First Lesson in Portability
Portability: It's one of the things that Perl is good at. Whether your Perl code is run on a VMS machine, Unix, a Macintosh, or under MS-DOS, there's a very high probability that the Perl code you write will work seamlessly under any architecture that Perl supports. When you need to interact with the underlying operating system, such as when you're doing file I/O, Perl tries to hide all the nitty-gritty details for you so that your code will just work.
By the Way
Some of the reasons that Perl is so portable are discussed at great length in Hour 16, “The Perl Community.”
Sometimes, though, there's a limit to what Perl can hide from you.
Throughout this hour, the examples have read “do this for Windows and MS-DOS, do ...