in reply to calling perl subroutine from shell
what you asked for is:
This starts a new perl process, loads the module a.pm, given it#s location is in @INC, and calls the subroutine clear_scr.perl -Ma -e 'a::clear_scr();'
I have a gut feeling that this is not want you really want, though - if I'm right, you'll have to clarify your intentions.
An intellectual is someone whose mind watches itself.
-- Albert Camus