Quick Lesson: Introduction to Command Line and SSH Key Pair

Terminal Learning Objectives

Understand the basic functions of a command-line interface (CLI).
Learn essential CLI commands like cd, ls, pwd, mkdir, touch, mv, cp, rm, and less.
Get familiar with keyboard shortcuts for Terminal navigation.
Understand what an SSH key pair is and its applications.

Introduction to Command Line Interface (CLI)

Think of the command line as the backstage of your computer. It allows you to perform tasks without a graphical interface, directly communicating with the computer in text form. Imagine it as a text-based remote control for your computer.

Basic Commands

cd (Change Directory)
Navigate between directories.
```
cd Documents
```
ls (List)
Display the list of files and directories.
```
ls
```
pwd (Present Working Directory)
Show the current directory.
```
pwd
```
mkdir (Make Directory)
Create a new directory.
```
mkdir NewFolder
```

Check for Understanding

What commands would you use to navigate to a directory and then list its contents?

File Operations

touch (Create File)
Create an empty file.
```
touch newfile.txt
```
mv (Move)
Move or rename files and directories.
```
mv oldfile.txt newfile.txt
```
cp (Copy)
Copy files and directories.
```
cp file1.txt file1_copy.txt
```
rm (Remove)
Delete files.
```
rm unwantedfile.txt
```
less (View File)
View file content in a scrollable manner.
```
less file.txt
```

Keyboard Shortcuts

⌘ K: Clear the Terminal window
option arrow: Move cursor by word
Ctrl A: Go to beginning of line
Ctrl E: Go to end of line
Ctrl K: Kill line to end
Ctrl U: Kill line to beginning
Ctrl Y: Paste killed line
cd -: Toggle previous directory

Check for Understanding

What keyboard shortcut would you use to clear the terminal window?

SSH Key Pair

An SSH key pair consists of a public key and a private key. They're like a set of digital keys used to authenticate to servers securely. The public key is shared openly, but the private key must be kept secret. It's akin to a two-layer security system: anyone you want can have or see the front door to your house (public key), but only you should have the key (private key) to open it.

Generating an SSH Key Pair

ssh-keygen -t rsa -b 4096

Key Takeaways

The CLI is a text-based way to interact with your computer.
Basic commands like cd, ls, pwd, etc., help in file and directory management.
Keyboard shortcuts streamline Terminal navigation.
An SSH key pair is used for secure authentication and consists of a public and private key.

By mastering these basics, you'll be well on your way to becoming proficient in software engineering tasks that require command-line skills.