var fs = require('fs');  
var txt = '\n' + tkn_psid_id + ':' + assetUrl;
var folderName = '/duplicates/bugging/videobug/' + tkn_psid_id + '.txt';
fs.appendFile(folderName, txt, function (err) {
       if (err) {
                console.log('Append Error');
           } else {
                   console.log('DuplicateFolder' + folder);
            }
      });