title: how to grep the error line and error caused by line
body: <p>I need to grep the error.log file to get the <code>*ERROR*</code> and <code>Caused by:</code> for the same error tag in next-next lines</p>
  
  <p>For example: i have the error.log like the following</p>
  
  <pre><code>08.02.2016 00:11:21.541 *ERROR* [158.151.84.34 [1454908281309] GET /content/user/home/people-search.html HTTP/1.1] com.day.cq.wcm.tags.IncludeTag Error while executing script content.jsp
  org.apache.sling.api.scripting.ScriptEvaluationException:
          at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:388)
          at org.apache.sling.scripting.jsp.taglib.IncludeTagHandler.dispatch(IncludeTagHandler.java:59)
          at org.apache.sling.scripting.jsp.taglib.AbstractDispatcherTagHandler.doEndTag(AbstractDispatcherTagHandler.java:129)
          at org.apache.jsp.libs.foundation.components.parsys.parsys_jsp._jspService(parsys_jsp.java:318)
          at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
          ... 180 common frames omitted
  Caused by: org.apache.sling.api.SlingException: javax.servlet.ServletException: java.lang.Exception: user person search is not available
  08.02.2016 05:28:56.748 *ERROR* [158.151.84.34 [1454927336516] GET /content/user/home/people-search.html HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught SlingException
  org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
          at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
          at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
          ... 20 common frames omitted
  Caused by: java.lang.Exception: user person search is not available
  08.02.2016 06:11:24.725 *ERROR* [158.151.84.34 [1454908281309] GET /content/user/home/people-search.html HTTP/1.1] com.day.cq.wcm.tags.IncludeTag Error while executing script content.jsp
  org.apache.sling.api.scripting.ScriptEvaluationException:
          at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:388)
          ... 10 common frames omitted
  Caused by: org.apache.sling.api.SlingException: javax.servlet.ServletException: java.lang.Exception: user person search is not available
  </code></pre>
  
  <p>I need to get the output as</p>
  
  <pre><code>08.02.2016 00:11:21.541 *ERROR* [158.151.84.34 [1454908281309] GET /content/user/home/people-search.html HTTP/1.1] com.day.cq.wcm.tags.IncludeTag Error while executing script content.jsp
  Caused by: org.apache.sling.api.SlingException: javax.servlet.ServletException: java.lang.Exception: user person search is not available
  08.02.2016 05:28:56.748 *ERROR* [158.151.84.34 [1454927336516] GET /content/user/home/people-search.html HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught SlingException
  Caused by: java.lang.Exception: user person search is not available
  08.02.2016 06:11:24.725 *ERROR* [158.151.84.34 [1454908281309] GET /content/user/home/people-search.html HTTP/1.1] com.day.cq.wcm.tags.IncludeTag Error while executing script content.jsp
  Caused by: org.apache.sling.api.SlingException: javax.servlet.ServletException: java.lang.Exception: user person search is not available
  </code></pre>
  
  <p>How will i get this? </p>