Data Science at the Command Line, 2nd Edition

Foreword

It was love at first sight.

It must have been around 1981 or 1982 that I got my first taste of Unix. Its command-line shell, which uses the same language for single commands and complex programs, changed my world, and I never looked back.

I was a writer who had discovered the joys of computing, and regular expressions were my gateway drug. I’d first tried them in the text editor in HP’s RTE operating system, but it was only when I came to Unix and its philosophy of small cooperating tools with the command-line shell as the glue that tied them together that I fully understood their power. Regular expressions in ed, ex, vi (now vim), and emacs were powerful, sure, but it wasn’t until I saw how ex scripts unbound became sed, the Unix stream editor, and then AWK, which allowed you to bind programmed actions to regular expressions, and how shell scripts let you build pipelines not only out of the existing tools but out of new ones you’d written yourself, that I really got it. Programming is how you speak with computers, how you tell them what you want them to do, not just once, but in ways that persist, in ways that can be varied like human language, with repeatable structure but different verbs and objects.

As a beginner, other forms of programming seemed more like recipes to be followed exactly—careful incantations where you had to get everything right—or like waiting for a teacher to grade an essay you’d written. With shell programming, there was no compilation and waiting. ...