Reminded me of when I used to work at a zipper factory, doing exactly that job.

I've been following this http://toroid.org/ams/git-website-howto for several years now.

I think there is much more that can be done to make tools more user-friendly.

An example that pops to my mind is when you misspell a git command, and git suggest what you could've intended:

    $ git pill
    git: 'pill' is not a git command. See 'git --help'.

    Did you mean this?
        pull

That's already one step towards a better UI, but it could go even one step further if I could answer the question, ie: I press 'y' and git will pull.

Of course I'm not criticizing GIT (which I think as a better UI than many tools already), it's just an example.

I'm not saying that the UI couldn't be improved - I'm just saying that what they're doing isn't really an improvement on the the command-line as a UI, as it's just a domain-specific application. (And, I implied this but didn't state it explicitly: domain-specific applications should aim to be as 'compatible' as possible from a UI standpoint with the generic tool - ie, Unix - deviating only when there's a specific need to, and defaulting to the generic toolset. I'd need to see more to judge if Opa fits this; it's just a general principle).

More importantly, though: what you're looking for can already be done! Just use zsh (or, even simpler: a bash correction tool).

Because Unix is so modular, you can make these kinds of UI changes without breaking or even changing the underlying toolset. That means that you and I can tailor the UI to our specific needs, and we don't even really have to touch the general purpose toolset. Other examples include using Vim keybindings for the shell instead of Emacs (try modifying keyboard shortcuts with most pre-compiled GUI applications!) or scripting and aliasing.

Thanks for mentioning that, actually, because it illustrates my point very well! The command-line UI's strength is that it's literally as modular and as minimal as possible (at least, as far as I can conceive of). That's what I personally love the most about it. It defines only the bare minimum of tools necessary to satisfy two conditions:

1. By default, [almost] everything works as expected, with no customization (but assuming knowledge of the system). 2. Those who want to customize will find that it provides all of the tools necessary to create the exact interface they want, without modifying the underlying toolset as well. (This customization can be done to an essentially arbitrary level -- the technical limitations are well beyond what a reasonable person would consider 'sane').

You may make the argument, then, that the command-line isn't even an interface at all! It's more like an abstract interface that lets you stitch the tools together to define the interface you want, all the while providing a 'default interface' - a sensible set of defaults for those who can't be bothered to customize.

(Edit: I understand that tools aren't perfect - the git-pull/git-push asymmetry is an example - but the inconsistencies are vastly outnumbered by the overarching uniformity. And again, with such a modular model, you can create the UI you want without waiting for Linus to change the behavior of git).

Another example of catastrophic UX is certainly the unix command 'find', as in: find . -name "*.opa" -exec cat \{\} \; | wc -l

I wonder if any Unix beginner has ever managed to find the syntax for -exec without copy-pasting the examples :)

One aspect of having composable components is knowing how they get composed. The fact that {} and ; may need to be escaped is something having to do with the shell, not with find and it's -exec syntax.

In fact, this is one of those things that is obvious once you learn about shell and how commands lines get expanded and executed. The problem there is that most people don't learn about the shell until forced to by being bitten by something goofy and unintuitive like -exec arguments. The order in which people learn about these things, and it being difficult to discover (in that I can suggest a way to "verify" the command line before running it, but that doesn't help if you don't know how to interpret the results, which also requires experience dealing with the system as a whole) is what causes the catastrophic failure.

That these may need to be escaped is even documented in the find(1) documentation.

    -exec command ;
    Execute command; true if 0 status is returned.
    All following arguments to find are taken to be arguments to
    the command until an argument consisting of `;' is encountered.
    The string `{}' is replaced by the current file name being
    processed everywhere it occurs in the  arguments to the command,
    not just in arguments where it is alone, as in some versions of
    find.  Both of these constructions might need to be escaped
    (with a `\') or quoted to protect them from expansion by the
    shell.

zsh will actually do this for commands if you make a typo when the correct option is turned on. I don't think it will correct options though (but can autocomplete).