Redstart - A Lisp Interpreter for Shell Scripting

Redstart (named after the bird) is a lightweight Lisp interpreter written in C++ with a focus on shell scripting. It lets you combine the expressive power of Lisp with the practicality of the Unix shell: you can run commands, capture output, pipe between processes, and still use Lisp syntax for logic and structure. Think of it as writing your shell scripts in Lisp instead of Bash.

How to install

bash <(curl -s https://raw.githubusercontent.com/gue-ni/redstart/refs/heads/master/tools/install.sh)

Quickstart

# Start the REPL
rst

# Run a script
rst my_script.lsp

Examples

; pipe output of 'ls' to 'grep'
(pipe (sh ls -la) (sh grep "*.txt"))

; save the output of 'cat' to variable 'content'
(defvar content ($ (sh cat "my-file.txt")))

; pipe the output of the function 'hello' into the 'rev' command
(defun hello (name)
  (strcat "Hello " name "!"))

(pipe (<<< (hello "Jakob")) (sh rev))
; => !bokaJ olleH

; eqivalent to 'sudo apt update && sudo apt upgrade -y' in bash
(and (sh sudo apt update) (sh sudo apt upgrade -y))

; define a function that uses 'scp' to upload some files to a server
(defun upload (source)
  (let ((user "root")
        (host "example.com")
        (target-dir "/var/www/files/")
        (target (strcat user "@" host ":" target-dir)))
    (sh scp source target)))

; execute 'ls' command, capture result
($ (sh ls))

; use _ to access result of last expression, split on newline
(defvar files (split "\n" _))

; upload all files
(for-each upload files)

; recursive functions
(defun factorial (n)
    (if (= n 0)
        1
        (* n (factorial (- n 1)))))

(factorial 5) ; => 120

; closures
(defun make-adder (a)
  (lambda (b) (+ a b)))

(defvar add5 (make-adder 5))

(add5 3) ; => 8

Documentation

• Getting Started
• Shell Scripting