Ellane learns the command line

Less is more

Great questions, and we'll get to drwxr-xr-x really soon.

For now, addressing the ls-F error, let's introduce you to the built-in help pages: known as man pages.

The reason the instruction from the page at ss64 didn't work is because that page is out of date.

So how do you view up-to-date information? Well let's start with how you view any information.

Do you have a plain text file handy? #

Typing this at my kitchen table I thought, I'll have to tell her to create a plain text file that she can use to test this next bit. Most people don't just have a bunch of plain text files knocking about.

The Picard facepalm. (If I do say so myself, I bear a resemblance to Jean-Luc.)

Then I remembered who I was talking to.

Let's view a file #

Emphasis on view: we have no desire to edit it.

This gets to one of the general principles in the CLI: the principle of least privilege.[1] If you don't need to edit a file, don't open it in a file editor: open it in a file viewer.

The oldest command, and the one you'll see referenced most often, is more. Unfortunately that's another one that's in my muscle-memory. Because there's a better command, and as you're new you might as well start using it.

In classic Unix style, it's called less.[2]

We'll use less, but if you see more in online instructions you can either use it, or substitute less.

less 🟢 #

cd yourself to a folder that has some text files.[3] And then, as you might expect:

less yourfile

It'll show the file #

Big whoop! What's more interesting is how we move around the file, because you should assume that your mouse won't work. (It will probably scroll up and down for you. But don't do that.)

Again, there are well-worn conventions that will serve you in many CLI situations.

There are tons more, and there's no point me listing them all: press h to bring up the help screen.

^ means the control key #

Another convention, and this one's universal. ^E means control-E.

Search is interesting #

If you hit /, you're in search mode. Type a word, hit return.

To find the next instance of the same search, hit n. The previous, N.

Again, this is how vim works.

When you get used to these shortcuts -- j, k, / to search -- you start to move around a lot more quickly.

(Just curious: do you touch-type?)

Homework: read all of the less help #

The help page has a lot of nerdy terminology that ties together everything we've learned so far. It might look scary to start, but just read it all slowly, try out the various options, and get used to how it all looks.

Being able to see a screen like this and absorb it all is the superpower we're aiming for. None of it's difficult; it's just unfamiliar.

Make sure you're really comfortable with that before we move on

man pages #

So this brings us to the man page, one of the wonders of the modern world.

Every (well-behaved) command has its own manual page. It tells you everything you need to know about that command: its flags, options, and the arguments that it takes.

So man is the command, and it takes flags, options, and arg... well, let's just have a look.

man man

You're looking at the man page for man. :-)

Convention: indicating flags and arguments #

Let's dissect this first line.

man [-adho] [-t | -w] [-M manpath] [-P pager] [-S mansect]
         [-m arch[:machine]] [-p [eprtv]] [mansect] page ...

This is telling us that:

There's a lot there, and I've never used any of those options to man. The point of this was just to decipher that stuff at the top.

So when we did man man, we typed the command, man, and supplied the only required argument, page, which just so happened to also be man!

Keep reading #

I wonder what -a does. I can either scroll down with space, or the smarter way is to search for it with / then -a and return.

The first search result shows us this line that we're reading. Hit n for the next result, and there we go.

-a   Display all manual pages instead of just
     the first found for each page argument.

Now, we still don't really care what this actually does. The lesson here is manoeuvring around the viewer, not understanding all of man's options.

man is less #

Because man uses less. You can prove this by hitting h to bring up the help.

BUILTIN(1) #

There's a small idiosyncrasy if you man cd. You'll see the man page for BUILTIN(1).

This is because cd isn't considered its own program: it's so core to everything, it's built-in to the shell. To see these man pages, type man zshbuiltins.[4]

Now you can view anything #

Check the man pages for stuff we've already seen. Now you can see that man ls doesn't have that weird ls-F thing going on.

Get comfortable with this and we'll move on. Start browsing and searching some of your own plain text files using less.

  1. A better writer would have had this in mind when they titled this post. ↩︎

  2. Apparently there's an even better version called most, but a) we don't need it, and b) it's not installed by default. ↩︎

  3. If you're following along at home and you don't have a plain text file handy, you can launch less --help and use the help file to practice navigation. ↩︎

  4. This one is obviously specific to the more modern zsh vs. bash. ↩︎