To understand the command line...

http://geekblog.oneandoneis2.org/index.php/2012/09/30/to-understand-the-command-line

by jonathansizz • 14 years ago

156 62 14 years ago

geekblog.oneandoneis2.org

pif• 14 years ago

> This is bad, because it means that the difference between a master and a beginner is almost nothing.

Wonderful!

Special thanks for explaining the genesis of thos tools names.

loeschg• 14 years ago

Where's the spoiler alert? Psh. No need to watch LOTR now... :)

smacktoward2• 14 years ago

I liked this piece overall, but there's one part that annoyed me.

Something else that had long-lasting influence over software we still use today was the ADM-3A terminal. If you ever wondered why vi uses 'hjkl' as left,down,up,right - this is why.

You won't find anyone who believes more strongly than I do in the importance of understanding our history. But understanding history is different than making a fetish of it, and this explanation tiptoes pretty close to the latter. OK, vi uses hjkl because the ADM-3A terminal didn't have arrow keys. But every keyboard for decades now has had arrow keys. Given that, what's the value in pretending they do not?

This explanation basically boils down to "we do it that way because we've always done it that way," which is poor argumentation.

It's also a good illustration of the distinction between 'easy' and 'efficient' - the modern cursor key layout, with the 'up' in front of the 'down', is obvious, intuitive, and easy to master. No argument. But it's not the most efficient layout - it's not possible to keep all four fingers on the four navigation keys - you have to settle for three fingers and move them around. And if you're typing and suddenly need to move, you have to move completely away from where you're typing and switch to the cursors.

hjkl answers both issues - the four keys in a line make it possible to keep one finger on each and so move about as quickly as possible, without ever having to move from the text-entry part of the keyboard to any other. It's not as easy, not as obvious, but it's quicker and more efficient when you're used to it. Even on my modern keyboard, I go for hjkl far more than I reach for cursors.

Well sure you do, because you have trained yourself to do that. But how many people can say that? And what's the value in leaving everybody else out when you design your tools?

Anytime you talk about how UNIX-like systems have evolved, there's a danger of falling into the trap of hailing historical cruft as "misunderstood features." But at the end of the day, it's still just historical cruft. It's there, it won't kill anyone if it stays there, but it's not something awesome either. It's just an evolutionary dead-end; the male nipple of software design.

jonathansizz• 14 years ago

vi/vim allow you to use the arrow keys for navigation if you want to. The choice is yours. I prefer keeping my fingers on the home row, and so I find hjkl to be much more efficient, especially on a laptop where the arrow keys aren't usually physically separated from the rest of the keys.

sp332• 14 years ago

I'd rather use ASDF but those keys are taken by other vi commands. Anyway, is there a way to press "Esc" without moving your whole arm?

prawks• 14 years ago

Also, you can't have fingers on all four arrow keys at once, while you can with hjkl. It's not only more ergonomic in the sense that you move your arm less, but also because you move your fingers less.

cturner3• 14 years ago

It's unfortunate vi uses arrow keys are in a non-intuitive layout. Still - it is a good idea to steer users away from arrows, inclduing to disable them in default files if you're mentoring.

If you introduce new users to vi on a keyboard that supports arrow navigation in insert mode, they're likely to build a habit of navigating around in insert mode, a very bad habit to have.

Transactional interaction is fundamental to becoming adept with vi. Modal editing is such a good thing that vi has remained part of the unix canon, despite all of the things that are wrong with it (not least of all - unintuitive arrows).

It's unfortunate that there's no block of unused letters in the vi keylayout - nowhere to put an asdw directional layout with harming key functions.

smacktoward2• 14 years ago

Still - it is a good idea to steer users away from arrows, inclduing to disable them in default files if you're mentoring.

Why?

This is the line of thinking that I was intending to challenge.

A wise man once said to me -- if the user and the software don't fit together elegantly, there's only two ways you can respond: by fixing the software, or fixing the user. In nearly every case, fixing the software to work the way the user expects is easier and cheaper than trying to fix every user who ever encounters it to work the way the program wants them to.

Steering users away from arrows is trying to fix the user. It's pushing her away from what every other bit of software on her system, including the OS itself, has trained her to do, to a different pattern that this one program believes is better.

kps• 14 years ago

Non-intuitive? ASCII ^H is Backspace, which moves left, and ^J is line feed, which moves down. How much more intuitive can you GET?!?

scott_s2• 14 years ago

I continue to use 'hjkl' to navigate in vi(m) because using the arrow keys requires me to move my whole arm. This is an awkward movement that requires time for my fingers to find the arrow keys. When using 'hjkl' to navigate, my right hand is always on home row, ready to either navigate or start typing. When typing in non-vi text boxes (such as this one), I do this movement, but I don't like it.

I do have an inefficiency: I move my hand for the escape key (which I should remap to caps lock, but I've never gotten around to it in the past decade), but I pivot at the elbow. It's far less awkward.

weaksauce5• 14 years ago

Try:

inoremap jj <Esc>

In insert mode you just press j twice and you get out of insert mode. This is my favorite key remap in vim.

