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Debian's Which Hunt

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Re: Debian's Which Hunt

#241

Post by lucb1e »

anonydsfsfs wrote: post #60
dilawar wrote: post #2

'command -v' is POSIX!! I have always avoided it in favor of which because its output doesn't feel machine friendly.

"command -v" in Dash (the Debian shell) has a serious bug that makes it non-POSIX compliant: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=874264

To be honest it's kind of weird to have things in your PATH that are not meant to be executed, so I'm not sure I agree about it being that important and it doesn't seem to have gotten any attention since 2017 despite a patch being available, but I take your point that this should not happen and is of course noncompliant.

Re: Debian's Which Hunt

#242

Post by lucb1e »

mikl wrote: post #140

`which` is an extremely commonly used command, has an intuitive name, is a very small program. Removing it from the standard distribution would be a huge annoyance to everyone who uses it. One more package you have to remember to install on every system to be productive.

> One more package you have to remember to install on every system to be productive.

Everyone has different preferences though, e.g. for me vim is an essential package. That's why I have a few functions in my bashrc that installs packages in different environments. Here are some of them, with a representative excerpt of the packages:

- function defaultinstall { apt install curl sudo vim ping etc. }

- function defaultinstall_laptop { apt install lshw powertop gnome-power-manager etc. }

- function defaultinstall_wifi { apt install wavemon iw etc.

- function defaultinstall_android { apt install sqlite3 etc. }

- function defaultinstall_optional with various languages like php and ruby, a mariadb client, cloc, gifsicle, iperf3, apt-file and it then runs apt-file update, etc.

Before having these functions, I noticed that I'd often be missing packages (sometimes while offline). If you really want `which`, you can install the variant you want. I would do the same (because, interactively, I find `which` easier to type, even if I use the portable `command -v` in scripts).

Re: Debian's Which Hunt

#243

Post by 22c »

throwaway09223 wrote: post #175
22c wrote: post #170

Earlier quoted context omitted.

You can use command -v in any POSIX compliant shell. csh is not POSIX compliant. Your list of shells in inexhaustive to the point of being almost misleading. bash and zsh are "heavy-weight" shells, a lot of lightweight shells also support command. If you're specifying your shebang as #!/bin/sh then you should not assume you have access to functions like type or binaries like which, but you can generally assume you ha…

Well the point is that it's a shell component, so it's not available from anything other than a shell which is undesirable. I understand Bourne style (POSIX) shells have the vast majority of the market, but the point is breaking other environments. "command -v" is not available everywhere so it is not a viable replacement for /usr/bin/which.

"which" is also not available everywhere, that's how I know about "command -v".

Re: Debian's Which Hunt

#244

Post by Seirdy »

quotemstr wrote: post #209
Seirdy wrote: post #187

Earlier quoted context omitted.

You should be using ShellCheck or an equivalent linter on your shell scripts in POSIX mode if you want them to be portable; in POSIX mode it warns when using "which" instead of "command -v", and I think it also warns when using "whence" or "where" outside of zsh. There's a host of other Bashisms/GNUisms and other noncompliant antipatterns it checks for too. It's also worth reading through the POSIX manpages for POSIX…

> It's also worth reading through the POSIX manpages for POSIX sh if you want to be a good shell scripter. Or you can give the middle finger to POSIX, write shell scripts for bash, or even zsh, and end up with faster, more correct, and more beautiful shell scripts that in practice are just as portable as the ones that mindlessly follow the limited and bizarre POSIX shell spec. I'll write POSIXly-correct shell scripts…

You're free to do this, but be aware that you'll then need to be aware of where your scripts will and won't run.

I regularly use Fedora, Alpine Linux, Void, Debian, and OpenBSD. Void uses dash as its default shell, Debian uses it as /bin/sh but still includes bash, OpenBSD uses another POSIXy shell, Fedora uses Bash. macOS also uses zsh as /bin/sh.

If you want portability, you don't have much of a choice. Devs not caring about portability is why less common operating systems are a struggle to use which only fuels monocultures.

