title: How to run a python file with a predetermined input
body: <p>really simple question,</p>
  <p>Okay so I have a python file, how can i run it so i can call it in the terminal like so:</p>
  <pre><code>python3 my_program -1
  </code></pre>
  <p>Where because ive used the number 1 afterwards in runs something different to if i ran the same thing with -2.</p>
  <p>This is the type of funcionality I am looking for, to be able to run code depending on what the user chooses, I dont really want an interactive python file.</p>
  <p>I apologise in advanced if this is a bad question, I am unsure as to what to google to get what I am looking for.</p>