Welcome to the Linux Foundation Certified IT Associate practice course. We abbreviate this certification with LFCA, and the certification is provided from the Linux Foundation through organizations. The goal essentially of this certification is to show the fundamental knowledge around Linux administration. This practice course is outlined in six different modules. The first is going to cover Linux fundamentals, we're then going to move into system administration. We'll follow that up with Cloud computing fundamentals, then security fundamentals, DevOps fundamentals, and we'll conclude with supporting applications and developers. Let's start off with the Linux fundamentals domain. This is a section on the exam, and these are the domain competencies you need to understand for that exam. Let's start off with; what is Linux? Linux is a family of open-source Unix-like operating systems that are based on the Linux kernel that was provided by Linus Torvalds. Linux is typically packaged in what we call a Linux distribution. There are hundreds of distributions, we've talked about them more in previous courses. But things like Debian or Ubuntu or Red Hat or Fedora, these are some of the distributions, but there's many of them out there. Linux was originally developed for personal computers based on the Intel X86 architecture but has since then been ported to more platforms than any other operating system, that's amazing when you think about it. You'll find Android phones, Android is Linux-based. This is the smartphone operating system that's used more than any other smartphone operating system on phones. Chromebooks which are the popular lightweight computing devices from Google run Linux kernel in the Chrome OS. Linux also runs on many embedded systems, embedded systems are computers that we have inside like our air conditioners, our refrigerators, our automobiles, our aircraft, that sort of thing. Ninety percent of all Cloud infrastructure is powered by Linux. How is Linux different? It has many advantages over other systems including it's open-source, and we'll talk more about that in a later module. But essentially open-source means that you're able to contribute back to the environment. It's community supportive. It has support for older hardwares, so you don't have to throw away your old system when you upgrade to a newer version of Linux. A big characteristic, and again we'll talk about this later on in a different module, but the GPL. This stands for General Public License, and this is the kernel in Linux, and a lot of the code from the GNU project which are the system commands or file commands, are licensed under the GNU GPL. This allows you to freely copy, change, and distribute derivatives of these products. You cannot impose any restrictions on further distribution. You also have to make your source code available if you give someone a compiled version of this code. Let's just drill into some of the file and system commands. PWD is going to return the path of the current working directory. You'll see an example here on the screenshot in front of you where I'm just showing my path as home/aspen. Now we'll have a lab where you'll play around with these commands and I'll demonstrate in the next video a lot of these commands. CD stands for change directory, and there's several different ways we can use a cd.. to move one directory up. You can go cd with nothing else to go to your home folder, or cd- to move to your previous directory. Ls will view the contents of your directory. So ls -R will list all the files in the subdirectories as well. Ls -a will show hidden files. Ls -al will list the files and directories with detailed information like the permissions, the size, the owner, that sort of thing. The cat command will list the contents of a file on to standard output. An example here would be cat, and we redirect standard output with a greater than symbol to a filename, it's going to create a new filename. Or we can cat two different files, so cat file1, file2 and redirect that to file3, it's going to join two files and store them as a new file. The cp command is going to copy files. The mb is going to move or rename files. The mkdir is going to create a new directory within the current directory. Lastly, rm is going to remove files and directories. There's a -r to remove the directories and all the files inside. Now, we're going to look at all these commands and run through them in the lab to make sure you're comfortable. You need to be comfortable with all the commands that I just talked about for the exam. You also need to think about file systems. Before you can assign a drive partition to mount a filesystem, you have to format it with a filesystem. Each operating system utilizes its own filesystem type for storing data on drives. Linux not only supports several of its own filesystem types, it also supports filesystem types from other operating systems. But the exam is really going to focus on Linux filesystems. Some interesting ones here is the first one, btrfs. This is a newer, high-performance filesystem that supports files up to 16 exbibytes. It also does a great job of compressing data. You can compress data with lots of these filesystems, but btrfs is probably the best one to do. If you want to encrypt files you can do eCryptfs, which is an enterprise cryptographic filesystem. You have ext3 and ext4, they both will compress, but ext4 is a little bit newer, it allows larger file sizes. Network commands, again we'll talk about this a little bit more later on in a future module. But the NMCLI is a command-line, that's the standard way of showing current network connections, or adding new connections, or modifying connections, or deleting connections. A little review here. There are hundreds of Linux distributions out there. Some require you to pay money and others are free, but they're all licensed under open-source or GPL, which means you're able to modify that code and give it to other people. The distribution may include other content that's not open-source such as branding, that sort of thing. I'll see you in the next module.