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In this video,

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we're going to discuss some basic Bash commands

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so you can start to use the shell

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to perform some basic functions here.

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There are several commands

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that are important for accomplishing basic tasks

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within the Linux operating system.

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Many of these commands are going to be covered

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in greater depth throughout this course

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but a few will be discussed now

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to provide you some basic command vocabulary

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and to get you started with some more hands on practice

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within the Bash shell.

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It's also important to take note

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that both of the commands

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and the syntax are really important to get correctly

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when you're typing them in.

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This is going to be important

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to get the proper way of entering in the command,

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as well as the right options to use

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so that that command's output

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creates the expected outcome you're trying to achieve.

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The first command I want to cover is known as echo.

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The echo command repeats input

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back to the user on the screen.

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This is commonly used to send information to the user

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when you're running a script

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or a long series of commands from a given file.

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For example, if I type in echo "Good morning!",

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this is going to return good morning

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inside of the command line interface.

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The next command we have is the list command.

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This is known as ls.

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The ls command lists the contents of a directory

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and can be given options to view their permissions,

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hidden files and other information.

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For example, I like to use the ls -a command

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because this lists the directory's contents,

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including all the hidden files.

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The next one we have

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is known as the present working directory.

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Now the pwd command is going to display

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the current working directory that you're in

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while the cd command is the change directory command.

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And you use this to change your current working directory

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to another directory.

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For example, if I typed in cd /etc,

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this is going to change my current working directory

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over to the /etc directory.

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The next command we have is the copy command.

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The copy command is written as cp.

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The cp command is going to copy a file

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or directory to another location.

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So if you type in cp file1 file2,

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this will copy the contents of file1 to file2.

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Now if I wanted to make a new directory,

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I can use the make directory command or mkdir.

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The mkdir command will create a new directory

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of the given name that I specify.

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So if I type in mkdir newdir,

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it's going to create a new directory called newdir.

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The next command we have is the clear command.

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The clear command is going to be used

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to clear the command line interface of all the text

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and bring you back to the top of the screen.

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I think about this like a magic eraser.

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It's going to clean everything off of my screen, instantly.

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This is really useful when you're starting a new task

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and you want to eliminate any distracting information

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from your past command entries.

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Another thing we want to talk about

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is how we can look at text files

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because Linux system configurations are usually held

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within these text files.

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So if you want to be able to view the contents of those files,

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you need to use the cat command.

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The cat command or CAT is going to be used

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to view the contents of a file

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without the option to edit that file.

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It's basically just a way to view it.

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An example of this would be typing in cat file1

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and that's going to display the contents of file1

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on the screen.

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Now, the problem with this

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is that if file1 is really long,

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it's going to scroll off the screen

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and you're not going to be able to see it all.

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So there's another command known as less.

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The less command is used to view the contents of a file

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when those contents won't fit entirely on one screen.

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So by using less, it's going to break the content

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into output pages, one screen at a time

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that you can scroll through using the CLI.

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An example of using this would be less file1.

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And this will break the contents of file1

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into multiple pages

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when its contents are going to be put on the screen

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one page at a time,

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so I can see it all as it goes.

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Then I can press page up or page down

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to scroll through the entire screen's worth of content,

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one screen at a time and when I'm done,

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I'll press Q to exit the less command

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and go back to the command prompt.

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Now, just as you need to view

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the contents of the text files,

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there's going to be times

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where you need to edit those text files too

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and this is where a text editor comes into play.

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Now in Linux, there are lots of different text editors

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but the three big ones are vi(m), nano and gedit.

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Vi(m) is the default text editor for Linux

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but it's pretty complicated to use for most people.

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Another one you can use is known as nano.

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It's a simple user friendly text editor,

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and personally, it's the one I use myself most of the time.

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Now, nano is not pre-installed

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on all distributions though, like vi(m) is,

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so if you don't have nano and you want to use it,

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you're going to have to install it before you can use it.

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We'll talk about how to install programs

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in a future lesson though.

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So don't worry too much about that right now.

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Now another one we can use is known as gedit.

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Gedit is a graphical user interface text editor.

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So it's really easy to use

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but it does require a desktop graphical environment.

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Something like Gnome or KDE

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that's installed on your Linux system

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if you want to use gedit.

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Now, another thing we need to talk about

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is how are you going to reboot or shut down your system?

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Periodically, it may become necessary

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to reboot or shut down your system

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and there's several different commands to accomplish this.

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The most common one that's used though,

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is the shutdown command.

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If you type shutdown -h now,

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this'll shut down the system immediately.

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The -h stands for halting it with no time delay

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and then it's going to halt the system

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and then shut it down all the way to powered off state.

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Now, if on the other hand,

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you just need to reboot your system,

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you can do that by typing shutdown -r now

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which says shut down and reboot the system

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and bring it right back up right now.

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And this will just reboot the system for you,

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instead of stopping it and powering it off.

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Now in Linux, the user with the administration credentials

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is known as our super user or our root user.

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It's generally considered a really bad security practice

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for you to log into the system as the super user.

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So instead, you should log in

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with a non-privileged account for your daily tasks,

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something like a standard user account.

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However, there's going to be times

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where you need to be a super user

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to perform some kind of administrative task.

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And so we can use the substitute user or SU command.

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If you use the su command,

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it's going to allow you to switch your user credentials

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and by using su, you can now switch your credentials

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to that of the root user.

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The system then, will prompt you

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to enter in the root user's password

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for authorization purposes

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and if you get it right,

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you're going to be logged in as root

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and be able to perform tasks

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that were previously unavailable to you

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because you were only a regular user.

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But now, you're the super user.

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So think about this like you would on a Window system

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of switching to an administrator user account

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or doing a run as administrator.

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Now, one of the great things about the Bash shell

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is that it keeps a history file

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of all the commands you've ever entered.

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You can reference this file and repeat previous commands

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without having to retype all of them.

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And therefore, you can increase your efficiency

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and your consistency of the commands you're entering.

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For example, if you type the history command,

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you're going to see the output

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of the most recently entered commands in the list format

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and you can use the up and down keys

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to cycle through that command history.

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When you press enter, it will reissue the desired command

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from the history to the command line interface.

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Another thing that Bash shell supports

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is something known as tab completion.

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This enables a user to type in enough of a command,

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a file name, or a directory name to be unique

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and then press tab to automatically fill in

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the remainder of that entry.

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This feature can reduce typographical errors

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and really speeds up the process of entering in commands.

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For example, if I type his and press tab,

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that'll automatically fill in the rest of the command

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and it'll become history.

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This can be a great time saver

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when you're working on the Linux system

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or as a cybersecurity analyst in the future.