This is kind of a rant, but mostly a plea.
There are times when BusyBox is the only tool you can use. You've got some embedded device with 32k RAM or something; I get it. It's the right tool. But please, please, In begging you: don't use it just because you're lazy.
I find BusyBox used in places where it's not necessary. There's enough RAM, there's more than enough storage, and yet, it's got BusyBox.
BusyBox tooling is absolutely aenemic. Simple things, common things, like - oh, - capturing a regexp group from a simple match are practically impossible. But you can do this in bash; heck, it's built in! But BusyBox uses ash, which is barely a shell and certainly doesn't support regexp matching with group capture. Maybe awk? Well, gawk lets you, with -oP, but of course BusyBox doesn't use GNU awk, and so you can't get at the capture groups because it doesn't support perl REs. It'd be shocking if BusyBox provided any truly capable tools like ripgrep, in which this would be trivial. I haven't tried BB's sed yet, because sed's RE escaping is and has always been a bizarre nightmarish Frankenstein syntax, but I've got a dime riding on some restriction in BB's sed that prevents getting at capture groups there, too.
BusyBox serves a purpose; it is intentionally barely functional; size constraining trumps all other considerations. It achieves this well. My issue isn't with BusyBox, it's with people using it everywhere when they don't need to, making life hell for anyone who's trying to actually get any work done in it.
So please. For the sanity of your users: don't reach for BusyBox just because it's easy, or because you're tickled that you're going to save a megabyte or two; please spare a thought for your users on which you are inflicting these constraints. Use it when you have to, because otherwise it doesn't fit. Otherwise, chose a real shell, at least bash, and include some tools capable of more than less than the bare minimum.
"Hey! The solution is to learn a new programming language, instead of using POSIX tools that have been around for literal decades."
Great advice, buddy.
Lua is as easy as python, potentially easier. I don't think writing a one-off script with it to solve a specific problem is a nuts idea.
Lua is 31 years old and has been included in OpenWrt by default for 15 years.
New to me.
I don't care if it's easy; suggesting Lua as solution is dissembling. I complained about poor tooling that doesn't follow defacto standards when the device it's running on could easily handle having a more common, older, standard bash than choosing some castrated shell.
If it were a forced choice, because of hardware limitations, of having Lua or bash, I could get it. Lua is more capable. But in this case, it's not a choice of either/or; the device could easily handle both.
BusyBox is, as I understand, configurable for how "complete" it is. That's why I say it's lazy to pick some default minimal compile when it could be more accessible, and less of a pain in the ass for users.
Dude I mean in this in the most genuine, kind way: a significant aspect of being a successful programmer is using the tools in your environment. If you can't do something without bringing in your Tool of Choice you're artificially limiting yourself.
If your environment does not have a specific tool or functionality that you would prefer, you work around it. OpenWrt is an immensely capable OS and it manages to perform complex network operations within its (admittedly) constrained environment.
In this case you're myopically focused on not even a specific language, but the language agnostic feature of regex capture groups. You should be asking yourself if there's any other way to accomplish your goal without this (spoiler: there are probably dozens of alternatives)
No offense taken.
If I were a professional programmer, I'd be doing this. I was a professional software engineer for 20 years before I took a management role, then managed software teams, and then organizations, for another decade before I chose to do something else. One of the things I decided was that I wasn't going to work on, or with, technology I didn't like anymore - as long as I had any choice, and since all my software development is voluntary pet projects, I'm able to do this. It has, in the aggregate, greatly improved my mental well-being to not have to work with crap anymore. I mostly avoided having to touch Windows in decades; I had only a brief brush with JavaScript that left only minor scarring, and with WASM there's every hope I can even do web-based projects should I get the itch without killing brain cells with JS. Having spent years with C++ and decades programming Java, I'm convinced that I've learned enough about what's horrible in software, and don't really need to spend more time being taught about new ways developers can screw up the software engineering space. SOAP alone covered most of the bases of bad design and architecture.
So now, I get to select where I play. I can focus on learning new things that I think are good, rather than being forced to figure out ways to work around the bad.
My original plea was simply: if you can use defacto standards, please do.
Insofar as the technology limits me in what's available, absolutely. Mainly, though, I choose to focus on supporting projects and products that support standards. If a project wants to be a Special Flower and use BrainFuck as it's tooling language, good for them! But I'm going to look for alternatives.
I would prefer, however, that projects - when they're using software that could be more standards compliant by using a few more MB, and have the space to do so, simply be compliant and ship something less stripped down.
To be precise, I'm focused on the fact that, in a toolset where usually at least one of many standard tools provides a functionality, none do. I'm not complaining that ash doesn't support regexp string matching with groups; in complaining that BB was compiled such that none of the standard tools do.
Yes. I tried 3 or 4 of the standard, usual ways to break out and parse data. My next attempt was going to resort to field cutting, hoping that that also hadn't been stripped out.
Eventually, I hacked a solution together in Lua, which will be useless the next time I encounter a stripped down BB that isn't in OpenWRT, and I'll have to waste time trying to work around broken tooling again.
To be fair learning lua isn't exactly a hard process, there's a reason it's embedded into so many other tools. If you're familiar with python you're like 85% of the way to writing something basic anyway.
I'm not (familiar with Python).
Years ago, I wrote and maintained one of the core libraries for Ruby. That experience put me off scripting languages for any serious, persistent work for good. I use them for one-offs, and therefore, I stick to languages that are ubiquitous: bash, awk, sed. Lua isn't everywhere. Neither is Python, or Ruby, or Perl. But bash, awk, and sed are.
Except that, in BB, they're often stripped down so much they're barely functional.
Look, somehow this has become about OpenWRT. That was just a latest example; my post was about BusyBox, and Lua isn't part of BusyBox. I just want developers to consider their deployment environment and maybe generate and include more capable, POSIX BB instead of just choosing the smallest and most useless.
This is completely fair, but the only example you gave to show this was about regexp in OpenWRT, and it seems from the other comments like there are several ways to go about doing this. You mentioned half of your RAM being free, but on the flip side of that, something with half as much RAM or less would be struggling a lot more. Admittedly I don't know much about OpenWRT but routers aren't exactly known for being powerful systems, so to me this seems like a perfect use case for a leaner set of utilities.
To your other point, languages like Python and Lua might not technically be everywhere but it they are common enough and simple enough to learn that you really are holding yourself back by avoiding them. Lua in particular is used by a lot of Linux projects (e.g. Neovim and Awesome WM are the most recent that I've used but there are tons of others) because of how easy it is to embed a configuration/plugin API into existing codebases.
Tldr; you're being dissed because the only example you gave about BusyBox being overused is (on the surface at least) a valid use case with easy solutions that you seem to be intentionally ignoring.
Yeah, fuck giving examples, because people ignore the stated problem and focus on the example. You're exactly right. It's stackexchange all over again, and I should know better than to provide any specifics, because people can not resist solving the wrong problem.
There's an actual term for this behavior, but it escapes me. It's the opposite of the X/Y problem, where people fixate on some irrelevant detail. I need to learn to ignore "can you give an example" comments, because all that leads to use someone trying to fix a specific instance of a larger, more general problem.