Easiest would be to have the perl program exit with a value; not very useful though.  You could equally print what you wanted passed and capture the data within your shell script.  Finally, you could init some system vars in your shell script and have the perl script pass data by setting them by using the %ENV hash.  The vars must be initialized in the shell script or, when the perl script exits, they will go out of scope (at least this is the behavior I have seen on my system).