IF you need two directories to match, in terms of actual file content as well as filenames,
then copy all the diifferent files from dir2 to dir1. Remove dir2 completely. Create dir2 as a link to dir1. Then you do not have to worry about synchronization. This assumes the directories are mounted on the same unix box. Otherwise, NFS mount dir1 on the remote box as dir2. In this case dir2 should not be at root level, ie. literally not : /dir2