I have jenkins working in local server on my mac and for a job, I need to run a script shell witch it need to read a json file. I tryied to put it in workflow-lib file. But when
I would highly suggest you run the Jenkins process as the jenkins user/group and not muck around in there as your own user account.
This will ensure your file permissions are proper and that the jenkins process only has access to the areas it needs as well as letting you spin up new slaves without worrying about permissions and custom settings.
You can always use sudo to become the 'jenkins' user to work with the files.