var argv = require('minimist')(process.argv.slice(2));
var exec = require('child_process').execSync;

// 1: Get usb/serial ports
try {
    var ports = exec('ls /dev/*usb*');
} catch (e) {
    // e is 'ls: /dev/*usb*: No such file or directory'
    console.error('No USB ports/devices detected');
    return 1
}

ports = ports.toString().trim().split("\n");

// 2: Check for port-by-list-index
if ('i' in argv) {
    let i = parseInt(argv['i'], 10);

    if (isNaN(i) || i >= ports.length){
        console.error(`invalid index: ${argv['i']}`);
        return 1;
    }
    console.log(ports[i]);
}