Linux Directory Structure

Understanding the Linux file system layout

What is the Linux Directory Structure?

In Linux, everything starts from / (called root). It's the top of the file system tree, and all other directories branch out from there. Unlike Windows with C:, D:, E: drives, Linux has one unified tree where everything - programs, files, even hardware - shows up as files or directories.

Think of it like: A real tree where / is the trunk and all directories are branches growing from it. No matter how many hard drives you have, they all fit into this one tree.

Windows vs Linux Approach

Windows

C:\Windows\System32
C:\Program Files\
D:\Games\
E:\Backup\
Multiple separate roots (C:, D:, E:)

Each drive has its own letter. Programs look in different places depending on the drive.

Linux

/usr/bin/
/home/john/
/var/log/
/mnt/backup/
One unified tree starting at /

Everything starts at root (/). All drives mount somewhere in this tree. Clean and consistent.

The Linux File System Tree


graph TD
    Root["/"]
    Root --> Bin["/bin"]
    Root --> Home["/home"]
    Root --> Etc["/etc"]
    Root --> Var["/var"]
    Root --> Usr["/usr"]
    Root --> Tmp["/tmp"]
    Root --> Opt["/opt"]
    Root --> Dev["/dev"]
    
    style Root fill:#fef3c7,stroke:#f59e0b,stroke-width:4px,font-size:18px
    style Home fill:#dbeafe,stroke:#3b82f6,stroke-width:3px
    style Etc fill:#fce7f3,stroke:#ec4899,stroke-width:3px
    style Var fill:#dcfce7,stroke:#16a34a,stroke-width:3px
    style Usr fill:#e0e7ff,stroke:#6366f1,stroke-width:3px
    style Bin fill:#fef9c3,stroke:#eab308,stroke-width:3px
    style Tmp fill:#fed7aa,stroke:#ea580c,stroke-width:3px
    style Opt fill:#ddd6fe,stroke:#8b5cf6,stroke-width:3px
    style Dev fill:#fecaca,stroke:#dc2626,stroke-width:3px

Everything branches from / (root). Each directory has a specific purpose in the system.

Important Directories You Need to Know

/

Root directory. The top of everything. All other directories live here.

Example: When you type cd / you go to the very top of the file system.

/home

User home directories. Each user gets their own folder here. Your personal files, documents, downloads - everything goes in your home directory.

Example: User "john" has /home/john/ where all his stuff lives. Like C:\Users\John in Windows.

/bin

Essential commands. Basic programs everyone needs like ls, cp, cat. These work even in emergency recovery mode.

Example: When you type ls, Linux runs /bin/ls to list files.

/etc

Configuration files. All system settings live here. Want to change how your network works or what programs start on boot? Look in /etc.

Example: /etc/hosts maps website names to IP addresses. /etc/passwd has user account info.

/usr

User programs and data. Most of your installed software lives here. Think of it as "C:\Program Files" but organized better.

Example: /usr/bin/ has programs like Firefox or vim. /usr/lib/ has shared libraries programs need.

/var

Variable data. Stuff that changes as the system runs - logs, caches, databases, mail queues. Things that grow over time.

Example: /var/log/ has system logs. If something breaks, look here. /var/cache/ stores temporary cached data.

/tmp

Temporary files. Anything here can disappear on reboot. Programs use it for scratch space. Don't store important stuff here.

Example: A program downloads a file, processes it in /tmp/, then saves the result elsewhere.

/opt

Optional software. Third-party applications that don't fit the standard Linux layout go here. Each app gets its own subdirectory.

Example: /opt/google/chrome/ for Chrome browser. /opt/slack/ for Slack app.

/root

Root user's home. This is the admin (root user) home directory. Not to be confused with / (root directory). Regular users can't access this.

Example: When you sudo su to become root, you land in /root/.

Less Common But Still Important

/dev: Device files. Your hard drives, USB sticks, even your terminal show up here as files. /dev/sda is your first hard drive.
/proc: Virtual files showing system info. CPU details, memory usage, running processes - all readable as files here.
/mnt & /media: Mount points for external drives. When you plug in a USB drive, it shows up in /media/. Admins mount drives manually in /mnt/.
/sys: Another virtual file system. Info about hardware and kernel modules. You rarely touch this directly.
/boot: Files needed to start the system. Kernel and bootloader live here. Don't delete anything from here!
/lib: Shared libraries that programs need to run. Like DLL files in Windows.

Common Tasks and Where to Look


graph LR
    A[What are you doing?] --> B[Installing software?]
    A --> C[Looking for logs?]
    A --> D[Editing config?]
    A --> E[Saving your files?]
    
    B --> B1["/usr/bin/ for programs
/usr/lib/ for libraries"]
    C --> C1["/var/log/ has all logs"]
    D --> D1["/etc/ has config files"]
    E --> E1["/home/username/ for your stuff"]
    
    style A fill:#fef3c7,stroke:#f59e0b,stroke-width:2px
    style B1 fill:#dbeafe,stroke:#3b82f6,stroke-width:2px
    style C1 fill:#dcfce7,stroke:#16a34a,stroke-width:2px
    style D1 fill:#fce7f3,stroke:#ec4899,stroke-width:2px
    style E1 fill:#e0e7ff,stroke:#6366f1,stroke-width:2px