Lul

Lul is a lightweight command runner, inspired by tools like just and if you squint hard enough, perhaps GNU Make.

Like just, lul is a command runner, not a build tool, but unlike it, it uses an embedded Lua runtime, so what you get is a full-blown Lua (actually, Luau) interpreter.

At its core, lul aims to be uncomplicated and stay out of your way: If you already know Lua, there's very little to learn: When invoked as lul <taskname> lul will locate the nearest lulfile[1] will load it as a lua script and invoke the function called <taskname> in it. Simple!

The other thing lul does for you is providing a set of builtin functions that will make your life easier when writing scripts. This list is currently evolving so check the source code in lua/prelude.lua for a quick summary.

[1]: Lulfile, lulfile.lua and .lulfile are also accepted.

Installation

Welcome lurker! You've just witnessed the birth of this tool, and thus, there are no binaries ready.

If you insist, you'll have to get your hands dirty with cargo, the rust build tool:

Install a Rust compiler toolchain (visit rustup.rs for instructions)
Clone this repository

git clone https://github.com/setzer22/lul

Build the project

cd lul
cargo build --release

Copy the resulting binary wherever you want, you'll find it under target/release/lul

Example

Here's an example lulfile to get you started. Note how task functions must be prefixed by a comment -- @task.

local buildDir = "./webapp/build"

-- @task
function setup()
    sh(`npm install`)
end

-- @task
function start()
    sh(`node webapp/app.js`)
end

-- @task
function test()
    sh(`npm test`)
end

-- @task
function build()
    sh(`npm run build --prefix webapp`)
    print(`Build completed. Files are in {buildDir}`)
end

-- @task
function deploy()
    build()
    sh(`scp -r {buildDir} user@deployment-server:/path/to/deployment`)
    print("Deployment successful.")
end

Why Luau and not Lua?

The reason Luau was chosen is that it supports string interpolation, something that is invaluable during scripts:

This:

sh("tar -czvf" .. buildsdir .. " -C " .. publishdir .. " .")

Becomes this:

sh(`tar -czvf {buildsdir} -C {publishdir} .`)

Did you spot the bug in that first version? :)

Disclaimer

Like most open source software, this tool scratches an itch, and the time I can devote to its maintenance beyond supporting my use case is limited. I am sharing this in hope it can be useful to others in its current state, but please understand I am unable to fulfill feature requests and review external contributor PRs in general.