code: function fetchLogs(root, msg, callback) {
      const number = msg.number;
      const logfile = msg.logfile;
      const serverId = msg.serverId;
      const filePath = path.join(root, getLogFileName(logfile, serverId));
  
      const endLogs = [];
      exec(`tail -n ${number} ${filePath}`, (error, output) => {
          const endOut = [];
          output = output.replace(/^\s+|\s+$/g, '').split(/\s+/);
  
          for (let i = 5; i < output.length; i += 6) {
              endOut.push(output[i]);
          }
  
          const endLength = endOut.length;
          for (let j = 0; j < endLength; j++) {
              const map = {};
              let json;
              try {
                  json = JSON.parse(endOut[j]);
              } catch (e) {
                  logger.error(`the log cannot parsed to json, ${e}`);
                  continue;   // eslint-disable-line
              }
              map.time = json.time;
              map.route = json.route || json.service;
              map.serverId = serverId;
              map.timeUsed = json.timeUsed;
              map.params = endOut[j];
              endLogs.push(map);
          }
  
          callback({ logfile: logfile, dataArray: endLogs });
      });
  }
docs: get the latest logs