title: How to execute certain commands if a file does NOT exist?
body: <p>I would like to check if a file exists, then if it does not, create it.</p>
  
  <p>Consider an equivalent of the following C code but with shell scripting.</p>
  
  <pre><code>if(!exist) {
      command;
      command;
  }
  else {
      command;
      command;
  }
  </code></pre>