Week 2, Day 1: File Systems

CMPSC 100 Computational Expression

Janyl Jumadinova

File Systems

File systems organize data in a tree-like structure

File Systems are Hierarchical

• Folders (also called directories) can contain:
  • Files (documents, images, code, etc.)
  • Other folders (creating nested structure)
• Think of it like boxes that hold objects and other boxes
• Two ways to visualize the same file system:

└── red
    ├── yellow
    │   ├── green
    │   └── purple
    └── orange

Parents, Children, Siblings

Family relationships describe folder connections:

• Parent: The folder that contains other folders
  • red is the parent of yellow and orange
• Children: Folders contained within a parent folder
  • green and purple are children of yellow
• Siblings: Folders that share the same parent
  • yellow and orange are siblings
  • green and purple are siblings

└── red
    ├── yellow
    │   ├── green
    │   └── purple
    └── orange

Directories

Directory = Folder (same thing!)

• Different operating systems use different terms:
  • Windows: “Folder”
  • Mac/Linux: “Directory”
  • Programming: Often “Directory”
• Contains files and other directories
• Organizes your digital workspace

Root Directory

The root directory contains everything else:

• Root: The top-level folder in the file system
• Contains all other directories and files
• In our example: red is the root directory
• Important: Every file system has exactly one root directory

└── red
    ├── yellow
    │   ├── green
    │   └── purple
    └── orange

File Paths

A path shows the route to a specific file or folder:

• Path: The full address from root to your target
• Always starts at the root directory
• Gets more specific as you go deeper
• Uses / (forward slash) to separate folders

Examples from our tree:

• Path to purple: red/yellow/purple
• Path to orange: red/orange
• Path to green: red/yellow/green

└── red
    ├── yellow
    │   ├── green
    │   └── purple
    └── orange

Navigating File Systems

Two main ways to explore your files:

• Graphical File Explorer:
  • Windows: File Explorer
  • Mac: Finder
  • Linux: Files/Nautilus
  • Click and visual navigation
• Terminal/Command Line:
  • Text-based navigation
  • More powerful and precise
  • We’ll use this in class!

Important: Be careful with cloud storage - files might not be locally stored!

Using the Terminal

Opening Terminal in VS Code

VS Code has a built-in terminal - perfect for our work!

• Keyboard shortcut:
  • Windows/Linux: `Ctrl + `` (backtick)
  • Mac: `Cmd + `` (backtick)
• Menu: View → Terminal
• Command Palette: Ctrl/Cmd + Shift + P → “Terminal: Create New Terminal”

Benefits:

• Integrated with your code editor
• Same directory as your project
• Easy to switch between coding and terminal commands

What is the Terminal?

The terminal is a text-based interface to your computer:

• Also called: Command line, shell, console
• No mouse needed - everything done with keyboard
• More powerful than graphical interfaces
• Faster once you learn the commands
• Essential skill for programming and development

Why use terminal?

• Automation and scripting
• Precise control over files and folders
• Works on all operating systems
• Many development tools are terminal-based

Terminal Basics

Key commands for navigation:

• pwd - Print Working Directory (where am I?)
• ls - List files and folders
• cd - Change Directory

pwd
# Output: /Users/yourname

ls
# Output: Desktop  Documents  Downloads  ...

cd Documents
pwd
# Output: /Users/yourname/Documents

Basic Navigation Commands

Essential commands for moving around:

List contents:

ls

• Shows files and folders
• ls -l for detailed view
• ls -a to show hidden files

Change directory:

cd foldername

• Moves into a folder
• Must spell folder name exactly

Go up one level:

cd ..

• Moves to parent directory
• .. means “parent folder”

Go to home directory:

cd

• Takes you to your user folder
• Same as cd ~

Creating and Managing Folders

Making new directories:

mkdir new_folder_name

Examples:

mkdir homework
mkdir "my documents"  # Use quotes for spaces
mkdir project1 project2 project3  # Create multiple

Best practices:

• Use descriptive names
• Avoid spaces (use underscore or dash)
• Use lowercase for consistency
• Examples: cmpsc100_f2025, lab1

More Useful Commands

File and directory operations:

Remove empty directory:

rmdir folder_name

Remove file:

rm filename

Copy file:

cp source destination

Move/rename:

mv old_name new_name

Create empty textfile:

touch filename.txt

Show file contents:

cat filename.txt

Special Directory Shortcuts

Helpful shortcuts to remember:

• . (dot) = Current directory
• .. (dot dot) = Parent directory
  
• ~ (tilde) = Home directory
• / (forward slash) = Root directory

Examples:

pwd            # Show current directory
cd .           # Stay in current directory
cd ..          # Go up one level
cd ../..       # Go up two levels
cd ~           # Go to home directory
cd /           # Go to root directory

Terminal Practice Tips

Getting comfortable with the terminal:

• Start small: Practice with simple commands
• Use tab completion: Type first few letters, press Tab
• Arrow keys: Up/down to recall previous commands
• Clear screen: clear command or Ctrl+L
• Don’t be afraid: You can always navigate back!

Safety tips:

• Be careful with rm (delete) commands
• Use ls to check contents before moving
• Practice in a safe folder first