Export file should use absolute paths

[SergioGasquez]

Motivations

At the moment, export_file is using a relative path, even in the config file we store a relative path. We need to store absolute path, so we know the location of the file in the future.

Also, it would be better to print the absolute path in the logs when we ask the user to source the export file, so they can copy-paste the command in the future and use it no matter what cwd they are in.