Command Line Basics

Most of the command line tools you use as a developer (like Git, Node and npm) will **assume that you are in the root directory (i.e. top folder) of your project**. We will cover the main system commands that help up us navigate the file system.

Introduction to Command line - Important Concepts

Operating System: supports the core functionality of a computer, peripherals and applications. Examples are Mac OS, Windows, Linux

Unix and Linux:

  • Unix is a type of OS
  • Linux is an evolved GNU free version of Unix and runs on all Macos systems.

Application: A program set to perform specific tasks. It usually runs within an operating system.

Shell: A user interface for both OS and Applications. There are 2 types:

  • GUI – Graphical user interfaces – allows apps to run using peripherals and a designed interface e.g apple macOS and photoshop.
  • CLI – Command Line interface – text input/output interface/interloper for an OS or an application

Terminal: The terminal is a text interface for executing text-based programs.

Command Line: Is the literal line for entering CLI commands used to interact with the OS, apps or smaller script and tools.

Command line syntax: each syntax broken down into:

  • Commands
  • Options
  • Parameters

Note: The examples below start with a $. DO NOT include this when typing commands; it’s there to represent the command prompt.

pwd - Present working directory

Use the `pwd` command to see where you are when you open the terminal. 
$ pwd

The starting directory for most systems will be your home directory.

/Users/YOUR-ACCOUNT-NAME

Your goal is to navigate to the root of your project. For example:

/Users/YOUR-ACCOUNT-NAME/Documents/projects/portfolio

ls - List directory contents

List the contents of your current directory with the ls command: 
$ ls

The -l flag lists extra information about the contents:

$ ls -l

Add the -a to list hidden files:

$ ls -a

You can also combine multiple options with a single flag. To list extra information and also all hidden files:

$ ls -la

mkdir Creates new directory/folder

$ mkdir media

mkdir takes in a directory name as an argument, and then creates a new directory in the current working directory. Here we used mkdir to create a new directory named media/.

cd - Change directory

Use the `cd` command to switch to another directory. Assuming you are currently in your home folder, you can move to your downloads folder with: 
$ cd Downloads

OR, move there from anywhere on the system with an absolute path (replace username with your login handle):

$ cd /Users/username/Downloads

Move up one directory:

$ cd ..

OR move up many directories

$ cd ../../..

Move multiple directories “downstream”:

$ cd some/path/relative/to/your/location

Combine ../ with a relative path for more flexibility. To move to a directory that adjacent to your _present working directory`:

$ cd ../adjacent-directory-name

If you get lost you can always move to your home directory:

$ cd

Quality of Life Tips

  • The tab key auto-completes file names and directories.
  • Use the Up Arrow to browse through the history of last used commands.
    • Pro tip: type your command first and the Up Arrow will filter the history!

Extra Reading