Sheller

🐚 Sheller is a shell command builder and standard command extension library written in Rust.

Why I Made This

I use Rust to write utility functions for managing Rust library and application projects.
For example, calling cargo clippy -- -D clippy::all -D clippy::pedantic.
Currently, this project is also a Rust project. Therefore, I wrote utility functions in Rust.

Let's take an example of the Git pre-push hook that verifies before pushing to Github.
The .cargo-husky/hooks/pre-push file of this project is a file that is copied to .git/hooks/pre-push when the Cargo project is set up, and when git push is called, this script is called before a push is actually made.
The implementation of this script is, to put it exaggeratedly, one line: cargo run --package tool-dev -- pre-push.
The script calls the Rust command line in one line. And the actual implementation is written in Rust code.
Within the code, call the command line again, such as cargo check ..., cargo clippy ..., cargo fmt ..., and cargo test ....

There are three reasons why it was written in Rust.

First, the syntax of Unix Shell or Windows Batch scripts is very difficult.
There is no major problem when writing one or two lines.
However, management requirements are gradually increading.
Conditional statements, loop statements, and function syntax are also not intuitive by my standards.
Since I can't memorize the syntax, I have to look up Stack Overflow or ask Chat GPT every time.

Second, to use easy JavaScript or Python, I need to add a dependency to the project development environment.
In fact, installing Node.js or Python runtime in my development environment doesn't require much effort.
However, Rust also has a convenient tool called cargo run.
Depending on the size of the project, the build may take quite a while.
However, once dependent libraries are built, no additional builds occur even if they are called multiple times.
So, the developer experience is not bad after the first build.

Third, I am a Rust newbie.
The Rust project was first started in 2024, when this article was written.
To become proficient, whenever I get a chance to program something, I try to write it all in Rust.

The introduction was long.
To get straight to the point, it's because of npm install.
To explain cause and effect, it is as follows.
I started a project to write a TypeScript compiler in Rust.
I was writing code in Rust to install the TypeScript sample project in the development environment.
To call npm install in Rust, I must call the shell command and pass npm install as an argument.
This is because the npm command is a script, not an executable file.
Because it is a script, it must be passed as an argument to the shell command.
And this shell command is largely different for each Windows and Unix platform.
The goal is not to create platform-independent scripts.
The goal is to be able to call command lines in a shell environment.

For this reason, I created the Sheller library.
This is to write utility functions in the Rust project I use, or to use them in a Rust application if needed in the future.

How to Use

Add sheller to your dependencies.

# Cargo.toml
[dependencies]
sheller = "0.2"

Below are examples using sheller.

⚠️ If you don't see the run method, check use sheller::CommandExt.

If you simply want to run a shell script, use it as follows.

use sheller::{CommandExt, Sheller};

Sheller::new("echo hello").run();
// The log below is output to stdout.
// 🐚 $ Running command: "/bin/bash" "-c" "echo hello"
// hello

If you don't want panic, you can use the Sheller::try_run methods to receive and process std::io::Result<()>.

use sheller::{CommandExt, Sheller};

// if the function returns std::io::Result<T>
Sheller::new("echo hello").try_run()?

// if the function does not return NOT std::io::Result<T>
Sheller::new("echo hello").try_run().map_err(|e| {
    // transform error
})?;

run and try_run use default configurations.
Configuration has the values prefix and writer.
The default value for prefix is "🐚 $ ".
The default value for writer is std::sync::Mutex::new(Box::new(std::io::stdout())).
This prefix and writer are used to print which command is executed before actually running, or which command is called when an error occurs.

If you want to change the configurations, please follow the example below.

use sheller::{CommandExt, Config, Sheller};

// binding to variable 
let config = Config {
    prefix: "🦀 $ ".to_string(),
    ..Default::default()
};
Sheller::new("echo hello").run_with_config(&config);

// without binding to variable
Sheller::new("echo hello").run_with_config(&Config {
    prefix: "🦀 $ ".to_string(),
    ..Default::default()
});

The Sheller::run_with_config method generates panic of the command failes.
If you do not want panic to occur, please use Sheller::try_run_with_config to process std::io::Result<()>.

Sheller uses std::process::Command.
If you want to change the current working path, stdout/stderr or environment variables, use the Sheller::build method.
This method returns std::process::Command.

Below is an example of changing the current working path.

use sheller::{CommandExt, Sheller};

let mut command = Sheller::new("echo hello").build();
command.current_dir("/my/dir").run();

Likewise, run, run_with_config, try_run and try_run_with_config can all be used.

In addition to the four methods above, you can of course also use the Rust official std::process::Command methods.
For more information about std::process::Command, please check the Rust official page.

The run, run_with_config, try_run, and try_run_with_config methods are implemented as CommandExt.
The purpose of these methods is utility.
So you don't necessarily have to use Sheller.

Below is an example that uses only CommandExt without using Sheller.

use sheller::{CommandExt};

let mut command = std::process::Command::new("echo");
command.arg("hello").run();

Internal Implementation

Windows

When target_family is windows.
Set the COMSPEC environment variable to program, and if the environment variable is not set, use cmd.exe as the fallback program.
Also set the args to ["/D", "/S", "/C"].

Unix