code: function makeRootDir(dest, cwd, savedir, callback) {
    let root = path.join(cwd, (savedir || ''), dest.split('/')[0]);
    console.log('delete: ', root)
  
    // 保存先フォルダがすでにある場合は一旦削除する
    let rm = 'if [ -e '+ root +' ]; then rm -rf ' + root + '; fi';
    let removed = exec(rm, (error, stdout, stderr) => {
      if (error !== null) throw ('[Error: makeRootDir:] ' + error);
    }).on('close', () => {
      // 削除後、保存先フォルダを作成
      let maked = exec('mkdir ' + root).on('close', () => {
        return callback && callback();
      });
    });
  }
docs: /*
  Make Root Dir
  @param {String} root
  @param {Function} callback