pwd stands for Print Working Directory.

Some examples of directories in the Linux OS are /root, /boot, /bin, /opt, /run, /usr and /home.

The pwd command tells you the current folder where you are.

The default directory that you start out with is the home directory of the user who is logged in.

If you are the root user, your first directory would be /.

If you are a user named duke, then your home directory would be /home/duke

ls stands for list directory contents.

The ls command displays the names of files contained within a directory, as well as any requested, associated information.

Type ls and hit enter.

You should see several directories. One directory that is of interest that we will use for our learning is the cybershaolin directory.

But do you see a folder called secrets listed?

Hidden Files Files that are named with a dot (.) are hidden and not shown when you run the ls command. To see hidden files, we need to modify the ls command with some additional information. This additional information that is added to a Linux command is called an operand.

Type ls -a and press enter. The -a operands will list directory entries whose names begin with a dot (.) and are hidden. You should see now see a directory called .secrets.

Another operand that is often used with the ls command is the -l operand. The -l operand lists the file in long format. If the output is to a terminal, a total sum for all the file sizes is output on a line before the long listing.

Type ls -la and press enter. If the -l option is given, the following information is displayed for each file:

• file mode,
• number of links,
• owner name,
• group name,
• number of bytes in the file,
• abbreviated month,
• day-of-month file was last modified,
• hour file last modified,
• minute file last modified,
• and the pathname.

In addition, for each directory whose contents are displayed, the total number of 512-byte blocks used by the files in the directory is displayed on a line by itself, immediately before the information for the files in the directory.

cd stands for Change Directory.

Type cd .secrets and press enter. NOTE: Don't forget the dot (.) in front of the word secrets.

What you just did was you changed your directory to the .secrets directory. You can check by typing pwd and pressing enter.

You will now be in the /.secrets directory.

Now type ls and press enter and you will see that there is a text file in there called TopSecret.

cd and ../(DotDotSlash))
In order to go to the previous folder, you can use the shortform ../ (DotDotSlash) along with the cd command.
Since you are in the .secrets directory now, you can go to the previous directory using the cd ../ command.

Type cd ../ and you will find yourself back at the / directory. By typing ls -la, you will find that you are indeed in the / directory.

mkdir stands for Make Directory.
It is used to create a folder or directory so that you can be organized.

You can think of directories like a bookshelf. In the top shelf you may have your school books, the middle shelf may have some fiction books and the bottom shelf may contain some activity books. So also in a computer system, you can organize your files in directories.

Let us first create your directory. This directory will store your favorite game files in it.

Type mkdir myGames and press enter.

What happened? It may seem like nothing happened if your command ran successfully.

To see if your directory was created successfully, you can use the ls command which will list all the contents of the current directory where you are.

Type ls and press enter.

You should see aa directory/folder called myGames

rmdir stands for Remove directory.

Sometimes you may want to or have to delete a directory or folder. Say you created a temporary directory called tmp or a top secret folder called .secrets that will hold some secret files for a short amount of time. Once you no longer need those files or the directory, you can delete (or remove) it. This is where the rmdir command can help.

Now type cd myGames to enter into the myGames directory.

Once you are in the directory, if you type ls and press enter, you will find that the directory is empty. There are no files to list.

Let us create some files. One of the easiest ways to create some files is to use the touch command.

Type touch angrybirds.txt candycrush.txt fortnite.txt halo.txt borderlands.txt and press enter.

Type ls -l to make sure that those files were created.

Since you are in the myGames directory, type cd ../ to go to its parent directory (e.g., /) so that you can delete the myGames directory that you created.

Now type rmdir myGames and press enter.

Since you have the files that you created inside the directory, this command will fail and you will see something like
rmdir: failed to remove 'myGames/': Directory not empty

To delete directory that have content inside them, you can use the rm command along with the operands called -rf which will do a recursive flush.

Try rm -rf myGames and press enter.

The DeathStars of the rm Commands Never ever, never ever, never ever run the following command
rm -rf *.*
unless you absolutely know that you are in the directory from which you want to delete ALL folders and files.
The *.* here is a wildcard syntax to mean any files of any type.

In this course, you have learned about some common directory (or folder) commands in Linux.