’t …
Jan 20, 2026
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Permission Denied Errors
Overview “Permission denied” is usually straightforward once you check the right thing — but there are several distinct causes …
Jan 20, 2026
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Package Management Commands
Two Major Families flowchart LR subgraph Debian-based APT["apt / apt-get"] --> DPKG["dpkg (.deb files)"] end subgraph "Red Hat-based" …
Jan 20, 2026
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Linux File Types
What Are Linux File Types? Linux recognizes seven file types, all visible through the first character of ls -l’s permission string. …
Jan 20, 2026
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Network Connectivity Issues
Overview “Can’t connect to X” can fail at any of several layers — the local network interface, routing, DNS, a firewall …
Jan 20, 2026
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Files & Directories
What Is a File, Really? On Linux, a filename is just a pointer (a directory entry) to an inode — a data structure holding the file’s …
Jan 20, 2026
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Disk & Storage Commands
Disk & Filesystem Usage df -h # disk usage per mounted filesystem, human-readable df -hT # + filesystem type (ext4, xfs, tmpfs...) df -i …
Jan 20, 2026
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Service Won't Start
Overview A systemctl start fails, or a service that should auto-start on boot never comes up. The fix depends entirely on WHY it failed, …
Jan 20, 2026
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Networking Commands
Interfaces & Addresses ip addr show # all interfaces + their IPs (modern replacement for ifconfig) ip a # short form ip link show # …
Jan 20, 2026
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Linux Filesystem
What Is the Linux Filesystem? Unlike Windows (C:\, D:\), Linux has one unified tree rooted at /. Every disk, partition, network share, or …
Jan 20, 2026
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Slow Disk I/O
Overview Applications feel slow, but CPU and memory both look fine. The bottleneck is often the disk — either the physical/virtual storage …
Jan 20, 2026
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Shell & Terminal
You’ve typed commands into a terminal a thousand times. But have you ever stopped to ask what’s actually happening between you …
Jan 20, 2026
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Permissions & User Commands
Permissions: chmod chmod 644 file.txt # owner rw-, group r--, others r-- (standard for files) chmod 755 script.sh # owner rwx, group r-x, …
Jan 20, 2026
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Process & Job Commands
Viewing Running Processes ps aux # every process on the system, BSD-style ps -ef # every process, standard/POSIX-style ps -ef --forest # …
Jan 20, 2026
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Linux Kernel
Let’s talk about the kernel — the part of Linux that does all the unglamorous, absolutely essential work while every application on …
Jan 20, 2026
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Disk Full — No Space Left on Device
Overview “No space left on device” can mean the disk is genuinely full, the inode table is exhausted (rarer, but df -h …
Jan 20, 2026
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Text Processing Commands
The Unix Pipeline Philosophy Linux text tools are designed to be small and composable — chained together with | (pipe), where each …
Jan 20, 2026
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Linux Architecture
What Is Linux Architecture? Linux architecture describes how the system is layered from raw hardware up to the applications you run, and — …
Jan 20, 2026
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High Memory Usage & OOM Kills
Overview A process was unexpectedly killed, or the server is grinding to a halt under memory pressure. Linux’s Out-Of-Memory (OOM) …
Jan 20, 2026
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Linux MCQ — Basics to Advanced
1 Strictly speaking, what does the word 'Linux' refer to? A A complete operating system including a desktop environment B Only the …
Jan 20, 2026
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Linux Command Cheatsheet
A fast, scannable reference. For explanations and examples behind any of these, see the Linux Commands and Linux Fundamentals sections. …
Jan 20, 2026
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Introduction to Linux
If you’re getting into DevOps, cloud, or backend engineering, Linux isn’t optional background knowledge — it’s the ground …
Jan 20, 2026
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High CPU Usage
Overview CPU pegged at 100% (or a load average far above core count) usually has one of two shapes: a single runaway process, or many …
Jan 20, 2026
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File & Directory Commands
Navigation pwd # print current working directory cd /var/log # change directory cd - # go back to previous directory cd ~ # go to home …
Jan 20, 2026
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Bash Fundamentals
What Is Bash Scripting? Bash (Bourne Again SHell) is both an interactive shell and a scripting language. A Bash script is just a text file …
Jan 20, 2026
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Interview Q&A Part 03
Q1 You cannot SSH into your EC2 instance. How do you systematically troubleshoot? Basic Ans: Work through each layer from outside in: Layer …
Apr 26, 2025
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Interview Q&A Part 02
A comprehensive guide covering real-world scenarios for Linux, Ubuntu, and AWS EC2 interviews. Q1 You launched an EC2 instance but cannot …
Apr 26, 2025
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Interview Q&A Part 01
Q1 Explain the booting process of Linux. Basic Ans: BIOS/UEFI - Hardware runs Power-On Self Test (POST). BIOS/UEFI finds the bootable …
Apr 26, 2025
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Linux Engineer Learning Path
Who Is This Path For? This path is for absolute beginners — you’ve never used a Linux terminal before, and that’s completely …
Jan 18, 2025
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