How to create a local lab environment using Vagrant and VirtualBox.

Instructions for creating a local lab environment using Vagrant and VirtualBox.

Note: Only use this lesson if you are using Windows as your operating system.  If you are not, proceed to the next lesson.

Learn how to install Vagrant and VirtualBox on Windows.

Note: Only use this lesson if you are using Mac with an Intel processor as your operating system.  If you are not, proceed to the next lesson.

Learn how to install Vagrant and VirtualBox on Mac.

Note: Only use this lesson if you are using CentOS or Red Hat Enterprise Linux as your operating system.  If you not, proceed to the next lesson.

Learn how to install Vagrant and VirtualBox on CentOS/RHEL.

Note: Only use this lesson if you are using Mac with an Apple Silicon processor as your operating system.  If you are not, proceed to the next lesson.

This lecture is only for those who are using computers with an Apple Silicon chip, such as the M1, M2, or later. If you are using a slightly older Mac computer using an Intel chip, skip this lesson. If you are not using Mac, you should also skip this lesson.

Note: This lesson is for everyone, no matter what operating system you are using.  (Windows, Mac, CentOS, RHEL)

If you encountered errors with Vagrant or Virtualbox, use the strategies in this lesson to fix those issues.

• Naming shell scripts and file extensions.
• Shell script file permissions and the chmod command.
• Shebangs
• Comments
• Variables
• Quoting – single vs double quotes.
• Shell Builtins including echo, type, and help.
• Displaying information to the screen with the echo shell builtin.
• Getting help on shell builtins by using the help builtin.
• Getting help on Linux commands by using the man command.
• The touch command.

Shell scripting concepts covered in this lesson:

• Pseudocode and pseudocoding.

• Special variables created by the shell including UID.

• How to store the output of a command in a variable with command substitution.

• The if statement.

• The id command.

• The whoami command.

• How to read help and man pages.

• Command options, order, and conventions.

• Conditionals, operators, and expressions.

• The [[, [, and, test shell builtins.

• The command separator.

• Exit statuses.

• Piping output to the less pager.

• Executing commands as root with the sudo command.

• Using the su command to switch users.

• Sanity and “idiot” checking.

Concepts covered in this lesson:

• Exit status conventions.

• Controlling the exit status of your shell script with the exit shell builtin.

• Shell Special Variables.

• Checking the return code or exit status of a command by examining the contents of the $? special variable.

• String test conditionals.

• DRY – Don’t Repeat Yourself.

Shell scripting concepts covered in this lesson:

• Getting input from the person executing the script using the read shell builtin.

• Introduction to standard input, standard output, and standard error.

• Creating accounts with the useradd command.

• Username conventions including length, case, and valid characters.

• Using the “-” or “-l” options to the su command to simulate a full login when switching users.

• Controlling the default account creation behaviors by editing the /etc/login.defs file.

• Using quotes to make a string that contains spaces behave as a single argument or item.

• Setting passwords with the passwd command interactively and programmatically.

• Using pipes to chain together multiple commands.

• Expiring accounts with the passwd command

The goal of this exercise is to create a shell script that adds users to the same Linux system as the script is executed on.

Shell scripting concepts covered in this lesson:

• Generating random data.

• How to automate the creation of a random password.

• The RANDOM shell builtin variable.

• Event designators (shell shortcuts).

• Display the current date and time using the date command in various formats.

• Unix time, POSIX time, and epoch time.

• Checksums and cryptographic hash functions.

• The sha1sum and sha256sum commands.

• Verifying downloads with checksums.

• The head, fold, and shuf commands.

• How to work through pipes. (Data munging, text manipulation, string manipulation.)

Shell Scripting concepts covered in this lesson:

• Positional parameters. ($0, $1, $2, $3, etc.)

• The difference between arguments and parameters.

• The which command.

• The command search path and the PATH shell variable.

• The hash shell builtin.

• The basename and dirname commands.

• Using command substitution within another command without assigning it to a variable first.

• The for loop.

• Special parameters including $#, $@, and $*.

Shell scripting concepts covered in this lesson:

• The while loop.

• The true shell builtin.

• The sleep command.

• Creating and breaking out of infinite loops.

• Send an interrupt signal by typing Ctrl-C.

• The shift shell builtin.

Concepts covered in this lesson:

• A deeper look at standard input, standard output, and standard error.
• File descriptors.
• Redirecting standard output to a file.
• Redirecting standard error to a file.
• Redirecting standard output and error to a file.
• Redirecting standard input from a file.
• Redirecting standard output and error through a pipe.
• Redirecting standard error to standard output.
• Redirecting standard output to standard error.
• Overwriting and appending output to a file.
• The null device.

Concepts covered in this lesson:

• A deeper look at standard input, standard output, and standard error.
• File descriptors.
• Redirecting standard output to a file.
• Redirecting standard error to a file.
• Redirecting standard output and error to a file.
• Redirecting standard input from a file.
• Redirecting standard output and error through a pipe.
• Redirecting standard error to standard output.
• Redirecting standard output to standard error.
• Overwriting and appending output to a file.
• The null device.

Learn how to use the "case" statement in your shell scripts.

Shell scripting concepts covered in this lesson:

• Reasons to create functions

• DRY vs WET programming concepts:

  • DRY: Don’t Repeat Yourself

  • WET: Write Everything Twice, We Enjoy Typing, Waste Everyone’s Time

• Defining functions

• Calling functions

• Sending messages to the syslog subsystem with the logger command.

• Where to place functions in your script.

• Variable scope and the local shell builtin.

• Passing in data to a function.

• Making variables read-only with the readonly shell builtin.

• How to backup files before you change them.

• Exit status of functions and the return command.

Shell scripting concepts covered in this lesson:

• How to accept and parse command line options.

• Why getopts is better than using an if or case statement.

• Performing mathematical calculations in your scripts.

• Using the basic calculator: bc.

Learn how to use "getops" in your shell scripts.

Shell scripting concepts covered in this lesson:

• Deleting users with the userdel command.

• Expiring and locking accounts with the chage command.

• How to find commands not in your PATH.

• Using the locate and find commands.

• Matching patterns with the grep command.

• Using the !! and !$ event designators to speed up your workflow at the command line.

• UID for system accounts and normal user accounts.

• Creating and restoring backups and archives with the tar command.

• How to compress files with gzip and uncompress them with gunzip.

• Why not to lock accounts with the passwd command or by using the nologin shell.

Demonstration of the userdel and id commands.

Demonstration of the tar, gzip, and gunzip commands.

Demonstration of using the chage, passwd, and usermod commands.

In this lesson, you will learn how to use the "cut" and "awk" commands.

Demonstration of using the cut and awk commands.

In this lesson, you will learn how to use the sort and uniq commands.

In this shell scripting exercise, you'll be parsing data using the awk, cut, sort, and uniq commands.

The goal of this exercise is to create a shell script that displays the number of failed login attempts by IP address and location.

In this lesson, you will learn how to use sed.

In this lesson you will learn how to create a small network of VMs that will simulate a company network.  You'll also learn how to configure ssh key authentication and execute commands on remote systems over ssh.

The goal of this exercise is to create a shell script that executes a given command on multiple servers.

This lesson is reminder of just some shell scripting concepts and techniques you've learned during this course.

In this lesson, you will learn:

• What shell scripts are.

• Why you should learn bash shell scripting.

• How shell scripts can be helpful to you.

• Shell scripting examples and use cases.

The contents of this lecture are so secret I'm not even allowed to describe it! Open, if you dare.