In a Rubygems enabled environment, it's recommended to
  export RUBYOPT=rubygems
to automatically require rubygems.

A typical rubygem port looks like this:

  name=activerecord
  version=1.11.1
  release=1
  source=(http://rubyforge.org/frs/download.php/5163/activerecord-1.11.1.gem)

  GEMS_KEEP_DOC=yes
  . /usr/share/rubygems/Pkgfile.template


The build() function comes from the template. Omit the GEMS_KEEP_DOC var if you
don't want any rdoc documentation