build.js

var task = require("monk")
var shell = require("monk-shell")

var buildTask = task("build", function (rule) {
    rule("hello.c", "hello.o",
        shell("gcc -Wall -c %i -o %o"))
        
    rule("square.c", "square.o",
        shell("gcc -Wall -c %i -o %o"))
    
    rule(["hello.o", "square.o"], "hello",
        shell("gcc %i -o %o"))  
})

module.exports = buildTask

if (require.main === module) {
    buildTask()
}

shell.js

var exec = require("child_process").exec

module.exports = shell

function shell(command) {
    return function (input, output, callback) {
        var cmd = command.replace("%i", input).replace("%o", output)
        
        exec(cmd, function (err, stdout, stderr) {
            callback(err)
        });
    }
}