Perl comes with a lot of documentation—more than you’d ever want to put on paper. You’d use a couple of reams of paper and a lot of toner to print it all. We lost count after the documentation got to be around 2,000 pages (on our virtual printer, so no trees harmed).

There is a huge amount of useful information in the documentation files, so it pays to be able to read them, but even more than that, to find information in them. Part of the ability to find what you need is knowledge, and part of it is tools.

The perldoc command searches the Perl tree for Perl modules (.pm) with embedded documentation, documentation-only .pod files (Item 82), and installed Perl programs. The perldoc command formats and displays the documentation it finds. To start, readperldoc’s own documentation:

Starting with Perl 5.10, you must explicitly enable new features. This ensures that the latest release of Perl can be backward compatible while at the same time letting people start new work using all of the latest nifty features.

For instance, Perl 5.10 adds a say built-in that is just like print except that it adds the trailing newline for you. Not only is your string a couple of characters shorter, but you don’t have to double-quote the string just for the newline:

If someone had already created their own say, their program might break if they run it with Perl 5.10 using the now built-in with the same name. Fortunately, Perl doesn’t enable new features by default:

If you want the new features, you can enable them with the new -E switch. It’s just like the -e that lets you specify your program text on the command line, but it also brings in the all of the latest features for your version of Perl: