We will occasionally need to take brief detours into Computer Science history to provide a bit of context. Computer Science moves quickly but is only around 100 years old, so we don’t need to dive deep.

Let’s rewind to 1980. My dad was in college and taking a class in Computer Science. The school only had one computer, a “mainframe”, that everyone had to share. My dad’s classwork had to be written down on paper and then punched out one line at a time on punch cards.

These punch cards were an existing mechanism used in textile manufacturing. A device called Jacquard’s loom used these cards to describe complex weaving instructions for intricate designs. Adapting punch cards for use in computers was a natural transition.

A punch card is a stiff piece of paper with a grid drawn on it. In programming, each column represents one letter based on which combination of holes you punched out. Whenever you wanted to move to a new line, you simply moved to a new punch card.

When you finished punching out your program, you stacked it on the “input” side of the computer. The computer would then run, pulling in your cards and processing them one by one. When it was done, it would punch out an answer on a new card and print it out to the “output” side.

This process was tedious, full of errors, and required waiting up to a day for your turn. It was unpleasant enough that my dad decided not to pursue programming.

But two solutions were coming. First, engineers adapted telegraph technology so that text could be sent from a typewriter, over a wire, to the computer instead of using punch cards. Second, programmers added support for multiple connections to the mainframe at the same time.

By combining these two ideas, they drastically improved the usability of computers. Instead of waiting in line to submit punch cards, users now sat down at one of the open “terminals” connected to the mainframe. The terminals had a keyboard for sending instructions to the computer and a screen for displaying the output of the instructions.

Around the same time, “graphical user interfaces”, or GUIs, were being developed for personal computers. The GUI abandoned the text-based interface of terminals in favor of the mouse and keyboard interface that you are probably more familiar with.

But programmers didn’t abandon their terminals for GUIs. Instead they simply built apps inside the GUIs that worked just like the terminals they were more familiar with. So now we have the best of both worlds.

The only problem is that the average user doesn’t know the terminal interface exists. It’s a powerful tool, but you are unlikely to discover it on your own. You are even less likely to understand what to do with it once you see it.

Finding the app seems like a good place to start.

Opening a Terminal

Modern usage of the word “terminal” generally refers to the app instead of the machines that were used to connect to mainframes. I will stick to that convention.

Note: I am going to do my best to avoid machine-specific instructions. But computer designers all put the terminal in slightly different places, so we’ll need to work to find them.

Linux

If you are on a Linux machine, you’ll have to dig around a bit. You might try looking for an app that has >_ in the icon. Alternatively, it will probably be named something that is close to “terminal” or “console”.

Mac

If you are on a Mac, you are looking for an application called “Terminal”. It is buried in the Applications folder, so it might be easiest to just do a search for it.

Windows

If you are on Windows, you will have to do a little more work.

Windows is different enough from Mac/Linux that it doesn’t have the terminal built into it. Luckily for us, they added a feature called “Windows Subsystem for Linux”, that lets you run an app that works just like a Linux computer.

Follow the official Microsoft documentation here: https://docs.microsoft.com/en-us/windows/wsl/install-win10

I would recommend installing the “Debian GNU/Linux” distro from the Microsoft Store because that will be closest to what I am using. However, you can choose whichever you would like.

Saying Hello

With a terminal window open, we can start with a basic introduction. First we ask the computer its name, by typing the command hostname and pressing enter.

$ hostname
fearow

Next, we can ask the computer what it knows about us,

$ whoami
patrick

The output of both of these commands will likely be different for every person.

You can also ask the computer for the date,

$ date
Sun 03 May 2020 05:22:28 PM CDT

Examples are not terribly helpful for understanding how you can use the terminal though. It’s a bit like trying to explain how you can use a pencil by writing down a few different words on paper.

Our main usage of the terminal is going to be to ask the computer prying questions so that we can understand how it works. Our first line of questioning will be about where it keeps all your data when it is turned off.