Linux CLI Basics

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Head to Linux CLI Basics to complete this training lab for yourself or perform on your home lab below

Requirements:

 • Windows PC w/ Internet Connection

 • USB Flash Drive w/ at least 8GB Capacity

 • Second PC w/ at least 1GB of Ram

1. Create Ubuntu Live USB

The lab utilizes a well know Linux Distribution Ubuntu based on Debian to explore basic CLI commands

You can use the operating system without having to install it onto your hard drive with a live USB

Download Ubuntu Desktop LTS: Ubuntu Desktop LTS Official Download

Download Rufus: Rufus Official Download

Insert USB Flash Drive, run rufus.exe, select target drive, select Ubuntu Desktop TLS Iso, start:

Remove USB Flash Drive and Insert into second PC. Start PC and press hot boot key on startup:

Select UEFI USB Flash Boot. Allow Ubuntu to load and scroll to select the Try Ubuntu Without Installing:

Now allow your workstation a moment to load and you will be taken to the Ubuntu setup utility

Navigate through the language and keyboard layout options until you reach the 'Try Ubuntu' option:

Once selected you will be able to close the setup window and enter the Ubuntu Graphical Desktop

This live system won't save anything on your PC's hard drive, and we will complete the lab here

2. Navigation Commands

Command Line Interfaces are known as shells, the most common for Linux is Bourne Again Shell (BASH)

Here we will explore some basic BASH commands, right click the desktop and select Open in Terminal:

The Terminal program is the method of accessing the Linux Command Line Interface from a Desktop GUI

Already this window is giving us quite a bit of information about how the system is configured:

 • ubuntu - username of the account currently logged in

 • @ - separator character from the active username and active hostname

 • ubuntu - hostname of the currently logged in system

 • : - separator character from the identifiers and the directories

 • ~ - character representing the home directory of the current user, for this user it is /home/ubuntu in the filesystem

 • /Desktop - since we opened the terminal from the desktop, it opens in the /home/ubuntu/Desktop location

 • $ - user privilege level indicator, this means that ubuntu does not have administrator level privileges

Run the following command from the terminal to display the current user:

Resulting Output:

Run the following command from the terminal to display the current host:

Resulting Output:

Run the following command from the terminal to display the current directory:

Resulting Output:

pwd stands for print working directory, remember that ~ stands for home or /home/ubuntu in this case

Run the following command from the terminal to display the user and group IDs for your account:

Resulting Output:

Each user account is assigned to a unique user ID, all standard non-root users have IDs greater than 1000

Each user account also has membership to one or more groups which are collections of users based on permissions

Run the following command from the terminal to change and then check the current working directory:

Resulting Output:

cd stands for change directory followed by the target (..) in this case which represents the parent directory

So, this command essentially tells the terminal to go up one level within the current place in the filesystem

Run the following command from the terminal to explore the files inside the current working directory:

Resulting Output:

ls stands for list and will create exactly that with the files and directories within the current directory

Run the following command from the terminal for more information on the files and directories in ~/:

Resulting Output:

With the -l or long option you can see information about the creation date, object type and permissions

The object type and permissions information are displayed within that long string at the beginning, sequentially:

 • d - stands for directory, indicating the object is a directory

 • r - stands for read permissions enabled

 • w - stands for write permissions enabled

 • x - stands for execute permissions enabled

 • - - means that permission in the sequence is not enabled

There are 3 sets of read, write and execute permissions with a leading directory indicator. These are as follows:

1. Directory Indicator (d or -)

2. File or Folder Owner Permissions (rwx or --- or combination)

3. Group Permissions (rwx or --- or combination)

4. All Other Users Permissions (rwx or --- or combination)

Run the following command from the terminal for detailed information on ALL files and directories in ~/:

Resulting Output:

Notice there are many more objects displayed here, -a display all files and directories including hidden ones

Each of the hidden files and directories start with a (.) which hides them from the standard terminal view

These files are system files with important functions, so they are hidden to prevent users from accidentally altering

Run the following command from the terminal to go upwards by two directories in the filesystem:

Resulting Output:

Notice that our home directory (~) has been changed to (/). This represents the root directory of the filesystem

The root directory is the highest level in the filesystem which all other directories and files branch off from

Run the following command from the terminal to explore the standard filesystem structure for Linux:

Resulting Output:

All the configuration files, logs, system files and included software are contained within one of these directories

Run the following command from the terminal to return to the home directory:

3. File Creation Commands

We will now move on from simply viewing the files/directories and begin building them with various BASH commands

Run the following command from the terminal to create a new directory:

No output is given for this operation; confirm it was successful by checking for it in the filesystem:

Resulting Output:

Success! Now let's change our working directory to our newly created /testdir with the following:

Resulting Output:

Run the following command from the terminal to create three empty files within our newly created directory and confirm success:

Resulting Output:

Run the following command from the terminal to append a string statement to a file:

The (>>) above is an example of an output redirector which adds a value to the end of an existing file

BASH also contains other output redirectors such as (>) which overwrites an existing file with a value

Run the following command from the terminal to output the contents of our file:

Resulting Output:

Cat stands for concatenate and can be used to show the text contents of files along with other uses

Run the following command from the terminal to display the file type of our file:

Resulting Output:

The file command can be used to reveal a files type even if it is mislabeled or has no file extension

Unlike Windows, Linux does not strictly require file extensions, it is seen as a courtesy to other users

Run the following commands from the terminal to file our other files and display the results:

Resulting Output:

Run the following command from the terminal to create three more directories within our test directory:

4. File Manipulation Commands

Making new files is great and comes in handy for building applications and doing deep work on the Linux OS

But what if you'd like to alter the structure of the filesystem or locations of files, we will explore this

Run the following commands from the terminal to create a copy of our file in another location and confirm:

Resulting Output:

The -R options for the ls command stands for recursive and will list all files, directories, and files within those directories

Notice that there are two instances of file1.txt at this point within both the ~/testdir and ~/testdir/green directories

Run the following command from the terminal to remove the instance within the ~/testdir: directory

Notice how the terminal makes you type y to confirm. This is due to the presence of the -i option for rm

Always use this option, otherwise Linux will erase the file beyond recovery without confirming with you

There have been many IT professional careers ruined by deleting their employers' critical assets beyond recovery

There is no Recycling Bin in Linux and no undo button. Show respect for the rm command as it can break things.

Run the following command from the terminal to test that your removal was successful:

Resulting Output:

Run the following commands from the terminal to move a file without leaving a copy behind and test:

Resulting Output:

Run the following command from the terminal to rename our file and confirm:

Resulting Output:

Run the cat command from the terminal to confirm the contents of the renamed file have not changed:

Run the following command from the terminal to move and rename our file and confirm:

Resulting Output:

There are more options for viewing the contents of files in Linux than the Cat command

More is the original terminal scrolling command which allows you to scroll forward in text

Less is the modern way to scroll through text allowing forwards and backwards scrolling

Run the following command from the terminal to generate a large text file:

This command has several statements, let's break down the components of this command:

 • /dev/urandom - directory included in Linux used to create a large volume of random characters

 • base64 - encoding method used to ensure the random characters are printable

 • | - Output Redirector used to 'pipe' the output from the first statement as input for the following statement

 • head - Reduces the file size by removing the first 1MB of the file

 • > - Output Redirector used to overwrite the existing contents of the target file with the given input

Use the long and all options for the ls command to view information about the new file:

Run the following command from the terminal to view the contents of the large file:

Resulting Output:

Scroll down the text file using the Enter key and exit back to the prompt with the q key

Run the following command from the terminal to use the modern less viewing tool for the file:

With the less command you can use Enter or the down arrow to scroll down one line at a time

With less you can also use the spacebar for faster scrolling, which scrolls one page at a time

Unlike the more command you can also scroll up with the up arrow by line or the b key by page

When you are done exploring the illegible gibberish you can quit out of the less command with q

5. File Locator Commands

An important skill within Linux is the ability to locate files and their placement in the system

While we already know how to navigate the filesystem, it is vast and difficult to search completely

Run the following command from the terminal to locate files and directories named 'more':

Resulting Output:

The /dev/null is a black hole directory and the 2> redirects any error messages there for readability

Run the following command from the terminal to locate all files with the .txt file extension:

Resulting Output:

Run the following command from the terminal to find files containing a particular word or phrase:

Resulting Output:

The grep command will show the files' locations and the line of text where the phrase is found

Use the cd ~ command within the terminal window to return to the home directory for the next section

6. File-Parsing Techniques

Run the following commands to generate a file filled with unsorted strings:

Run the cat command to view your newly created unsorted list:

Run the following command from the terminal to sort the list and view the sorted contents:

Run the following command from the terminal to sort the list and remove duplicate entries:

Run the following command from the terminal to view the files word, line and character count:

Run the same command from the terminal with the -w option to view only the word count:

Run the following command from the terminal to count the number of lines in the unsorted file:

Congratulations, this marks the end of our lab discussing the basic Linux Command Line Interface

You are now prepared to navigate your way around these systems and alter the files and directories

Check out our future upcoming labs where we take these skills and this platform to the next level:

Linux Advanced CLI Commands

Cybrary Linux CLI Challenge Lab Solution