Duplicate the object with id="path123", rotate the duplicate 90 degrees, save the file, and quit Inkscape
inkscape {{filename.svg}} --select=path123 --verb="{{EditDuplicate;ObjectRotate90;FileSave;FileQuit}}"
inkscape {{filename.svg}} --select=path123 --verb="{{EditDuplicate;ObjectRotate90;FileSave;FileQuit}}"