The `IO::Tee' constructor, given a list of output handles,
returns a tied handle that can be written to but not read from.
When written to (using print or printf), it multiplexes the
output to the list of handles originally passed to the
constructor. As a shortcut, you can also directly pass a string
or an array reference to the constructor, in which case
`IO::File::new' is called for you with the specified argument or
arguments.

WWW: http://search.cpan.org/dist/IO-Tee/