Day 3 - Showing the content of a file

– So, have a look inside.

Enemy Mine (1985)

Do you remember when I said that the second most important thing a computer can do is to move

four ghosts in a labyrinth flooded with beads that you are trying to eat? I didn’t lie, it’s true. The

third one, however, is to show the content of text files.

Back in the ages when I was a teenager (the 90s, just to be clear) we used to exchange data on floppy

disks. Yes I know, it sounds like a time where dinosaurs still walked on earth and men went hunting

with flint spears (spoiler alert, these two things never happened during the same age), but it’s true.

Text files were very important, song lyrics, programming tutorials, jokes, all these things came in

text files. And you know what? Now, when I open a web page with some band lyrics and my screen

is flooded by advertisements, pop-ups, cookie alerts, and unwanted videos I definitely miss those

amazing plain dull simple text files.

OK, enough riding the train of nostalgia. My point is that these days text files are… still one of the

most important things in the world of computer science! Let’s consider this: every Web page and

every computer program are, at their source, text files. That’s it, easily 80% of what is travelling on

data networks these days is still a text file. So, let’s see the content of a text file, for once without

firing up a text editor.

If you followed the instructions in the setup section, you should have the example files in your

current directory. One of these files is examples.txt, and we will use it throughout the next lessons

to test some commands.

$ cat examples.txt

You should have been glorified by the content of the examples.txt file, and you are probably

wondering why things so unrelated with each other are listed together in a text file. Trust me, I’m

not completely crazy yet, these things will come in handy.

There is not much more to say, so far. I warned you, text files are not as exciting as all those pop-ups

and advertisements you get on your browser.

As this lesson was a bit short and there are not many smart exercises that you can run through, I

will entertain you with a fun fact about cat. While it is a very appealing name for feline lovers like I

am, cat actually stands for conCATenate. Indeed, you can name multiple file names on its command

line, and what you will get as an output is the concatenation of their content. A side effect is that if

you name only one file you are just asking the command to print its content.