Standards compliance and implementation diversity have a symbiotic relationship that is necessary for the health of open platforms. I described the benefits in more detail in a blog post:

https://seirdy.one/2021/02/23/keeping-platforms-open.html

Re: Debian's Which Hunt

#245

Post by coolgeek »

denton-scratch wrote: post #237
sevensor wrote: post #176

Earlier quoted context omitted.

In bash, such things are documented in the help system: $ help command command: command [-pVv] command [arg ...] Execute a simple command or display information about commands. Runs COMMAND with ARGS suppressing shell function lookup, or display information about the specified COMMANDs. Can be used to invoke commands on disk when a function with the same name exists. Options: -p use a default value for PATH that is g…

I didn't know about the "help" command in bash. I've always gone to "man bash", and then scrolled up and down for an hour or so. Or just cranked-up a search engine. So thanks for that.

Apparently, there's an "info" command, as well

Re: Debian's Which Hunt

#247

Post by gnubison »

StillBored wrote: post #150
gnubison wrote: post #142

Earlier quoted context omitted.

That’s not usually how standards are supposed to work — a POSIX operating system should not reimplement Linux, it should only have to reimplement what’s portable to existing systems.

Except POSIX has historically always been the intersection of the major Unix vendors. Which is why its always been the lowest common denominator, and is largely crap as a result. Of course to a certain extend all non defacto-standards suffer from this because invariably one group or the other doesn't want to rework their system to fit the standard so they NAK it.

POSIX does simplify things, diverging from historical practice, when it’s reasonably the only way to standardize stuff that arguably should be standardized. And the vast majority of scripts are easily converted to POSIX-compliant shell script anyways — it’s certainly not “largely crap”.

Re: Debian's Which Hunt

#248

Post by int_19h »

denton-scratch wrote: post #79
Taywee wrote: post #56

Earlier quoted context omitted.

Notable sections from that page: > The command -v and -V options were added to satisfy requirements from users that are currently accomplished by three different historical utilities: type in the System V shell, whence in the KornShell, and which in the C shell. Since there is no historical agreement on how and what to accomplish here, the POSIX command utility was enhanced and the historical utilities were left unmo…

Hmm. So you have two conflicting conventions; and the solution is a third convention. Now you have three conflicting conventions. I think I've come across this somewhere else.

The third convention isn't conflicting with the rest - that's the whole point!

Re: Debian's Which Hunt

#249

Post by account42 »

quotemstr wrote: post #209
Seirdy wrote: post #187

Earlier quoted context omitted.

You should be using ShellCheck or an equivalent linter on your shell scripts in POSIX mode if you want them to be portable; in POSIX mode it warns when using "which" instead of "command -v", and I think it also warns when using "whence" or "where" outside of zsh. There's a host of other Bashisms/GNUisms and other noncompliant antipatterns it checks for too. It's also worth reading through the POSIX manpages for POSIX…

> It's also worth reading through the POSIX manpages for POSIX sh if you want to be a good shell scripter. Or you can give the middle finger to POSIX, write shell scripts for bash, or even zsh, and end up with faster, more correct, and more beautiful shell scripts that in practice are just as portable as the ones that mindlessly follow the limited and bizarre POSIX shell spec. I'll write POSIXly-correct shell scripts…

If your shell scripts are complex enough for you to be limited by POSIX then they probably shouldn't be shell scripts in the first place.

Re: Debian's Which Hunt

#250

Post by dangerface »

Liquix wrote: post #105
overgard wrote: post #103

When I read stuff like this I can't help but wonder how anything ever even gets done on this project. The amazing thing is 'which' was working perfectly fine for everyone. Just leave it alone? The amount of time they wasted on debating this is staggering compared to just not changing it.

>I can't help but wonder how anything ever even gets done on this project Slowly, methodically, and with minimal user impact. As mentioned at the end of the article, what first appears a waste of time for a small issue could also be seen as a beautiful illustration of the democratic process that makes Debian so stable/widely adopted.

> Slowly, methodically, and with minimal user impact.

I am confused. Isn't the article about an individual just randomly deciding to deprecate which and the resulting fallout that impacted all of Debians users?

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