Introduction to the Command Line

February 17th, 2017

Introduction

The command line interface (CLI) is an operating system application where you type in commands to run various tasks. As far as managing files and folders in the GUI, the CLI can do all that, but more. With the CLI we can install and update packages, edit a file and perform git related tasks. But before we can get into that, we’ll dive into the basics. In this lesson we’ll learn how to create, rename, delete, copy folders and files, as well as how to move around the filesystem.

What We’ll Need

To follow along in this lesson we will need a unix-based CLI. Why unix? At the time of this post, 2 out of 3 major operating systems run on unix (Mac and Linux), Windows is the only major OS that doesn’t run on unix, but no problemo, we can download Cmder. Cmder will give you the ability to use all the basic unix commands as well as a sleek and beautiful interface.

Opening The Command Line

Let’s open the CLI and start learning. For mac and linux users, you’ll open an application called terminal. If you’re on Windows, navigate to where you extracted cmder and open the Cmder executable. Once you open the CLI, it should look something like this for Windows users:

For Mac and Linux users, the text will look slightly different, it will show your computer’s name and username like so:

Mac

1MacbookName:~ username$

Linux

1username@MyLinux ~ $

Before we dive into running commands, lets familiarize ourselves with the different parts of the console.

• The initial text you see in the console is the path to your current working directory (Think of the current working directory as the equivalent of using your operating system’s file explorer to navigate into a specific folder), it should default to the currently logged in user’s home folder. For Mac and Linux, the ~ refers to the user’s home folder.

• The $ or λ followed by a cursor is where you start typing in your commands.

Our First Command

Now we’re ready to run commands. In the command line, type in the command: pwd and hit enter. Pwd stands for Print Working Directory. This command will print out your current working directory, useful when you’re not sure where you are in the filesystem.

Changing Directories

We can change our current working directory by using the cd command. By default you should be in your user home folder. Let’s go into the desktop folder.

1cd Desktop

If you run pwd now, you should notice the path changed to your desktop.

Going Up A Directory

Let’s say we want to go back to our home folder. We can go there with two periods ..

1cd ..

Alternatively, if you’re using Mac or Linux, we can achieve the same thing with the tilde character, remember that the tilde refers to the user’s home folder.

1cd ~

Going Up Multiple Directories

If you’re in two directories of where you want to be, you can navigate back up with two more periods prepended with a forward slash like so:

1cd ../..

If you’re three directories deep, add another backslash and two periods.

Going Down Multiple Directories

Essentially the same as going up, but instead of periods you’ll enter the name of the directory.

1cd firstDir/secondDir

Creating A Directory

We create directories with the mkdir command which stands for Make Directory. Let’s navigate to the desktop and create a directory called myWebsite.

1mkdir myWebsite

Creating Files

Change directories into myWebsite. We will create two files: index.html and main.css using the touch command.

1touch index.html main.css

Listing Files/Folders

To list files and folders, use the ls command, it stands for list.

1ls

You should see index.html and main.css listed out.

There are options you can append to the ls command to show extra information:

• [ls -l] Shows files and folders in long form along with permissions, file size, date that it was updated.

• [ls -a] Shows hidden files and folders (files and folders prefixed with a period).

• [ls -sh] Shows sizes of files and folders in human readable form.

Moving Files/Folders

Let’s reorganize and move the main.css file into a css folder. Create a css folder with the mkdir command, make sure your current working directory is myWebsite. Now we can move main.css with the mv command. We type mv followed by the file or folder we want to move and then follow that by the directory we want to move it to.

1mv main.css css

Cd into the css folder and use the ls command. You should see main.css relocated.

Renaming Files/Folders

Renaming and moving files/folders are very similar, they both use the mv command. Instead of specifying the folder you want to relocate to, you just makeup a name that you want to rename your file/folder. Let’s rename main.css to styles.css.

1mv main.css styles.css

Let’s run ls again to check that we did it correctly.

Deleting Files/Folders

To demonstrate deletion commands, create one new folder named test and one new file named custom.css. The command we will use is rm, it stands for remove and it will completely remove those files/folders from your computer. Let’s remove the custom.css file.

1rm custom.css

For the test folder we cant just use rm, it will result in an error, we must use the -r option which stands for recursively. So run:

1rm -r test

Double check that they’re gone using ls.

Copying Files/Folders

If you need to copy a file/folder, use the cp command. The syntax for that is cp folderToBeCopied newCopiedFolder. Let’s recreate the test folder and custom.css file that we deleted in the last section. Now let’s copy custom.css into a new file called custom2.css.

1cp custom.css custom2.css

With directories, we have to use the -r flag again, or else we’ll get an error. Let’s recreate the test folder into a folder named test2.

1cp test test2

Tips And Tricks

Clearing The Command Line

Nearing the end of the tutorial, you should notice the command line getting bloated with multiple lines of commands. You can clear the screen with the clear command to have a cleaner work area.

Cycling Through Commands

If ever you need to run a previous command you can use the up and down arrow keys to cycle through your previous commands.

Tab Auto-Completion

Whenever you’re running a task on a file or folder, instead of typing out the entire name, you can type part of the name then hit the tab key to autocomplete the name of the file or folder. For example lets say I’m in the myWebsite directory and I’m trying to get into the css folder, I would type cd c then hit tab to autocomplete the folder name. Highly useful when dealing with long file/folder names.

Conclusion

You should now feel comfortable using the command line, but you know what they say, practice makes perfect. Try using the command line instead of your Operating System’s GUI when creating and managing new projects.