traced

sass --watch style.scss:/css/style.css --trace
>>> Sass is watching for changes. Press Ctrl-C to stop.
  directory /css
/Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:245:in `mkdir': Permission denied - /css (Errno::EACCES)
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:245:in `fu_mkdir'
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:219:in `block (2 levels) in mkdir_p'
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:217:in `reverse_each'
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:217:in `block in mkdir_p'
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:203:in `each'
    from /Users/jschreiber/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:203:in `mkdir_p'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin/compiler.rb:356:in `update_stylesheet'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin/compiler.rb:203:in `block in update_stylesheets'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin/compiler.rb:201:in `each'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin/compiler.rb:201:in `update_stylesheets'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin/compiler.rb:235:in `watch'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/plugin.rb:107:in `method_missing'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/exec.rb:455:in `watch_or_update'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/exec.rb:318:in `process_result'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/exec.rb:41:in `parse'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/lib/sass/exec.rb:21:in `parse!'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/gems/sass-3.2.10/bin/sass:9:in `<top (required)>'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/bin/sass:23:in `load'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/bin/sass:23:in `<main>'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/jschreiber/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `<main>'