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Terminal

This page from Ada Developers Academy

Learning Goals

  • Understand the terms Terminal, command line, commands
  • To know advantages of the command line and why programmers use it
  • To utilize the terminal to navigate, create, delete, and modify files and folders
  • To know and utilize terminal commands including: ls, cd, touch, mkdir, rm, mv, cp, man, pwd, whoami, cat

Activities

Notes

Folder Setup

When you are writing code, it is good to have a folder structure which is logical to you so you can quickly find the code and files you are looking for.

  1. Create a new folder called ada inside of your home directory (you can get to your home directory by typing cd ~) to store Ada-related folders and files; once the folder is created, switch into that new folder.

    cd ~
mkdir ada
cd ada

  2. Create a new folder called jumpstart inside of your new ada folder which will store all folders and files related to this Jumpstart work. Once the folder is created, switch into that new folder.

    mkdir jumpstart
cd jumpstart

  3. Verify that the folder structure was created appropriately by running the pwd command, the output should include your home directory and end with /ada/jumpstart.

The Command Line

As a programmer, you should become fluent with your computer's command line, in OSX that command line application is called Terminal. To get started find the application named 'Terminal', add it to your dock, and then open it.

Terminal Terminology

Term Definition
Console The system as a whole
Command Actions that we want our computer to do
Arguments Any additional information the command needs to execute; not all commands require arguments
Prompt This is the beginning of the command line, it usually provides some contextual information like who you are, where you are and other useful info; after the prompt is where you will be typing commands
Terminal The software application we use to interact with the console

How the command line works

The terminal operates in a repeating sequence of steps:

  1. Displays a single line of text (called a prompt)
  2. Accepts a single line of text (called a command)
  3. Executes or runs the command
  4. Displays output (not all commands display output)
  5. Repeats, starting from step 1

Parts of a command

Commands almost usually have 3 parts

[command] [options] [arguments]

Sample commands

Try out these commands first, and record what happened.

Command What happened?
ls -a .
man ls
q
pwd
cd ~
cd .
cd ..
cd -

Then use man to explore these commands. For example try man ls in terminal. You can exit with the q key.

Command Explanation
man Manual: Open the manual for a specific command ('q' to quit out of manual mode)
pwd Present Working Directory: Display the current location as a "path" (sequence of child directories separated by /) starting with the root directory /
ls List Directory: Display all of the child files and directories for the current location
cd Change Directory: Move to a different location, all further commands execute at that location
mkdir Make Directory: Create a new directory with the name specified
touch Create new file or update timestamp of existing file: If the file argument does not exist, create it as an empty
cp Copy file: Copy argument1 to argument2
mv Move file: Move argument1 to argument2 (removes argument1). This can be used for renaming.
rm Remove: Delete the file or folder passed to rm
less Print the contents of the argument to the screen with the ability to scroll through (also more; less is more, more or less)
cat Print the contents of the argument to the screen (no scrolling)
whoami Tells you what user you are currently working as

Practice making files and folders (i.e., directories)

Overview

Each practice example will first list the commands followed by the directory structure those commands created, followed by any notes relative to that example.

  1. market

    Commands
    $ mkdir market
$ cd market
$ mkdir fruits
$ mkdir vegetables
$ mkdir sweets
$ cd sweets
$ mkdir chocolate
$ cd ..
$ cd fruits
$ mkdir apples
$ mkdir lychee
$ cd ..
$ cd vegetables
$ mkdir carrots
$ mkdir celery
$ cd ..
$ cd sweets
$ mkdir caramels
$ pwd
    Directory structure
    market/
market/fruits/
market/fruits/apples/
market/fruits/lychee/
market/vegetables/
market/vegetables/carrots/
market/vegetables/celery/
market/sweets/
market/sweets/caramels/
market/sweets/chocolate/
    Notes
    • pwd at the end of the commands should result in market/sweets/

  2. lessons

    Commands
    $ mkdir lessons
$ cd lessons
$ mkdir 00-learning-style
$ mkdir 00-learning-style/assignments
$ mkdir 00-learning-style/notes
$ touch 00-learning-style/assignments/things-to-try.md
$ cd 00-learning-style/notes
$ touch learning-styles.md
$ cat learning-styles.md
$ cd ../..
    Directory structure
    lessons/
lessons/00-learning-style/
lessons/00-learning-style/assignments/
lessons/00-learning-style/assignments/things-to-try.md
lessons/00-learning-style/notes/
lessons/00-learning-style/notes/learning-styles.md

  3. songs

    Commands
    $ mkdir songs
$ touch songs/song1.md
$ touch songs/song2.md
$ touch songs/song10.md
$ rm songs/*1*
$ cd songs
$ cp song2.md song3.md
$ touch song4.md
$ mv song4.md song1.md
    Directory structure
    songs/
songs/song1.md
songs/song2.md
songs/song3.md

  4. card games

    Commands
    $ mkdir card-games
$ cd card-games
$ mkdir war
$ touch war/rules.md
$ touch war/game.txt
$ cp -r war hearts
$ cp -r war blackjack
$ pwd
$ ls
$ rm hearts/*.md
$ rm -r blackjack
    Directory structure
    card-games/
card-games/hearts/
card-games/hearts/game.txt
card-games/war/
card-games/war/game.txt
card-games/war/rules.md
    Notes
    • The flag -r means recursive
    • The wild card (*) deletes any files inside the hearts directory that end with '.md'; in this case there was only one file that met this criteria, but if there had been more files with '.md' at their end, they would also have been removed