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Command Line Reference

Table of Contents

What is the command line?

How do I find it?

Common Commands

What is command line?

The command line is simply a means for using lines of text to communicate with programs on your computer. If you haven't used it much yet, you will become very familiar with it as a programmer.

How do I find it?

For everyone on a Mac, it is called Terminal, and you can find this in your applications, or by pressing the command + space buttons to open up Spotlight Search, then type Terminal.

For those of you using Ubuntu, you can press Ctrl + Alt + T, or navigate to it using Dash Home, which is similar to Spotlight Search on Mac.

A few things first

When working in the terminal, you will immediately see something like this:

austin@Austins-MacBook-Pro ~ $

First, you see your user's name. Then you see the name of the computer that is being used. Followed by this, there is a ~, which refers to the current directory. A tilde (~) refers to the Home directory, which is likely the folder that belongs to your user. As you move to different folders, that tilde will change to reflect the directory that you are currently in.

File Paths

You will see two types of file paths, absolute paths and relative paths.

An absolute path refers to the full path, from the root of the file system:

/Users/austin/Movies/Vertigo - Alfred Hitchcock.mp4

A relative path refers to where a file is relative to your current directory.

If you are looking for a file in your current folder, you will use ./folder-name, but if you want to get a file that is next to your current folder, you can move one level up with ../my-other-folder. It's not uncommon to see something like ../../../../some-folder.

Common Commands

sudo

sudo is a command that allows you to override any file permissions and perform actions as the superuser.

There is a reason some commands require sudo, at times you are performing operations that can be harmful. Don't use sudo without being sure about what you are doing.

man

First of all, man is a useful command to display manual pages. If you don't remember how a command works, just type man {command}.

man ls

LS(1)                     BSD General Commands Manual                    LS(1)

NAME
     ls -- list directory contents

SYNOPSIS
     ls [-ABCFGHLOPRSTUW@abcdefghiklmnopqrstuwx1] [file ...]

...

ls

Use ls to list all files and folders in your current directory.

austin@Austins-MacBook-Pro / $ ls
Applications			Users				data			installer.failurerequests	 tmp
Library				    Volumes			dev				net				                 usr
Network				    bin				  etc				private				             var
System				    cores				home			sbin

Note: You can also view hidden files with the option, -a.

cd

cd is an essential command for the terminal. cd will allow you to change directory, allowing you to move from one folder to another.

austin@Austins-MacBook-Pro ~ $ ls
Applications					 Dropbox							Public
Creative Cloud Files	 Library							Sites
Desktop							   Movies							  
Documents						   Music							
Downloads						   Pictures
austin@Austins-MacBook-Pro ~ $ cd Movies/
austin@Austins-MacBook-Pro Movies $ ls
Vertigo - Alfred Hitchcock.mp4

mkdir

mkdir is the command to make a new directory. Essentially it is your New Folder method in command line.

austin@Austins-MacBook-Pro Desktop $ ls

austin@Austins-MacBook-Pro Desktop $ mkdir my-new-folder
austin@Austins-MacBook-Pro Desktop $ ls
my-new-folder

mv

mv is the move command, allowing you to move a file or directory to another location. Below, I am moving new_file from my-new-folder to Desktop.

austin@Austins-MacBook-Pro my-new-folder $ ls
new_file
austin@Austins-MacBook-Pro my-new-folder $ mv new_file ../new_file
austin@Austins-MacBook-Pro my-new-folder $ cd ../
austin@Austins-MacBook-Pro Desktop $ ls
my-new-folder	new_file
austin@Austins-MacBook-Pro Desktop $

cp

cp is the copy command, and works very similarly to the mv command.

rm

rm is the remove command, allow you to delete files from the command line.

WARNING: Files deleted with rm will not go to the trash! They will be gone!

austin@Austins-MacBook-Pro Desktop $ ls
new_file
austin@Austins-MacBook-Pro Desktop $ rm new_file
austin@Austins-MacBook-Pro Desktop $ ls
austin@Austins-MacBook-Pro Desktop $

To remove a directory, you will need to use the -r option, which will remove all files and folders within that directory as well, or use rmdir instead

austin@Austins-MacBook-Pro ~ $ ls
my-new-folder
austin@Austins-MacBook-Pro ~ $ rm my-new-folder/
rm: my-new-folder/: is a directory
austin@Austins-MacBook-Pro ~ $ rm -r my-new-folder/
austin@Austins-MacBook-Pro ~ $ ls