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Comment by keepamovin | Hacker News Reader

Hahaha, lol. Where does this come from?

I've certainly accelerated my Bash game since ChatGPT came to Earth. Do you know there's a syntax for defaults?

  ${MY_BIG_VAR:-your_tiny_default}

Or that you can completely non-sensically extract the file extension with?

  file_extension="${1##*.}"

How to pronounce that? dollar open-brace 1 pound pound star dot close-brace

Reminds me of those codes on the phone system to get service functions...*69#

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That's called parameter expansion, see https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V...

Alright, when you put it like that, it does make sense. Thanks, that's a great resource! I'm gonna start using

  ${MY_ESSENTIAL:?"Error: need to supply an essential"}

You can also nest those, so this way you can get a value from an argument, or an env var, and if none is set, error.

    echo "${1:-${env_var:?I need a value for that!}}"

Ooh, I didn't know you could nest 'em! ChatGPT never told me that! Now we're getting somewhere! :)

    echo "${1:-${env_var:?I need a value for that!}}"

That is awesome! :)

Like massively concise construct. I don't know what other language can compete:

  console.log(process.argv[2] || process.env.VAR || console.error("I need a value for that"));

I personally prefer the bash v

It blows my mind how big a deal argument parsing is in legacy scripting languages (including python).

That snippet is concise, but relies on the user supplying arguments in the order you demand. AFAICS, non-trivial scripts require you to loop over arguments, testing against long and short forms of parameters, and shifting if the parameter expects an argument.

In Powershell, you define your parameter and apply constraints. Voila:

    [Parameter(Mandatory)]
    [ValidateRange(1, 20)]
    [int]$foo

That's it, the entire thing, done.

If you call python a legacy scripting language, i'll call Windows (where powershell runs on) a legacy operating system.

Sure, Windows doesn't have "legacy" like VMS or Unix etc, but it's been in use by every day people longer than any other current OS except for MacOS, which really isn't the same OS it launched as, whereas Windows has maintained backwards compatibility (for better for for worse) for decades. So.. Legacy? Why not.

This is the most civilized flame war I have ever seen. :)

I didn't mean to describe python as "legacy"; it is a great choice for scripting in the year 2023. It's second only to pwsh for that.

I use pwsh on Linux every day.

Anything that isn't a lisp machine is a legacy OS ;-)

I realise I've given offense, for which I'm sorry, but I'm driven not so much to denigrate bash as to advocate for a world where shells are semantic.

Thanks for that. I'm currently migrating a set of bash scripts to PS1 for win compatibility. This is gonna help me! Undeniably a good feature. Sure there's the case / getopts idiom for parsing args in bash as you say, but I'd say this is a place PS excels them in. I totally agree that arg parsing should be standardized and simple like this. A nice CLI is just such a joy to use. Ideally something that includes usage info and (like the PS example seemingly) optionality.

Syntactically I'd even prefer a single line, like

  [Pram(musthave):In(1, 20)/"Foos excessive or inadequate":int/$foo:"Foo count"/"Please supply how many foos you want."]

Not only is parameter expansion delightfully esoteric, it can replace sed for many applications. Or, as you’ve done, inverse basename.

Since it’s a shell built-in, it avoids the overhead of exec. Ever wonder why asdf is slow? Go peek at the source code. This is why. I have a draft PR that fixes it, but there are still some failing tests I need to fix.

Hmm, I only see a little bit of bash in asdf, but it's mostly wrappers that I don't expect to have much impact on performance? E.G. https://gitlab.common-lisp.net/asdf/asdf/-/blob/master/make-...

I always assumed asdf is mostly pure CL…

Presumably https://github.com/asdf-vm/asdf

Oh no, that is a very unfortunately named project! Neither ASDF, not a virtual machine… but I suppose it is kind of Another System Definition Facility

Gen Z has gleefully name collided all the things.

Replacing external program calls such as usual sed usage with shell (including bash specific) built-ins was also core in neofetch's design when was made as alternative to screenfetch. Will say that checking dylanaraps, someone worthy to be called a bash wizard, programs is a nice way to learn how to do complex shell scripting.

I can't tell if this is a joke or not.

Don't take this the wrong way but doesn't anyone ever read the manual any more?

https://www.gnu.org/software/bash/manual/html_node/index.htm...

I did use the file extension thing recently to differentiate between HTML and Markdown files. Very handy.

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