code: function executeCommand(cmd, option) {
      option = option || {};
      return new Promise((ac, rj)=>{
          let okMsg = '';
          let erMsg='';
          log('Exec:'+cmd.join(' '));
          let child;
          if (option.sudo) {
              child = sudo(cmd, {password: option.password});
          } else {
              child = spawn(cmd[0], cmd.slice(1));
          }
          child.stdout.on('data', (dat)=>{
              okMsg += dat.toString();
          });
          child.stderr.on('data', (dat)=>{
              erMsg += dat.toString();
          });
          child.on('close', (code)=>{
              if (code == 0) {
                  ac(okMsg);
              } else {
                  rj('Error in executing\n'
                     +'$ '+cmd.join(' ')+'\n\n'
                     + erMsg);
              }
          });
          child.on('error', (err)=>{
              rj(err);
          });
      });
  }
docs: Execute command with sudo
  @param {Array.<string>} cmd : Array of command
  @param {object} [option] : option parameter
  @return {Promise} Return stdout strings