title: Grep - print lines until line is empty
body: <p>In grep, is there option to show output until line meets some regex? In example</p>
  
  <p>foo.log:</p>
  
  <pre><code>request1: POST /foo
  params
  some payload
  
  request1: tag
  some payload
  
  request2: POST /foo
  params
  some payload
  </code></pre>
  
  <p>I would like to <code>grep</code> <code>foo.log</code> to get all information about request1, like this:</p>
  
  <pre><code>request1: POST /foo
  params
  some payload
  
  request1: tag
  some payload
  </code></pre>
  
  <p>Is this possible (something like -A options) or I just need to use regexps??</p>