fatCopy.js

var fs = require('fs'),
   spawn = require('child_process').spawn;

var dataFiles = fs.readdirSync('./data');

function spawnAsPromise() {
  var args = Array.prototype.slice.call(arguments);
  return new Promise(function(resolve, reject) {
    var stdout = '', stderr = '';
    var cp = spawn.call(null, args.shift(), args, {cwd: __dirname});
    cp.stdout.on('data', function(chunk) {
      stdout += chunk;
    });
    cp.stderr.on('data', function(chunk) {
      stderr += chunk;
    });
    cp.on('error', reject)
      .on('close', function(code) {
        if (code === 0) {
          resolve(stdout);
        } else {
          reject(stderr);
        }
      });
  });
}

function logAndExit (err) {
  console.error('ERROR:', err);
  process.exit(1);
}

// ----------------------------------------------------------------------------


if(!dataFiles.length) {
  logAndExit('No files found in data directory!');
}

spawnAsPromise('diskutil', 'list')
  .then(function (result) {
    return result.split('\n')
      .filter(function (line) {
        return line.match(/DOS_FAT_32/);
      })
      .map(function (line) {
        return line.split(/\W+/).pop();
      });
  })
  .then(function (diskIds) {
    if(!diskIds.length) {
     logAndExit('No FAT disks found!');
    }

    // get mount points
    return Promise.all( diskIds.map(function (id) {
      return spawnAsPromise('diskutil', 'info', id)
        .then(function (result) {
          return result.split('\n').reduce(function (prev, line){
            if (prev) { return prev; }
            var m = line.match(/Mount Point:\s+(\/Volumes\/.+)$/);
            return m && { id: id, mountPoint: m[1] };
          }, null);
        });
    }) );
  })
  .then(function (disks) {

    return Promise.all(disks.map(function (disk) {
      console.log(disk);

      return Promise.all( dataFiles.map(function (one) {
        console.log('copying', one, 'to', disk.mountPoint);
        return spawnAsPromise('cp', 'data/'+one, disk.mountPoint+'/'+one);
      }))
      .then(function () {
        console.log('renaming', disk.id);
        return spawnAsPromise('diskutil', 'rename', disk.id, 'WHATEVER');
      })
      .then(function () {
        console.log('ejecting', disk.id);
        return spawnAsPromise('diskutil', 'eject', disk.id);
      });

    }))
  })
  .then(function () {
    console.log('\nall done!');
  });