# Welcome to week 3; Linux commands via bash the bourne-again shell

Learning to communicate in a new way can be exciting.

Maybe you've learned a new language and can remember this feeling.

Perhaps a lot of us share this excitement with young children as they are expanding their vocabulary.

Others, including me, remember a sense of wonder when we first used a specialized language to communicate with their computer.

In this section, we'll continue to learn more about Linux and how to communicate with the OS through its shell.

You'll utilize the command line to communicate with the OS.

You'll learn how to input commands in the shell and learn about some of the core Linux commands that you'll use as a security analyst.

Specifically, this includes navigating and managing the file system.

You'll also focus on authenticating and authorizing users.

This means you'll be able to use a command line to add and delete users from the system and to control what they have access to.

Finally, there's always more to learn.

We'll cover accessing resources that support learning new Linux commands.

I remember when I first learned about the command line and was shocked at the capabilities it provided.

I didn't need to click through multiple screens to get tasks done.

Although it took some practice and time to get used to, it has been one of the biggest tools at my disposal.

After this section, you'll have a practical experience in an area important to the work of a security analyst: using Linux commands.

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Welcome back. Before we get into specific Linux commands, let's explore in more detail the basics of communicating with the OS through the shell.

Being able to utilize Linux commands is a foundational skill for all security professionals.

As a security analyst, you will work with server logs and you'll need to know how to navigate, manage and analyze files

remotely without a graphical user interface.

In addition, you'll need to know how to verify and configure users and group access.

You'll also need to give authorization and set file permissions.

That means that developing skills with the command line is essential for your work as a security analyst.

When we learned about the Linux architecture, we learned that the shell is one of the main components of an operating system.

We also learned that there are different shells.

In this section, we'll utilize the Bash shell.

Bash is the default shell in most Linux distributions.

For the most part, the key Linux commands that you'll be learning in this section are the same across shells.

Now that you know what shell you'll be using, let's go into how to write in Bash.

As we discussed in a previous section, communicating with your OS is like a conversation.

You type in commands, and the OS responds with an answer to your command.

A command is an instruction telling the computer to do something.

We'll try out a command in Bash.

Notice a dollar sign before the cursor.

This is your prompt to enter a new command.

Some commands might tell the computer to find something like a specific file.

Others might tell it to launch a program.

Or, it might be to output a specific string of text.

In the last section, when we discussed input and output, we explored how the echo command did this.

Let's input the echo command again.

You may notice that the command we just input is not complete.

If we're going to use the echo command to output a specific string of texts, we need to specify what the string of text is.

This is what arguments are for.

An argument is specific information needed by a command.

Some commands take multiple arguments.

So now let's complete the echo command with an argument.

We're learning some pretty technical stuff, so how about we output the words: "You are doing great!"

We'll add this argument, and then we'll press enter to get the output.

In this example, our argument was a string of text.

Arguments can provide other types of information as well.

One thing that is really important in Linux is that all commands and arguments are case sensitive.

This includes file and directory names.

Keep that in mind as you learn more about how to use Linux in your day-to-day tasks as a security analyst.

Okay, now that we've covered the basics of entering Linux commands and arguments through the Bash shell, we're ready to learn some specific commands.

This is exciting, so let's get to our next video!