Linux File System

 Linux File System

Essential Linux Commands Every IT Professional Should Know

 Essential Linux Commands Every IT Professional Should Know

Linux is the backbone of servers, DevOps, cybersecurity, and cloud infrastructure.
Whether you’re a beginner or want to organize your knowledge, these core Linux commands are a must 👇

📁 File & Directory Management
ls, cd, pwd, mkdir, cp, mv, rm

📄 File Viewing & Editing
cat, less, nano, vim

⚙️ Process Management
ps, top, htop, kill, pstree

👥 User & Group Management
useradd, usermod, groupadd, passwd, id

🌐 Network Configuration & Monitoring
ip, ping, ss, netstat, ssh, traceroute

📦 Package Management
apt, apt-get, yum, dnf, dpkg, snap

🧠 System Information
uname, df, du, free, lscpu
These commands form the foundation for working with Linux in DevOps, System Administration, and Cybersecurity.

File System Hierarchy (Linux)

 File System Hierarchy (Linux)

👉 The File System Hierarchy defines the directory structure and directory contents in Linux.
👉It organizes files logically so the operating system and users can easily find and manage data.
👉In Linux, everything is treated as a file, and all files are arranged in a tree structure starting from the root directory (/).

Root Directory /
Top-most directory in Linux
All other directories are created under /
Important Directories & Description

👉/bin – Binary Executables
Essential user commands
Example: ls, cp, mv, cat

👉/sbin – System Binaries
System administration commands
Example: reboot, shutdown, ifconfig

Mostly used by root user

👉/etc – Configuration Files
System-wide configuration files
Example:
👉/etc/passwd – user accounts
👉/etc/fstab – file system mounts

👉/home – User Home Directories
Personal directories for users
Example: /home/venu
Stores documents, downloads, settings

👉/root – Root User Home
Home directory for root
Different from /

👉/var – Variable Data
Frequently changing files
Example:
👉/var/log – log files
👉/var/spool – mail, print jobs

👉/tmp – Temporary Files
Temporary files created by applications
Cleared automatically on reboot

👉/usr – User Programs & Data
Installed software and libraries
Subdirectories:
👉/usr/bin – user commands
👉/usr/lib – libraries
👉/usr/share – documentation

👉/lib & /lib64 – Libraries
Shared libraries needed by /bin and /sbin
Kernel modules also stored here

👉/boot – Boot Loader Files
Files required to boot the system
Example:
vmlinuz
initramfs
grub

👉/dev – Device Files
Represents hardware devices as files
Example:
👉/dev/sda – hard disk
👉/dev/null

👉/proc – Process Information
Virtual filesystem
Provides system & process info
Example:
👉/proc/cpuinfo
👉/proc/meminfo

👉/sys – System Information
Interface to kernel and hardware
Used for device and driver info

👉/mnt – Temporary Mount Point
Used for temporarily mounting filesystems

👉/media – Removable Media
Mount point for USB, CD/DVD

👉/opt – Optional Software
Third-party applications

Example: /opt/oracle

Linux is one, but why are there so many types?

 Linux is one, but why are there so many types?

Many people are confused: “What exactly is Linux?” Essentially, Linux is a kernel (the core of an operating system), not a complete operating system. A Linux distro (distribution) is a “complete package” built around that kernel.

Each distro is like a car with different specifications and purposes, even though the basic engine (the Linux kernel) is similar.

Philosophy & Stability:
➡️Debian/Ubuntu: User-friendly, stable, suitable for beginners and servers.
➡️Fedora: Innovative, uses the latest technology, gateway to RHEL.
➡️Arch Linux: Minimalist, continuous updates, for those who love extreme customization.  
➡️openSUSE: Powerful, equipped with complete system administration tools (YaST).  
➡️Gentoo: Compiled from source code for maximum optimization (expert level).
➡️Linux Mint: It's very similar to Windows (Start menu in the left corner), so you won't get lost. It's stable, lightweight, and “just works” for everyday use.
➡️Zorin OS: Specifically designed for migrating from Windows. Its interface is beautiful, intuitive, and easy to customize. A very smooth experience for beginners.
➡️Kali Linux: Specially designed for professional security testing, security auditing, and network penetration.
➡️Parrot OS: A security distro that also focuses on privacy, software development, and can even be used for general work with the right configuration.

In essence, all distros are Linux, but packaged for different needs and tastes. The best one is the one that best suits your workflow.