I'm writing something similar, but it's based on its own scripting language. The idea of transpiling C sounds appealing but impractical: how do they plan to compile, say, things using mmap, setjmp, pthreads, ...? It would be better to clearly promise only a restricted subset of C.
Pnut: A C to POSIX shell compiler you can trust
41–50 of 124 posts
Re: Pnut: A C to POSIX shell compiler you can trust
#42I was puzzled by the example C function containing pointers. Do I understand correctly that you implement pointers in shell by having a shell variable _0 for the first "byte" of "memory", a shell variable _1 for the second, etc.?
Author here, That's correct! Unlike Bash and other modern shells, the POSIX standard doesn't include arrays or any other data structures. The way we found around this limitation is to use arithmetic expansion and indexed shell variables (that are starting with `_` as you noted) to get random memory access.
Since I experimented with something similar in the past to mimick multidimensional arrays: depending on the implementation this can absolutely _kill_ performance. IIRC, Dash does a linear lookup of variable names, so when you create tons of variables each lookup starts taking longer and longer.
Re: Pnut: A C to POSIX shell compiler you can trust
#43If the end goal is portability for C, would Cosmopolitan Libc be a better choice because it supports a lot more features and probably runs faster?
Re: Pnut: A C to POSIX shell compiler you can trust
#44If the end goal is portability for C, would Cosmopolitan Libc be a better choice because it supports a lot more features and probably runs faster?
I cant run cosmolibc on Android, for example. Then again this converter is somewhat limited and didn't accept any of the IOCCC code I gave it.
Re: Pnut: A C to POSIX shell compiler you can trust
#45Hrmmm. But why? Quite frankly I think Bash scripting is awful and frequently wish shell scripts were written in a real and debuggable language. For anything non-trivial that is. I feel like I’d rather write C and compile it with Cosmopolitan C to give me a cross-platform binary than this. Neat project. Definitely clever. But it’s headed in the opposite direction from what I’d prefer...
Master Foo once said to a visiting programmer: “There is more Unix-nature in one line of shell script than there is in ten thousand lines of C.” The programmer, who was very proud of his mastery of C, said: “How can this be? C is the language in which the very kernel of Unix is implemented!” Master Foo replied: “That is so. Nevertheless, there is more Unix-nature in one line of shell script than there is in ten thous…
This koan shows the power of a one-liner, not shell scripting in general. Both Master Foo and Nubi would agree that a string/array manipulating function in bash isn’t worth their time when python exists.
Re: Pnut: A C to POSIX shell compiler you can trust
#46Earlier quoted context omitted.
My rule of thumb: Shell: 500 lines Although to be honest I'd be perfectly happy if Shell was restricted to single line commands only. I've wasted a lot of time and energy deciphering undebuggable shell scripts that were written to "save programmer time". Not a fan.
This rule of thumb is clearly too simplified, even as far as the definition goes. Sometimes you just want to execute 50 lines with little logic. Sometimes you just have some simple logic that needs to be repeated. Sometimes that logic is complicated, sometimes it is not.
Sometimes someone writes 50 lines of simple logic. And then sometimes someone else needs to figure out why it’s not working. That person gets very cranky and wastes a lot of time when those “simple” 50 lines aren’t debuggable.
If shell scripting didn’t exist I would be totally fine with that. There are far more scripts that I wish were written in a real language than the other way around.
Re: Pnut: A C to POSIX shell compiler you can trust
#47If the end goal is portability for C, would Cosmopolitan Libc be a better choice because it supports a lot more features and probably runs faster?
I cant run cosmolibc on Android, for example. Then again this converter is somewhat limited and didn't accept any of the IOCCC code I gave it.
> I cant run cosmolibc on Android, for example.
You can:
> After nearly one year of development, I'm pleased to announce our version 3.0 release of the Cosmopolitan library. [...] we invented a new linker that lets you build fat binaries which can run on these platforms: AMD ... ARM64
https://github.com/jart/cosmopolitan/releases/tag/3.5.3
> This release fixes Android support. You can now run LLMs on your phone using Cosmopolitan software like llamafile. See 78d3b86 for further details. Thank you @aj47 (techfren.net) for bug reports and and testing efforts.
Re: Pnut: A C to POSIX shell compiler you can trust
#48Earlier quoted context omitted.
Author here, That's correct! Unlike Bash and other modern shells, the POSIX standard doesn't include arrays or any other data structures. The way we found around this limitation is to use arithmetic expansion and indexed shell variables (that are starting with `_` as you noted) to get random memory access.
Since I experimented with something similar in the past to mimick multidimensional arrays: depending on the implementation this can absolutely _kill_ performance. IIRC, Dash does a linear lookup of variable names, so when you create tons of variables each lookup starts taking longer and longer.
I hope you're not compiling C to sh for performance reasons.
Re: Pnut: A C to POSIX shell compiler you can trust
#49Earlier quoted context omitted.
I cant run cosmolibc on Android, for example. Then again this converter is somewhat limited and didn't accept any of the IOCCC code I gave it.
> I cant run cosmolibc on Android, for example. You can: https://justine.lol/cosmo3/ > After nearly one year of development, I'm pleased to announce our version 3.0 release of the Cosmopolitan library. [...] we invented a new linker that lets you build fat binaries which can run on these platforms: AMD ... ARM64 https://github.com/jart/cosmopolitan/releases/tag/3.5.3 > This release fixes Android support. You can now…
Thanks for the link!
My comment was based on cloning master yesterday and trying to build redbean but hitting what looks like https://github.com/jart/cosmopolitan/issues/940
Indeed it lioks like the commit you mentioned should have fixed the issue with the pointer having too many bits for the weird kernel used on android and some raspis. Fingers crossed that release works.
edit:
Testing that release on Termux 118, stock Android 14 on a moto g73 5G (XT2237-2):
~/cosmopolitan $ uname -a
Linux localhost 5.10.205-android12-9-00027-g4d6c07fc6342-ab11525972 #1 SMP PREEMPT Mon Mar 4 18:49:33 UTC 2024 aarch64 Android
~/cosmopolitan $ /data/data/com.termux/files/home/cosmopolitan/build/bootstrap/cocmd
ape error: /data/data/com.termux/files/home/cosmopolitan/build/bootstrap/cocmd: prog mmap failed w/ errno 12Re: Pnut: A C to POSIX shell compiler you can trust
#50If you are wondering how it handles C-only functions.. it does not. open(..., O_RDWR | O_EXCL) -> runtime error, "echo "Unknow file mode" ; exit 1" lseek(fd, 1, SEEK_HOLE); -> invalid code (uses undefined _lseek) socket(AF_UNIX, SOCK_STREAM, 0); -> same (uses undefined _socket) looking closer at "cp" and "cat" examples, write() call does not handle errors at all. Forget about partial writes, it does not even return -…
maybe access to libc functions can be achieved through something like https://github.com/taviso/ctypes.sh>. Although that very specific implementation seems to require explicitly bash and is not broadly POSIX Shell compatible as Pnut wants to be.