# Welcome to week 2; introduction to linux

Welcome back! We have another important topic to explore.  
Previously, you learned aboutoperating systems and user interfaces.  
You learned how operating systems work and how resources are allocated in computers.  
We also reviewed several common operating systems.  
You may already have a favorite operating system.  
It's common to hear that people are fans of one over another, but in the security world,  
Linux is commonly used.  
In this section, you'll be learning more about the Linux operating system and how  
it's used in everyday tasks in security.  
First, you'll learn about the architecture of Linux.  
After this, we'll compare the different distributions of Linux that are available.  
Lastly, you'll explore the shell, a key Linux component that allows you to communicate with the system.  
I remember when I first learned about the Linux OS, and I'm really happy to explore it with you now.

# Introduction to Linux

<div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-you-might-have-seen-"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item"><div class="phrases"><div aria-label="toggle video from You might have seen or heard the name Linux in the past." class="rc-Phrase css-ugczj4" data-cue="1" data-cue-index="0" role="button"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">You might have seen or heard the name Linux in the past. </span></div><div aria-label="toggle video from But did you know Linux is the most-used operating system in security today?" class="rc-Phrase css-ugczj4" data-cue="2" data-cue-index="1" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">But did you know Linux is the most-used operating system in security today? </span></div><div aria-label="toggle video from current lecture segment: Let's start by taking a look at Linux and how it's used in security." class="rc-Phrase active css-ugczj4" data-cue="3" data-cue-index="2" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Let's start by taking a look at Linux and how it's used in security. </span></div></div></div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item">  
</div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-linux-is-an-open-sou"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item"><div class="phrases"><div aria-label="toggle video from Linux is an open-source operating system." class="rc-Phrase css-ugczj4" data-cue="4" data-cue-index="3" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Linux is an open-source operating system. </span></div><div aria-label="toggle video from It was created in two parts." class="rc-Phrase css-ugczj4" data-cue="5" data-cue-index="4" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">It was created in two parts. </span></div><div aria-label="toggle video from In the early 1990s, two different people were working separately on projects to" class="rc-Phrase css-ugczj4" data-cue="6" data-cue-index="5" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">In the early 1990s, two different people were working separately on projects to </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">improve computer engineering. </span></div><div aria-label="toggle video from The first person was Linus Torvalds." class="rc-Phrase css-ugczj4" data-cue="8" data-cue-index="7" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">The first person was Linus Torvalds. </span></div><div aria-label="toggle video from At the time, the UNIX operating system was already in use." class="rc-Phrase css-ugczj4" data-cue="9" data-cue-index="8" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">At the time, the UNIX operating system was already in use. </span></div><div aria-label="toggle video from He wanted to improve it and make it open source and accessible to anyone." class="rc-Phrase css-ugczj4" data-cue="10" data-cue-index="9" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">He wanted to improve it and make it open source and accessible to anyone. </span></div><div aria-label="toggle video from What was revolutionary was his introduction of the Linux kernel." class="rc-Phrase css-ugczj4" data-cue="11" data-cue-index="10" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">What was revolutionary was his introduction of the Linux kernel. </span></div><div aria-label="toggle video from We're going to learn what the kernel does later." class="rc-Phrase css-ugczj4" data-cue="12" data-cue-index="11" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">We're going to learn what the kernel does later. </span></div></div></div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk--1"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item">  
</div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-around-the-same-time"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item"><div class="phrases"><div aria-label="toggle video from Around the same time, Richard Stallman started working on GNU." class="rc-Phrase css-ugczj4" data-cue="13" data-cue-index="12" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Around the same time, Richard Stallman started working on GNU. </span></div><div aria-label="toggle video from GNU was also an operating system based on UNIX." class="rc-Phrase css-ugczj4" data-cue="14" data-cue-index="13" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">GNU was also an operating system based on UNIX. </span></div><div aria-label="toggle video from Stallman shared Torvalds' goal of creating software that was free and" class="rc-Phrase css-ugczj4" data-cue="15" data-cue-index="14" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Stallman shared Torvalds' goal of creating software that was free and </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">open to anyone. </span></div><div aria-label="toggle video from After working on GNU for a few years, the missing element for" class="rc-Phrase css-ugczj4" data-cue="17" data-cue-index="16" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">After working on GNU for a few years, the missing element for </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">the software was a kernel. </span></div><div aria-label="toggle video from Together, Torvalds' and Stallman’s innovations made what is commonly referred" class="rc-Phrase css-ugczj4" data-cue="19" data-cue-index="18" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Together, Torvalds' and Stallman’s innovations made what is commonly referred </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">to as Linux. </span></div></div></div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk--2"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item">  
