📁 Linux: File System Hierarchy – Understanding Linux Directory Structure

🧲 Introduction – Why Learn the Linux File System Hierarchy?

The Linux file system is more than just folders—it’s a well-organized, logical hierarchy designed for both simplicity and scalability. Understanding this structure is essential for system navigation, software installation, permission control, and troubleshooting. Unlike Windows, everything in Linux is a file, including hardware and processes.

🎯 In this guide, you’ll learn:

• The purpose of each top-level directory in Linux
• How Linux treats files, directories, and devices
• Common paths used by users, admins, and developers
• Best practices for file storage and configuration

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🗂️ Overview: Linux Directory Structure

The Linux file system is rooted at / (root directory) and branches out like a tree. Below is a simplified overview:

/
├── bin
├── boot
├── dev
├── etc
├── home
├── lib
├── media
├── mnt
├── opt
├── proc
├── root
├── run
├── sbin
├── srv
├── sys
├── tmp
├── usr
└── var

Let’s explore each of these in detail.

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📂 / – Root Directory

• The top-most directory in Linux.
• All other directories stem from here.
• Equivalent to C:\ in Windows.

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🔧 /bin – Essential User Binaries

• Contains essential binary commands needed for system boot and repair.
• Common commands: ls, cp, mv, cat, mkdir

🧪 Example:

/bin/ls

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⚙️ /sbin – System Binaries

• Contains system administration binaries.
• Commands typically used by root user: fsck, reboot, ifconfig

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📦 /lib, /lib64 – Shared Libraries

• Essential libraries for binaries in /bin and /sbin.
• Think of them as Linux’s DLLs (like in Windows).

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🧩 /etc – Configuration Files

• System-wide configuration files live here.
• Examples: /etc/passwd, /etc/ssh/sshd_config, /etc/fstab

🧪 View hostname config:

cat /etc/hostname

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🏠 /home – User Home Directories

• Personal folders for users.
• Files, downloads, and settings are stored here (e.g., /home/john).

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👑 /root – Root User’s Home

• Home directory for the root (superuser).
• Not to be confused with /.

🧪 Access only via:

sudo su
cd /root

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💾 /boot – Boot Loader Files

• Contains files needed to boot the OS.
• Includes the Linux kernel (vmlinuz), initrd, and grub.

⚠️ Caution: Modifying this folder can make the system unbootable.

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🖥️ /dev – Device Files

• Represents devices as files.
• Includes: /dev/sda (hard disk), /dev/null, /dev/tty

🧪 Example:

ls /dev

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🧠 /proc – Process & Kernel Information

• Virtual file system providing real-time system info.
• Files like /proc/cpuinfo, /proc/meminfo, and /proc/uptime

🧪 View CPU Info:

cat /proc/cpuinfo

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📤 /sys – System and Hardware Info

• Similar to /proc, but for devices and drivers.
• Used by the kernel and udev.

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📍 /run – Runtime Variable Data

• Stores temporary runtime data like PID files, sockets.
• Cleared at every reboot.

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📁 /tmp – Temporary Files

• Used by apps and users to store temporary files.
• Automatically cleared after reboot.

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📦 /opt – Optional Software Packages

• Used for installing third-party software not from default repos.
• E.g., /opt/google/chrome for Google Chrome.

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🌐 /srv – Service Data

• Contains files related to system services like ftp, httpd.

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🔌 /mnt and /media – Mount Points

Directory	Usage
/mnt	Temporary mount points (manually mounted devices)
/media	Auto-mounted removable devices (USB, CD-ROM)

🧪 Example:

mount /dev/sdb1 /mnt

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📌 Summary – Recap & Next Steps

The Linux file system hierarchy is designed for modularity, security, and predictability. Mastering it helps you navigate, configure, and troubleshoot like a pro. Each directory has a dedicated role, which contributes to system stability and organization.

🔍 Key Takeaways:

• Everything starts at / and branches downward.
• /etc = config, /home = users, /bin = essential binaries, /boot = boot files.
• Device files (/dev), process info (/proc), and temporary data (/tmp) are managed by the kernel.
• Understanding the file system helps in backups, scripting, permissions, and system recovery.

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❓ FAQs

❓ What is the root directory in Linux?
✅ The root directory / is the base of the Linux file system. All other files and directories are placed under it.

❓ What’s the difference between /bin and /sbin?
✅ /bin contains essential user commands; /sbin holds administrative/system commands for root users.

❓ Where are user files stored in Linux?
✅ In the /home/username/ directory. Each user gets their own subfolder.

❓ What is /proc used for?
✅ /proc is a virtual filesystem that displays system and process info directly from kernel memory.

❓ Can I delete files in /tmp?
✅ Yes, but it’s usually cleared automatically on reboot. Use with care during active sessions.

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