Sams Teach Yourself Perl in 24 Hours

Hour 5. Working with Files

Until now, your Perl programs have been self-contained. They have been unable to communicate with the outside world other than to provide messages to the user and receive input from the keyboard. All of that is about to change.

Perl is an exceptional language for doing file input and output (file I/O). Perl's scalars can stretch to hold the longest possible record in a file, and Perl's arrays can stretch to hold the entire contents of files—memory allowed, of course. When the data is contained within Perl's scalars and arrays, you can perform endless manipulations on that data and write new files.

Perl tries very hard not to get in your way while reading or writing files. In some places, Perl's built-in statements ...