NSWorkspace.sharedWorkspace.recycleURLs:completionHandler: fails for me when run via normal macruby, yet works in macirb. Sample code: #!/usr/bin/env macruby framework 'Cocoa' path = "#{ENV['HOME']}/Desktop/Y-U-NO-TRASH-ME-MACRUBY.txt" system "touch #{path}" url = NSURL.fileURLWithPath(path) urls = [url] NSWorkspace.sharedWorkspace.recycleURLs(urls, completionHandler:nil) puts "Should be false: #{File.exists?(path)}" (or: https://gist.github.com/960048c72a9b55db40b3) Output from running it: $ macirb foo.rb # … irb output elided Should be false: false $ macruby foo.rb Should be false: true Running on public release of Lion, clean install, with latest macruby nightly, bridgesupport preview 3. The equivalent code works fine in Nu.