title: Using grep to get 12 letter alphabet only lines
body: <p>Using grep</p>
  
  <p>How many 12 letter - alphabet only lines are in testing.txt?</p>
  
  <p>excerpt of testing.txt</p>
  
  <pre><code>tyler1
  Tanktop_Paedo
  xyz2@geocities.com
  milt@uole.com
  justincrump
  cranges10
  namer@uole.com
  soulfunkbrotha
  timetolearnz
  hotbooby@geocities.com
  Fire_Crazy
  helloworldad
  dingbat@geocities.com
  </code></pre>
  
  <p>from this excerpt, I want to get a result of 2. (helloworldad, and timetolearnz)</p>
  
  <p>I want to check every line and grep only those that have 12 characters in each line. I can't think of a way to do this with grep though.</p>
  
  <p>For the alphabet only, I think I can use</p>
  
  <pre><code>grep [A-Za-z] testing.txt
  </code></pre>
  
  <p>However, how do I make it so only the characters [A-Za-z] show up in those 12 characters?</p>