IO - load various IO modules

    use IO qw(Handle File);  # loads IO modules, here IO::Handle, IO::File
    use IO;                  # DEPRECATED

IO provides a simple mechanism to load several of the IO modules in one go. The IO modules belonging to the core are:

      IO::Handle
      IO::Seekable
      IO::File
      IO::Pipe
      IO::Socket
      IO::Dir
      IO::Select
      IO::Poll

Some other IO modules don't belong to the perl core but can be loaded as well if they have been installed from CPAN. You can discover which ones exist by searching for "^IO::" on http://search.cpan.org.

For more information on any of these modules, please see its respective documentation.

    use IO;                # loads all the modules listed below

The loaded modules are IO::Handle, IO::Seekable, IO::File, IO::Pipe, IO::Socket, IO::Dir. You should instead explicitly import the IO modules you want.