Mac Command Line: File System & Navigation

Becoming a Cap10 of the Command Line 🚀

Objective: Teach absolute beginners how to confidently navigate and manage files in macOS using the Terminal.

Launching the Terminal

First, find the Terminal app in /Applications/Utilities or via Spotlight. When it opens, you’ll see a prompt—your helm for issuing commands.

$ pwd
/Users/YourName   # Shows you're in your Home directory (home is shown as ~)

Think of your Home directory as the captain’s quarters—your personal space where your files and folders reside.

1. Understanding the Mac File System

Before diving into the Terminal, let’s get a clear picture of how macOS organizes files.

Key Concepts

• Root Directory (/): The top-level directory where the entire file system begins.
• User Folders: Located in /Users/, each user has a home directory (e.g., /Users/yourname).
• Applications: Stored in /Applications.
• System Directories: Folders such as /Library, /System, and /usr.
• Paths: Absolute paths start with / and uniquely define a file’s location.

Example Structure

/
 ├── Applications
 ├── Library
 ├── System
 ├── Users
 │   └── yourname
 │       ├── Documents
 │       ├── Downloads
 │       ├── Desktop
 │       └── Pictures
            

2. Navigating the File System

Use these commands to move around and manage files:

pwd

pwd

Prints your current working directory.

ls

ls

Lists files and folders. Try ls -l for details or ls -a to include hidden files.

cd

cd /Users/yourname/Documents  # Move to Documents
cd ..                         # Up one level
cd ~                          # Go to Home
cd -                          # Switch to last directory
            

Change directories.

mkdir

mkdir MyFolder

Create a new folder.

touch

touch myfile.txt

Create an empty file or update its timestamp.

rm

rm myfile.txt         # Delete a file
rm -r MyFolder        # Delete a directory and its contents
            

Remove files or folders (permanent—no trash!).

cp / mv

cp myfile.txt Backup/   # Copy file
mv myfile.txt Backup/   # Move or rename file
            

Copy or move files.

Editing Files from the Command Line

Edit text right in Terminal with built-in editors:

• nano: nano file.txt. Type text, then Ctrl+X, Y to save, Enter to exit.
• vim: vim file.txt. Press i to insert, edit text, then Esc, :wq to save and quit.

Troubleshooting on the Command Line

When apps go rogue:

• Find a process: ps aux | grep AppName.
• Kill it: kill PID or kill -9 PID. Or killall AppName.
• Monitor system: top (press q to quit).
• Watch logs: tail -f /var/log/system.log (stop with Ctrl+C).

Backing Up Files

A savvy captain keeps backups:

• cp file1.txt file2.txt: Simple copy.
• cp -R folder1 folder2: Copy folders recursively.

rsync -av ~/Documents/ ~/Documents_backup/

Archive with tar:

tar -czvf backup.tar.gz folder_to_backup/

Unpack: tar -xzvf backup.tar.gz.

3. Intermediate Command Line Power Moves

Elevate your command-line mastery:

• Chaining: cmd1 && cmd2 runs second only if first succeeds (e.g., mkdir test && cd test).
• Piping: cmd1 | cmd2 sends output of one into another (e.g., ls | grep ".txt").
• Repeat Last: Type !! to rerun previous command.
• History: Use history or ↑/↓ arrows to browse past commands.
• Manual Pages