As computer scientists, we know that computers are great at aiding in repetitive tasks. However, far too often, we forget that this applies just as much to our use of the computer as it does to the computations we want our programs to perform. We have a vast range of tools available at our fingertips that enable us to be more productive and solve more complex problems when working on any computer-related problem. Yet many of us utilize only a small fraction of those tools; we only know enough magical incantations by rote to get by, and blindly copy-paste commands from the internet when we get stuck.
This class is an attempt to address this.
We want to teach you how to make the most of the tools you know, show you new tools to add to your toolbox, and hopefully instill in you some excitement for exploring (and perhaps building) more tools on your own. This is what we believe to be the missing semester from most Computer Science curricula.
The class consists of 11 1-hour lectures, each one centering on a particular topic. The lectures are largely independent, though as the semester goes on we will presume that you are familiar with the content from the earlier lectures. We have lecture notes online, but there will be a lot of content covered in class (e.g. in the form of demos) that may not be in the notes. We will be recording lectures and posting the recordings online.
We are trying to cover a lot of ground over the course of just 11 1-hour lectures, so the lectures are fairly dense. To allow you some time to get familiar with the content at your own pace, each lecture includes a set of exercises that guide you through the lecture’s key points. After each lecture, we are hosting office hours where we will be present to help answer any questions you might have. If you are attending the class online, you can send us questions at [email protected].
Due to the limited time we have, we won’t be able to cover all the tools in the same level of detail a full-scale class might. Where possible, we will try to point you towards resources for digging further into a tool or topic, but if something particularly strikes your fancy, don’t hesitate to reach out to us and ask for pointers!
Computers these days have a variety of interfaces for giving them commands; fanciful graphical user interfaces, voice interfaces, and even AR/VR are everywhere. These are great for 80% of use-cases, but they are often fundamentally restricted in what they allow you to do — you cannot press a button that isn’t there or give a voice command that hasn’t been programmed. To take full advantage of the tools your computer provides, we have to go old-school and drop down to a textual interface: The Shell.
Nearly all platforms you can get your hand on has a shell in one form or another, and many of them have several shells for you to choose from. While they may vary in the details, at their core they are all roughly the same: they allow you to run programs, give them input, and inspect their output in a semi-structured way.
In this lecture, we will focus on the Bourne Again SHell, or “bash” for short. This is one of the most widely used shells, and its syntax is similar to what you will see in many other shells. To open a shell prompt (where you can type commands), you first need a terminal. Your device probably shipped with one installed, or you can install one fairly easily.
When you launch your terminal, you will see a prompt that often looks a little like this:
missing:~$
This is the main textual interface to the shell. It tells you that you are on the machine missing and that your “current working directory”, or where you currently are, is ~ (short for “home”). The $ tells you that you are not the root user (more on that later). At this prompt you can type a command, which will then be interpreted by the shell. The most basic command is to execute a program:
missing:~$ date
Fri 10 Jan 2020 11:49:31 AM EST
missing:~$
Here, we executed the date program, which (perhaps unsurprisingly) prints the current date and time. The shell then asks us for another command to execute. We can also execute a command with arguments:
missing:~$ echo hello
hello