Io::pager is lightweight and can be used to locate an available pager and set the pager environment variable sanely or as a factory for creating objects defined elsewhere such as io::pager::buffered and io::pager::unbuffered.

io::pager subclasses are designed to programmatically decide whether or not to pipe a filehandle's output to a program specified in pager. subclasses may inherit from io::pager, and implement the io handle methods desired.