hellspawn.js

// stupid Node.js tricks
// accepts JS object literal of commands & their args
// executes each in series, pipes child process output to parent
// e.g. `node hellspawn.js '{"ls": "-al", "pwd": null, "echo": "Hello world!"}'`
var spawn = require('child_process').spawn
    , cmds = JSON.parse(process.argv[2])
    , cmd
    , key
    , val;

for (key in cmds) {
    if (cmds.hasOwnProperty(key)) {
        val = cmds[key];

        // spawn's 2nd param is an array so ensure we're passing it one
        if (typeof val === 'string' || typeof val === 'number') {
            cmd = spawn(key, [val]);
        } else if (Array.isArray(val)) {
            cmd = spawn(key, val);
        } else {
            // assume there's no argument
            cmd = spawn(key);
        }

        // pipe child's output to parent
        // otherwise it isn't visible on cli
        cmd.stdout.pipe(process.stdout);
        cmd.stderr.pipe(process.stderr);
    }
}