title: How can you open a file that the user specifies on the command line?
body: <p>Suppose you want to allow the user to specify a file to open on the command line. How can this be achieved if the user will enter data such as:</p>
  
  <p>/User/desktop/input.txt</p>
  
  <p>How can I then convert this directory into something that the program actually opens/reads?</p>