title: How to modify @timestamp with an entry in logs using logstash
body: <p>I have some logs which has only time as its entries</p>
  
  <pre><code>   1. 17:20:45.331|ERR|....
     2. 17:20:54.715|SYS|.....Logging started for [....] (Date=[07/28/2014], ...
     3. 17:20:54.716|SYS....
  </code></pre>
  
  <p>and so on</p>
  
  <p>I have the date in only one line of the logs. based on that i want to create a timestamp such as that logging date in logs + the time in each entry</p>
  
  <p>Iam able to get the time in each entry. i can get the log_message => " Logging started for [....] (Date=[07/28/2014], ..." as one entry. </p>
  
  <ol>
  <li>Is it possible to get the date from this entry and modify all other entry's timestamp?</li>
  <li>how can I add time and the date and modify the timestamp?</li>
  </ol>
  
  <p>Any help will be appreciated as iam new to logstash</p>
  
  <p>My filter in logstash conf</p>
  
  <pre><code>filter {
    grok { match =&gt; [ "message", "%{TIME:time}\|%{WORD:Message_type}\|%{GREEDYDATA:Component}\|%{NUMBER:line_number}\| %{GREEDYDATA:log_message}"] 
  }
  
  
   date {
      match =&gt; ["timestamp" , "dd/MMM/yyyy:HH:mm:ss Z" ]  =&gt; need to modify this as date+%{time}
    }
  
  }
  </code></pre>
  
  <p>time field has milliseconds also. </p>