title: Alternative to using the linux cp command without the -n flag available?
body: <p>I'm making a script in bash that requires files to be copied. I tried using the <code>cp</code> command with the <code>-n</code> flag set but I found out that on some systems the <code>-n</code> flag is not available.</p>
  
  <pre><code>cp: invalid option -- n
  </code></pre>
  
  <p>I want this script to be portable enough so that users won't be required to update their <code>cp</code>.</p>
  
  <p>What the <code>-n</code> flag does is copy only files from the source that are not already in the destination without prompting.</p>
  
  <p>Is there an alternative to this?</p>