Command Line Mastery: From Terminal Zero to Hero

Course Duration: Self-paced (Estimated 1-2 Months) Goal: To navigate, control, and automate your computer without a mouse.

Module 1: The First Steps (Beginner)

1. Concepts & Setup

• The Terminal vs. The Shell: Understanding that the Terminal is the window, and the Shell (Bash/Zsh) is the language running inside it.
• The Prompt: Decoding user@hostname:~$.
• Setup:
  • Mac/Linux: Open "Terminal".
  • Windows: Install WSL2 or Git Bash.

2. Navigation (Moving Around)

• pwd (Print Working Directory): Where am I right now?
• ls (List): Seeing files. Flags: ls -a (hidden files), ls -l (detailed view).
• cd (Change Directory): Moving folders.
  • cd foldername (Go in)
  • cd .. (Go back/up one level)
  • cd ~ (Go Home)
• The Tab Key: The most important key—auto-completing file names.

3. File Manipulation (Creating & Destroying)

• mkdir: Make directory (create a folder).
• touch: Create an empty file.
• cp: Copy files and folders (cp -r for folders).
• mv: Move files (also used to Rename files).
• rm: Remove (delete) files.
  • Warning: rm -rf deletes folders recursively and force—use with extreme caution!

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Module 2: The Power of Text (Intermediate)

4. Viewing Content

• cat: Dump the whole file content to screen.
• less: Scroll through large files page by page.
• head / tail: View just the top or bottom 10 lines of a file (tail -f is vital for watching live logs).

5. Editing Files

• Nano: The beginner-friendly editor.
  • nano filename -> Edit -> Ctrl+O (Save) -> Ctrl+X (Exit).
• Vim: The pro editor (optional but powerful).
  • Modes: Insert vs. Command.
  • :wq (Write and Quit).

6. Search & Filter (The "Pipeline")

• grep: Search for specific text inside files.
  • Example: grep "error" server.log
• The Pipe |: Taking the output of one command and feeding it into another.
  • Example: cat huge_file.txt | grep "password"

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Module 3: System Control (Intermediate)

7. Permissions & Users

• sudo (SuperUser Do): Running commands as Administrator/Root.
• File Permissions: Understanding Read (r), Write (w), Execute (x).
• chmod: Changing permissions (e.g., chmod +x script.sh to make a file executable).
• chown: Changing file ownership.

8. Process Management

• top / htop: The Task Manager of the terminal (CPU/RAM usage).
• ps: Snapshot of current processes.
• kill: Stopping a crashed program (e.g., kill -9 PID).

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Module 4: Streams & Redirection (Advanced)

9. Input/Output Redirection

• Standard Output (>): Save command results to a file.
  • ls > my_files.txt (Overwrites).
• Append (>>): Add results to the end of a file.
  • echo "Log entry" >> log.txt.
• Standard Error (2>): Redirecting only error messages.

10. Environment Variables

• Variables: Creating shortcuts (MY_NAME="Chidi").
• $PATH: How the computer finds programs to run.
• .bashrc / .zshrc: Configuration files to make aliases (permanent shortcuts) and customize your prompt.

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Module 5: Networking & Remote Access (Advanced)

11. The Internet from CLI

• ping: Check if a server is alive.
• curl: Transfer data from URLs (downloading files or testing APIs).
• wget: downloading files (simpler than curl for downloads).
• ifconfig / ip addr: Check your IP address.

12. SSH (Secure Shell)

• Remote Access: Logging into a remote server (ssh user@192.168.1.5).
• SSH Keys: Generating keys (ssh-keygen) to log in without passwords (essential for servers/GitHub).

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Module 6: Scripting & Automation (Pro)

13. Bash Scripting Basics

• The Shebang: #!/bin/bash.
• Variables & Math: Doing calculations.
• Loops: for loops to rename 1,000 files at once.
• Conditionals: if [ -f file.txt ]; then... (If file exists, do this).

14. Cron Jobs

• Automation: Scheduling scripts to run automatically (e.g., "Run backup.sh every day at 3 AM").
• crontab -e: Editing the schedule.

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Practical Projects

Project 1: The Organizer

Write a script that looks at your "Downloads" folder and automatically moves images to a "Pictures" folder and documents to a "Docs" folder.

Project 2: The Server Setup

Use ssh to connect to a cloud server (AWS/DigitalOcean), install a web server using apt-get install apache2, and change the default index.html using nano.

Project 3: Log Analyzer

Download a massive log file and use grep, awk, and | (pipes) to count exactly how many 404 errors occurred on a specific date.

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Essential Cheat Sheet Resources

• tldr: A better man page (Type tldr tar for practical examples instead of reading the manual).
• Explainshell.com: Type a complex command string, and it breaks down exactly what every flag does.