title: Find patterns across multiple log files?
body: <p>I have eight log files in the following format: </p>
  
  <p>log01:</p>
  
  <pre><code>[Tue Feb 24 07:39:37 2015] *** MARK ***
  [Tue Feb 24 07:40:38 2015] *** MARK ***
  [Wed Feb 25 17:13:33 2015] *** MARK ***
  [Wed Feb 25 17:14:09 2015] *** MARK ***
  [Wed Feb 25 17:16:46 2015] *** MARK ***
  [Wed Feb 25 17:17:48 2015] *** MARK ***
  [Wed Feb 25 17:22:31 2015] *** MARK ***
  [Wed Feb 25 19:10:36 2015] *** MARK ***
  [Wed Feb 25 19:10:52 2015] *** MARK ***
  [Wed Feb 25 19:11:08 2015] *** MARK ***
  [Wed Feb 25 19:11:34 2015] *** MARK ***
  [Wed Feb 25 19:12:00 2015] *** MARK ***
  [Wed Feb 25 19:12:26 2015] *** MARK ***
  [Wed Feb 25 19:13:17 2015] *** MARK ***
  [Wed Feb 25 19:13:33 2015] *** MARK ***
  [Wed Feb 25 19:15:05 2015] *** MARK ***
  [Wed Feb 25 19:37:53 2015] *** MARK ***
  [Wed Feb 25 19:38:19 2015] *** MARK ***
  [Wed Feb 25 19:38:35 2015] *** MARK ***
  [Wed Feb 25 23:08:47 2015] *** MARK ***
  [Wed Feb 25 23:09:28 2015] *** MARK ***
  [Wed Feb 25 23:11:55 2015] *** MARK ***
  [Wed Feb 25 23:12:21 2015] *** MARK ***
  [Wed Feb 25 23:12:52 2015] *** MARK ***
  [Wed Feb 25 23:13:08 2015] *** MARK ***
  ...
  </code></pre>
  
  <p>log02:</p>
  
  <pre><code>[Wed Feb 25 07:01:39 2015] *** MARK ***
  [Wed Feb 25 17:13:49 2015] *** MARK ***
  [Wed Feb 25 17:15:20 2015] *** MARK ***
  [Wed Feb 25 17:16:47 2015] *** MARK ***
  [Wed Feb 25 17:17:38 2015] *** MARK ***
  [Wed Feb 25 17:19:56 2015] *** MARK ***
  [Wed Feb 25 17:22:53 2015] *** MARK ***
  [Wed Feb 25 19:10:47 2015] *** MARK ***
  [Wed Feb 25 19:11:13 2015] *** MARK ***
  [Wed Feb 25 19:11:34 2015] *** MARK ***
  [Wed Feb 25 19:11:50 2015] *** MARK ***
  [Wed Feb 25 19:12:11 2015] *** MARK ***
  [Wed Feb 25 19:12:37 2015] *** MARK ***
  [Wed Feb 25 19:12:53 2015] *** MARK ***
  [Wed Feb 25 19:13:14 2015] *** MARK ***
  [Wed Feb 25 19:13:40 2015] *** MARK ***
  [Wed Feb 25 19:14:06 2015] *** MARK ***
  [Wed Feb 25 19:14:22 2015] *** MARK ***
  [Wed Feb 25 19:14:38 2015] *** MARK ***
  [Wed Feb 25 19:38:30 2015] *** MARK ***
  [Wed Feb 25 21:17:08 2015] *** MARK ***
  [Wed Feb 25 23:08:56 2015] *** MARK ***
  [Wed Feb 25 23:10:37 2015] *** MARK ***
  [Wed Feb 25 23:11:08 2015] *** MARK ***
  [Wed Feb 25 23:11:24 2015] *** MARK ***
  [Wed Feb 25 23:12:20 2015] *** MARK ***
  [Wed Feb 25 23:12:46 2015] *** MARK ***
  ...
  </code></pre>
  
  <p>Every log file is generated by an instance of the same program reading different sensors. A log entry is created if a sensor detects an issue. If every sensor detects an issue within about a minute, it indicates a global problem has occured. For example:</p>
  
  <p>The log entries <code>[Tue Feb 24 07:39:37 2015] *** MARK ***</code> and <code>[Tue Feb 24 07:40:38 2015] *** MARK ***</code> from log01 do not corresponds to anything in log02 so this is not a global problem and can be ignored. The log entries <code>[Wed Feb 25 07:01:39 2015] *** MARK ***</code> and <code>[Wed Feb 25 21:17:08 2015] *** MARK ***</code> in log02 can also be ignored.</p>
  
  <p>However, entry <code>[Wed Feb 25 19:10:36 2015] *** MARK ***</code> in log01 and <code>[Wed Feb 25 19:10:47 2015] *** MARK ***</code> in log02 is within a minute so this indicates a global problem that lasts until entry <code>[Wed Feb 25 19:15:05 2015] *** MARK ***</code> in log01 and <code>[Wed Feb 25 19:14:38 2015] *** MARK ***</code> in log02. So I can conclude that from around 19:10 to 19:15 on Feb 25 something was wrong.</p>
  
  <p>I'm looking for suggestions and tips on how to approach this problem, preferably by using UNIX utilities.</p>