title: How can I use the UNIX shell to count the number of times a letter appears in a text file?
body: <p>I have a few text files and I'd like to count how many times a letter appears in each?</p>
  
  <p>Specifically, I'd like to use the UNIX shell to do this, in the form of: cat file | .... do stuff...</p>
  
  <p>Is there a way I can get the wc command to do this?</p>