If you're trying to stick to the POSIX standard, you have to use short options for standard commands like grep, since the long options are GNU extensions.
Let's be honest it's outdated, has a bad UX and is with the standards I would hold such a standard against today generally not so good.
Sure systems seen try to somewhat be POSIX compliance but from my experience not because they care about POSIX but because that happen to overlap with the idea to be somewhat compiland with other similar systems so that porting software/scripts is easier.
So if the systems you use support long options for POSIX commands go ahead and use them. Furthermore if the command you can are not in the standard anyway you again can use long options because they are as much standard as the short ones. Let's be honest this leaves very little use-cases where long options are a problem.
The most vivid example is test, aka /bin/[. POSIX specifies that, if test is invoked with one argument, you must "Exit true (0) if $1 is not null; otherwise, exit false" [1].
This means that `test --help` is forbidden from printing any help. It means that `test -d $argv` expands to `test -d` if $argv is empty, which then must "succeed" because "-d" is not null. It bites users over and over again [2].
Implementing this POSIX piece has resulted in more headaches, not fewer. I regret implementing a POSIX-conformant test, I wish I had just picked mostly-compatible but also-sane semantics.
1: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/t...
2: https://stackoverflow.com/questions/29635083/fish-shell-chec...
To be fair, while the POSIX behaviour is obviously wrong, using `$argv` on a bourne-style shell[0] is also wrong; that should be either `test -d "$argv"` or (if I recall the syntax correctly) `test -d "${argv[@]}"` if you actually intended argv to be a list rather than a single directory ("argv" suggests the former, but `test -d X` only accepts a single argument).
0: more specifically, a shell that does word splitting at the wrong place (after parameter expansion)
https://pubs.opengroup.org/onlinepubs/9699919799/
> Sure systems seen try to somewhat be POSIX compliance
The mainstream systems you know and use adhere very rigorously to POSIX. GNU Libc, Kernel, Coreutils, ... and their counterparts in BSD Unixes, proprietary Unixes, Cygwin and whatnot all take POSIX seriously.
POSIX is very helpful, and smart coders and sysadmins use it as one of their references for required behavior.
https://news.ycombinator.com/item?id=10104203
Although I would agree that there's a slight hole there: you still need to port stuff like coreutils and all the dependencies, which has been done of course. But I'd be happier if something like busybox was actually portable.
The Autoconf system is predicated on the idea that writing a portable shells script is hard, and so we hide the shell programming behind a mountain of M4 macros.
It's not necessarily easier to port a shell script today than 22 years ago, which was not written with portability in mind. There are more shells with more extensions, and then beyond the language concerns, and the environments have exploded. A shell script can easily depend on all sorts of cruft you've never heard of. Oh, just install these five things from the following github repos ...
If this is your own dotfiles or utilities, sure, but if I'm working on something collaborative, yes, I care about the standard.
It's just way too easy to run into a unexpected gotcha on some platform/configuration.
http://www.oilshell.org/blog/2018/01/28.html#limit-to-posix
Recent comment about this:
https://news.ycombinator.com/item?id=24428347
POSIX is just too limited and not what people use in practice.
If you want a portable shell script, in many cases my (biased) advice would be to make your script work on both bash and Oil. (Obviously there are short shell scripts which you may want to run on BSD, etc. This is more about big scripts, which POSIX falls down for.)
Oil already runs some of the biggest shell scripts in the world, many of them unmodified. Moreoever, when there's a patch necessary to run it, it often IMPROVES the program.
http://www.oilshell.org/blog/2020/06/release-0.8.pre6.html#p...
You'll be less tied to the vagaries of bash.
If anyone's script doesn't run under Oil, I'm interested. See https://github.com/oilshell/oil/wiki/What-Is-Expected-to-Run...
Though sometimes you don't need to go that far to break stuff, for instance switching from Fedora to Ubuntu. I've seen many scripts fail on debian derivatives because people think using #!/bin/sh as a shebang is fine since it works on their computer where sh was in fact a symlink to bash.
But on debian based distributions /bin/sh is often dash, not bash, and dash is basically the strict POSIX subset + local, all fancy stuff like [[ ]], &>, arrays, ... will fail.
Though this is less about long options here and more about general shell scripting.
But, still, that's no reason to adopt a mindset of actively wrecking the chances of such success.
(Which is what passive ignorance amounts to, effectively).
It's not difficult to do, but it is annoying. I don't blame people for ignorance, but it'd be nice if people thought about portability.
Non-portable scripts can also bite you on Linux, where Debian, for example, will swap out the shell from bash to dash for performance. but others will not. So, even within the Linux ecosystem, you can end up with scripts that behave differently across distros.
From the bash man page, "If bash is invoked with the name sh, it tries to mimic the startup behavior of historical versions of sh as closely as possible, while conforming to the POSIX standard as well." Also you should not be including bashisms if your shebang is sh and not bash. So using bash as sh shouldn't generally be a problem, if you stick to the published Shell Command Language [0], unless you hit one of the cases where the spec is a bit ambiguous and shells implement it differently [1].
[0] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V... [1] https://stackoverflow.com/questions/16069339/different-pipel...
From what I remember, it doesn't do a particularly good job.
And, again, this still bites whenever using different linux distros.
#!/bin/bash
#!/usr/bin/env bashHomebrew comes to mind, and any other piece of software that does the installation via a shell script.