</div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-now-that-you%27ve-lear"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item"><div class="phrases"><div aria-label="toggle video from Now that you've learned the history behind Linux," class="rc-Phrase css-ugczj4" data-cue="21" data-cue-index="20" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Now that you've learned the history behind Linux, </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">let's take a look at what makes Linux unique. </span></div><div aria-label="toggle video from As mentioned before, Linux is open source," class="rc-Phrase css-ugczj4" data-cue="23" data-cue-index="22" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">As mentioned before, Linux is open source, </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">meaning anyone can have access to the operating system and the source code. </span></div><div aria-label="toggle video from Linux and many of the programs that come with Linux are licensed under the terms" class="rc-Phrase css-ugczj4" data-cue="25" data-cue-index="24" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Linux and many of the programs that come with Linux are licensed under the terms </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">of the GNU Public License, which allow you to use, share, and modify them freely. </span></div><div aria-label="toggle video from Thanks to Linux's open-source philosophy as well as a strong feature set," class="rc-Phrase css-ugczj4" data-cue="27" data-cue-index="26" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Thanks to Linux's open-source philosophy as well as a strong feature set, </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">an entire community of developers has adopted this operating system. </span></div><div aria-label="toggle video from These developers are able to collaborate on projects and" class="rc-Phrase css-ugczj4" data-cue="29" data-cue-index="28" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">These developers are able to collaborate on projects and </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">advance computing together. </span></div><div aria-label="toggle video from As a security analyst," class="rc-Phrase css-ugczj4" data-cue="31" data-cue-index="30" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">As a security analyst, </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">you'll discover that Linux is used at different organizations. </span></div><div aria-label="toggle video from More specifically, Linux is used in many security programs." class="rc-Phrase css-ugczj4" data-cue="33" data-cue-index="32" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">More specifically, Linux is used in many security programs. </span></div><div aria-label="toggle video from Another unique feature about Linux is the different distributions, or" class="rc-Phrase css-ugczj4" data-cue="34" data-cue-index="33" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Another unique feature about Linux is the different distributions, or </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">varieties, that have been developed. </span></div><div aria-label="toggle video from Because of the large community contribution," class="rc-Phrase css-ugczj4" data-cue="36" data-cue-index="35" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Because of the large community contribution, </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">there are over 600 distributions of Linux. </span></div><div aria-label="toggle video from Later you'll learn more about distributions." class="rc-Phrase css-ugczj4" data-cue="38" data-cue-index="37" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Later you'll learn more about distributions. </span></div></div></div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk--3"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item">  
</div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk-finally%2C-let%27s-take-"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item"><div class="phrases"><div aria-label="toggle video from Finally, let's take a look at how you would use Linux in an entry-level" class="rc-Phrase css-ugczj4" data-cue="39" data-cue-index="38" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Finally, let's take a look at how you would use Linux in an entry-level </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">security position. </span></div><div aria-label="toggle video from As a security analyst, you'll use many tools and programs in everyday work." class="rc-Phrase css-ugczj4" data-cue="41" data-cue-index="40" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">As a security analyst, you'll use many tools and programs in everyday work. </span></div><div aria-label="toggle video from As a security analyst, you'll use many tools and programs in everyday work." class="rc-Phrase css-ugczj4" data-cue="41" data-cue-index="40" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">You might examine different types of logs to identify what's going on in the system. </span></div><div aria-label="toggle video from For example," class="rc-Phrase css-ugczj4" data-cue="43" data-cue-index="42" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">For example, </span></div><div aria-label="toggle video from you might find yourself looking at an error log when investigating an issue." class="rc-Phrase css-ugczj4" data-cue="44" data-cue-index="43" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">you might find yourself looking at an error log when investigating an issue. </span></div><div aria-label="toggle video from Another place where you will use Linux is to verify access and" class="rc-Phrase css-ugczj4" data-cue="45" data-cue-index="44" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Another place where you will use Linux is to verify access and </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">authorization in an identity and access management system. </span></div><div aria-label="toggle video from In security, managing access is key in order to ensure a secure system." class="rc-Phrase css-ugczj4" data-cue="47" data-cue-index="46" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">In security, managing access is key in order to ensure a secure system. </span></div><div aria-label="toggle video from We'll take a closer look into access and authorization later." class="rc-Phrase css-ugczj4" data-cue="48" data-cue-index="47" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">We'll take a closer look into access and authorization later. </span></div></div></div></div><div class="cds-1665 css-xl5mb3 cds-1666" id="bkmrk--4"><div class="cds-1665 rc-Paragraph css-1lz62pp cds-1667 cds-grid-item">  
</div></div><div class="phrases" id="bkmrk-finally%2C-as-an-analy"><div aria-label="toggle video from Finally, as an analyst, you might find yourself working" class="rc-Phrase css-ugczj4" data-cue="49" data-cue-index="48" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Finally, as an analyst, you might find yourself working </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">with specific distributions designed for a particular task. </span></div><div aria-label="toggle video from For example, you might use a distribution that has a digital forensic tool" class="rc-Phrase css-ugczj4" data-cue="51" data-cue-index="50" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">For example, you might use a distribution that has a digital forensic tool </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">to investigate what happened in an event alert. </span></div><div aria-label="toggle video from You might also use a distribution that's for" class="rc-Phrase css-ugczj4" data-cue="53" data-cue-index="52" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">You might also use a distribution that's for </span><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">pen testing in offensive security to look for vulnerabilities in the system. </span></div><div aria-label="toggle video from Distributions are created to fit the needs of their users." class="rc-Phrase css-ugczj4" data-cue="55" data-cue-index="54" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">Distributions are created to fit the needs of their users. </span></div><div aria-label="toggle video from I hope you're excited to learn more about Linux." class="rc-Phrase css-ugczj4" data-cue="56" data-cue-index="55" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">I hope you're excited to learn more about Linux. </span></div><div aria-label="toggle video from This will be a very useful skill in the security field." class="rc-Phrase css-ugczj4" data-cue="57" data-cue-index="56" role="button" tabindex="0"><span aria-hidden="true" class="cds-1801 css-80vnnb cds-1803">This will be a very useful skill in the security field. </span></div></div>