Using shell variables

Variables are something that you probably understand, even if only conceptually. We are not talking about programming here; our everyday life is full of variables. Basically, a variable is something that holds a value and that can provide us with that value once we need it.

Getting ready

In everyday language, we could say an activity such as driving is full of variables. This means that the weather temperature, the amount of ambient light, the quality of the road surface, and many other things are going to change as you move along. Even though they are changing all the time, it is important that at any given point, we are able to see what the actual value of the weather is, what is the actual value of the temperature, how much light we have, and how the road behaves or how it is structured.

This is what we mean by variables and looking variables up.

As soon as we establish what the weather is actually like, it stops being a variable since it has...