To make this work in Catalina, replace /..Volumes/my_mount with /System/Volumes/Data/Volumes/my_mount . The / mount in Catalina is read-only now. All update have to be done to an overplayed FS mount. Additionally, you will need to create the my_mount folder before resetting the auto mounter. And I have noticed that periodically I have to recreated the folder after a restart (though not always).
To make this work in Catalina, replace
/..Volumes/my_mountwith/System/Volumes/Data/Volumes/my_mount. The / mount in Catalina is read-only now. All update have to be done to an overplayed FS mount. Additionally, you will need to create themy_mountfolder before resetting the auto mounter. And I have noticed that periodically I have to recreated the folder after a restart (though not always).