Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

Unix

In the strictest sense, it can't be done -- the script executes as a different process from the shell it was started from. Changes to a process are not reflected in its parent, only in its own children created after the change. There is shell magic that may allow you to fake it by eval()ing the script's output in your shell; check out the comp.unix.questions FAQ for details.