You should look at your code and simply extend the existing functionality using which ever method is being used already (likely Getopt::Std), unless you expect your argument parsing requirements to become substantially more complex, in which case the modules suggested by mfriedman and larsen will be of interest.

On a related note, I notice that you have posted a number of SoPW's simply asking fellow Monks to craft code to solve (what appear to be related) problems.
You should make the effort to understand the code you are faced with, then try to resolve the problem yourself - post your attempts, even if they are faulty!
You should find that as you spend more time attempting to fix your own problems you should become familiar with basic functions and modules and it will much easier for you to program once you have that understanding.

Cheers.

BazB