This shell should be both POSIX compatible and yet modern and exciting. Fancy features should not be prevented by POSIX compatibility. This will effect the design of the shell.
The name of the shell is oursh
which is both somewhat unique, and memorable.
It's also a nice name to play with pseudo-satirical themes... right comrade?
It's short (ish) and sneakily fits rs
in it, which is the extension of Rust
programs, the language this will be written in.
- POSIX compatibility
- Simple commands
ls
- Quotes
echo "foo"; echo 'bar'
- Assignment
LOG=trace cargo run
- Variables
echo $foo
- Special variables
echo $?; echo $1
- Boolean status syntax
! true && false || true
- Conditionals
if ; then ; elif ; then ; else ; fi
- Compound commands
{ ls; date; }
- Subshells
(sleep 1; date)
- Background jobs
{ sleep 1; date; }& date
- Redirection
date > now.txt
- Pipes
ls | wc -l
- Simple commands
- Shebang block programs
- Alternate syntax
{# ...}
- Hashlang syntax
{#lang; ...}
, i.e.{#posix ls}
- Shebang syntax
{#!/usr/bin/env ruby; puts :sym}
- Alternate syntax
- bash/zsh autocomplete compatibility
- Command completion
- Path completion
- Variable completion
- Job completion
- Syntax completion
-
man
/-h
/--help
parsing
- Multi-line input
- Modern scripting language
- Macros
- Types
- Higher-order functions
- Threading?
- Obfuscated strings (
!'password'!
) - mosh like remote session support
- Smart history, sync'd across devices
- Pipe old commands without rerunning
- Package manager
- Sane defaults
- Fast
While this project is in early stages, there are no OS packages to use.
However, you can compile and run directly from source easily. Just ensure you
have rustup
installed.
cargo build
cargo run
We have four kinds of tests in this program. Crate unit tests, Executable unit tests, subprocess based integration tests, and documentation tests.
# Run all tests.
cargo test
I've been using fish
as my main shell for a few years now. Fish
inspires a lot of the modern syntax.
POSIX compatibility comes from my desire to use this shell as my chsh -s ...
shell on Arch Linux. See the full POSIX reference for more information.
Some of the shebang language interoperation was inspired by my time with the
Northeastern University PL group, and generally from writing Racket.
The beauty of of merging the UNIX style #!...
with Racket's #lang ...
here
is very exciting to me. I might just have to make a {#lang ...}
shortcut
for Racket!
I've built and wrote a few things about shells before:
rush
A glorified homework assignment for computer architectureshell.py
My submission for computer organization a8- Building a Shell - Part 1 Start of this project
- Building a Shell - Part 2
program
module intro
See the following sections for building the POSIX sh
compliant program
language, and interactive terminal based REPL.
- 3§2 Shell Command Language
- 10.2 Shell Grammar Rules
- 2§2.5 Standard I/O Streams
- 3§1.6 Built-In Utilities
- 3§1.4 Utility Description Defaults
- 2§2.3 Error Numbers
- 1§11 General Terminal Interface
- 2§2.4 Signal Concepts
This shell will be written in Rust with minimal dependencies. Notably termios and libc will likely be used. The parsing library will be lalrpop, which should support the syntax we want somewhat easily, though grammar's in general can be a tricky beast.
We will want to create a few internal modules for the shell.
This design is subject to change.
job
- sub-process execution management.program
- parser and interpreter for the syntax of the shell.posix
- POSIX (sh
-like) syntax.modern
- Modified syntax for supporting "modern" features, like lambdas.
repl
- syntax aware, read eval print loop for an underlying terminal.history
- records previous execution to a shared DB.completion
- searches for autocompletions based on partial syntax.bash
- bash completion support.zsh
- zsh completion support.parse
- dynamic completion generation, fromman
for example.
sync
- remote session and DB synchronization.
config
- loading for.ourshrc
and others.package
- simplistic package manager support (builtin function).
Current modules as of: 2018-10-14
oursh : crate
├── job : public
├── program : public
│ ├── basic : public
│ └── posix : public
│ ├── ast : public
│ │ └── tests : private @ #[cfg(test)]
│ ├── builtin : public
│ └── lex : public
│ └── tests : private @ #[cfg(test)]
├── repl : public
│ ├── completion : public @ #[cfg(feature = "completion")]
│ └── history : public @ #[cfg(feature = "history")]
└── tests : private @ #[cfg(test)]└── tests : private @ #[cfg(test)]