Perl module to duplicate streams like the tee unix command

 File::Tee is able to replicate data written to a Perl stream into another
 streams. It is the Perl equivalent of the shell utility tee(1).
 .
 It is implemented around fork, creating a new process for every tee'ed stream.
 That way, there are no problems handling the output generated by external
 programs run with system|perlfunc/system or by XS modules that don't go
 through perlio.