Show HN: Using Rust to write shell-script like tasks • Hacker News Board

Re: Show HN: Using Rust to write shell-script like tasks

#51

Post by rattray » Sun, Aug 23, 2020, 1:39 PM UTC

geowwy wrote: post #11

> A lot developers just choose shell(sh, bash, ...) scripts for such tasks, > by using to redirect output and '|' to pipe outputs. > In my experience, this is the only good parts of shell script. If you try to use shell as a general purpose programming language, of course it sucks. If you treat shell as a DSL for files and streams, nothing can beat it. Shell is amazing. I'm sceptical a bunch of Rust macros can beat s…

> If you treat shell as a DSL for files and streams, nothing can beat it.

That sounds exactly like the approach of this crate - easily let you use "the files and streams DSL" directly from a general purpose programming language (Rust). You get full access to shell, but only need to use it where it's useful.

I've done the same thing many times with Python, Node, and Ruby, just with template strings which isn't as pretty as this rust macro (even if the latter can be a bit mysterious)

Re: Show HN: Using Rust to write shell-script like tasks

#52

Post by sneak » Sun, Aug 23, 2020, 1:42 PM UTC

Does anyone know of something similar for Go?

Re: Show HN: Using Rust to write shell-script like tasks

#53

Post by MetaDark » Sun, Aug 23, 2020, 1:54 PM UTC

darthrupert wrote: post #23

If this is a fun proof of concept, it's nice. If somebody uses this in an actual system, it's terrifying. edit oh, Rust is now a thing where even the bad ideas need to be praised without caveats. Gotcha

I don't think you deserve to be down voted for this. You bring up a valid concern. Although, I don't agree that this project should be outright dismissed either.

So many times, I've run into the issue where I've wanted to chain a set of commands with a concise syntax (specifically in Python) without having to shell out to bash.

What I really like about this library is that it gives you the concise composability of bash, without having to deal with its pitfalls (eg. variable escaping, lack of Windows support, clunky interface for anything that's not a command invocation...).

Using a DSL will always come with certain tradeoffs, and it won't be the best solution for every use case, but I think this library fills a certain need very well.

Re: Show HN: Using Rust to write shell-script like tasks

#54

Post by rustshellscript » Sun, Aug 23, 2020, 2:06 PM UTC

oconnor663 wrote: post #49

I'm going to shamelessly plug my own library here: https://github.com/oconnor663/duct.rs I wanted to solve the same problem, originally in Python ( https://github.com/oconnor663/duct.py ). It's surprisingly annoying to do pipelines and redirections, compared to how easy they are to do in the shell. Lots of libraries try to address this, but most of them seem do it by emulating shell syntax within the host language, u…

It can be supported with internal APIs, even without macros: Cmds::from_cmd(Cmd(...).current_dir(..)) .pipe(Cmd(...).current_dir(...)) .run_cmd(...)

As you can see, it is very verbose and that's why I choose to hide the lower APIs at this moment.

Re: Show HN: Using Rust to write shell-script like tasks

#55

Post by joobus » Sun, Aug 23, 2020, 2:17 PM UTC

rustshellscript wrote: post #54

oconnor663 wrote: post #49

I'm going to shamelessly plug my own library here: https://github.com/oconnor663/duct.rs I wanted to solve the same problem, originally in Python ( https://github.com/oconnor663/duct.py ). It's surprisingly annoying to do pipelines and redirections, compared to how easy they are to do in the shell. Lots of libraries try to address this, but most of them seem do it by emulating shell syntax within the host language, u…

It can be supported with internal APIs, even without macros: Cmds::from_cmd(Cmd(...).current_dir(..)) .pipe(Cmd(...).current_dir(...)) .run_cmd(...) As you can see, it is very verbose and that's why I choose to hide the lower APIs at this moment.

I like your approach more than duct.rs :)

Re: Show HN: Using Rust to write shell-script like tasks

#56

Post by staktrace » Sun, Aug 23, 2020, 2:49 PM UTC

I wrote a tool to do the opposite thing: allow writing "shell scripts" using Rust. Still early days but https://github.com/staktrace/khaki is where it lives.

Re: Show HN: Using Rust to write shell-script like tasks

#57

Post by laumars » Sun, Aug 23, 2020, 3:11 PM UTC

oconnor663 wrote: post #49

I'm going to shamelessly plug my own library here: https://github.com/oconnor663/duct.rs I wanted to solve the same problem, originally in Python ( https://github.com/oconnor663/duct.py ). It's surprisingly annoying to do pipelines and redirections, compared to how easy they are to do in the shell. Lots of libraries try to address this, but most of them seem do it by emulating shell syntax within the host language, u…

‘cd’ is a shell builtin so you couldn’t use ‘cd’ in any of these solutions unless they then spawn a shell instance...and that worries me if you are because then you really might as well just have a separate .sh file and launch that instead (at least that is more auditable with tools like Shellcheck than any inlined code would be).

Re: Show HN: Using Rust to write shell-script like tasks

#58

Post by zelphirkalt » Sun, Aug 23, 2020, 3:14 PM UTC

kazinator wrote: post #6

laumars wrote: post #4

Please people, don’t do stuff like this for anything other than personal projects. You might think it’s safer than writing Bash but it isn’t. It results in unsafe Rust code since you’re now forking external code that might be missed by people who are strictly vetting for code inside “unsafe” blocks. Ironically anyone who writes she’ll scripts will know that there are problems with shell scripting but thankfully dot-s…

> unsafe Rust ... since you’re now forking external code Are you saying that Rust becomes unsafe because it used a C program as a subroutine? E.g. "tar xvf -" or whatever? What is the fix: rewrite tar, awk, scp and whatever else as Rust functions? That's a lot of work. I'm surprised that you're simultaneously overlooking what ought to be a more gaping problem: that every system call made by a Rust program is a trip t…

Actually I think Python did that? There is tarfile in the standard library and in my experience it worked quite well. So perhaps that is actually the answer. I do not know how tarfile is implemented though, so pergaps it is itself using any available tar implementation?

Re: Show HN: Using Rust to write shell-script like tasks

#59

Post by hnlmorg » Sun, Aug 23, 2020, 3:17 PM UTC

rossmohax wrote: post #48

Nothing can fix the fact, that pipes carry dumb byte streams. Powershell addressed this, but sadly remains unpopular in Unix crowd

Actually there are several shells out there that fix that problem and still support existing UNIX tools too (which Powershell doesn't play nice with).

My own shell, https://github.com/lmorg/murex does this by passing type information along with the byte stream. So _murex_ aware tools can have structured data passed and POSIX tools can fall back to byte streams. Best of both worlds.

The problem, however, is that as long as Bourne Shell and Bash are installed everywhere, people will write scripts for it. This is less about the popularity of UNIX tools and more about the ubiquity of them (though the two points aren't mutually exclusive).

Re: Show HN: Using Rust to write shell-script like tasks

#60

Post by IshKebab » Sun, Aug 23, 2020, 3:26 PM UTC

foota wrote: post #30

IshKebab wrote: post #10

Earlier quoted context omitted.

I agree, this is a misguided idea. The whole point of not using Bash is that you don't have to use it's terrible design and syntax surely?

This only seems to use the good parts of the shell, easy piping and redirection, while dropping the language for logic.

It also appears to use some bad parts, e.g. command line switches and unquoted arguments.