Comment 1 for bug 1449251

You need to use absolute paths for any (all) files referenced on the command line (with '/Applications/Inkscape.app/Contents/Resources/script' you had to do this with Inkscape 0.48 too btw) - a known limitation with the current structure of X11-based, self-contained and fully relocatable application bundles for OS X (which are not optimized for such command line usage btw - it is recommended to install a regular command line build of inkscape via MacPorts, Fink or Homebrew if using it on the command line is the major use case).

Proposing to link as duplicate to
* Bug #181639 “Command-line invocation on Mac OSX partially broken”
  https://bugs.launchpad.net/inkscape/+bug/181639