> fs.readdirSync('./upload/')
[ 'c21142262b6e78eeeed5ddbc173efe0d.jpg',
  '3e90077423737f7986a559a355631046.jpg',
  '8a3aee002f1740d3ec4f1eba3d703b8c.jpg',
  'df5f8c5af3311df01d002bbdcdb89925.jpg',
  '5074358977fdcbca7667571f7246004e.jpg',
  '85baa7049a7b87e9b35369a01aae33b9.jpg',
  '62e9071d0b685f32d423e3d74c3eaab1.jpg',
  
 
'65bd0cb519c557fd4f519ae5bef1b97d.jpg' ]
> var jpg = gm('./upload/' + fs.readdirSync('./upload/')[0]);
undefined
> jpg.size(function(){console.log(arguments);});
{ domain: null,
  _events: { size: [Function] },
  _maxListeners: 10,
  _options: {},
  data: {},
  _in: [],
  _out: [],
  _outputFormat: null
 
,
  _subCommand: 'convert',
  source: './upload/c21142262b6e78eeeed5ddbc173efe0d.jpg',
  _sourceFormatters: [ [Function] ],
  bufferStream: false }
> { '0': undefined, '1': { width: 1280, height: 800 } }