LISH

Lish is a unix shell emulator written in Rust. Lish uses a lisp syntax instead of the traditional POSIX shell.

Building

Clone the repository then run cargo build.

Using

Run the built binary ./target/debug/lish. The shell will start with a simple dollar sign prompt. Type in your command and have fun.

What can Lish do?

History (up/down arrow keys)
Line editing (left/right arrow keys, DEL, Home, End, etc.)
Ctrl-c to quit current command
Custom prompt (define a function named prompt)
Startup file (~/.config/lish/init.lisp)

Why Lisp

Lisp is a rather odd choice for a shell language. I'll admit that. I choose it mainly out of curiosity to see if it could work. For the most part it does. There are a few times when the syntax gets a little messy, but I tried to design Lish and the Lazuli language it uses to be simple for simple commands. Allowing the user to use advanced syntax if needed but not force it.

For example, when using Lish as a command prompt, the outer most parentheses aren't necessary. They're added in by the shell. This makes simple commands look like most other shells. For example the usage of echo doesn't change. echo Hello is valid Lish as it is valid POSIX sh. The only difference is internally, Lish is actually executing (echo Hello).

Builtins

(call VAL...) - Call an external application, default handler for vm symbol not found.
(capc VAL...) - Like call but forces a map return with process output and status.
(cd NEW-PATH) - Change current working directory.
(exit [CODE]) - Exit shell.
(export SYMBOL) - Export environment variable.
(unexport SYMBOL) - Unexport environment variable.
(pipe ()[ ()...]) - Connect output and input for a chain of commands.
(| ()[ ()...]) - Alias for (pipe).
(pwd) - Return current working directory
(prompt) - Called on each interactive loop. This function must return a string which will be used as the user prompt. Note that multi-line prompts have a few bugs.

TODO

Tests
Run commands in the background
Implement redirection