If you want any level of maintainability or reusability - go with a config file.

For example if your script will end up running in more than one environment, you'll probably want to scan a different set of directories in each environment. And you don't want to be maintaining multiple versions of the script for that.

Also, if you're working on a team with multiple developers, and use a version control product, separating into 2 parts will improve the granularity.