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Linux — Directories

Short & clear revision notes · 7 topics

01 · What is a Directory?

A directory in Linux is a special file whose only job is to store file names and their related information. Every file — whether ordinary, special, or a directory — is contained inside a directory.

Linux organises all files and directories in a hierarchical tree structure. At the very top is the root directory, represented by a single slash /. Every other file and directory lives somewhere below it.

🏢 Think of it like a company — the CEO is / (root), departments are directories, and employees are files. Everything has a place in the hierarchy.

02 · Linux Directory Structure

These are the standard directories found directly under / in every Linux system:

Directory Purpose
/bin Essential binary programs (commands like ls, cp, mv)
/boot Boot files, kernels, and configs needed at startup
/dev Device files representing hardware (disks, terminals)
/etc System configuration files and startup scripts
/home Home directories for all regular users
/lib Shared system libraries used by programs
/media Auto-mounted removable media (USB, CD-ROM, cameras)
/mnt Manually mounted filesystems and drives
/opt Optional third-party applications
/proc Virtual files showing running processes and system state
/root Home directory of the root (admin) user
/sbin System binaries — admin/maintenance commands
/srv Files served to other systems (web, FTP data)
/sys Virtual filesystem exposing kernel and hardware info
/tmp Temporary files — cleared on reboot
/usr User applications and files accessible to all users
/var Variable data — logs, databases, mail spools

03 · Home Directory

When you log in, Linux places you in your home directory — your personal space, usually at /home/your-username.

Command What it does
cd ~ Go to your own home directory from anywhere
cd ~username Go to another user's home directory
cd - Go back to the previous directory you were in

💡 The tilde ~ is a shortcut for your home directory path. Instead of typing /home/rauneet, just type ~.

04 · Absolute vs Relative Pathnames

A pathname describes the location of a file or directory in the filesystem. There are two types:

  • Absolute path — always starts from the root /. It gives the full address of a file, no matter where you currently are.
  • Relative path — starts from your current location. It does not begin with /. Use ../ to go one level up.
Example Type Meaning
/etc/passwd Absolute Starts from root, always works
/users/john/notes Absolute Full path from root
../chem/notes Relative Go up one level, then into chem/notes
personal/res Relative Go into personal folder from current location
Command What it does
pwd Print current working directory — shows where you are

💡 Use pwd (print working directory) whenever you are lost — it shows your exact location in the filesystem.

05 · Listing, Creating & Removing Directories

Command What it does
ls dirname List all files inside a specific directory
mkdir dirname Create a new directory in the current location
mkdir /tmp/test-dir Create a directory at an absolute path
mkdir docs pub Create multiple directories at once
mkdir -p a/b/c Create nested directories — makes parent dirs too
rmdir dirname Remove an empty directory
rmdir d1 d2 d3 Remove multiple empty directories at once

⚠️ rmdir only works on empty directories. If a directory has files inside, you must delete the contents first before removing it.

💡 mkdir -p is very useful — it creates the full path in one go. Without -p, mkdir will fail if the parent directory doesn't exist yet.

06 · Changing & Renaming Directories

Use cd to move between directories and mv to rename them.

Command What it does
cd dirname Move into a directory (relative or absolute path)
cd /usr/local/bin Move into a directory using absolute path
cd ../../home/user Go up two levels, then navigate down
mv mydir yourdir Rename a directory from mydir to yourdir

Going up levels with ..

cd ..        →  move one level up
cd ../..     →  move two levels up
cd ../../..  →  move three levels up  (chain as many as needed)

07 · The Dot (.) and Double Dot (..) Entries

Every directory in Linux contains two special hidden entries that help with navigation:

Entry Refers to Common use
. The current directory itself cp file . — copy a file here
.. The parent directory — one level above cd .. — go up one level

💡 You can see these entries by running ls -la — they appear at the top of the listing with their own permissions and ownership details.

These entries exist in every single directory — even newly created empty ones. They are how Linux keeps track of the directory tree.

Linux Directories Notes — for revision use