title: How to grep for two characters at specific file position
body: <p>I need to grep a file for 2 consecutive characters at a specific position in a file. I can grep for a single character using (in this example I'm grepping for the number 1):</p>
  
  <pre><code>grep -E '^.{50}[1]' file.txt
  </code></pre>
  
  <p>This searches the first character, but I have no idea how to check the 2nd character.
  The 2 characters are a timestamp and I need to search for hours 18 through 23, and 00 through 06.
  Any help, as always, appreciated :)</p>