Installing ruby_libgtop requires permission to create a directory
inside Ruby's `site_local' directory (by default,
/usr/local/lib/ruby/site_local/X.Y).  This means you may need root
permissions, depending upon your operating system.

Alternately, you can copy the ruby_libgtop.so file anywhere, as long
as your Ruby installation can find it. 

* Extract the distribution. This creates a directory named
  ruby_libgtop-<version> (where <version> is the ruby_libgtop version
  number).

    tar -xzf ruby_libgtop-<version>.tar.gz
    cd ruby_libgtop-<version>

* Install it to Ruby's `site_local' directory.

    ruby install.rb
