So...I made a mistake. I generally prefer to use array and reference hashes, so shift @{$dir_listing} was out of habit. However, the code I gave actually declared an array so, shift @dir_listing;is the correct way to do it.

Regarding your comments, the while loop looks at the first element in the array and checks to see if it is just a series of dots using a regex, i.e., either '.' or '..'. If so, it removes the first element and checks again.

For map, you can think of it as a very specialized foreach loop (map { <expr> } <array>) that returns values depending on the code used in the brackets. However, it is a little slower than a foreach loop so you generally only want to use it when you're using its output. It's a great way to modify or filter out values from an array.