This has also bugged my since forever and was almost promised years ago: 14795-request-relative-path-for-exporting
I can't see why the editor turns everything into an absolute path, when it could just let the user have it and let the filesystem sort it out.
I can edit an export.json and have a relative path in there, but you can't edit or touch that path in the editor.
Same for the input property in the export.json, its absolute. So if I want to export from command line, without overriding the input/output, ie automatic, then it has to be in the right location and not moved elsewhere.