As always, we have put our best efforts into making this book's content relevant to user requirements. All command lines covered in this book are based on CentOS 7. You can use any minor release of CentOS 7, from CentOS 7.1 through to CentOS 7.6. A CentOS 7 operating system is the only requirement for this book. For beginners, however, it is recommended installing and practicing CentOS 7 in any desktop virtualization application, such as VirtualBox, and VMWare Workstation.

For Windows and macOS users who would like to use a virtual environment, they can use VMWare or VirtualBox to set up CentOS 7 and execute the given command-line examples. For those who are new to Linux, the installation of CentOS 7 is covered in Chapter 1, Getting Started with CentOS 7.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "For example, DIRECTORY.. in mkdir usage means we have to insert the directory name we want to use with the mkdir command."

Any command-line input or output is written as follows:

$ mkdir -p -v demo/linux/centos

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Thereafter, the Begin Installation button will be enabled."