The Command Line

• the TERMINAL is a window into which you can talk directly to your computer
  • aka console or command line or command prompt
• very low level, based entirely on text and typing, not graphics and mousing
• when you type into the terminal, you are always issuing COMMANDS
  • which is why it's called the Command Line

Opening the Terminal

• to open your terminal:
  • Mac OS: launch the "Terminal" application
  • Windows with Railsinstaller: launch "Command Prompt with Ruby and Rails"
• Important: make your terminal as tall as possible

Directories

• a DIRECTORY is a location on your hard disk
  • also called a FOLDER
• directories can contain FILES
• directories can also contain other directories (called SUBDIRECTORIES)

The Current Directory

• inside the Terminal, you are always inside a directory
• it is very important not to get lost! You must try to remember which directory you are in.
• If you forget, you can use a special command called pwd

Home Directory

• when you open the Terminal you are in your HOME DIRECTORY
• usually you don't want to store files directly in here

Listing Directory Contents

• when you type ls ("list") it shows the contents of the current directory

Making a directory

• when you type mkdir ("make dir") it creates a new SUBDIRECTORY inside the current directory

  mkdir code
  

Changing directories

• cd ("change dir") moves you into a different directory
• For example, cd code would move you into a directory named code
• If you ever get lost, type cd all on its own and press the return key. This will send you back to your home directory.

Basic Command Line Glossary

• pwd ("print working dir") -- shows the name of the current directory
• ls ("list") -- shows the contents of the current directory
• mkdir ("make dir") -- creates a new SUBDIRECTORY inside the current directory
• cd ("change dir") -- move into a different directory
• touch whatever.txt -- creates an empty file named whatever.txt inside the current directory

LAB: make a subdirectory and then enter it

1. open Terminal
2. make a new subdirectory using mkdir code
3. change into that directory using cd code
4. list its contents using ls (and note that it's empty)

Files

• a file is a place on disk for storing stuff
• "stuff" here could be anything at all
  • documents, pictures, sounds, applications...
• every file lives inside a directory

Text Editor

• a text editor is a program that edits a text file
• a text editor is like a word processor
• but a text editor is not a word processor
• You probably have Atom
  • or another text editor
  • but NOT TextEdit or Notepad or Microsoft Word

Source File

• source code is the essence of a program
• source files are text files that contain source code

• to RUN a program you type ruby and then the name of the source file

• The Recipe Metaphor

  • source file = recipe
  • running = cooking

LAB: Hello, World

1. Make sure you are in your code subdirectory using pwd
2. Create a file named hello.rb using touch hello.rb
3. Open hello.rb in your favorite text editor

4. Inside this file, put the following source code:

   puts "Hello, World!"
   

5. Save the file

6. Go back to the terminal

7. Run this file using ruby hello.rb

What happens? Is this what you expected?