Okay I did as suggested:

#!/usr/bin/env ruby
$Verbose=true
   response = `./ati-driver-installer-8.40.4-x86.x86_64.run --buildpkg Ubuntu/feisty`
   puts response

outputs:
   ./test.rb:6: command not found: ./ati-driver-installer-8.40.4-x86.x86_64.run --buildpkg Ubuntu/feisty
but the same with
   response = `sh ./ati-driver-installer-8.40.4-x86.x86_64.run --buildpkg Ubuntu/feisty`
is working correctly?

Is this a bug?
-- 
kazaam <kazaam / oleco.net>