In this recipe, you will learn about environment variables. When interacting with the system through a shell session, there are many pieces of information that the shell requires in order to determine the program access, the available resources, default configuration, system properties, and so on. Some of these settings are configured within the system as variables, and these settings are commonly called environment variables.
While hardcoding this information during installation is one way to go, it makes the entire system a monolith that cannot be reconfigured without what is known as nuking-and-paving. With environment variables, another layer of flexibility is introduced.
