Linux File System Basics

What You'll Learn

Every Linux system organizes files and folders in a single tree starting at / (called "root"). Unlike Windows with C:\, D:\ drives, Linux uses one unified hierarchy. This guide explains the most important directories so you know where everything lives.

The Root Directory Structure

Type ls / to see all top-level folders. Here's what each one does:

Directory	Purpose
`/bin`	Essential command binaries (ls, cp, grep) — available to all users.
`/etc`	Configuration files for the system and applications.
`/home`	User home directories. Your files live in `/home/yourusername`.
`/var`	Variable data — logs (`/var/log`), mail, caches.
`/tmp`	Temporary files. Cleared on reboot.
`/usr`	User programs and libraries — the largest directory on most systems.
`/opt`	Optional/add-on software packages (e.g., Google Chrome, Slack).
`/root`	The root user's home directory. You need sudo to access it.
`/dev`	Device files — hardware is represented as files here.
`/proc`	Virtual filesystem showing process and kernel information in real time.
`/sys`	Another virtual filesystem for kernel and device parameters.

Navigating the File System

Key Commands

pwd — Print Working Directory. Shows where you are right now.
ls — List files and folders in the current directory.
cd /path — Change Directory to a different location.

Important Path Concepts

Absolute path: Starts from root. Example: /home/alex/documents
Relative path: From your current location. Example: documents/report.txt
. — Refers to the current directory.
.. — Refers to the parent (one level up).
~ — Shortcut for your home directory (/home/alex).

Try It

pwd                    # Where am I?
ls -la                 # List everything including hidden files
cd /var/log            # Go to the log directory
ls                     # See what logs exist
cd ~                   # Go back home
cd ..                  # Go up one level

Hidden Files and Dotfiles

Any file or folder starting with a dot (.) is hidden by default. These usually store configuration for your user:

~/.bashrc — Bash shell configuration (aliases, environment variables).
~/.ssh/ — SSH keys and known hosts.
~/.config/ — Application settings.

Show them with: ls -a ~

Troubleshooting

"bash: cd: no such file or directory" — Double-check the path. Use pwd to confirm where you are.
"Permission denied" — You may need sudo to access system directories like /root or /etc.

What's Next?

Now that you understand the file system layout, learn the essential commands every beginner needs:

Your First Linux Commands →