title: Search multiple strings in one line using regex in nested files/directories and output matched results
body: <p>For example, if there are files and directories:</p>
  <pre><code>/tmp/temp_dir/subdir_001/file_001.txt
  /tmp/temp_dir/subdir_001/file_002.txt
  /tmp/temp_dir/subdir_002/file_003.txt
  /tmp/temp_dir/subdir_003/file_004.txt
  </code></pre>
  <p>And those have various contents with specific lines that can be found by regex. For example, here is the content of the file <code>file_001.txt</code>:</p>
  <pre><code>abc cba
  little boy writes -54321_12345 and goes to street 987
  bca acb
  little boy writes -12345_54321 and jumps to street 789
  cab bac
  </code></pre>
  <p>What I'm interested is those lines that are started with <code>little boy writes</code>.
  I'm using this regex pattern to find important data that I would like to save as output:
  <code>little boy writes (\-\d+\_\d+).*street (\d+)</code></p>
  <p>How can I search it recursively and output only matched strings? So in output file I would only have this:</p>
  <pre><code>54321_12345 987
  12345_54321 789
  </code></pre>