Introduction to Bash

Ninety percent of most magic merely consists of knowing one extra fact.

— Terry Pratchett

Computers do four basic things: store data, run programs, talk with each other, and interact with people. They do the interacting in many different ways, of which graphical user interfaces (GUIs) are the most widely used. The computer displays icons to show our files and programs, and we tell it to copy or run those by clicking with a mouse. GUIs are easy to learn but hard to automate, and don’t create a record of what we did.

In contrast, when we use a command-line interface (CLI) we communicate with the computer by typing commands,and the computer responds by displaying text. CLIs existed long before GUIs; they have survived because they are efficient, easy to automate, and automatically record what we have done.