You can put that in your .vimrc file or just try it out from the command bar.

mateuszf• 14 years ago

You could use Ctrl+C which works great for getting out of insert mode. Also Ctrl+J can be used instead as Enter. It also does work great in bash/zsh. It took me some time to switch but it was totally worth it. Caution: Switching caps lock with control was needed as prerequisite.

ephemient• 14 years ago

After switching between keyboards with Esc in different places, I've learned to use

    Ctrl-[

instead. Can hit it without moving that far, and it works just as well in GVim as it does in all terminal programs.

The only downside is being confused when nothing happens in a browser...

s00pcan• 14 years ago

Remap caps lock to control and use ^c or ^[

jvm2• 14 years ago

Remap caps lock to escape. After I did this I realized Esc is a really useful key in a wide variety of contexts.

oneandoneis22• 14 years ago

it's not something awesome either. It's just an evolutionary dead-end; the male nipple of software design.

I disagree. I started out using the cursor keys all the time because they were what I was used to.

It wasn't until I had been using vim for hours every day for well over a year that I came to slowly prefer hjkl - it's not a habit from "the old days"; it's not leftover cruft we'd be better off without; it genuinely is better to use hjkl than the cursor keys.

If you do enough editing to make it worthwhile to build up the muscle memory, that is.

Having said that, I remapped the "up" and "down" cursor keys and I've started using them a lot more since:

noremap <Up> gk noremap <Down> gj

They now allow me to navigate up & down wrapped lines the more intuitive way of one keypress per visible line, rather than the still-useful vim way of one keypress per actual line.

YMMV.

-- The author :)

bo10242• 14 years ago

Well...

1. I didn't get the feeling that the author was claiming (here) that hjkl was so awesome, just saying, "hey, have you ever wondered why hjkl and ~home and esc key? Well, this is why."

2. It turns out that some of these original design decisions, made on systems with much more limited capabilities, are really efficient. HJKL, if you are used to it, is an order of magnitude faster than arrow key navigation when typing, because every time you want to use arrow keys you have to move your hand.

On the other hand, ~ being HOME is just historical cruft, as you say, and using the ESC key to exit insert mode is worse -- historical cruft that actually is worse and slows us down compared to, for example, using CAPSLOCK as many do instead.

graywh• 14 years ago

But Escape on those old terminals was where Tab is now.

cmccabe• 14 years ago

Well sure you do, because you have trained yourself to do that. But how many people can say that? And what's the value in leaving everybody else out when you design your tools?

No, but there is value in RTFM before you comment. The arrow keys work perfectly well in vim, and you're welcome to use them if you want. Page Up and Page Down too.

But at the end of the day, it's still just historical cruft. It's there, it won't kill anyone if it stays there, but it's not something awesome either. It's just an evolutionary dead-end; the male nipple of software design.

Did you miss the part where he explained why hjkl were more efficient than the arrow keys? It's right there in the part you quoted.

Kids these days. Next thing you know, you're going to be telling us you discovered a great new editor named emacs...

xntrk• 14 years ago

sounds like an emacs user... :)

dean• 14 years ago

For reference, here's the keyboard layout of the ADM-3A terminal: http://en.wikipedia.org/wiki/File:KB_Terminal_ADM3A.svg

There's also a nice picture linked in the article in case anyone missed it.

dreamdu5t• 14 years ago

This article assumes the reader already knows a lot about the CLI.

A much better introduction to the commandline is Neal Stephenson's "In the Beginning was the Command Line."

Read it here: http://www.cryptonomicon.com/beginning.html

oneandoneis22• 14 years ago

Well, in fairness, I did write it for a Linux User Group :)

keithpeter• 14 years ago

How did the, er, extended description of the last 10 minutes of the film adaptation of The Lord of the Rings go down?

Did you have a live terminal on the projector and demonstrate a few commands and then show how the output of one can be piped into another?

I'm interested in the balance between demo and explanation for this kind of audience.

jff• 14 years ago

You should make it clear that while Thompson did allocate a week to the editor, he did not write vi--although one might think so, with that quote coming right in the middle of a block about vi.

tmhedberg• 14 years ago

Pretty much any question about why things are done a particular way in Unix can be answered the same way: "for historical reasons".

I'm a full-time Linux user, so that's not intended as a dig against Unix, but merely an observation. Each of the traditional Unix utilities evolved from some earlier tool, and carries with it to this day both the quirks of its predecessors and many artifacts of the design constraints of the time. Some argue that this diminishes usability, and they may have a point. But I find that it gives Unix a certain charming character that I've grown quite fond of. I suspect this sentiment is fairly pervasive, and probably contributes substantially to Unix's resistance to change over time. Maybe it isn't the simplest thing to learn from scratch, but it's robust and highly dependable once you've learned it.

dsego• 14 years ago

Nice article, for a better understating of Unix and its history I recommend the awesome UNIX-HATERS Handbook (http://m.simson.net/ugh.pdf).

ktf• 14 years ago

So the "show me matching lines" functionality, which ed users made massive use of, could be summed up as "globally search for the regular expression and print it" - or, in ed format, g/regular expression/p. Or, to shorten it a bit more, g/re/p

Thanks, I've always wondered where "grep" came from! (But somehow have never gained the momentum necessary to look it up...)

Dirlewanger• 14 years ago

Hahaha, same. This article was full of answers for me regarding Unix stuff that I use everyday and was only half-curious of their origins but never cared enough to look up. Articles like these are the best.

To understand the command line...

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