kryndex / ion

The Ion Shell. Compatible with Redox and Linux.

Ion Shell

Ion is still a WIP, and both it's syntax and rules are subject to change over time. It is still quite a ways from becoming stabilized, but we are getting very close. Changes to the syntax at this time are likely to be minimal.

Ion Manual

We are providing our manual for Ion in the form of a markdown-based book, which is accessible via:

• The official page for Ion's manual on Redox's website: https://doc.redox-os.org/ion-manual/
• Installing the mdbook via our setup.ion script and having Ion open an offline copy via ion-docs.
• Building and serving the book in the manual directory yourself with mdBook

Note, however, that the manual is incomplete, and does not cover all of Ion's functionality at this time. Anyone willing to help with documentation should simply do so and submit a pull request. If you have any questions regarding certain implementation details, feel free to ask in whichever venue you are most comfortable with.

Contributors

Guidelines

Code Formatting

When submitting a pull request, be sure to run env CFG_RELEASE_CHANNEL=nightly cargo +nightly fmt on your project with a nightly version of rustfmt. This will prevent me from having to push PR's specifically to format the code base from time to time. To install rustfmt-nightly, simply run cargo install rustfmt-nightly --force.

On Unit & Integration Tests

If you see an area that deserves a test, feel free to add extra tests in your pull requests. When submitting new functionality, especially complex functionality, try to write as many tests as you can think of to cover all possible code paths that your function(s) might take. Integration tests are located in the examples directory, and are the most important place to create tests -- unit tests come second after the integration tests.

Integration tests are much more useful in general, as they cover real world use cases and stress larger portions of the code base at once. Yet unit tests still have their place, as they are able to test bits of functionality which may not necessarily be covered by existing integration tests.

In order to create unit tests for otherwise untestable code that depends on greater runtime specifics, you should likely write your functions to accept generic inputs, where unit tests can pass dummy types and environments into your functions for the purpose of testing the function, whereas in practice the function is hooked up to it's appropriate types.

Issue Board

Please visit the issue board for a list of curated issues that need to be worked on. If an issue has the WIP tag, then that issue is currently being worked on. Otherwise, the issue is free game. Issues are also labeled to guide contributors into finding problems to tackle at a given skill level. Not to worry though, because most issues within Ion are relatively simple C-Class issues. The most difficult issues are marked as A-Class.

Chatroom

Send an email to [email protected] to request invitation for joining the developer chatroom for Ion. Experience with Rust is not required for contributing to Ion. There are ways to contribute to Ion at all levels of experience, from writing scripts in Ion and reporting issues, to seeking mentorship on how to implement solutions for specific issues on the issue board.

Discussion

In addition to the chatroom, there's a thread in the Redox forums that can be used for discussions relating to Ion and Ion shell development. These are mostly served by the GitHub issue board, but general discussions can take place there instead.

Introduction

Ion is a modern system shell that features a simple, yet powerful, syntax. It is written entirely in Rust, which greatly increases the overall quality and security of the shell, eliminating the possibilities of a ShellShock-like vulnerability , and making development easier. It also offers a level of performance that exceeds that of Dash, when taking advantage of Ion's features. While it is developed alongside, and primarily for, RedoxOS, it is a fully capable on other *nix platforms.

Why Not Windows Support?

Windows is not, and may never be supported due to certain limitations in the NT kernel. Namely, where in all non-Windows operating systems, the kernel takes an array of strings that defines the command to execute, and all of that command's arguments; Windows instead takes a single string that contains both the command and all of it's arguments. This pushes the job of parsing arguments from the system shell onto the individual program, and may account for why the command-line in Windows is so funky.

In addition, Windows does not support forking, a concept by which a new sub-process is spawned with the same state as the parent, for the purpose of continuing execution down a different path from the parent. This enables for subshells to be spawned, as commonly seen by process expansions ($()), among piping builtins and functions.

Goals

Syntax and feature decisions for Ion are made based upon three measurements: is the feature useful, is it simple to use, and will it's implementation be efficient to parse and execute? A feature is considered useful if there's a valid use case for it, in the concept of a shell language. The syntax for the feature should be simple for a human to read and write, with extra emphasis on readability, given that most time is spent reading scripts than writing them. The implementation should require minimal to zero heap allocations, and be implemented in a manner that requires minimal CPU cycles (so long as it's also fully documented and easy to maintain!).

It should also be taken into consideration that shells operate entirely upon strings, and therefore should be fully equipped for all manner of string manipulation capabilities. That means that users of a shell should not immediately need to grasp for tools like cut, sed, and awk. Ion offers a great deal of control over slicing and manipulating text. Arrays are treated as first class variables with their own unique @ sigil. Strings are also treated as first class variables with their own unique $ sigil. Both support being sliced with [range], and they each have their own supply of methods.

Compile / Install Instructions

Rust nightly is required for compiling Ion. Simplest way to obtain Rust/Cargo is by installing the Rustup toolchain manager, in the event that your OS does not ship Rust natively, or if you want more flexibility in Rust compilation capabilities.

Then, it's just a matter of performing one of the following methods:

Install Direct From Git

cargo install --git https://github.com/redox-os/ion/

Build Locally

git clone https://github.com/redox-os/ion/
cd ion && cargo build --release

Git Plugin

Plugins support within Ion is still a work in progress, and so the plugin architecture is likely to change. That said, there's an official git plugin that can be installed to experiment with the existing plugin namespaces plugin support. To install the git plugin, first install ion, and then execute the following:

./setup.ion install plugins

It can be tested out by navigating to a directory within a git repository, and running the following:

echo Current Branch: ${git::branch}${git::modified_count}${git::untracked_count}

Vim/NeoVim Syntax Highlighting Plugin

We do have an officially-supported syntax highlighting plugin for all the vim/nvim users out there.

Plugin 'vmchale/ion-vim'