title: How to grep word, exclude this word from the string
body: <p>I need to find all strings, that contain "foo", but exclude this "foo"</p>
  
  <pre><code>grep "foo" | grep -ve "foo" return zero strings
  </code></pre>
  
  <p>Example input:</p>
  
  <pre><code>"category": "aaaa",
  "amount": 0.01208210,
  "vout": 0,
  "fee": 0.00007523,
  "confirmations": 12345,
  "blockhash": "12345",
  "blockindex": 12345,
  "blocktime": 12345,
  </code></pre>
  
  <p>On output I need just:</p>
  
  <p>0.01208210</p>