Ruby 1.8.6 after installation has associated the file extension .rb within Windows to Ruby. Hence I can call a Ruby program directly from the Windows command line: ruby t2.rb t2.rb t2 all work the same. This does not work, however, if the program is executed from within Ruby itself. Example: Assuming I have a file t2.rb containing only the line puts "hello" and another file containing x.rb containing only the line %x(t2.rb) When I execute on the Windows command line x.rb I get the error message: H:/tmp/x.rb:1:in ``': Exec format error - t2.rb (Errno::ENOEXEC) from H:/tmp/x.rb:1 Is this a bug or intended behaviour? Changing x.rb to %x(ruby t2.rb) works well. -- Ronald Fischer <ronald.fischer / venyon.com> Phone: +49-89-452133-162