The Hacker Ways

A gentle introduction to the command line and the UNIX toolset.

Note, 12 years later: I wrote this booklet to try to help my two kids learn how to use a computer. It would be presumptuous to say that it worked, but it is a fact that both of them have become good programmers. We are now in the age of the LLM, when AI-assisted programming makes us so much more efficient, yet we are all worried about our jobs being taken over by the machine. But if they were starting today I would still be encouraging them to learn how things work, and how to use computers. It is a bad idea to subcontract your brain away.

The UNIX toolset, like the one you’ll find in Linux and macOS, is the work environment of choice of most programmers and research scientists. If you are interested in a career as a programmer, data analyst, or researcher, you’ll need to master it.

This book will teach you what you need to get started. UNIX can be daunting until you understand its logic: by the end of the book you will, and you’ll know where to look for more.

Chapters

Introduction

There is a better way to deal with computers. Hackers have been developing and using it for at least 40 years: it is the way of the command line, of the conversation with the computer in languages that are neither human nor machine, but a carefully crafted middle ground. Hackers, by the way, is how we call people who know well their tools, who dare to explore, and who need to build things. In the words of Paul Graham, “To programmers, ‘hacker’ connotes mastery in the most literal sense: someone who can make a computer do what he wants”. ...

The way of the terminal

Learning only happens with practice. Throughout this booklet I shall strive to make it easy for you to actually go to your computer and try things out: but unless you get excited about a project —something you want to build— and start working on it you’ll find it very hard to learn. In this chapter we’ll start a project: we’ll begin a web site. As we are about to start with a new project, the first thing we need to is to build a home for it in you computer. A directory (or folder, as some people call it) of its own. And we are going to build it with the terminal, because it will be the preferred way to talk to the computer and we might as well start using it as soon as possible. ...

Basic UNIX tools

Most of the tools you’ll be using in the terminal, including those presented in the previous chapter, were designed by the people who created UNIX back in the late sixties and early seventies. They did an amazing job. People like Ken Thompson and Dennis Ritchie are heroes in the computing world: the system they created is at the heart of most servers running the internet, and at the core of all macOS and Linux computers. Dennis also invented the C programming language, with which most of the rest has been written. ...

The way of the editor

Remember how we said that everything is text (it was not strictly true; images, videos, songs and compiled programs are not text… but most of what we are talking about in this booklet is). In plain text files you write programs, configure websites, select options for how to interact with many programs —including the shell— and store your data. Let’s look at the text editors, the programs designed to create and modify text files. Two stand out among the many available: Vi and Emacs. Which one is better is subject to much controversy, but don’t pay too much heed to it. You should be familiar with both before deciding which one is best for you. I find both are useful in different contexts. ...

From the shell to a program

Programming is a natural extension of the types of conversation that we’ve been having with the computer. If, instead of writing directly to the shell, you write the commands in a file, you can then ask the shell to run whatever it finds in it. Writing directly in the shell is like interactively asking somebody to do something, wait for the result, then ask something else, and so forth; writing the commands in a file is like leaving a note with instructions for somebody. ...

Speaking python

So far we have been talking to the shell, and our programs have been a sequence of commands that the shell has executed one after the other. But there are many other languages we can talk to the computer —assuming, that is, that we are running a program that understands them. Python is a great language to learn. Invented by Guido van Rossum in the late 1980s, it has become extremely popular. It emphasizes readability, making it simple to write programs that will be easy to read an understand by other programmers (including you, some months after you wrote the program). It is clear, concise, and it runs pretty much everywhere. It is often recommended as the best language to learn programming, but it is also a very powerful language: it runs many web sites, and it is the language of choice for many scientists and engineers. ...

Making the computer work for you

In the previous chapter we saw how to interact with Python. In this chapter we want to start using it to do interesting stuff, but before we’ll spend some time improving our work environment. First we’ll introduce screen, a wonderful piece of software that will allow you to do many things at once within the terminal, without losing track of any; get used to screen, and you won’t be able to be without it. ...