It calls rm -rf / which, on a Unix system, tries to delete everything on the machine. The return value of this is used as the index in the @INC array. That part is meaningless. The point is, if Perl tried interpolating variables in the content of files as you read them, it would be terribly insecure, like opening every attachment you get through some Windows email program.
Jeff japhy Pinyan,
P.L., P.M., P.O.D, X.S.:
Perl,
regex,
and perlhacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart