Also, look at oilshell[1]; it is bash compatible out-of-the-box, but has several options to make it incompatible, but safer (e.g. no field splitting of parameter expansion by default, making quotes much less needed).
Somebody integrated ShellCheck into Google's code review system about four years ago, right before I left.
So the result was that every code review I sent with a shell script was filled with red squigglies -- "add double quotes here". Most code reviewers don't really know shell, but if they see red squigglies, they will say "fix this".
The double quotes are of course technically correct, but when you're writing a shell script in a subdir 8 levels deep in the repo that only operates on 3 files in that subdir, it's overkill and makes everything ugly.
In other words, it was the typical "static analysis has annoying false positives" issue.
Most of the shell scripts I write deal with "trusted" filenames -- i.e. those checked into the repo. If you want to deal with untrusted filenames, then there are a lot of ugly techniques to do that.
So Oil is basically meant to make the default thing the right thing, and the common thing the short thing (Huffman coding, as Larry Wall calls it).
Once it becomes habit the cost is zero, though.
And the alternative you're implicitly suggesting is: "Follow shellcheck except you are allowed to make an expert judgement and ignore it when you know it won't be dangerous and have determined that the code is unlikely to change in the future so that this exception will be safe going forward too."
I think it's clear that this isn't a practical rule on a team with many people -- especially where they are not all experts in shell, which is 100% of teams of many people.
Making the experts "add those annoying double quotes they don't really need in this case" is the far lesser of the two sins.
I just find it annoying, hence the new shell :)
There's a lot more to Oil, but that's definitely one of the surface annoyances I want to fix. Although zsh actually does fix that, and for some reason I've almost never seen a zsh script.
I guess it's because zsh is not POSIX compatible by default.
But as soon as the script is something that should be potentially sooner or later maintained by anybody else than the original author (and in any successful project that's practically sure) the only right policy is to produce the source code that's obvious and passes the source checks.
An "expert" would have no problem to in no time adjust his three-line code to fulfill all the expectations of ShellCheck.
If it takes more than that, that only proves that the checks are actually beneficial and even more important than the "expert" tells to himself: it proves that writing that specific code "cleanly" is actually hard for everybody.
The only way you know this is being a person who routinely writes shell scripts.
There is no substitute for knowing what you're doing.
Try running shellcheck on configure scripts.
Or try this
curl -4O https://ftp.netbsd.org/pub/NetBSD/NetBSD-release-8/src/build.sh
shellcheck build.sh
These scripts are "safe" enough for hundreds or thousands of competent users to be running them every day.
double quotes, mixing string and array, unused variables. Why is this normal?
It does today. Will it change tomorrow? Will someone rename one of the files to include a space? It sounds like people saying "I don't need to escape this value in a query, it comes from a static list and it's safe." Yes - it's safe right now...
Quotes are tools that affect the correctness of your control flow quite vividly. Of course if there are multiple tools for solving the correctness issue you're welcome to choose any of them (and maybe the choice between the tools is something you can ascribe to religion), but that doesn't absolve you of the need to solve the issue itself. When the argument is that a piece of code is executing objectively wrong instructions (and ones that would be so obviously wrong in other languages!), that's pretty much the diametrical opposite of what you can casually dismiss as religious dogma...
As mentioned, the default should be right in Oil. The defaults are wrong in shell, and ShellCheck is meant to alert you of that.
Oil should have a style linter / formatter, but if it's designed correctly it shouldn't need the analogue of ShellCheck, which is more about correctness.
The most likely thing is that Oil is going to be a much better language this year (more expressive, with safety features, and it should be fast), but the interactive UI will still be more bash-like than fish-like:
https://www.oilshell.org/blog/2020/01/making-plans.html
So I encourage anyone who's interested in that to get involved now as the interactive shell is also a years-long effort :) There are many links on the home page about how to get involved, and I wrote many blog posts so people can understand how it works.
----
Here are a couple posts on why Oil is a good foundation for an interactive shell:
https://www.oilshell.org/blog/2020/01/history-and-completion...
Although I have to say I do feel the tradeoff right now between having a strong design / globally consistent code vs. allowing local variation / a lot of people to contribute quickly. That is, allow people to get in, add their useful patch, their useful bit of knowledge, and get out, without caring at all about the rest of the program.
I think Linux, git, and GNU are the prototypical examples of the latter. Those projects are too big for one person, so the code is set up in a way to allow hacking locally. They're also arguably a mess. Anyone who's ever written against the container APIs in Linux knows what I mean (namespaces, cgroups, etc.)
The git UI is another famous example, i.e. the plethora of commands and flags that make little sense. Empirically it seems that you can move faster if you disregard consistency and coherence.
The shell language of course grew like that over 50 years. Bourne shell is pretty consistent, but one thing I learned is that ksh added a lot of bash misfeatures (they're ksh-isms not bash-isms), and it's pretty bad.
But shell is actually a significantly smaller problem than git (after all bash is maintained more or less by one person). So it should be possible to fix it and redesign it. Unfortunately I'm not sure if the lessons generalize to bigger projects, but I would like it if they do.
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On a more practical note, feel free to send more people this way if you want to see the project succeed :) The design is there, and it will hold up, but it needs a bit more manpower, especially for things like the interactive shell.
Most single-person project maintainers have trouble relaxing the latter and end up staying a single-person project because of it.
Most companies that are anti-GPL aren’t so open about it.
Just because you can do something, doesn't necessarily mean you should. That rule applies to the implementation of corporate policies regarding licensing, too.
Indeed, which is why Linux is never found in a professional setting. /s
2) Not everything in the FOSS world is GPL'd.
3) There are plenty of users who have this restriction in their work and it is a real restriction to be aware of when discussing tooling.
4) That's just how the code is licensed and is related to the topic at hand.
It really tells many of the rules you're supposed to abide by and helps you write cleaner shell script.
https://github.com/koalaman/shellcheck